Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS  

This paper aims to establish confidence intervals of the quantification of brightness enhancement effects resulting from the use of pulsing bright light. It is found that the methods used so far may yield significant bias in the published results, overestimating or underestimating the enhancement effect. The authors propose to use a linear algebra method called the total least squares. Upon an example dataset, it is shown that this method does not yield biased results. The statistical significance of the results is also computed. It is concluded over an observation set that the currently used linear algebra methods present many patterns of noise sensitivity. Changing algorithm details leads to inconsistent results. It is thus recommended to use the method with the lowest noise sensitivity. Moreover, it is shown that this method also permits one to obtain an estimate of the confidence interval. This paper neither aims to publish results about a particular experiment nor to draw any particular conclusion about existence or nonexistence of the brightness enhancement effect. (c) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)

DOI： 10.1117/1.OE.56.11.114103

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute of Physics Publishing  

We have developed a new micro-discharge plasma (MDP)-based gene transfection method, which transfers genes into cells with high efficiency and low cytotoxicity
however, the mechanism underlying the method is still unknown. Studies revealed that the N-acetylcysteinemediated inhibition of reactive oxygen species (ROS) activity completely abolished gene transfer. In this study, we used laser-produced plasma to demonstrate that gene transfer does not occur in the absence of electrical factors. Our results show that both electrical and chemical factors are necessary for gene transfer inside cells by microplasma irradiation. This indicates that plasma-mediated gene transfection utilizes the synergy between electrical and chemical factors. The electric field threshold required for transfection was approximately 1 kV m-1 in our MDP system. This indicates that MDP irradiation supplies sufficient concentrations of ROS, and the stimulation intensity of the electric field determines the transfection efficiency in our system. Gene transfer by plasma irradiation depends mainly on endocytosis, which accounts for at least 80% of the transfer, and clathrin-mediated endocytosis is a dominant endocytosis. In plasmamediated gene transfection, alterations in electrical and chemical factors can independently regulate plasmid DNA adhesion and triggering of endocytosis, respectively. This implies that plasma characteristics can be adjusted according to target cell requirements, and the transfection process can be optimized with minimum damage to cells and maximum efficiency. This may explain how MDP simultaneously achieves high transfection efficiency with minimal cell damage.

DOI： 10.1088/1361-6595/aa70de

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© 2017 by Begell House, Inc. The aim was to characterize by optical emission spectroscopy measurements our µ-air plasma discharge successfully used for gene transfection. We estimated rotational Trot and electron Tetemperatures, and densities of charged particles.

DOI： 10.1615/plasmamed.2018019247

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This study has been done to know what kind of factors in plasmas and processes on cells induce plasma gene transfection. We evaluated the contribution weight of three groups of the effects and processes, i.e. electrical, chemical and biochemical ones, inducing gene transfection. First, the laser produced plasma (LPP) was employed to estimate the contribution of the chemical factors. Second, liposomes were fabricated and employed to evaluate the effects of plasma irradiation on membrane under the condition without biochemical reaction. Third, the clathrin-dependent endocytosis, one of the biochemical processes was suppressed. It becomes clear that chemical factors (radicals and reactive oxygen/nitrogen species) do not work by itself alone and electrical factors (electrical current, charge and field) are essential to plasma gene transfection. It turned out the clathrin-dependent endocytosis is the process of the transfection against the 60% in all the transfected cells. The endocytosis and electrical poration are dominant in plasma gene transfection, and neither permeation through ion channels nor chemical poration is dominant processes. The simultaneous achievement of high transfection efficiency and high cell survivability is attributed to the optimization of the contribution weight among three groups of processes by controlling the weight of electrical and chemical factors.

DOI： 10.1016/j.abb.2016.04.013

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Plasma gene transfection is expected as a safe and useful method of gene transfection. However, in this method, there is difficulty in keeping both high transfection efficiency and less cell damage simultaneously. The authors have evaluated transfection efficiency and cell viability using four different plasma sources, such as arc discharge, plasma jet, dielectric barrier discharge (DBD), and microplasma. A high transfection efficiency was achieved by discharge forms in which the electric current flows via the cells. This suggested that an electric current plays an important role in plasma gene transfection. The total volume of gas flow must be small or zero and the area in which the cells are directly irradiated by plasma must be small in order to achieve a higher cell viability. The microplasma that satisfies these conditions achieved both the highest transfection efficiency and the highest cell viability simultaneously. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.07LG09

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

In order to clarify the mechanism of plasma gene transfection, the relationship between transfection efficiency and transferred molecular size was investigated. Molecules with low molecular mass (less than 50 kDa; dye or dye-labeled oligonucleotide) and high molecular mass (more than 1 MDa; plasmid DNA or fragment of plasmid DNA) were transferred to L-929 cells. It was found that the transfection efficiency decreases with increasing in transferred molecular size and also depends on the tertiary structure of transferred molecules. Moreover, it was suggested the transfection mechanism is different between the molecules with low (less than 50 kDa) and high molecular mass (higher than 1 MDa). For the amount of gene transfection after plasma irradiation, which is comparable to that during plasma irradiation, it is shown that H2O2 molecules are the main contributor. The transfection efficiency decreased to 0.40 +/- 0.22 upon scavenging the H2O2 generated by plasma irradiation using the catalase. On the other hand, when the H2O2 solution is dropped into the cell suspension without plasma irradiation, the transfection efficiency is almost 0%. In these results, it is also suggested that there is a synergetic effect of H2O2 with electrical factors or other reactive species generated by plasma irradiation. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.07LG06

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

A micro-air corona discharge, which is one of the plasmas successfully used for gene transfection in terms of high transfection and cell viability rates, is characterized by optical emission spectroscopy. This non-equilibrium low temperature plasma is generated from the tip of a pulsed high voltage micro-tube (0.2 mm inner diameter and 0.7 mm for outer diameter) placed 2 mm in front of a petri dish containing deionized water and set on a grounded copper plate. The electron temperature, equal to about 6.75 eV near the electrode tip and decreased down to 3.4 eV near the plate, has been estimated, with an error bar of about 30%, from an interesting approach based on the experimental ratio of the closest nitrogen emission spectra of N-2(+) (FNS) at 391.4 nm and N-2(SPS) at 394.3 nm. This is based on one hand on a balance equation between creations and losses of the excited upper levels of these two UV spectra and on the other hand on the electron impact rates of the creation of these upper levels calculated from solution of the multi-term Boltzmann equation. Then using the measured H alpha spectrum, electron density n(e) has been estimated from Stark broadening versus the inter-electrode position with an average error bar of about 50%. n(e) approximate to 1 x 10(15) cm(-3) is near the tip coherent with the usual magnitude of electron density in the streamer head developed near the tip of the corona discharges. Rotational temperatures, estimated from comparison of synthetic and experimental spectra of OH(A - X), N-2(+) (FNS) at 391.4 nm, and N-2(SPS) at 337 nm are respectively equal to 2350 K, 2000 K and 700 K in the gap space. This clearly underlines a thermal non-equilibrium of the corresponding excited species generated inside the thin streamer filaments. But, due to the high dilution of these species in the background gas, these high rotational temperatures do not affect the mean gas temperature that remains close to 300 K. Then, N-2(+) (FNS) for (0,0) and (1,1) head bands spectra at 391.4 nm and 388.4 nm allowed estimation of the vibrational temperature T-vib from around 3000 K near the tip electrode up to about 6500 K near the plate. Last, the spatial variation along the z axis of the nitrogen ion density has been determined, with an error bar of about 50%, from the relative intensities of the same close wavelength spectra (N-2(SPS) at 394.3 nm and N-2(+) (FNS) at 391.4 nm) when assuming a prior calibration of 10(15) cm(-3) at z = 0 mm taken from literature streamer dynamics simulations. The present experimental plasma characteristics are used to better understand the mechanisms and the processes involved during plasma gene transfections in a Monte Carlo poration model previously developed to simulate the membrane permeabilization and pore formation when the cells are impacted by the present micro-air plasma fluxes.

DOI： 10.1088/0741-3335/58/7/075006

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

The characteristics of microhollow dielectric barrier discharge devices in a thin monolithic planar structure with many holes were analyzed regarding the production of OH radicals, using optical emission and laser-induced fluorescence (LIF) spectroscopy techniques. Spatial distributions of OH radical density depended on the diameter of electrode holes from 0.6 to 1.5 mm and the discharge operating gas species. Apparent emission intensity from OH radicals and the LIF signals were very high in He and Ar gases but quite low in N-2. However, taking into account the LIF quenching rate in each gas, the existing densities of OH radicals in all tested gases were not greatly different from each other. The absolute density of OH radicals estimated by a comparison of the LIF intensity with our measured result on a conventional He plasma jet referring to reported densities in similar situations was on the order of 10(14)cm(-3). (C) 2016 The Japan Society of Applied Physics.

DOI： 10.7567/JJAP.55.07LB01

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

A Monte Carlo poration model is developed to simulate formation pores of few nanometer of width through cell multilayer membranes when impacted by air plasma species. Each species is assumed as a super-particle involving a large particle number. It is assumed a simple membrane model superposing four layers of phospholipids and proteins. Each layer is composed by super-sites subjected to plasma macro-processes (recombination, reflection, activation, opening). Electrons play a main role on super-site activations and openings but ions and radicals have also their own role on pore formation. Judicious choices probabilities data of macro-processes lead to sizes of pores compatible with gene transfection. Present model, validated by comparisons with measured rates of transfected and surviving cells, is a tool for understanding the mechanisms of gene transfection.

DOI： 10.1002/ppap.201500144

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DOI： 10.4236/opj.2016.61002

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：EDP SCIENCES S A  

From an intention of summarizing present understandings of positive corona discharges in water and atmospheric pressure gases, we tried to observe streamers in those media by reproducing and complementing previously reported results under a common experimental setup. We used a point-to-plane electrode configuration with different combinations of electrode gap (7 and 19 mm length) and pulsed power sources (0.25 and 2.5 mu s duration). The general features of streamers were similar and the streamer-to-spark transition was also observed in both the media. However, in the details large differences were observed due to inherent nature of the media. The measured propagation speed of streamers in water of 0.035 x 10(6) ms(-1) was much smaller than the speed in gases (air, N-2 and Ar) from 0.4 to 1.1 x 10(6) ms(-1) depending on species. In He the discharge looked glow-like and no streamer was observed. The other characteristics of streamers in gases, such as inception voltage, number of branches and thickness did also depend on the species. The thickness and the length of streamers in water were smaller than those in gases. From the volumetric expansion of a streamer in water after the discharge, the molecular density within the streamer medium was estimated to be rarefied from the density of water by about an order of magnitude in the active discharge phase. We derived also the electron density from the analysis of Stark broadened spectral lines of H and O atoms on the order of 10(25) m(-3) at the earlier time of the streamer propagation. The analyzed background blackbody radiation, rotational temperature of OH band emission and population density of Cu atomic lines yielded a consistent temperature of the streamer medium between 7000 and 10 000 K. Using the present data with a combination of the analysis of static electric field and previously reported results, we discuss the reason for the relatively low streamer inception voltage in water as compared to the large difference in the medium density between water and gases.

DOI： 10.1051/epjap/2015140518

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Illuminating Engineering Institute of Japan  

This research focused on the development of a mercury-free light source through the use of radio frequency (RF) and microwave discharges. RF at 13.56 MHz and microwave at 2.45 GHz were applied to generate the plasma. With the use of this kind of high frequency power generator, plasma can be ignited without using the electrodes inside the chamber or discharge tube, which could significantly increase the lamp lifetime. The potential for high luminance, excellent colour rendering and environmental-friendliness makes xenon the most promising candidate as the replacement for the mercury fluorescent lamp. In this research, RF energy at 13.56 MHz was induced to the cylindrical discharge tube in order to investigate the characteristics of the xenon RF-inductively coupled plasma discharge as a light source. The luminance, spectral distribution and colour rendering index were measured. The values of the luminance and colour rendering index were comparative to the values for a conventional discharge lamp. For microwave plasma, in order to develop a planar-type lamp, surface wave plasma was applied. A few types (transverse, inclined, longitudinal) of slot antennas were tested and the lamp brightness and discharge uniformity were evaluated. The chamber window (front or rear) was coated with a three-colour phosphor from the combination of red, green and blue phosphors and the excitation effect was investigated. From phosphor coating and slot structure optimisations, lamp luminance and discharge uniformity could be improved.

DOI： 10.2150/jlve.IEIJ130000533

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Illuminating Engineering Institute of Japan  

The authors propose a new method for tunnel illumination using LED lights. The luminous characteristics of tunnel lighting employing LED luminaires were measured in the Shiratori tunnel on the Japanese expressway. The results show that this method achieves over 0.9 of luminance uniformity. Moreover, the visual impression evaluation that was conducted using 29 subjects, shows that roads with over 0.9 luminance uniformity and luminance of 2.3 cd/m2, have equivalent or better visibility than roads with low uniformity and luminance of 3.5 cd/m2. This result suggests that the High Luminance Uniformity Method which we propose could save up to 20% of the energy used for illumination and improve safety due to higher visibility.

DOI： 10.2150/jlve.IEIJ120000487

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Purpose:
The aim of this study was to evaluate the impact of attached shadow cues for laparoscopic task performance.
Methods:
We developed a soft-light overhead illumination system (SOIS) that produced attached shadows on objects. We compared results using the SOIS with those using a conventional illumination system with regard to laparoscopic experience and laparoscope-to-target distances (LTDs). Forty-two medical students and 23 surgeons participated in the study. A peg transfer task (LTD, 120 mm) for students and surgeons, and a suture removal task (LTD, 30 mm) for students were performed. Illumination systems were randomly assigned to each task. Endpoints were: total number of peg transfers; percentage of peg-dropping errors; and total execution time for suture removal. After the task, participants filled out a questionnaire on their preference for a particular illumination system.
Results:
Total number of peg transfers was greater with the SOIS for both students and surgeons. Percentage of peg-dropping errors for surgeons was lower with the SOIS. Total execution time for suture removal was shorter with the SOIS. Forty-five participants (69% in total) evaluated the SOIS for easier task performance.
Conclusions:
The present results confirm that the SOIS improves laparoscopic task performance, regardless of previous laparoscopic experience or LTD.

DOI： 10.1097/SLE.0b013e31828f7245

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TECHNICAL ASSOC PHOTOPOLYMERS,JAPAN  

The authors investigated the parameter space of a micro capillary discharge used for gene transfection. Several factors and the time scale at which they become effective were studied. The conclusion is that half of transfections occur during plasma irradiation and the other half occur after plasma irradiation is stopped. As the electric field and current become zero after plasma irradiation is terminated, we conclude that during that period radical species are necessary for the transfection.

DOI： 10.2494/photopolymer.27.399

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

A phosphor, SrAl12O19 doped with Pr (SA : Pr), is investigated in this research in order to improve the luminous efficacy of a mercury-free Xe discharge fluorescent lamp (FL). The obtained sample works as a quantum cutting phosphor which converts an absorbed photon of Xe emission at 172 nm into two visible photons, one at 401.8 nm and the other at 486.3, 526.3, 623.7 or 644.6 nm. The concentration of Pr is optimized and the visible emission of the phosphor becomes maximum at 5 mol%. The photoluminescence measurements show that the relative quantum efficiency of SA : Pr (Pr: 5 mol%) is 38.4% of BaMgAl10O17 : Eu2+ (BAM : Eu). The luminance of a Xe dielectric-barrier-discharge (DBD) FL coated with SA : Pr (Pr: 5 mol%) achieves 28.8% of the same lamp with BAM: Eu. The CIE colour coordinate of the SA : Pr (Pr: 5 mol%) excited by the Xe-DBD lamp is x = 0.307 and y = 0.292. The SA : Pr phosphor has an excitation band peaking at 468 nm corresponding to the I-1(6) state and a low intensity excitation band lying from 250 to 420 nm. The latter is attributed to the self-trapped exciton (STE) band. This STE band causes an energy path due to non-radiative transition from S-1(0) to P-3(0) in the excitation at 172 nm. The former excitation band around 468 nm coincides with an ordinary blue LED's emission. When the phosphor is excited at this wavelength, the emission spectra are observed at 486.3, 526.3, 623.7 and 644.6 nm. Therefore, the SA : Pr may alternatively be useful for white LEDs excited by blue light.

DOI： 10.1088/0022-3727/46/6/065305

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Language：English   Publishing type：Research paper (international conference proceedings)  

Discharges in mixtures containing xenon and iodine are interesting because the exciplex XeI*emits in germicidal spectral region (λ max = 253 nm). In this paper the optimization of a dielectric barrier discharge (DBD) excited lamp operated with a Xe/I 2 mixture is reported. Approximately 76% of the excilamp output was due to the B-X transition of XeI*exciplex at 253 nm. Short voltage rising and falling time under pulse excitation is more important for the efficiency enhancement than the pulse duration. The average radiation power of 10.3 mW/cm 2 was measured under pulsed excitation at a frequency of 80 kHz. An efficiency improvement from about 3% for AC to 5-9% for square pulse excitation was obtained. A good cleaning effect of glass surface and sterilization action was achieved with the DBD-driven XeI*exciplex lamp. The contribution of an atomic iodine emission in the range of 178-207 nm has been confirmed. Germ reduction experiments with the XeI*excilamp have been carried out in a water flow reactor. © 2012 Springer Science+Business Media B.V.

DOI： 10.1007/978-94-007-2852-3_20

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

As the environmental awareness of people becomes stronger, the demand for mercury-free light sources also becomes stronger. The authors have been developing cold cathode fluorescent lamps in which xenon gas is filled as an ultraviolet radiator instead of mercury. Previously the authors reported the luminous flux enhancement method using a grounded auxiliary external electrode (AEE). In this paper, in order to improve the luminous flux much more, a positive voltage pulse which was synchronized to the main driving negative voltage pulse was applied to the AEE. As a result, the maximum input power increased under which the positive column did not constrict and the luminous flux improved by 70% at the xenon filling pressure of 6.7 kPa. It is proved that the positive voltage pulse application to the AEE with the amplitude of more than 2 kV expands the positive column in the radial direction. It is attributed to the phenomenon that the residual ions and electrons, which are generated by dielectric barrier discharge between the AEE and the anode during the falling edge of the negative pulse to the cathode, spread the discharge path from the anode towards the AEE during the cold cathode discharge mode. By increasing the xenon filling pressure, luminous efficacy was improved to 25 lm W(-1).

DOI： 10.1088/0022-3727/44/22/224013

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Synchronized generation of single bubbles and an underwater discharge in the bubbles was performed using pulsed injection of feed gas with a piezoelectric valve. The differences in the discharge appearance and the after-effect on the bubble were systematically studied with different kinds of gases. In molecular gases such as N(2) and O(2), surface discharge along the inner bubble surface predominated and the disturbance caused wrinkles on the bubble surface, while in rare gases, such as He, Ne and Ar, a large hump formed on the smooth surface due to a rather volumetric discharge. When the input power was increased, the discharge sometimes caused the collapse of a single bubble, producing smaller bubbles. It was observed by emission spectra that excited species of OH, H and O radicals were produced in the discharge plasma. The emission intensity ratio of the H a line to the OH band was larger in He and Ne gases than in other gases, suggesting differences in the dissociation channels.

DOI： 10.1088/0963-0252/20/3/034005

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We observed bright red emission at an intersection of an infrared (IR) laser beam and an atmospheric-pressure plasma jet (APPJ). The APPJ had a coaxial dielectric barrier discharge configuration and generated a plasma plume in a He gas flow ejected into air from a glass capillary. Although the laser-beam wavelength was 1083 nm corresponding to He I (2(3)P-2(3)S) atomic transition, the enhanced red emission peaked in the visible region at 640 nm and had broad bandwidth corresponding to He-2 (d(3)Sigma(+)(u)-b(3)Pi(g)) molecular transition. This result indicates that the IR laser excitation of He metastable (2(3)S) atoms leads to selective formation of excited He-2 (d(3)Sigma(+)(u)) molecules from excited He (2(3)P) atoms. The 640 nm emission intensity decreased as the laser beam moved downstream in the plasma plume, because of the quenching effects on the excited He atoms and the excited He2 molecules by air entrainment. We believe that the He-2 (d(3)Sigma(+)(u)) molecular formation follows two potential curves of He-2 (f(3)Sigma(u) or f(3)Pi(u)) and (d(3)Sigma(+)(u)) states, overcoming a potential hump by three-body collision processes.

DOI： 10.1088/0022-3727/44/4/042001

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

In this paper, we compared the inactivation of Bacillus subtilis spores in water by means of a dielectric-barrier-discharge (DBD)-driven XeI* excilamp and a low-pressure mercury lamp. The main part (similar to 76%) of the excilamp output was due to the B -> X transition of XeI* exciplex at 253 nm. It is shown for the first time that a better sterilization action is achieved with the DBD-driven XeI* excilamp compared with the monochromatic mercury lamp at the same UV dose. The contribution of an atomic iodine emission in the range of 178-207 nm has been confirmed. Germ-reduction experiments with the XeI* excilamp have been carried out in a steady-state mode and in a water-flow reactor.

DOI： 10.1109/TPS.2010.2044588

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Mercury-free metal halide lamps (MHLs) for automotive purposes have been developing in the market. When mercury is not used, the electric and emission characteristics of the lamp strongly depend on the xenon filling pressure. Therefore a non-destructive gas pressure estimation technique is required to obtain stable performance of the lamps as commercial products. The authors have developed an estimation method by which the gas pressure is estimated from the current peak value at the initial stage of ignition under pulsed operation. It is shown that accuracy of the order of +/-(0.1-0.3) atm is obtained using an empirical formula.

DOI： 10.1088/0022-3727/43/23/234003

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Since there is much concern about environmental preservation, the authors have paid attention to the uses of mercury in lighting application. They have focused on the application of the xenon low-pressure inductively coupled plasma (ICP) discharge in developing cylindrical type mercury-free light sources. ICP can be operated at low filling gas pressures and demonstrates significant potential in producing high density plasma. Xenon pressure was varied from 0.1 to 100 Torr and the lamp luminance was measured. The gas pressure dependence shows an increase in luminance at pressures below 1 Torr. In order to clarify this behaviour, measurement of plasma parameters was carried out using the double probe method and its relation to lamp luminance is discussed. As the gas pressure is decreased (from 1 to 0.01 Torr), the electron temperature increases while the electron density decreases while at the same time the lamp luminance increases. There are several factors that are believed to contribute to the increase in luminance in the very low pressure region. Increases in luminance are considered to be due to the electron-ion recombination process which brings a strong recombination radiation in continuum in the visible region and also due to the effect of stochastic heating.

DOI： 10.1088/0022-3727/42/9/095202

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High color rendering index (CRI) has been obtained from mercury-free ICP's lamp. Due to the strong demand on the development of mercury-free light sources, the authors investigated xenon and CO as an alternative element. These rare (Xe) and molecule (CO) gases have been used as a substitute for mercury as the environmental problems related necessitate the development of new type of light sources. The target of this study is to develop a new type of mercury-free lamp without using a phosphor where the authors concentrate on how to obtain a strong visible light instead of UV. In this paper, the colors, luminance and emission characteristics of these types of mercury-free ICP's lamp is discussed. Without the use of phosphor, the authors obtained a good color rendering from xenon and CO ICP's lamp where their CRI's above 90. A strong continuum emission in visible region is obtained where luminance are ranged from 2000 to 25000 cd/m 2 at 100 W of input power. Spectral distribution shows the continuum emissions are similar to the daylight distribution and chromaticity diagrams shows they are close to white region in color coordinates and color temperatures bringing a high index of the lamp's color rendering.

DOI： 10.2150/jlve.33.7

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By using Blue, Green and Red LEDs it is shown that the Broca-Sulzer effect holds for a repetitive pulse operated LED lighting system. In other words Talbot-Plateau Law does not hold. The effective enhancement at 60 Hz with a 5% duty ratio is about 1.5 to 2.7 times that of DC operation for blue and green light. This result suggests that pulsed operation can be a way to solving the energy saving problem of lighting.

DOI： 10.2150/jlve.32.170

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Language：English   Publishing type：Research paper (scientific journal)  

By using Blue, Green and Red LEDs it is shown that the Broca-Sulzer effect holds for a continuous pulse operated LED lighting system. The effective enhancement at 5% duty ratio and frequency of 60 Hz is between 1.01 to 2.22 times that of DC operation although this is not as high as it is in the single pulse discharge lamp case. However, this result shows that there is a possibility of improving the efficiency of an LED and a PWM circuit for pulsed operation for developing a highly efficient lighting system.

DOI： 10.2150/jlve.32.161

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

The authors have demonstrated an argon low-frequency microplasma jet and experimentally investigated the gas-specific difference compared with a helium jet, which has been used in many studies. Both argon and helium plasma jets show ambient neutral nitrogen molecule emissions as well as those of carrier gases; however, the emission of nitrogen molecule ions is observed only in the helium plasma jet. This is determined by whether the metastable level of the carrier gas is higher or lower than the ionization potential of the nitrogen molecule. Moreover, for a larger flow rate, the jet length decreased and green emission was observed, which is assigned to O (I) and ArO emissions.

DOI： 10.1143/JJAP.46.L939

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Language：Japanese   Publisher：一般社団法人照明学会  

As the introduction to numerical modeling plasma for light sources the fundamental key points such as, governing equations, EEDF, datasets and programming languages, are explained in this paper.

CiNii Books

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

As the environmental awareness of people becomes stronger, the demand for mercury-free light sources also becomes stronger. The authors have been keeping their interest in developing mercury-free discharge lamps, especially in low-pressure xenon as the most promising UV sources to substitute mercury. In this paper the authors report the effect of auxiliary external electrode (AEE) on the pulsed xenon fluorescent lamps. In this research two types of structures are used. One is the standard type, which has one anode and one cathode inside the lamp. The other is the double anode type, which has two anodes and one cathode inside the lamp. By using the AEE the luminance and the efficacy are improved simultaneously. The luminance is improved by about 129% for the standard structure type and 20% for the double anode type. The efficacy is improved by 60% for the standard type and by 63% for the double anode type. We call this effect/method the Jinno-Motomura effect/method (JM-effect/method). Regarding the result of the xenon metastable atom distribution, measured by LIF, this effect is attributed to the plasma potential control and enlargement of the positive column by AEE.

DOI： 10.1088/0022-3727/40/13/S08

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Mercury which is used in fluorescent lamps for general lighting has a possibility to cause environmental problems. Authors have been developing lamps which contain only rare gases without mercury. The rare gas lamps are environmentally-friendly, but it has lower luminance than the mercury lamp has. Therefore, the authors have tried expanding positive column by using an external electrode, and 12000 cd/m2 was achieved by cylindrical xenon fluorescent Lamp. In this paper it is reported that the same method is also useful for fiat lamps with multi anodes. An external auxiliary electrode controls electric field and potential in the flat lamp. The external electrode is effective to expand the column in a flat lamp and make it uniform and finally improve luminance.

DOI： 10.2150/jlve.31.54

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Language：Japanese   Publisher：技術情報協会  

J-GLOBAL

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Language：English   Publishing type：Research paper (scientific journal)  

When applying a pulsed voltage to a discharge tube using dielectric barrier discharge, discharge occurs two times in a pulse at a rising and a falling edge of a voltage pulse. The timing of the second discharge can be changed by controlling the pulse width. In this study the influence of the pulse width on the luminance of the barrier discharge lamp with an inner electrode is investigated. The lamp used in this study has two electrodes, one is set in the lamp and the other is set on the outside surface of the lamp. Internal electrode is connected to the high voltage side and the external electrode is connected to the ground side. Luminance is observed under the condition of pulse repetition frequency of 10 kHz, peak voltage from 1 kV to 3 kV and pulse width from 2 μs to 98 μs. Luminance took almost same value from 30 μs to 90 μs, whereas it decreased by both deceasing the pulse width less than 30 μs and increasing it more than 90 μs. It means that the higher luminance is obtained by avoiding the overlap of the two radiations at rising and failing edge of applied voltage. Copyright © 2006 The Illuminating Engineering Institute of Japan.

DOI： 10.2150/jlve.30.58

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Recently as interests in environmental issues increase, demands for mercury-free fluorescent lamps are increasing because mercury is harmful to human beings and creatures. As one of the solutions of this issue the authors have developed a new-type of mercury-free fluorescent lamps using double helical external electrodes. In this paper the fundamental characteristics of Xenon-Neon discharge in the Double Helical External Electrodes Lamps (DHEL) such as the luminance, power consumption and lamp current are investigated. When the pressure ratio of Xe: Ne was fixed at 7 : 3, total pressure at 1.33 kPa and external electrode pitch as 10 mm, luminance over 10000 cd/m 2 is achieved. In addition as a prototype 1 m length DHEL is prepared and demonstrated to show basically there is no limit in length of DHEL. Copyright © 2006 The Illuminating Engineering Institute of Japan.

DOI： 10.2150/jlve.30.55

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Language：English   Publishing type：Research paper (scientific journal)  

Although xenon pulsed dielectric barrier discharge is one of the most promising substitutes for mercury low-pressure discharge for fluorescent lamps, the efficacy of xenon fluorescent lamp is not enough for practical use for general lighting. To improve the efficacy it is indispensable to clarify mechanisms of vacuum ultraviolet (VUV) emissions, which excite phosphor, from xenon discharge related to plasma characteristics. In this paper emission waveforms and temporal change of metastable atom density are measured and temporal VUV emission characteristics related to generations and losses of metastable atoms in xenon pulsed barrier discharge is investigated. It is shown that the lamp efficacy is improved by about 10% with shorter pulse in which the two VUV emission peaks in a pulse are overlapped. It is also shown that at the lower pressure of 1.3kPa metastable atoms generated during on-period of the voltage pulse are not efficiently consumed for VUV emissions in the off-period of the voltage pulse because of lower rate of three-body collision and quenching. This fact is thought to be one of the reasons why the lamp efficacy is low at lower pressure. Copyright © 2006 The Illuminating Engineering Institute of Japan.

DOI： 10.2150/jlve.30.81

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The near-UV and visible mercury emissions from low-pressure discharges were studied under a range of rare gas hosts and different modes of operation. The optimization of the emission line intensities is achieved under different buffer gases for different operating modes. It is hypothesized that energy transfer processes occur between the rare gas metastable states and mercury atoms leading to the observed spectra.

DOI： 10.2150/jlve.30.13

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In this paper we demonstrate the influence of buffer gas atoms on the emission spectrum of a low-pressure nitrogen discharge. If the conditions of operation of the discharge allow for the population of the energy levels of the buffer gas atoms then energy stored in the metastable states of these atoms can be transferred through collisions to the atoms of the active medium. This results in a higher degree of excitation of the latter with significant effects on the optical output of the source.

DOI： 10.2150/jlve.30.9

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Ehime University  

The fluorescent lamps are widely used for general lighting because of their high efficacy, long life and so forth. However, fluorescent lamps in general contain mercury, which has a possibility to cause environmental problems. So we have been developing fluorescent lamps that contain only rare gases in place of mercury. The rare gas lamps are environmentally friendly, but its luminous flux and efficacy were lower than those of mercury lamp. Therefore, we have tried improving luminous flux of the rare gas lamp by expanding positive column. By winding an external electrode on the outside wall of the lamp that has multi anodes and single cathode, positive column expanded and luminous flux increased. The increase of metastable atoms and expansion of its radial distribution was confirmed by laser induced fluorescence method. It is found that the external electrode has an effect of field distortion leading to the positive column expansion. Finally, by connecting large resistance to limit the current flowing through external electrode, power consumption decreased and luminance of 13 000 cd/m2 and luminous efficacy of 90 lm/W are obtained, which are comparable with those of mercury fluorescent lamps.

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Other Link： http://iyokan.lib.ehime-u.ac.jp/dspace/handle/iyokan/1465

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Illuminating Engineering Institute of Japan  

The characteristics of xenon fluorescent lamp with two pairs of anode and cathode in pulsed discharge are demonstrated. By increasing the number of electrodes from one pair to two pairs, luminance is improved by 13 % and achieves 9500 cd/m² but estimated efficacy at a positive column is decreased from 68.0 lm/W to 45.6 lm/W. The narrow pulse width is preferred for higher luminance because a higher current density can be attained. It is also shown that there is the critical value of the energy consumed from the time when the current is turned on to the time when the current value reaches maximum and that when the energy excess this limit the discharge state changes from diffused to contracted one.

DOI： 10.2150/jlve.29.99

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Illuminating Engineering Institute of Japan  

The profile of vacuum ultraviolet (VUV), visible and near IR emissions of xenon and xenon-rare gas pulsed discharge fluorescent lamps were observed as a fundamental research on developing a mercury-free fluorescent lamp. All lamps were operated by pulsed dielectric barrier discharge (DBD). As the pulse width decreases, higher intensity of VUV emissions is obtained, while luminance and efficacy also increase. As the pulse frequency increases, the intensity of VUV emissions increases, however the radiative output per one pulse period decreases and the efficacy decreases. The decay time of VUV emissions which are exciting a phosphor, can be controlled by introducing a rare-gas mixture into xenon.

DOI： 10.2150/jlve.29.91

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Language：Japanese   Publisher：社団法人 プラズマ・核融合学会  

The sensitivity of human eye is not flat against wavelength of light. In the field of light sources, this forces us to calibrate physical indexes by human eye sensitivity. For example, light power is expressed in a physical unit of Watt [W], however, in the filed of lighting it is converted to “luminous flux” with unit of lumen [lm]. Since these indexes have no physical quantities any longer, it is difficult for the researchers not related to lighting to guess their meanings instinctively. Therefore the luminous characteristics are explained in this section.

DOI： 10.1585/jspf.81.922

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Language：Japanese   Publisher：社団法人 プラズマ・核融合学会  

Examples and basic theories of various methods of laser diagnostics of plasmas for light sources are introduced. Most introduced papers were presented at International Symposium on the Science and Technology of Light Sources (LS), which is the only international symposium on the science and technology of light sources.

DOI： 10.1585/jspf.81.917

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Language：Japanese   Publisher：社団法人 プラズマ・核融合学会  

As interests in environmental friendly products, demands from market for mercury-free fluorescent lamps become stronger. Xenon is the most expected material as a substitution for mercury for fluorescent lamps. So many researches have been done by so many researchers and recently by using external electrode with conventional discharge tube with internal electrodes droved by pulsed discharge has achieved 90 lm/W and 12000 cd/m<sup>2</sup>. Another effort is using molecular gas as discharge medium. For example Ar-N<sub>2</sub> mixture and CO are proposed.

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Language：Japanese   Publisher：社団法人 プラズマ・核融合学会  

Argon-Mercury fluorescent lamp is one of the most old and popular plasma applications. The argon-mercury fluorescent lamp is one of the oldest discharge light sources. Its materials and structure have been modified and improved. Recently new-type of fluorescent lamps, cold cathode fluorescent lamps (CCFL) have become popular as back light of liquid crystal panel display (LCD backlight). In this section basics of fluorescent lamps are described.

DOI： 10.1585/jspf.81.801

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Nitrogen is well known as a UV-emitter because of its 2nd positive band lying around 350 nm. However, it is a molecular gas and when energy is stored in rotational or vibrational levels, the gas temperature can become high enough to melt even the glass tube. To avoid such problems the authors tried to use the Penning-like effect between the argon metastables and nitrogen C(3)Pi(u) states with very low partial pressure of nitrogen compared with that of the argon. By adding a very small amount of nitrogen to argon, the discharge changes drastically. Though pure argon discharge and pure nitrogen discharge are both unstable and easy to constrict, a small amount of nitrogen improves the stability of the discharge and emits the nitrogen 2nd positive band UV light by energy transfer from the argon metastable to the nitrogen molecule C(3)Pi(u) state. Nitrogen-added argon fluorescent lamps operated at 30 kHz of alternative square voltage wave achieve about 4500 cd m(-2) at 3.75 W and at 9.3 kPa of pressure with good dimming characteristics. The maximum luminance should be higher than this because the input power is limited by the power supply. At this condition the luminous efficacy achieves 7.11mW(-1). These results show a possibility of argon-nitrogen fluorescent lamps as mercury-less fluorescent lamps.

DOI： 10.1088/0022-3727/38/17/S36

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The fluorescent lamps are widely used for general lighting in Japan because of their high efficacy, long life, high general color rendering index and so forth. Mercury which is used in fluoresent lamps for general lighting has a possibility to cause environmental problems. So we have been developing fluorecent lamps which contain only rare gases in place of mercury. The rare gas lamps are environmentally-friendly, but it has lower luminous flux than the mercury lamp has. Therefore, we have tried improving luminous flux of the rare gas lamp by expanding positive column. By setting an external electrode on the outside wall of lamp which has multi-pairs of electrodes, positive column expands and luminous flux increases. Luminous flux changes by setting position and width of an external electrode. Then luminous efficiency achieves 5 lm/W. We obtain relatively larger luminous flux when setting an external electrode near the cathode comparing with the lamp without external electrode. Luminous flux also changes by changing a way of setting an external electrode. We have achieved largest luminous flux when spiral external electrode is wound on the lamp. © 2005, The Institute of Electrical Engineers of Japan. All rights reserved.

DOI： 10.1541/ieejfms.125.447

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In these days, there are strong needs to reduce harmful mercury used for light sources. We have been developing mercury-free fluorescent lamps using xenon. In this study, we have investigated characteristics of the xenon fluorescent lamps which have an internal and an external electrodes by changing the shape of the electrodes and how to set them. It is shown that luminance is improved by enhancing ionization by thin inner electrode, or increasing the capacitance between electrodes by increasing the pitch of wound external electrode. © 2005, The Institute of Electrical Engineers of Japan. All rights reserved.

DOI： 10.1541/ieejfms.125.434

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The Lattice Boltzmann Method (LBM) which is derivative of the lattice gas automata (LGA) has recently studied as a numerical scheme for simulating fluid flows governed by the Navier-Stokes equation. The LBM is a discrete numerical method based on the Boltzmann equation. The dynamics of the LBM is divided into a propagation step and a collision step. We have proposed a model for weakly ionized plasma by introducing diffusion as a velocity to LBM. In our LBM model, ionization, recombination at the wall and ambipolar diffusion are considered. This model uses 2D9V (2 dimensions, 9 velocities) model and BGK collision operator. We have simulated various shape of discharge tubes by this model. MATLAB is suitable for matrix calculation and has a command for shifting matrix which is important in LBM. By this work, it is shown that our model simulates weakly ionized plasma well. © 2005, The Institute of Electrical Engineers of Japan. All rights reserved.

DOI： 10.1541/ieejfms.125.229

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Language：English   Publishing type：Research paper (scientific journal)  

Since high-pressure mercury lamps have high luminance and emit large luminous flux, they are widely used for outdoor lighting. One of the problems of them is difficulty to re-ignition just after turn off because of high mercury vapor pressure during discharge. One solution is to make photo pre-ionization in the lamp to reduce starting voltage. In this study, ultraviolet laser beam from XeCl excimer laser is introduced to the lamp and the phenomena occurring between laser inlet to starting discharge have been investigated. From the calculation of the time required for ions and electrons to drift between electrodes, it is found that the streamer is formed and it makes an important role to start discharge. Moreover, multi-step discharge was observed and under this condition probability of starting discharge decreased. © 2005, The Institute of Electrical Engineers of Japan. All rights reserved.

DOI： 10.1541/ieejfms.125.235

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As a first step to understand the processes taking place in a pulsed xenon discharge, the temporal behavior of the radial metastable atom distribution in a xenon lamp was measured by IR laser absorption spectroscopy. During the first 10 µs after starting the discharge, high electron density and the depletion of the ground state atoms at the center of the discharge brought about an almost flat distribution of the metastable atoms within the half-radius area. Following that, the metastable atom density became higher at the center than outside because of recombination between electrons and ions. After the metastable density increase and following voltage cut off, the metastable density decreases again. Considering the diffusion equation alongside these results, it becomes clear that the decrease of the metastable density is caused by quenching to the resonace level from the metastable level or three-body collisions forming excimers. © 2005, The Institute of Electrical Engineers of Japan. All rights reserved.

DOI： 10.1541/ieejfms.125.669

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Illuminating Engineering Institute of Japan  

In this paper the phenomena of mode transition and hysteresis in xenon ICP (Inductively Coupled Plasma) discharge are studied. Xenon has been used as an alternative for mercury since there are environmental issues related to mercury. The transition from E-mode (electrostatic mode) discharge to H-mode (electromagnetic mode) discharge in a xenon cylindrical tube was investigated. RF energy at 13.56 MHz was induced to the tube through matching network. In this study, all the transitions occurred at a certain threshold input power which is a function of the xenon pressure. Hysteresis was observed as the input power was varied from 1 to 100 W. When the input power is increased the discharge starts in E-mode changes into H-mode, whereas when the input power is decreased the H-mode turns into the E-mode or there is a sudden switch-off as the function of the gas pressures. Mode transition is determined by sudden and huge change of luminance. H-mode is characterized by a much higher luminance and plasma density. Luminance and optical emission spectra were recorded. At high pressure more power is required to transform the discharge mode compared to low pressure. Continuum visible emission was obtained only in H-mode. At H-mode, many ionic and atomic spectrum are observed compared to E-mode. With high luminance and continuum visible emission that obtained from H-mode xenon ICP discharge, xenon is one of the most suitable alternatives in developing mercury-free light sources.

DOI： 10.2150/jlve.29.85

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Language：English   Publishing type：Research paper (scientific journal)  

Color variable pulsed Hg-Ne discharge lamp was invented and reported by Itatani's group in 1973. The color of Hg-Ne discharge was controlled by changing electron temperature by changing pulse frequency. Maya's group reported about color variable mercury fluorescent lamps using burst pulse and different type of phosphors. Kroesen's group proposed Hg-Ne color variable lamp using depletion effect. All these lamps use electrodes inside a tube. The authors propose a new type of color variable discharge lamp using inductively coupled plasma (ICP), electrodeless discharge. Color variable lamp using ICP is demonstrated. Just after starting discharge of Hg-Ne, the luminescent color of the lamp is red because of Ne emission. After that, the color changes gradually toward blue resulting from increase in mercury vapor pressure. When the color change stoppes and it is in the steady state with blue color, the color can be changed toward red by increasing input power. This is due to Ne emission resulting from increase in current density. © 2005, The Institute of Electrical Engineers of Japan. All rights reserved.

DOI： 10.1541/ieejfms.125.521

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Application of ICP in the development of mercury-less light sources have been investigated. Xenon has been used as a replacement for mercury as the environmental issues related to it necessitate the development of new type of light sources. RF energy at 13.56 MHz was induced to the cylindrical tube with input power ranging from 1 W up to 100 W. By changing the xenon gas pressure, coil turns and phosphor coating conditions, differences in emission intensities (luminance), spectra and discharge states were observed. In order to obtain the ICP discharge, the lamp was operated first in capacitive mode and then in inductive mode. These modes are known as E-mode (capacitively or CCP) and H-mode (inductively or ICP) respectively. High luminance can only be obtained when operating the lamp in H-mode. The optical emission spectra of these two modes (E and H) were analysed carefully. © 2005, The Institute of Electrical Engineers of Japan. All rights reserved.

DOI： 10.1541/ieejfms.125.602

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Applicability of Fourier transform infrared (FTIR) spectroscopy to an in situ diagnostics tool of plasma-surface interactions is described. After a brief review of conventional reflection absorption spectroscopy (RAS) and phase-modulated RAS (PMRAS), our FTIR phase-modulated spectroscopic ellipsometry (PMSE) is described in detail. The FTIR PMSE is constructed by insertion of a grid polarizer as an analyser in front of an infrared detector in addition to the conventional set-up of PMRAS. This simple change brings about a higher sensitivity than that of conventional PMRAS, which enables us to detect chemical species generated on (or removed from) the top surface layer during plasma processing. This feature is demonstrated by the fact that our FTIR PMSE can be applied to surface diagnostics during reactive ion etching processes such as for Si, SiO2/Si, SiO2/Si3N4, SiO2/photo-resist and low-dielectric-constant films.

DOI： 10.1088/0022-3727/37/6/ROI

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Illuminating Engineering Institute of Japan (IEIJ)  

We investigated a developing mechanism of emission in a xenon discharge lamp with inner and outer electrodes using a high-speed electronic camera. At a low operating frequency, a negative glow appears on the inner surface of the glass tube during the positive half cycle while the inner electrode operates as an anode, and a diffused positive column appears in the discharge space during the negative half cycle while the inner electrode works as a cathode. At a high operating frequency, a contracted positive column appears in the center of discharge space near the inner electrode during the positive half cycle and the negative half cycle. VUV radiation intensity and phosphor emission intensity in the diffused positive column are three-times greater than those in the contracted positive column.

DOI： 10.2150/jieij1980.87.2_98

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Illuminating Engineering Institute of Japan (IEIJ)  

A small diameter xenon fluorescent lamp that is suitable for LCD backlighting has been developed. It consists of one inner electrode and one outer electrode. A pulsed current flows when a rectangular wave voltage is applied between these electrodes. The positive column is diffused at lower operating frequency and lower wattage, and is contracted at higher operating frequency and higher wattage. When the positive column is diffused, the light output becomes stable and the VUV radiation and phosphor emission become stronger. The luminous efficiency of this lamp was about 60% of that of a conventional Hg-type cold cathode fluorescent lamp.

DOI： 10.2150/jieij1980.86.8_535

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：A V S AMER INST PHYSICS  

The generation of large molecular species in an inductively coupled plasma using fluorocarbon gases was investigated to elucidate the selective etching mechanism of SiO2 to photoresist. In this study, the source gases C2F6, C4F8, and C5F8 were used to provide a range of fluorine-to-carbon content ratios. It was found that larger quantities and a wider variety of large-mass species are generated in C5F8 plasma than in C2F6 and C4F8 plasmas. Our results also revealed that the gas residence time was an important parameter for controlling the radical composition of the plasma. With increased residence time, the ratio of species with larger masses than the parent molecule to the sum of all product species increased in the C2F6 plasma, whereas this ratio decreased in the C4F8 and C5F8 plasmas. The ratio of larger mass species correlates apparently with the selectivity of SiO2 to photoresist etch rates. However, in any explanation of physical mechanisms, the redeposition of etching byproducts should be taken into account as well as the dependence of polymer deposition tendency on substrate materials under biased etching conditions. (C) 2002 American Vacuum Society.

DOI： 10.1116/1.1495503

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Illuminating Engineering Institute of Japan (IEIJ)  

An electronic ballast is described that uses fewer parts and costs less than conventioal ballast, which require separate switching element and control units for the half-bridge inverter and power-factor-correction(PFC)circuits because these circuits operate independently. In this paper, the operation of an electronic ballast in which the switching element of the half-bridge inverter works as a buck-boost converter has been analyzed and harmonic components that an input current included is calculated theoretically. The proposed ballast reduced the harmonics component in the input current to below by IEC Standard 61000-3-2 for Class C, because the amplitude of a sine wave is kept than 2.6 times of the amplitude of a rectangular wave.

DOI： 10.2150/jieij1980.86.2_97

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Surface reactions induced by fluorocarbon plasmas were studied on Si substrates with SiO2 and photo-resist overlayers using an inductively coupled plasma source. As source gases, C4F8 and C5F8 were employed to investigate their differences in the etching performance and the selectivity between SiO2 and photo-resist. Deposition of fluorocarbon polymer was noticed in both gases by Fourier-transform infrared ellipsometric measurements when substrate bias was not applied. With the bias application, etching started on both substrate from certain threshold values of the bias voltage and the rate increased with increase of the voltage. However, in C5F8 plasma the increasing tendency on photo-resist was much less than on SiO2, while in C4F8 plasma the difference is small. This difference is attributed to a larger deposition ability of C5F8 plasma with higher content of fluorine atoms in the polymer than that of C4F8 plasma as confirmed by X-ray photoelectron spectroscopy. © 2001 Elsevier Science B.V.

DOI： 10.1016/S0040-6090(01)00948-8

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

Electronic excited states of various perfluorocarbons were investigated using an ab initio molecular orbital calculation. The chemical reactions via the excited states were also predicted from the antibonding characteristics of the molecular orbitals concerned and the first-or der derivative of the potential surface of the excited state. In marked contrast to saturated perfluorocarbons, unsaturated perfluorocarbons can be easily excited to the lowest triplet state with a pi-pi* transition, generating biradicals and subsequently leading to polymerization. in addition to the conventionally used perfluorocarbons, the possibility of two-double-bonded. one-triple-bonded and aromatic perfluorocarbons for application to plasma processing was examined on the basis of quantum chemistry. The use of these novel types of fluorocarbon is predicted to be promising for chemical vapor deposition (CVD) of low dielectric constant interlayer films and etching with high selectivity of SiO2 to Si and Si3N4 because of the excellent potential shown by them to yield a high polymerization and deposition rate.

DOI： 10.1143/JJAP.40.847

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DOI： 10.2150/jieij1980.85.Appendix_78

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Surface reactions induced by fluorocarbon plasmas were studied on SiO2 and Si3N4 substrates using an inductively coupled plasma source. C4F8 and C5F8 were employed as source gases to investigate their differences in etching performance and selectivity on both SiO2 and Si3N4 substrates. Polymer deposition was noticed in both gases by Fourier transform infrared ellipsometric measurements when substrate bias was not applied. When the bias was applied, etching started on the SiO2 surface from a certain threshold bias voltage and the rate increased with the increase in voltage. However, on the Si3N4 surface this increasing tendency in C5F8 plasma was much less than that in C4F8 plasma. This difference provides a greater selectivity of SiO2 to Si3N4 in C5F8 plasma. The reason for this increased deposition tendency in C5F8 plasma is attributed to the presence of higher mass species in a larger abundance than in C4F8 plasma, as confirmed by electron attachment mass spectrometry. (C) 2000 Elsevier Science S.A. All rights reserved.

DOI： 10.1016/S0040-6090(00)01157-3

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN J APPLIED PHYSICS  

In situ Fourier transform infrared ellipsometry has been used to investigate the characteristics of fluorocarbon films deposited in inductively coupled CHF3 and C4F8/H-2 plasmas. Chemical composition and thickness of the films have been studied as a function of process parameters. For the CHF3 plasma, the mode strength of CF2 bond group increases monotonically with pressure varying from 3 to 20 mTorr. The mode strength ratio of hydrogen-containing fluorocarbon bond groups (CHFx) to CF2 bond group increases with decreasing pressure. If He gas is admired to CHF3, the CHFx/CF2 ratio also increases. Changes in the film structure have been discussed in terms of the relationship between electron temperature and CHF3 dissociation. As the discharge power is increased, the deposition rate increases linearly without considerable changes in the chemical composition of the film. For the C4F8/H-2 plasma, relative concentration of CHFx species increases linearly with H-2 mixing ratio.

DOI： 10.1143/JJAP.37.4522

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

In situ Fourier-transform infrared (FTIR) ellipsometry has been performed on silicon substrates processed in a rf-biased transformer coupled plasma reactor. Plasmas in CHF3, CF4, C2F6, and C4F8 have been used. The reaction layer, which is present on the surface of the silicon wafer during the plasma process, has been analyzed in detail, addressing both chemical composition and thickness. The absolute reliability (expressed in terms of thickness) of the results is of the order of 0.01 nm, which corresponds to 3% of a monolayer. The instabilities of a silicon surface, which have been observed under specific conditions, can be of the order of tens of percents of a monolayer, which clearly illustrates the advantage of using a real in situ technique like FTIR ellipsometry over quasi in situ techniques like x-ray photoemission spectroscopy and Auger electron spectroscopy. For CHF3 plasmas it has been found that, if the bias increases to moderate levels (30-50 V), the fluorocarbon film deposition rate decreases and the silicon etching reaction rate increases. The reaction layer changes from a thick, predominantly CFx polymerlike film to a thin, carbon dominated layer of plasma and etching products showing vibrational absorptions of SIFx, C-C, and CF2. Increasing the bias voltage in a CHF3 plasma has a similar effect as increasing the F/C ratio of the feed gas. (C) 1998 American Vacuum Society.

DOI： 10.1116/1.580976

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The authors have been developing high efficacy mercury-free cold cathode fluorescent lamp with auxiliary external electrode (AEE). In this study the inside electrodes were optimized and it is found that thinner and longer cathode (high voltage side) and thicker and shorter anode (ground side) are preferred for sleeve shape electrodes.

DOI： 10.11485/iteac.2010.0_6

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The authors reported that the human perception is enhanced for the repetitive pulsed light even over the critical fusion frequency (CFF) by using fast turn-on and turn-off light such as LEDs. However, the color shift of the pulsed LED may affect the observer's decision. The authors tried separating the effect of the color shift from statistically derived value of human perception enhancement degree. The color shift was quantified by CIELAB color space. As an example of the experiments, the effect of the pulsed operation itself was obtained when blue LED is used for illumination of objects.

DOI： 10.11515/ieijac.43.0.118.0

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Language：Japanese   Publisher：The Illuminating Engineering Institute of Japan  

Mercury-free metal halide lamps for automotive purpose have been developing in the market. When mercury is not used, the electric and emission characteristics of the lamp strongly depend on the xenon filling pressure. Therefore a simple and non-destructive gas pressure estimation technique used in production lines is required to obtain stable performance of the lamps as commercial products. The authors have developed an estimation method by which the gas pressure is estimated from the current peak value at the initial stage of ignition under pulsed operation. It is shown that the accuracy of the order of +-(0.1--0.3) atm is obtained using an empirical formula.

DOI： 10.11515/ieijac.43.0.15.0

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The photoluminescence and excitation spectra of Pr3+ activated strontium aluminate (SAO), which are Hot Isostatic Pressing (HIP) processed and normally sintered, has been investigated at the room temperature (300 K). The luminescence excited by Xe 172 nm consists of optical transitions emanating from the 4f5d and the 1S0 states of Pr3+. As for the HIP-processed samples, the emission from 1S0 and 3P0 were observed. On the other hand, as for the samples which were made in a tubular furnace, no emission from 1S0was observed and UV emission of 250-350nm (4f15d1->4f2) was observed. The results of energy-dispersive X-ray spectroscopy (EDS) analysis show that SrAl14O25 is made by HIP-processed, and that SrAl2O4 was made with a tubular furnace. These results show that quantum-cutting phosphors can be obtained by Pr3+ activated SrAl14O25.

DOI： 10.11515/ieijac.43.0.127.0

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The authors have been developing mercury-free fluorescent lamps and reported a luminance and efficacy improvement method by using an auxiliary external electrode (AEE). In this study, instead of simply grounding the AEE, another HV pulse was applied to the AEE, which was synchronized to the driving HV pulse and further luminance and efficacy improvement was achieved.

DOI： 10.11515/ieijac.43.0.5.0

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The authors have been developing mercury-free fluorescent lamp, mainly for general lighting purpose (inside diameter of 26 mm), and enhancing its luminance and efficacy using auxiliary external electrode (AEE). In this study, for thinner lamp (inside diameter of 8.7 mm) with the AEE, the shape and the size of the inside electrodes were optimized. It is found that thinner and longer cathode (high voltage side) and thicker and shorter anode (ground side) are preferred when sleeve shape electrodes.

DOI： 10.11515/ieijac.43.0.6.0

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It is possible to enhance the injection current to xenon cold cathode mercury-free fluorescent lamps with suppression of positive column contraction by using an auxiliary external electrode. Investigation of electron density distribution is required in order to analyze mechanisms of positive column contraction after local ionization concentration. The authors employed CO2 laser interferometry to measure electron density distribution because it has high special resolution and does not disturb the plasma. The electron density of 2.5×10<sup>13</sup> cm<sup>-3</sup> was obtained at the center of positive column for the lamp with 50 Torr xenon, 50 mm of inter-electrodes, 14 mm of lamp inside diameter and 25 mA of injection current. As a future task, variations of electron density distribution by the auxiliary external electrode will be examined.

DOI： 10.11515/ieijac.43.0.9.0

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Restricted gas region close to substrate is strongly heated by plasma, which is generated in open-air by microwave excitation through coaxial-cable plasma torch. The torch is constructed with thin central electrode-column which is surrounded by outer cylindrical metal tube, that is coaxial-cable, and the tip does not poke, or slightly does, out of the cross section of the end of outer cylinder. Heated plasma-spot emerges in the clearance between the tip of electrode and substrate which is placed in parallel close to the end cross section of torch. Temperature change is measured in the reverse of substrate, the other surface of which is heated by plasma.

DOI： 10.1299/jsmemecjo.2009.3.0_45

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DOI： 10.11515/ieijac.42.0.19.0

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The authors have developed a mercury free sterilization lamp using 253 nm emission of xenon iodide. The lamp consists of two coaxial tube made of synthesized silica. The dielectric barrier discharge is initiated in the gap between two tubes.<BR>Several I* atomic emissions were observed around 200 nm as well as XeI* emission at 253 nm. Both of them overlap peaks of DNA absorption spectrum. From the experimental result of the lamp irradiation to B. subtilis spores, it was found that equivalent sterilization effect was obtained with less UV dose than commercial low pressure mercury lamp for sterilization (Toshiba, GL-4).

DOI： 10.11515/ieijac.42.0.134.0

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A large ballast resister is connected to the ground side electrode of our Xe fluorescent lamp with keeping the positive column in diffusive mode. In this configuration the potential of the ground side electrode becomes higher and floating, therefore the current flows out through the stray capacitor between glass wall of the lamp and ground becomes large and not negligible. In this paper we report the effect of ballast resistances ration between hight voltage side and ground side on the optical characteristics of the lamp. As the result, luminous efficacy increased and to maintain the diffuse state became easy by decreasing the ground side resistance. It is necessary to verify this effect by changing the driving frequency and the pulse width in the future.

DOI： 10.11515/ieijac.42.0.1.0

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In order to realize mercury-free metal-halide lamp, it is important to know the spatial distribution of emission spectra in the lamp. However, since the arc shape is not symmetrical, it is imposible to know the spatial distribution using the Abel inversion. Therefore, the authors employed computed tomography technic to create the tomogram image from measured spectra.From the comparison between the tomogram images for In (450.87 nm) and Na (818.92 nm) emissions, it is found that the In emission shrinks into the arc center, whereas the Na emission diffuses. It is thought that the reson for this phenomenon is less diffusion for In because of larger atomic diameter compared to Na.

DOI： 10.11515/ieijac.42.0.19.0

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The authors have been studying human perception of emission intensity from pulsed LEDs. Since pulsed emission waveforms from the LEDs have very fast rising and falling time, it is expected that improved rerceived luminance by human eyes is obtained. The authors have found that 1.49-2 times improvement using pulsed blue LED. In this paper we have investigated the dependence of the improvementof perceived luminance on the duty ratio of the pulsed drivingwaveform. As the result, the perceived luminance was enhanced byusing lower duty ratio waveform.

DOI： 10.11515/ieijac.42.0.74.0

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DOI： 10.1109/PLASMA.2009.5227300

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DOI： 10.1109/PLASMA.2009.5227474

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DOI： 10.1109/PLASMA.2009.5227352

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DOI： 10.1109/PLASMA.2009.5227286

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In this research, it is verified that the human perception of pulsed light with fast rise and fall by using LEDs of Blue, Green and Red colors. At 60Hz of repetition frequency with 5% duty ratio in the case of direct light the perception of pulsed light becomes between 1.01 to 2.22 times larger than DC light. On the other hand for indirect light the perception of pulsed light becomes between 0.71 to 2.70 times of DC light. These results open the completely new approach of energy saving lighting.

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This article makes a report on the 11th International Symposium on the Science and Technology of Light Sources [LS:11] held in Shanghai, China in May, 2007.

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Language：Japanese   Publisher：化学工業社  

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It was found in the previous work that the luminance and efficacy of pulse driven xenon fluorescent lamps are improved using auxiliary external electrode. In this study the effect of lamp diameter is examined.Xenon filling pressure was 10.7 kPa and inside diameter were 14, 27 or 32 mm.In all cases consumption power through stray capacitor suppressed using auxiliary external electrode. Highest efficacy was obtained in the case of 14 mm diameter, whereas improvement was highest in the case of 27 mm diameter.

DOI： 10.11515/ieijac.41.0.7.0

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Effective Illuminance Improvement of Light Sources by using PulseModulation and its Psychophysical Effect on Human Eye

DOI： 10.11515/ieijac.41.0.65.0

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This reseach theme is development of RF Plazma light source.This research aimed light source which is no using mercury andelectrode.Rare gas used instead of mercury.And We chose Inductivelycoupled plazma(ICP)as discharge method.So we will be able to realize light source with long lifetime and harmless for environment. When we were measuring luminance,we found that luminance was changed by the temperature.We report on the result this time.

DOI： 10.11515/ieijac.41.0.18.0

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In this paper the authors report the effect of Auxiliary External Electrode (AEE) on the pulsed xenon fluorescent lamps.By using the AEE the luminance and the efficacy are improved simultaneously.The luminance is improved by about 129% for the standard structure type and 20% for the double anode type.The efficacy is improved by60% for the standard type and by 63% for the double anode type.Regarding the result of the xenon metastable atom distribution,measured by LIF,this effect is attributed to the plasma potentialcontrol and enlargement of the positive column by AEE.

DOI： 10.11515/ieijac.40.0.3.0

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As the environmental awareness of people becomes stronger, the demand for mercury-free light sources also becomes stronger. The authors have been keeping their interest in developing mercury-free discharge lamps, especially in low-pressure xenon as the most promising UV sources to substitute mercury. In this paper the authors report the effect of auxiliary external electrode (AEE) on the pulsed xenon fluorescent lamps. In this research two types of structures are used. One is the standard type, which has one anode and one cathode inside the lamp. The other is the double anode type, which has two anodes and one cathode inside the lamp. By using the AEE the luminance and the efficacy are improved simultaneously. The luminance is improved by about 129% for the standard structure type and 20% for the double anode type. The efficacy is improved by 60% for the standard type and by 63% for the double anode type. We call this effect/method the Jinno-Motomura effect/method (JM-effect/method). Regarding the result of the xenon metastable atom distribution, measured by LIF, this effect is attributed to the plasma potential control and enlargement of the positive column by AEE.

DOI： 10.1088/0022-3727/40/13/S08

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In these days, the damage of hot springs quality by bacilli is getting serious problem. The bacilli can be killed out by heating, chlorination or ultraviolet rays irradiation in general. However, some of bacilli have the tolerance in heat and chlorine, on the other hand they do not have the tolerance in ultraviolet rays. Therefore, most bacilli can be killed out by using ultraviolet rays [1]. The wavelength of effective ultraviolet rays for sterilization is in the vicinity of 250 nm. Mercury has a spectrum with strong resonance wavelength 253.7 nm. Therefore, mercury is used for the ultraviolet source. However, there are strong needs to reduce harmful mercury, because mercury can cause environmental problems. Then, the authors have paid attention to XeI emitting the radiation of 253 nm, which is near resonance radiation (253.7 nm) of mercury. In this study, the authors investigated the characteristics of the ultraviolet-rays light source that used XeI. Dielectric Barrier Discharge (DBD) is used as a lighting method. Parameter of xenon filling pressure was 39.9 Pa or 1.33 kPa. The vapor pressure of the iodine in the discharge tube was assumed to be 46.6 Pa from the temperature of the discharge tube wall. Two aluminum tapes (60 mm long and 20 mm wide) have been set in the opposite position of the outer wall of a discharge tube to each other as external electrodes. And the sinusoidal wave voltage or the pulsed negative voltage was impressed to the external electrode. By the dielectric barrier discharge, XeI excimers were generated and radiation around 253 nm from XeI was obtained. Consequently, when the partial pressure of the xenon was low, the continuous spectrum (peak wavelength 342 nm) from the iodine molecule was strongly radiated. However, when the partial pressure of the xenon was high, the continuous spectrum (peak wavelength 253 nm) from XeI was strongly radiated. © 2006 IEEE.

DOI： 10.1109/DEIV.2006.357395

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Because argon metastable levels (11.5 eV and 11.7 eV) lie near nitrogen C<SUP>3</SUP>Π<SUB>u</SUB> level (11.05 eV), which is upper state of 2nd positive band, energy transfer from argon metastable to nitrogen C<SUP>3</SUP>Π<SUB>u</SUB> state is expected in the nitrogen-argon discharge. However, there is another problem that the amount of nitrogen molecule decreases during discharge, which is confirmed from decrease in intensity of nitrogen molecule emission. The mechanisms of decrease in nitrogen molecule are under investigation.

DOI： 10.11515/ieijac.39.0.15.0

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In recent years, abolition of an environmental toxic substance is called for in various fields from the point of environmental preservation. If it says about a lamp, losing use of mercury will be mentioned as the first subject.In this research, the color rendering of the lamp was examined, and it evaluated it as a lamp.

DOI： 10.11515/ieijac.39.0.13.0

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The positive column expands in the direction of the diameter by arranging an external electrode on the wall outside the xenon fluorescent lamp. Luminous flux increases because it can flow more currents with diffusion maintained. However, the phenomenon in plasma is uncertain concretely. Then, a metastable atom density of the xenon was measured. Moreover, power consumption by an external electrode was suppressed and making to highly effective was tried.

DOI： 10.11515/ieijac.39.0.12.0

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Mercury which is used in fluorescent lamps for the general lighting and LCD backlight has a possibility to cause environmental issues. So we have been developing fluorescent lamps using nitrogen in place of mercury.<BR>We have observed the ultraviolet radiation from cold cathode lamps filled with the gas of argon and nitrogen mixture, we have measured the luminance of these lamps coated with green phosphor. The luminous efficacy of nitrogen lamps is lower than that of mercury lamps. But we found that the luminance increased by changing the admixture concentrations of nitrogen.

DOI： 10.11515/ieijac.39.0.123.0

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In these days, mercury is used for the main ultraviolet rays source of light. However, there are strong needs to reduce harmful mercury because of the bad influence on environment. The authors investigated the ultraviolet rays source of light that used iodine-xenon gas mixture. <BR> Dielectric Barrier Discharge (DBD) is used as a lighting method. A molecular spectrum of the iodine is strongly radiated when the gas pressure of the xenon is almost equal to the vapor pressure of the iodine. A molecular spectrum of XeI is strongly radiated when the gas pressure of the xenon is higher than the vapor pressure of the iodine.

DOI： 10.11515/ieijac.39.0.14.0

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Emission characteristics of low-pressure, i.e. less than 6.65 kPa, xenon inductively coupled plasma (ICP) was investigated. The discharge tube was made of Pyrex glass with outer diameter of 30 mm. A 4-turns coil was wound on the tube and RF power up to 100 W with frequency of 13.56 MHz was input to initiate a discharge. The luminance of the xenon discharge drastically changed depending on the pressure. When decreasing the pressure from 6.65 kPa to 26.6 Pa, the luminance basically had a tendency to decrease except of the case when the pressure was around 39.9 Pa
the luminance was suddenly increased up to 28 000 cd/m2 at 39.9 Pa, whereas it was about 2500 cd/m2 at 133 Pa. The emission spectrum at 39.9 Pa showed a continuum ranged over the visible region, on the other hand, atomic and ionic line spectra were dominant at 133 Pa. At 39.9 Pa, the discharge color was white and general color rendering index was 90, which is enough for the general lighting. It is thought that the wide range visible continuum is attributed to the ion-electron recombination radiation and results in the increase in the luminance. The detailed investigation of the mode change mentioned above through the measurements of the plasma parameters such as electron density etc. is now under progress. © 2006 IEEE.

DOI： 10.1109/DEIV.2006.357376

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The fluorescent lamps are widely used for general lighting because of their high efficacy, long life and so forth. Mercury which is used in fluorescent lamps for general lighting has a possibility to cause environmental problems. The author's group has been developing fluorescent lamps which contain only rare gases without mercury. The wavelength of the xenon resonance line is the longest in the rare-gas resonance lines, so that the Stokes-loss becomes smaller than the other rare-gases' cases. Therefore the authors have investigated pulsed xenon fluorescent lamps. However luminous flux of xenon fluorescent lamps was not large enough. The authors have been making efforts to improve luminous flux of the xenon lamp by expanding positive column. By setting an auxiliary external electrode on the outside wall of the lamp, positive column expands and luminous flux increases. However luminous efficacy decreases because power consumption through the external electrode is too large. So by using resistor, the current flowing through the external electrode is suppressed and power consumption decreased. Consequently higher luminous efficacy up to 100 lm/W with high luminance 6894 cd/m2 is achieved. © 2006 IEEE.

DOI： 10.1109/DEIV.2006.357375

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Nitrogen is known as a gas that has many emission spectra in ultraviolet region named 2nd positive band and they are thought to be suitable for phosphor excitation instead of harmful mercury. However, a molecular gas in a discharge has a tendency to get a high temperature because energy is stored as vibrational and rotational energy. This is a serious problem when the nitrogen discharge is used for light sources. Moreover, nitrogen requires fairy higher voltage to ignite and maintain a discharge compared with mercury-argon mixture. Because argon metastable levels (11.5 eV and 11.7 eV) lie near nitrogen C 3Πu level (11.05 eV), which is upper state of 2nd positive band, energy transfer from argon metastable to nitrogen C 3ΠΠu state is expected in the nitrogen-argon discharge. By limiting the amount of nitrogen to small portion, which is like a relationship between mercury and argon as a Penning gas, the discharge becomes stable and the temperature decrease, whereas the positive column of pure nitrogen or pure argon discharge tend to shrink and the pure nitrogen discharge have a high temperature. This result is attributed to the efficient energy flow to the C3Πu level through the energy transfer mentioned above. However, there is another problem that the amount of nitrogen molecule decreases during discharge, possibly by adsorption of nitrogen to the wall of discharge tube or the electrodes, which is confirmed from decrease in intensity of nitrogen molecule emission. The mechanisms of decrease in nitrogen molecule are under investigation. © 2006 IEEE.

DOI： 10.1109/DEIV.2006.357394

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Xenon dielectric barrier discharges are expected to be useful as an environmentally friendly light sources instead of that containing mercury. The authors have demonstrated new type of dielectric barrier discharge using double helical external electrodes (DHEL) method with xenon. The filling gas pressure ratio of Xe: Ne was 7:3, total pressure was 1.33 kPa and external electrode pitch was 10 mm. This DHEL was operated by sinusoidal waveform voltage, which is preferable to pulsed operation for preventing EMI, with enough phosphor luminance, i.e. 10 000 cd/m2. As a result of the observation of temporal behavior of the discharge by an ICCD camera, two discharges were observed in a half cycle of the sinusoidal input voltage. Moreover, it is found that the emission from the first discharge is intense on the electrode wire, whereas the intense emission position separates and repulsively moves to both sides of the electrode wire. This is explained from the repulsive force between the wall charge and the electrode polarity. © 2006 IEEE.

DOI： 10.1109/DEIV.2006.357377

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Language：Japanese   Publisher：社団法人プラズマ・核融合学会  

Argon-Mercury fluorescent lamp is one of the most old and popular plasma applications. The argon-mercury fluorescent lamp is one of the oldest discharge light sources. Its materials and structure have been modified and improved. Recently new-type of fluorescent lamps, cold cathode fluorescent lamps (CCFL) have become popular as back light of liquid crystal panel display (LCD backlight). In this section basics of fluorescent lamps are described.

DOI： 10.1585/jspf.81.801

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As interests in environmental friendly products, demands from market for mercury-free fluorescent lamps become stronger. Xenon is the most expected material as a substitution for mercury for fluorescent lamps. So many researches have been done by so many researchers and recently by using external electrode with conventional discharge tube with internal electrodes droved by pulsed discharge has achieved 90 lm/W and 12000cd/m^2. Another effort is using molecular gas as discharge medium. For example Ar-N_2 mixture and CO are proposed.

DOI： 10.1585/jspf.81.807

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Language：Japanese   Publisher：The Illuminating Engineering Institute of Japan  

Now the low pressure mercury-argon(Hg-Ar) fluorescent lamp is widely used because of high luminance and high efficiency. But there is lack of data of radial structure of the discharge. Besides, the fact that this structure changes with the operating conditions also affects the distributions of the Hg excited states and hence the UV efficiency of the lamp. This study is aimed at investigating the radial variations of the properties of a DC Hg-Ar discharge by devising a one dimensional collisional-radiative lamp model.

DOI： 10.11515/ieijac.38.0.23.0

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In these days, there are strong needs to reduce harmful mercury used for light sources. We have been developing mercury-free fluorescent lamps using xenon. In this study, we have investigated characteristics of the xenon fluorescent lamps which have an internal and an external electrodes by changing the shape of the electrodes and how to set them. It is shown that luminance is improved by enhancing ionization by thin inner electrode, or increasing the capacitance between electrodes by increasing the pitch of wound external electrode. © 2005, The Institute of Electrical Engineers of Japan. All rights reserved.

DOI： 10.1541/ieejfms.125.434

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The influence of change of power supply frequency on luminance and luminance flux of electroderess discharge lamp with inductively coupled plasma is measured. As power supply frequency is increased time derivatire of magnetic field increases, and then higher vortex current is obtained. Thus ionization collision rate increases, and produced ions and electrons increase. As a result luminance and flux rise. In addition as power supply frequency is increased, skin depth become narrower, supplied power from coil current to the plasma increases. Thus threshold value of the input power when the mode jump from E-mode to H-mode occurs becomes small.

DOI： 10.11515/ieijac.38.0.26.0

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Xenon emits strong radiation in the ultra-violet (UV) region and hence is one of the most promising candidates as an alternative to mercury. Nevertheless, the efficiency with which UV radiation is emitted from a xenon discharge is in general lower than that of mercury. Besides, the positive column of a xenon discharge tends to contract at high current density and the intensity of the phosphor-converted emissions from a contracted discharge is very low. In this study, the relations between the contraction process and the pulse width used in the pulsed discharge are discussed. Moreover, two pairs of electrodes are placed in a xenon fluorescent lamp so that the positive column in a diffused state occupies a larger volume for improving the luminance and the efficiency. The lamps were sustained by pulsed discharge. In the diffused state, as the current was gradually increased, the contraction of the,positive column occurred at a specific value. Under all conditions, the luminous intensity of the phosphor-converted emissions reached a maximum prior to the transition of the state of discharge from diffused to contracted. When the pulse width was decreased, the luminance and efficiency of the lamps of any electrode types increased. However, the energy consumed from the turn-on of the current pulse to its peak did not vary as the pulse width was varied. This shows that narrow pulse width is preferred for improving the luminance as a higher current density is attained before the positive column becomes contracted. In fact, the measured current peaks at which the positive column entered a contracted state are increased by decreasing the pulse width. At narrow pulse widths, the maximum luminance was 3000 cd/m2 obtained at a pulse repetition frequency of 17 kHz and a pulse width of 1 μs for the lamp with a single pair of electrodes, whereas 5000 cd/m2 was obtained for the lamp with two pairs of electrodes. However, the efficiency decreased from 65 lm/W to 30 lm/W by increasing the number of electrodes. In general, the contraction of the positive column in rare gas discharges at higher current density causes non-linear process in the plasma such as step-wise ionization. The results shows that the energy consumption mentioned above limits the excitation and ionization processes in xenon fluorescent lamps. More detailed discussions about the mechanism of these processes are presented in the full paper and at the conference.

Scopus

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Language：Japanese   Publisher：The Illuminating Engineering Institute of Japan (IEIJ)  

CiNii Books

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Language：Japanese  

J-GLOBAL

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Language：Japanese  

J-GLOBAL

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Language：English   Publisher：愛媛大学工学部  

CiNii Books

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Publisher：The Illuminating Engineering Institute of Japan  

In this research, the radiative characteristics of noble of mercury-less lamp, which has a pair of internal and external electrodes, were measured. I measured the voltage, the current, the input power and the luminance, when the negative polarity voltage pulse was applied to these types of lamps the frequency of 10 to 60 kHz. Both the luminous and the efficacy of the lamp with an internal electrode was larger than that of the lamp without an internal electrode. This result is due to the wider area though which more emission luminous flux come out without protection by external electrode. From now on, the optimisation of the conditions such as the voltage waveform, the filling gas and pressure is necessary for higher efficacy.

DOI： 10.11515/ieijac.36.0.15.0

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Language：Japanese  

J-GLOBAL

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Language：Japanese  

CiNii Books

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Publisher：The Illuminating Engineering Institute of Japan  

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Language：Japanese   Publisher：The Illuminating Engineering Institute of Japan (IEIJ)  

CiNii Books

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Language：Japanese  

CiNii Books

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Language：Japanese  

CiNii Books

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Language：Japanese  

CiNii Books

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Language：Japanese   Publisher：The Illuminating Engineering Institute of Japan (IEIJ)  

CiNii Books

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Language：Japanese   Publisher：The Illuminating Engineering Institute of Japan (IEIJ)  

CiNii Books

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J-GLOBAL

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Event date： 2023.3

Language：English   Presentation type：Poster presentation  

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Event date： 2022.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2022.9

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Event date： 2021.10

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Event date： 2021.7

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Event date： 2021.5

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Event date： 2021.3

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Event date： 2020.12

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Event date： 2020.9

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Event date： 2020.9

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Event date： 2020.3

Language：Japanese   Presentation type：Symposium, workshop panel (nominated)  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Sapporo  

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Venue：Saitama  

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Venue：Sapporo  

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Venue：Sapporo  

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Venue：Boston, USA  

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Venue：Tokyo  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Tokyo  

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Venue：Boston, USA  

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Venue：Fukuoka  

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Venue：Fukuoka  

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Venue：Nagoya  

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Venue：Nagoya  

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Venue：Hiratsuka  

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Venue：Hiratsuka  

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Language：Japanese  

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Language：Japanese  

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Language：English   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：English   Presentation type：Poster presentation  

Venue：Bratislave, Slovakia  

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Language：English   Presentation type：Oral presentation (general)  

Venue：Bratislave, Slovakia  

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Language：English   Presentation type：Oral presentation (general)  

Venue：Kyoto  

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Language：English   Presentation type：Poster presentation  

Venue：Kyoto  

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Language：English   Presentation type：Poster presentation  

Venue：Kyoto  

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Venue：Kyoto  

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Venue：Kyoto  

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Venue：Kyoto  

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Venue：Bochum, Germany  

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Language：Japanese   Presentation type：Poster presentation  

Venue：Niigata, Japan  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：English   Presentation type：Poster presentation  

Venue：Bratislave, Slovakia  

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Language：English   Presentation type：Poster presentation  

Venue：Bratislave, Slovakia  

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Language：English   Presentation type：Poster presentation  

Venue：Bratislave, Slovakia  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Niigata, Japan  

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Language：English   Presentation type：Poster presentation  

Venue：Bratislave, Slovakia  

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Language：Japanese   Presentation type：Poster presentation  

Venue：Niigata, Japan  

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Language：Japanese   Presentation type：Poster presentation  

Venue：Niigata, Japan  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Hiratsuka  

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Language：English   Presentation type：Oral presentation (general)