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

The presence of obstacles on expressways often results in major traffic accidents. Therefore, ensuring the visibility of obstacles on roads is an important factor for maintaining a safe and comfortable visual driving environment. The visibility of obstacles on road, especially in tunnels, is related to the lighting environment. In this study, we have proposed two lighting-control methods and evaluated the visibility of obstacles under a combination of light-distribution control and lighting-time control and a combination of light-distribution control and color-temperature control. Further, we evaluated the effectiveness of these two lighting-control methods and obtained good visibility by combining the pro-beam lighting operated using direct current (DC) and symmetric lighting operated by pulses having a frequency of 60 Hz and a duty ratio of 50%. The visibility can be effectively improved by increasing the luminous contrast between the background road surface and the object. In addition, when lighting-time control was applied, temporal luminance contrast was achieved, and the perceived luminance was enhanced by the pulse (Broca–Sulzer effect), thereby improving the visibility. Further, the visibility can be improved by changing the color temperature with the light-distribution angle because of the difference in chromaticity between the background road surface and the object.

DOI： 10.2150/jstl.IEIJ170000620

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The authors introduce LED tunnel illumination for improving the vertical illuminance by considering the light as vectors when designing the light distribution. This new illuminating devices installed and evaluated the visibility of the road at Hanzan Tunnel for the down line of Takamatsu Expressway. As the result, the vertical illuminance is improved by 40% when increasing the ratio of vector component of light by using the Pro-bean. Actually, according to the questionnaire result of subjects who had a driver’s licence were different by gender, ages and driving experience, by increasing the vertical illuminance the visibility of the leading vehicle are improved significantly. Therefore, it is expected that the Pro-Beam illumination for improving the visibility by increasing the vertical illuminance is effective in reducing traffic accidents in tunnel.

DOI： 10.2150/jstl.IEIJ140000551

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

DOI： 10.25039/x46.2019.PO175

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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 (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 Te temperatures, and densities of charged particles.

DOI： 10.1615/plasmamed.2018019247

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© 2017 by Begell House, Inc. We investigated on the mechanism of plasma gene transfection. It is suggested that reactive oxygen species (ROS) directly or indirectly acts on endocytosis for gene transfection. The intracellular Ca2+ concentration was increased by plasma irradiation, and it was confirmed there is some kind of relationship between ROS and release of the intracellular Ca2+. It is clear that ROS are the most important chemical factors in plasma gene transfection and that Ca2+ is not a dominant factor but a subsidiary or consequential factor. Our studies also confirmed that the transfer mechanism for low molecular weight substances, such as YOYO-1, is different from the mechanism for molecules of higher weight, such as plasmid DNA. In the case of larger molecules, ROS play an important role by inducing endocytosis in plasma gene transfection. But in the case of smaller molecules, neither ROS nor ROS-dependent endocytosis is dominant. Some kind of “endocytosis-independent and ROS-free” transfer processes may exist for smaller molecules to be transferred into cells by plasm irradiation. To discuss the mechanism of micro-plasma gene transfection, it is important to note that the transfer mechanism is different for substances of different molecular sizes.

DOI： 10.1615/plasmamed.2018019510

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

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  

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  

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

DOI： 10.4236/opj.2016.61002

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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：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 (scientific journal)   Publisher：NATO Science for Peace and Security Series A: Chemistry and Biology  

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  

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  

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：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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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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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 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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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)   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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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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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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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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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 1.3 kPa 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.

DOI： 10.2150/jlve.30.81

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

In this paper we demonstrate the influence of buffer gas atoms on the emission spectrum of a lowpressure 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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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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Language：English   Publisher：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 9500cd/m^2 but estimated efficacy at a positive column is decreased from 68.0lm/W to 45.6lm/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：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 13.56MHz 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 100W. 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   Publisher：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：The Japan Society of Plasma Science and Nuclear Fusion Research  

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/m². Another effort is using molecular gas as discharge medium. For example Ar-N₂ mixture and CO are proposed.

DOI： 10.1585/jspf.81.807

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Other Link： http://dl.ndl.go.jp/info:ndljp/pid/10456072

Language：Japanese   Publisher：The Japan Society of Plasma Science and Nuclear Fusion Research  

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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Other Link： http://dl.ndl.go.jp/info:ndljp/pid/10456070

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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Language：Japanese   Publisher：The Institute of Electrical Engineers of Japan  

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 10μs 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.

DOI： 10.1541/ieejfms.125.669

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Language：Japanese   Publisher：The Institute of Electrical Engineers of Japan  

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.

DOI： 10.1541/ieejfms.125.521

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Language：Japanese   Publisher：The Institute of Electrical Engineers of Japan  

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 5lm/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.

DOI： 10.1541/ieejfms.125.447

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Language：Japanese   Publisher：The Institute of Electrical Engineers of Japan  

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.

DOI： 10.1541/ieejfms.125.229

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Language：Japanese   Publisher：The Institute of Electrical Engineers of Japan  

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.

DOI： 10.1541/ieejfms.125.235

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

A dynamic collisional-radiative model of a low-pressure mercury (Hg)-argon (Ar) discharge lamp for application in circuit simulations is presented. The model is implemented in MATLAB as a set of coupled rate equations that are solved simultaneously to give the electron density, the density of the 6(3)P(0,1,2) states and the electron temperature. These parameters are used to compute the electrical parameters of the discharge positive column and hence the time-dependent voltage-current characteristics of the lamp. The parameters predicted by the model are compared with published experimental data and show good agreement. Calculated lamp voltage-current characteristics based on the model are shown to be in good agreement with direct measurements on commercial fluorescent lamps.

DOI： 10.1109/TPEL.2004.830071

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In this paper, we explain the physical reasons for the enhancement of near-UV and visible emissions from a low-pressure mercury-argon discharge under pulse drive conditions. The conditions of operation that maximize the enhancement of near-UV and visible radiation, including the effect of the buffer gas, are investigated. We show that for a pulsed discharge, electron-ion recombination followed by cascade radiative transitions is the process responsible for most of the 365 nm emission and that argon with a small admixture of krypton is the buffer gas composition that leads to maximum radiative emission due to near-resonant energy transfers to mercury high-lying levels.

DOI： 10.1088/0022-3727/37/12/007

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Language：Japanese   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   Publisher：The Illuminating Engineering Institute of Japan  

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 the proposed ballast, the switching element of the half-bridge inverter works as a buck-boost converter, eliminating the need for a PFC circuit. Even though it has fewer operating parts, the proposed ballast still reduces the number of harmonic components in the input current to below that specified by IEC Standard 61000-3-2 for Class C equipment.

DOI： 10.2150/jieij1980.86.2_92

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The characteristics of xenon-neon discharge fluorescent lamps with inner electrodes and of xenon discharge lamps with external electrodes are described in this paper.All these lamps were operated at pulsed discharge.In the case of inner electrode type, when the partial pressure of neon is high, the ignition voltage is low because of the Penning effect.Then, the high mixing ratio of neon is desirable for the lower ignition voltage.However, the luminance of phosphor increases as the mixing ratio of xenon increases.Therefore, in order to obtain high luminance, xenon should be filled at high mixing ratio.In both cases, that is, inner electrode type and external electrode type, as the pressure of xenon increases, the afterglow peak of phosphor emission increases.These increases seem to be caused by the VUV radiation of xenon excimers.The emission of light from phosphor shows that xenon excimers are generated effectively by pulsed discharge of high pressure xenon, because they are generated by three-body collision at the low electron temperature T_e during the non-discharge period.

DOI： 10.2150/jlve.24.1_29

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PHYSICS ACAD SCI CZECH REPUBLIC  

High Intensity Discharge (HID) lamps are difficult to re-ignite rapidly because of the high pressure of metal vapor at high temperatures. We have succeeded in reducing the re-ignition time of high-pressure mercury lamps by using a pre-ionization stop where an excess of electrons are generated by UV laser irradiation into the lamp. The effect of changing the laser focal point of the UV laser in the lamp and the position of an auxiliary electrode were also investigated. The time interval for re-ignition was reduced from 230 s to 100s by laser irradiation near to the cathode, The results clearly showed that the effect of accelerating the re-ignition time by the pre-ionization step was determined by the behavior of excess electrons generated during the UV laser irradiation.

DOI： 10.1007/BF03165931

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PHYSICS ACAD SCI CZECH REPUBLIC  

In this study, the spectroscopic characteristics of radiations from xenon pulsed plasma are measured experimentally as a study on a mercury-free fluorescent lamp. Each radiation waveform. has two peaks and they vary according to the inner diameter of lamp and the pressure of xenon as follows: (a) As the inner diameter of lamps increases, the afterglow radiation, that is the second peak, decays faster. (b) As the xenon pressure increases the first peak of radiation just after the start of discharge decreases and the afterglow increases. The characteristics of afterglow are explained by the rate equation of metastable xenon atoms Xe-m, and its coefficients are determined through the experimental results. This equation shows that in order to obtain intense phosphor afterglow, i.e. strong radiation of xenon excimer, high pressure of xenon and large lamp diameter are desirable. Moreover, high pressure of xenon brings fast decay of afterglow. Then the afterglow radiation has no overlap on the first peak of next discharge at a high frequency. Consequently, higher pressure of xenon and large lamp diameter are desirable for high intensity and high efficacy for xenon fluorescent lamps.

DOI： 10.1007/bf03165923

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Cold cathode discharge lamps are usually operated with a capacitor ballast, and are supplied by a high-frequency sinusoidal voltage. At some frequencies of the supply voltage, the current waveform of the positive period differs from that of the negative one and the luminance of the lamp is lower than when the current waveform is symmetrical. In an asymmetrical waveform, the current waveform in one half-cycle is pulse-like with a high peak and the waveform in another half cycle has a low amplitude. We calculated the equation of a simple equivalent circuit, and found that the discharge current consists of a sinusoidal steady component and a transient pulse component which increases as the delay time for re-ignition increases. The asymmetrical waveform of the discharge current occurs when the supply voltage, the operating frequency, the lamp diameter, or the capacitance of the ballast is decreased. Since decreasing the value of those parameters increases the delay time for re-ignition in one half-cycle, the re-ignition voltage drops and the delay time for re-ignition becomes shorter in the other half-cycle. Copyright © 2007 The Illuminating Engineering Institute of Japan.

DOI： 10.2150/jlve.24.1_19

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Applied Physics  

The characteristics of electrodeless xenon discharge fluorescent lamps using dielectric barrier discharge are described in this paper. All lamps were operated with pulsed discharge. The luminance of phosphor increases as the pressure of xenon increases. As the pressure of xenon increases, the second peak of phosphor emission increases. These increases seem to be caused by the VUV light of xenon excimers. Therefore, in order to obtain high luminance, xenon should be filled at high pressure. In the case of the lamp operated by inner electrodes, if only xenon is contained in the lamp, the cathode is bombarded and is damaged by the large mass of a xenon ion. On the other hand, the external electrode type is never damaged by the ions or electrons. Moreover, the efficacy of the external electrode type is as great as the inner electrode type, and it can be improved by increasing the distance between electrodes.

DOI： 10.1143/jjap.38.4613

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Applied Physics  

The delay time of discharge triggered by a laser-produced plasma is investigated in a mixture of oxygen and nitrogen. When oxygen exists in the mixture, the delay time of discharge has two styles of “late discharge” and “early discharge”. The delay time of “late discharge” agrees with the transit time of oxygen negative ions between electrodes. The delay time of “early discharge” approaches the transit time of electrons between electrodes as the applied voltage between the electrodes increases. There exists a threshold voltage at which the delay time leaps from “late discharge” to “early discharge”. Calculation of the electron detachment cross section reveals that the leap of the delay time is caused by changing of negative particle triggering discharge from oxygen negative ions to electrons due to an increase in electron detachment as the applied voltage becomes higher.

DOI： 10.1143/JJAP.36.2870

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DOI： 10.1143/JJAP.38.4608

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DOI： 10.2150/jieij1980.81.5_457

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Language：Japanese   Publisher：The Institute of Electrical Engineers of Japan  

This paper describes the experiment of plasma formation and heating in the open air by superpotion of microwave and XeCl excimer laser beam as a fundamental study for Laser Triggering of Lightning. This experiment shows that a plasma can be formed by superposition of XeCl laser beam and microwave, and that continuous microwave can heat a laser plasma and can make it steady-state and big.<br>By superposing microwave on XeCl laser, the threshold value of XeCl laser energy for plasma formation is reduced to 20%. On the other hand, by superposing XeCl laser beam on microwave, the required power of microwave for plasma formation is reduced to 8%. Thus, superposition of XeCl laser and microwave will work effective for plasma formation and for triggering of lightning.

DOI： 10.1541/ieejfms1990.116.5_446

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DOI： 10.1541/ieejfms1990.116.7_657

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DOI： 10.1541/ieejfms1990.116.7_657

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DOI： 10.1541/ieejfms1990.116.5_446

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This paper describes the experiment triggering and guiding discharge by weak ionized channel produced by XeCl excimer laser as fundamental study for Laser Triggering of Lightning. In this experiment it was shown that XeCl excimer laser can make weak ionized channel on its light path and that CO₂ laser can't make it. This weak ionized channel can guide discharge path. In order to guide discharge path, electron density required to be higher than 1.1&times;1016m-3. This is about only 0.05% of the density required for triggering of discharge by an air breakdown plasma.<br>By using both the weak ionized channel produced by XeCl excimer laser and the air breakdown plasma heated by CO₂ laser, the flashover voltage is lowered and the guided length of discharge becomes longer than those of using only XeCl excimer laser. Combining air breakdown plasma and weak ionized channel by using different wavelength laser beams, for example UV laser and IR laser, will work effective for plasma formation, triggering of lightning and guiding a lightning path.

DOI： 10.1541/ieejfms1990.115.7_595

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DOI： 10.1541/ieejfms.139.NL7_8

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DOI： 10.11470/jsapmeeting.2018.2.0_1795

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DOI： 10.11470/jsapmeeting.2018.2.0_1792

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DOI： 10.11470/jsapmeeting.2018.1.0_1927

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Language：Japanese   Publisher：電気学会  

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Language：Japanese   Publisher：電気学会  

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J-GLOBAL

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J-GLOBAL

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Language：Japanese   Publisher：照明学会  

CiNii Books

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Language：Japanese   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2017.1.0_1794

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Language：Japanese   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2017.1.0_1796

CiNii Research

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Language：Japanese   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2017.1.0_1790

CiNii Research

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J-GLOBAL

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Language：Japanese   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2017.1.0_1783

CiNii Research

J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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Language：Japanese   Publisher：照明学会  

CiNii Books

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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CiNii Books

J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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

2002年に筆者らにより発見されたプラズマ遺伝子導入法は,遺伝子導入効率と細胞生存率の両立が難しくまた不安定で再現性が低かったが,その後の改良でプラズマを極小化し空間的および時間的な揺動の影響を限定することで大きく性能が改善された.本章ではまず,従来の遺伝子導入法とそれに対するプラズマ法の長所と短所,プラズマ法の課題を紹介し,続いて,各々の研究者のデータを比較する際には導入効率の単純比較をしてはならず,導入物質の分子量と構造を考慮しなければならないことを実験データを基に説明する.次いで標的細胞と導入プラスミドを揃え導入効率と細胞生存率を生成法の異なるプラズマ間で比較した結果,およびプラズマの極小化により性能改善ができた理由を説明した後,プラズマ遺伝子導入法の機序について現在までに判明していることを説明する.

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Other Link： http://dl.ndl.go.jp/info:ndljp/pid/10459732

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J-GLOBAL

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Language：Japanese   Publisher：照明学会  

CiNii Books

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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Language：Japanese   Publisher：電気学会  

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Language：Japanese   Publisher：電気学会  

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CiNii Research

J-GLOBAL

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

CiNii Books

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

CiNii Books

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Language：English   Publisher：The Illuminating Engineering Institute of Japan  

DOI： 10.2150/jlve.IEIJ14A000004

Scopus

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DOI： 10.2150/jlve.IEIJ13A000106

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Language：Japanese   Publisher：(公社)日本生化学会  

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CiNii Books

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CiNii Books

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Language：Japanese   Publisher：The Illuminating Engineering Institute of Japan  

The 44th annual conference will be held in Ehime University from 15th to 17th September 2011. The venue is in Shikoku and the city Matsuyama is famous of hot spring "Dogo-Onsen" and of the birth place of Akiyama brothers who brought the win of Russo-Japanese war to Japan. In this special issue lighting in Shikoku, especially light up, is described and the background and efforts in new style of annual conference are explained.

DOI： 10.2150/jieij.95.354

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