Atmospheric Pressure Argon Plasma Jets I -Measurements of Spatial Distribution for Visible Emission Spectrum and Vacuum Ultraviolet-

大気圧アルゴンプラズマジェットI -可視域発光スペクトルと真空紫外光の空間分布測定-

IEEJ Transactions on Fundamentals and Materials

電気学会論文誌A (基礎・材料・共通部門誌)


Experiment and Calculation of Amount of Ozone Decomposition in Stainless-Steel Pipe

ステンレス鋼パイプ中のオゾン消滅量の実験と計算

Measurements of ozone concentrations at the inlet and outlet of the ozone destructor were carried out proving the thermal decomposition of ozone produced in the ozone generator. The destructor was employed to simulate the ozone zero phenomena (OZP) in an ozone generator, thus which was separated functionally from the ozone source in the ozone generator. It was found that the thermal decomposition of ozone starts around 453 K, and the decrease of ozone concentration similar to OZP occurs at higher temperatures. In this paper, we report that the thermal decomposition of ozone is promoted by increasing the mixing ratio of oxygen atom O contained in the ozonized gas, based on a simple calculation using our measured basic coefficients.

電気学会論文誌A (基礎・材料・共通部門誌)


Advancement of ozone zero phenomenon by surface deterioration of stainless-steel electrode


Nanosecond pulsed electric fields induce the integrated stress response via reactive oxygen species-mediated heme-regulated inhibitor (HRI) activation.

The integrated stress response (ISR) is one of the most important cytoprotective mechanisms and is integrated by phosphorylation of the α subunit of eukaryotic translation initiation factor 2 (eIF2α). Four eIF2α kinases, heme-regulated inhibitor (HRI), double-stranded RNA-dependent protein kinase (PKR), PKR-like endoplasmic reticulum kinase (PERK), and general control nonderepressible 2 (GCN2), are activated in response to several stress conditions. We previously reported that nanosecond pulsed electric fields (nsPEFs) are a potential therapeutic tool for ISR activation. In this study, we examined which eIF2α kinase is activated by nsPEF treatment. To assess the responsible eIF2α kinase, we used previously established eIF2α kinase quadruple knockout (4KO) and single eIF2α kinase-rescued 4KO mouse embryonic fibroblast (MEF) cells. nsPEFs 70 ns in duration with 30 kV/cm electric fields caused eIF2α phosphorylation in wild-type (WT) MEF cells. On the other hand, nsPEF-induced eIF2α phosphorylation was completely abolished in 4KO MEF cells and was recovered by HRI overexpression. CM-H2DCFDA staining showed that nsPEFs generated reactive oxygen species (ROS), which activated HRI. nsPEF-induced eIF2α phosphorylation was blocked by treatment with the ROS scavenger N-acetyl-L-cysteine (NAC). Our results indicate that the eIF2α kinase HRI is responsible for nsPEF-induced ISR activation and is activated by nsPEF-generated ROS.


Decolorization of indigo carmine solution by argon dielectric barrier discharge produced on liquid surface


Fundamental Investigation of Streamer Discharges in Coaxial Reactor for NOx Treatment Using Nanosecond Pulsed Power


Re-evaluation of rate coefficients for ozone decomposition by oxygen in wide range of gas pressures (20-1000 Torr) and temperatures (293-423 K)


Introduction of Tensioned Inner Wire Electrode for NOx Treatment With Nanosecond Pulsed Power System


Ozone Production by Streamer Discharges Using Nanosecond Pulsed Powers and Coaxial Reactor With Tensioned Inner Electrode


Surfactant Treatment Using Nanosecond Pulsed Powers and Action of Electric Discharges on Solution Liquid


Indigo carmine solution treatment by nanosecond pulsed power with a dielectric barrier electrode

IEEE Transactions on Dielectrics and Electrical Insulation


Influences of Pulsed Electric Fields on the Gene Expression of Pathogenic Bacteria

病原性細菌の遺伝子発現に対するパルス電界印加の影響に関する研究

電気学会論文誌A (基礎・材料・共通部門誌)


In Vivo Experimental Study of Nanosecond Pulsed Electric Field Effects on Solid Tumors


Effect of Small-diameter Coaxial Reactors on Ozone Production Using Nanosecond Pulsed Power


Investigation of Ozone Concentration Measurement by Visible Photo Absorption Method


Nanosecond Pulsed Power Application to Nitrogen Oxides Treatment with Coaxial Reactors


Investigation of Ozone Zero Phenomenon Using New Electrode and Surface Analysis Technique

The European Physical Journal - Applied Physics


容量結合型リアクタを用いたナノ秒パルスパワーによる高濃度オゾン生成の検討

容量結合型リアクタを用いたナノ秒パルスパワーによる高濃度オゾン生成の検討

Journal of The Institute of Engineers on Electrical Discharges in Japan


Self-Organization Phenomenon Observed in Piezoelectric Transformer-Based Excimer Lamp

圧電トランスを用いた誘電体バリア放電型エキシマランプで観測される自己組織化現象

An excimer lamp constructed by a piezoelectric transformer (PT) has been developed and studied in our laboratory. The excimer lamp is based on the excitation of dielectric barrier discharge (DBD) generated by the PT surface that induces high-voltage due to the piezoelectric effect. Spectroscopic measurement in the vacuum ultraviolet (VUV) region is performed for the excimer lamp filling with a He-Xe mixture and Ar. Emission spectra having a peak at 172 and 126 nm are found, which are respectively radiated from the Xe2* and Ar2* excimers that returns to ground states. A self-organization phenomenon (SOP) is also recognized in the He and Ar DBD. Static and time-resolved observations of the self-organized patterns are performed by a single reflex and ICCD cameras, respectively. The formation of self-organized patterns in argon requires a small amount of the air as an additive. From the time-resolved observation, we found dark spots arrayed hexagonally in a weak emission on the PT surface whose arrangement well coincides with that of bright hexagonal filaments. The dark spots are considered as the traces of the accumulated charges on the dielectric electrode, which interrupt the hexagonally filamentary discharges.

IEEJ Transactions on Fundamentals and Materials

電気学会論文誌A (基礎・材料・共通部門誌)


Recent Topics Related to Ozone Generation Technology in Japan


Development of Nanosecond Pulsed Power Generator

ナノ秒パルスパワー電源装置の開発

The Journal of the Institute of Electrical Installation Engineers of Japan


Development of Dielectric Barrier Discharge-Type Ozone Generator Constructed with Piezoelectric Transformers: Effect of Dielectric Electrode Materials on Ozone Generation


Decolorization of Indigo Carmine Solution Using Nanosecond Pulsed Power

IEEE Transactions on Dielectrics and Electrical Insulation


Experimental Investigations of the Ozone Zero Phenomenon


Application of Nanosecond Pulsed Power to Ozone Production by Streamer Corona

A pulsed power generator with a nanosecond pulsewidth has been developed and applied to ozone production. Coaxial reactors connected in parallel are used in the experiment. The system ozone production yield, which is evaluated from the initial energy in the primary storage capacitors, is approximately 190 g/ $hbox{kW}!cdot!hbox{h}$ when dry oxygen is used as the ingredient gas. A four-parallel chamber reactor gives higher concentrations of ozone and higher yields in the experimental conditions. This reactor seems to be most suitable to obtain the proper streamer corona volume and also to match the impedance of the generator. The connection between the generator and the reactor also affects the efficiency.


Self-Organized Patterns of Dielectric-Barrier Discharge Generated by Piezoelectric Transformer


VUV Spectroscopic Measurement for Dielectric Barrier Discharge Excited by Piezoelectric Transformer in He-Xe Mixture


Observation of VUV Emission Spectra from DC Positive Corona Discharge

It has been reported that the experimental investigations on the synchronization probabilities of the two surface streamers in atmospheric air by the authors. This synchronization phenomenon is interpreted by following processes. When an impulse voltage is applied to the parallel connected electrodes, a prior streamer occurs and the propagating streamer emits light. This light passes through the air and reaches the other electrode area. In this area, the initial electrons are supplied by the light and the initial electrons trigger the second streamer. The wavelength region of the light effective for the synchronization was confirmed experimentally. The region was shorter than 250 nm but the detailed wavelength cannot be specified by the experiments. Accordingly, as the first step to specify the effective wavelength, VUV emission spectra from DC positive corona discharges in air are observed together with nitrogen and oxygen gases. Several strong line spectra emitted from the discharges in air are recognized. They are identified that the emission lines of 174 nm, 149 nm and 118 nm are radiated from atomic nitrogen. On the other hand, the emission lines of 120 nm and 130 nm are originated from atomic oxygen. The preliminary experimental results show that these lights are absorbed immediately in air, so on-site photoabsorption measurements were carried out in air. The absorption coefficients of the air are estimated in this study. Even if the wavelength of the light is in the region of VUV, the light can pass through in the air. The facts suggest that the VUV light can pass through long distance in air and the light is effective for the propagation and the synchronization of streamer discharges through the photoelectron emission.

IEEJ Transactions on Fundamentals and Materials


A Compact Excimer Lamp Constructed by Piezoelectric Transformer

A compact excimer lamp constructed with a piezoelectric transformer (PT) has been developed in our laboratory. This excimer lamp is designed based on the excitation of a dielectric barrier discharge (DBD) in a He-Xe mixture generated by the PT, which is driven with low applied voltages of several tens of volts (15-45V). Vacuum ultraviolet (VUV) radiated from the lamp is detected by a phototube having a spectral response region ranging from 160 to 320 nm in conjunction with an optical filter to discriminate the VUV and UV regions. The VUV radiation in the wavelength range 160-200 nm is recognized in this experiment. This may be derived from the 172-nm light emission by the transitions of the Xe_2 excimers to the ground state. Investigations into the radiated VUV intensity are carried out by varying the gas pressure and the gap length. The optimal condition for the present excimer lamp is determined.


Discharge Plasmas Generated by Piezoelectric Transformers and Their Applications


Absolute Measurement of Surface Potential and Discharge Power Distributions for Piezoelectric Transformer-Based Plasma Reactor

A new method for absolute measurement of surface potential distributions on a Rosen-type piezoelectric transformer (PT) was investigated using a sensing electrode proposed in this study. The sensing electrode consists of a dielectric layer having striped back electrodes arrayed in the longitudinal direction of the PT, which is basically similar to the electrode for generating a dielectric barrier discharge (DBD). An equivalent circuit was defined for each striped electrode and a constant in the circuit necessary for the estimations of the absolute surface potential distributions was determined experimentally. The absolute measurements of the surface potential distributions of the PT were performed at $(1/2)ambda $ mode vibration both with and without a potential divider (PD) connected to the secondary terminal. Surface potential distribution without the PD connected, i.e., the unloaded condition of the PT, is in good agreement with the theoretical curve of the surface potential distribution. Moreover, the surface potential distribution while the DBD appears and the discharge power distribution of the DBD generated by the PT was also determined at absolute values using the same electrode configurations.

Japanese Journal of Applied Physics, Part 1 (Regular Papers & Short Notes)


Glow Discharge Around Piezoelectric Transformer Operated Under Higher-order Vibration Modes


Dielectric Barrier Discharge Generated by Piezoelectric Transformer in Atmospheric Pressure


A Novel Generation Method of Dielectric Barrier Discharge and Ozone Production Using a Piezoelectric Transformer

A novel generation method of a dielectric barrier discharge (DBD) using a piezoelectric transformer (PT) is proposed. Spatio-temporal variations of microdischarges were investigated and discussed on the basis of the observations using a charge-coupled device (CCD) camera. As an example of a practical application of the DBD to a plasma reactor, an ozonizer using the PT was developed and ozone productions were performed in air and oxygen. Maximum ozone concentrations of 3.38 and 20.3 g/Nm3 were obtained in air and oxygen, respectively. The ozonizer can be designed in a compact configuration and driven with low applied voltages because the PT serves as both a high-voltage generator and a discharge electrode.


Luminescence from Fluorescent Material Excited by Piezoelectric Transformer

This paper describes a luminous phenomenon of fluorescent materials excited by a piezoelectric transformer (PT). Light emission from fluorescent materials is observed together with N_2 discharge in a chamber. The fluorescent materials may be excited by ultraviolet (UV) light which is emitted from the N_2 discharge or fast electrons accelerated in high electric field generated by the PT. To clarify the excitation source of the fluorescent materials, emission spectra of the two kinds of phosphors, ZnO:Zn and ZnS:Cu,Au, in the N_2 discharge and the gas pressure dependence are examined. Temporal variations of both light emissions are observed using a charged couple device (CCD) camera to investigate the dynamic behavior of the luminous phenomenon. As a result, it is found that ZnO:Zn is excited by fast electrons under low-pressure conditions. ZnS:Cu,Au is excited by UV light from 315 to 479 nm because the wavelength region is in good agreement with the excitation spectrum for ZnS:Cu,Au. The excitation process of fluorescent materials is clarified in this study.


Observation of Light Emission in Silent Discharge Using Piezoelectric Transformer

圧電トランスを用いた無声放電の発光状態の観測

The Transactions of The Institute of Electrical Engineers of Japan


Observation of Light Emissions Around a Piezoelectric Transformer in Various Gases


Dynamic Behavior of Light Emissions Generated by Piezoelectric Transformers


圧電トランスを用いた蛍光板と放電の発光

圧電トランスを用いた蛍光板と放電の発光

Journal of The Institute of Engineers on Electrical Discharges in Japan


Luminous Phenomenon of Silent Discharge Using a Piezoelectric Transformer


Introduction of Embryonic Chick Assay on Experiment Applying Nanosecond Pulse Electric Fields on Solid Tumor

Embryonic chick assay was introduced as a biological method for an experiment to apply a nanosecond pulse electric field on a tumor. Embryonic chick assay allowed many in vivo tests. Pulsed electric fields were applied on a solid tumor of the mouse breast adenocarcinoma cell, EMT6/KU, which was formed on the chorioallantoic membrane. We found that average weight of solid tumors applied pulsed electric fields was significantly smaller than that of controls.

IEEJ Transactions on Fundamentals and Materials


Pulsed Discharge in Helium and Nitrogen Bubbles in Humate Solution


Observational Study of Appearance of Streamer and Spark Discharges to Design Chemical Reactor Using Nanosecond Pulsed Power


Time-Resolved Observation of Self-Organized Filaments Formed in a Helium-Dielectric Barrier Discharge


誘電体電極上の蓄積電荷により誘起されるDBDの自己組織化現象

誘電体電極上の蓄積電荷により誘起されるDBDの自己組織化現象

Regularly arrayed patterns of microdischarge light in dielectric barrier discharge (DBD) and dark spots surrounding glow-like discharge on the dielectric electrode are found in the self-organization phenomenon (SOP). The discharge is generated using a piezoelectric transformer (PT) in the Ar/air mixture. Time-resolved images are captured with an ICCD camera during one cycle of a sinusoidal applied voltage and the voltage-current waveforms are recorded using an oscilloscope. The observed dark spots are the traces of the accumulated charges by the DBD on the dielectric electrode and are considered as the sources of initial charges that induce the next microdischarge development, resulting in the hexagonally-arranged discharge spots.

電気学会論文誌A (基礎・材料・共通部門誌)