Global model for flashover phenomena in vacuum: A comprehensive perspectiveGuan-Jun Zhang; Guang-Yu Sun; Bai-Peng Song; Andreas Neuber; Yasushi Yamano
Journal of Applied Physics,
Volume：137,
Number：10, Mar. 2025,
[Reviewed]Flashover is an electrical breakdown along the dielectric-gas/vacuum/liquid interface under high electric field excitation. Surface flashover phenomena in vacuum greatly impede a variety of vacuum insulation devices and systems. Here, a comprehensive perspective of the vacuum flashover global model is provided to integrate existing understandings and highlight featured prospects of the flashover mechanisms, mitigation approaches, and applications. An overview of physical processes involved in the entire vacuum flashover process is first given. Recent advances and perspectives for the understanding of these processes are then discussed separately, including the surface discharge above dielectric, and the charge transport and breakdown within dielectric bulk and surface layer. Scaling laws and empirical formulas for flashover threshold prediction are assessed as well. The mechanisms of recent vacuum flashover mitigation approaches are analyzed, such as using physical structures and geometrical modifications, material-based approaches, and applying external electromagnetic field, and possible novel flashover mitigation methods are predicted. In addition, potential applications using vacuum flashover are discussed. Finally, promising research topics, imminent challenges, and open questions of the vacuum flashover studies are presented. It might be instructive for the fundamental and application research studies of surface flashover in vacuum in future.
AIP Publishing, English, Scientific journal
DOI：https://doi.org/10.1063/5.0255764DOI ID：10.1063/5.0255764,
ISSN：0021-8979,
eISSN：1089-7550 Relaxation of Electric Field by Covering Cathode Edge With Vanadate GlassSouichi Katagiri; Tatsuya Miyake; Takashi Naito; Hiroshi Morita; Yasushi Yamano
IEEE Transactions on Plasma Science,
Volume：52,
Number：9,
First page：4390,
Last page：4395, Sep. 2024,
[Reviewed]Institute of Electrical and Electronics Engineers (IEEE), English, Scientific journal
DOI：https://doi.org/10.1109/tps.2024.3396468DOI ID：10.1109/tps.2024.3396468,
ISSN：0093-3813,
eISSN：1939-9375 Triple Junction as a Weak Point of Electrical InsulationYasushi YAMANO
The Journal of The Institute of Electrical Engineers of Japan,
Volume：144,
Number：4,
First page：213,
Last page：216, Apr. 2024,
[Invited],
[Lead]Institute of Electrical Engineers of Japan (IEE Japan), Japanese, Scientific journal
DOI：https://doi.org/10.1541/ieejjournal.144.213DOI ID：10.1541/ieejjournal.144.213,
ISSN：1340-5551,
eISSN：1881-4190 Internal State of Fuse Arc Differentiating Interruption Success and Failure in Fuse‐SemiconductorDCCircuit BreakerYuta Miyaoka; Mitsuaki Maeyama; Yasushi Yamano; Yuki Inada
IEEJ Transactions on Electrical and Electronic Engineering,
Volume：19,
Number：1,
First page：41,
Last page：50, Oct. 2023,
[Reviewed]For the realization of sustainable society installing renewable energy sources, we have proposed a compact, low‐cost, versatile DC circuit breaker that combines a fuse and a power semiconductor. However, even under the same interruption conditions, there are cases where the interruption success and failure are observed probabilistically; the reason for this is still unknown. In the interruption failure, thermal reignition of an arc discharge occurs inside the fuse under transient recovery voltage. In this study, the spatiotemporal dynamics of the fuse arc was diagnosed for both interruption success and failure by a voltage–current waveform recording, high‐speed arc‐emission videography and borescope‐integrated optical emission spectroscopy, in order to identify the difference between the interruption success and failure. The waveform recording and videography demonstrated that at the arc initiation inside the fuse, the radial arc length for the interruption failure was longer than the interruption success. In the current interruption phase, the radial arc length was still longer, axial arc length was shorter, and arc column resistance was lower for the interruption failure. Further, the optical emission spectroscopy showed that localized regions with higher temperature and electrical conductivity existed for the failure in the current interruption phase. From these results, the dominant factors differentiating interruption success and failure were identified as the arc shape and electrical conductivity of the arc. To improve the interruption performance of the fuse and our DC circuit breaker, it is effective to increase the axial arc length, suppress the radial arc length, and reduce the electrical conductivity of the arc. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.
Wiley, English, Scientific journal
DOI：https://doi.org/10.1002/tee.23928DOI ID：10.1002/tee.23928,
ISSN：1931-4973,
eISSN：1931-4981 Spatiotemporal evolution of electrical conductivity in current-limiting-fuse arcYuki Inada; Yusuke Fukai; Naoki Takayasu; Yusuke Nakano; Shungo Zen; Wataru Ohnishi; Yasushi Yamano; Mitsuaki Maeyama; Naoto Kodama
Journal of Physics D: Applied Physics,
Volume：56,
Number：50,
First page：505205,
Last page：505205, Oct. 2023,
[Reviewed]Abstract
To improve the interruption capacity of a current-limiting fuse, a detailed diagnosis of the spatial electrical conductivity distribution inside the fuse arc under the current limiting phase around current zero is required, because this distribution determines the distribution of transient recovery voltage inside the fuse. However, well-established methodologies applicable to fuse arcs are lacking, so the spatial distribution remains unknown. This study presents a borescope-integrated spectroscopic system that simultaneously obtains single-shot recordings of the axial distributions of the electron density and arc temperature in the fuse arc just before extinction. Combining the electron densities and arc temperatures, we can identify the fuse arc composition and hence calculate the axial electrical conductivity distribution under the first Chapman–Enskog approximation. The electrical conductivity provided by this systematic methodology includes no large uncertainties, thus demonstrating its superiority against previous estimation methods of the electrical conductivity.
IOP Publishing, English, Scientific journal
DOI：https://doi.org/10.1088/1361-6463/acf9b2DOI ID：10.1088/1361-6463/acf9b2,
ISSN：0022-3727,
eISSN：1361-6463 Conditioning Saturation Diagnosis With Breakdown Electric Field and Breakdown Time in VacuumShimin Li; Yasushi Yamano; Yingsan Geng; Chaohai Zhang
IEEE Transactions on Dielectrics and Electrical Insulation,
Volume：30,
Number：2,
First page：862,
Last page：868, Apr. 2023,
[Reviewed]Institute of Electrical and Electronics Engineers (IEEE), English, Scientific journal
DOI：https://doi.org/10.1109/tdei.2022.3228757DOI ID：10.1109/tdei.2022.3228757,
ISSN：1070-9878,
eISSN：1558-4135 Dependence of Vacuum Electrical Breakdown Field and Field Enhancement Factor on the Number of Apertures Drilled in Small Electrodes Ryo Ishida; Yasushi Yamano; Shinichi Kobayashi; Atsushi Kojima; Masaya Hanada; Yoshio Saito
ELECTRICAL ENGINEERING IN JAPAN,
Volume：196,
Number：3,
First page：3,
Last page：12, Aug. 2016,
[Reviewed]Dark current based on field emission current is considered to be a factor causing the vacuum electrical breakdown between multiaperture acceleration grids in the JT-60 negative ion source. In this paper, we focus on field enhancement factor, which is a key parameter of field emission from the electrode. Vacuum breakdown testing for small-sized electrodes simulating the multiaperture acceleration grids of the negative ion source was performed. We found the field enhancement factor and breakdown field for multiaperture electrodes, and we investigated the dependence of each parameter on the number of apertures. The results revealed that an increase in the average field enhancement factor after the end of conditioning resulting from an increase in the number of apertures led to a decrease in the dielectric strength of the multiaperture electrodes.
WILEY-BLACKWELL, English, Scientific journal
DOI：https://doi.org/10.1002/eej.22842DOI ID：10.1002/eej.22842,
ISSN：0424-7760,
eISSN：1520-6416,
Web of Science ID：WOS:000374692400001 Analysis of Gases Desorbed from Oxygen-Free Copper by Irradiation with Single-Pulsed Electron Beam Hiroki Kaneko; Yasushi Yamano; Shinichi Kobayashi; Yoshio Saito
ELECTRONICS AND COMMUNICATIONS IN JAPAN,
Volume：97,
Number：10,
First page：30,
Last page：37, Oct. 2014,
[Reviewed]Desorbed gases from an anode stimulated by electron irradiation are regarded as one of the causes of vacuum breakdown. To understand vacuum breakdown phenomena, it is important to analyze the composition and quantity of electron-stimulated desorption gases. The single-pulse electron beam irradiation method was developed for detailed analysis of desorbed gas characteristics. It is possible for this method to reduce the modification of surface conditions due to electron beam irradiation, and it makes it possible to measure the transitions of the gas desorption rate from the virgin surface state to a certain period. Using this method, we investigated the desorbed gases from an oxygen-free copper electrode. It was found that electron irradiation caused H-2 gas desorption from the copper electrode and produced conditioning of the gas desorption. A large amount of H-2 gas was desorbed in the initial electron beam irradiation. By analysis of the gas desorbed by irradiation with a single-pulse electron beam, it is possible to observe the change of the gas desorption rate from the virgin surface to a certain number of electron-irradiated surface states. Detailed analysis of the gases desorbed from a sample can be used to evaluate the electrode material in a vacuum. (C) 2014 Wiley Periodicals, Inc.
WILEY-BLACKWELL, English, Scientific journal
DOI：https://doi.org/10.1002/ecj.11575DOI ID：10.1002/ecj.11575,
ISSN：1942-9533,
eISSN：1942-9541,
Web of Science ID：WOS:000341986800005 Dependence of vacuum electrical breakdown field and field enhancement factor on the number of apertures drilled in small electrodes
Ryo Ishida; Yasushi Yamano; Shinichi Kobayashi; Atsushi Kojima; Masaya Hanada; Yoshio Saito
PROCEEDINGS OF THE 2014 26TH INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM (ISDEIV-2014), First page：45, Last page：48, 2014, [Reviewed]
Pre-breakdown current based on field-emission current is regarded as one of factors causing the vacuum electrical breakdown (BD) between the multi-aperture acceleration grids in the JT-60 negative ion source. In this paper, we focused on field enhancement factor beta which is a key parameter of field-emission on the cathode. Vacuum BD tests for small-size electrodes drilled different number of apertures were carried out to investigate the beta and BD field characteristics in the conditioning process of each electrode. Experimental results revealed that the increase of the number of apertures drilled in the electrode causes the increase of beta value, and high beta value reduces the dielectric strength of these electrodes. This result demonstrates that flowing field-emission current between the multi-aperture electrodes causes vacuum BD event.
IEEE, English, International conference proceedings
ISSN：1093-2941, Web of Science ID：WOS:000369858100013
Voltage holding capability of large-size acceleration grid with multiple-apertures and multiple-stage for negative ion source Atsushi Kojima; Masaya Hanada; Takashi Inoue; Yasushi Yamano; Shinichi Kobayashi
Journal of the Vacuum Society of Japan,
Volume：56,
Number：12,
First page：502,
Last page：506, 2013,
[Reviewed]Voltage holding capability of a large negative ion source for fusion application is experimentally examined, which is characterized by multiple-stage acceleration with multiple-apertures over 1000 on large-area grids of 2 m2 for the multiple-beamlet accelerations. From the observation of the vacuum discharge between the grids, it was found that the aperture generated 10 times larger dark current than the flat region and initiated the vacuum discharge associated with the breakdown. As a result, it was found that the sustainable voltages were dominated by not only the surface area but also the number of the apertures. Because these effects were originated in the area effects by weak and strong electric field profiles, these results implied the surface integration of the electric field were the key parameter for the vacuum insulation.
Japanese, Scientific journal
DOI：https://doi.org/10.3131/jvsj2.56.502DOI ID：10.3131/jvsj2.56.502,
ISSN：1882-2398,
SCOPUS ID：84891779702 Basic Research on the Fuse Element Pattern Changing a Current Pathway in the Process of Current Interruption
Masaki Tsuchiya; Yasushi Yamano; Shinichi Kobayashi; Kengo Hirose
2013 2ND INTERNATIONAL CONFERENCE ON ELECTRIC POWER EQUIPMENT - SWITCHING TECHNOLOGY (ICEPE-ST), 2013, [Reviewed]
In recent years, power semiconductor devices are indispensable for electric power control systems. Since their operating voltage and current have been increasing more and more, the accident of the short circuit fault gives rise to the serious damage to not only the semiconductors but also the whole power control systems. Therefore, the protection techniques for the semiconductors are regarded as an important issue. This paper reports new type of etched fuse element pattern which has possibility of improving the current interruption performance. The element of etched fuse is created by chemical etching of copper plated on the ceramic substrate. This etching method enables to form fine structure of the element pattern at the current interruption points. Newly developed fuse element has the network current pathway on the ceramic substrate, and the pathway automatically changes rapidly when the short current flows. We named this fuse Intelligent Fuse. The basic design of the element of the Intelligent Fuse and the results of the interruption test are described. Two kinds of test fuse elements were prepared and the interruption tests were done under the short circuit current of about 30kA and a recovery voltage of about 180V. The result shows that the fault current pathway could be commutated from the ordinary current path by altering the number of the series interruption points. In addition, it is found that this commutation of the current pathway contributed to interruption of fault current.
IEEE, English, International conference proceedings
Web of Science ID：WOS:000355108400092
Relationship between vacuum surface flashover and charging characteristics for alumina ceramics of lowered resistivity
H. Fukuda; Y. Yamano; S. Kobayashi; S. Michizono; Y. Saito; T. Maeda
2013 2ND INTERNATIONAL CONFERENCE ON ELECTRIC POWER EQUIPMENT - SWITCHING TECHNOLOGY (ICEPE-ST), 2013, [Reviewed]
Alumina ceramic is widely used for an insulator of vacuum interrupter. Occurrences of surface flashover along the insulator in vacuum have been a major obstacle to apply the vacuum interrupter for the higher rated voltage class, more than 100kV or further higher voltage. Therefore a superior alumina having high surface flashover voltage performance is required. Such a vacuum flashover occurrence is considered to be related to surface charging on the insulator. To investigate more superior alumina ceramics for high voltage application and clarify the mechanism of the surface flashover phenomena in vacuum, we carried out surface flashover test under negative impulse voltage application to four kinds of alumina in which dielectric constant and resistivity differ, and measured surface charge distribution before and after flashover occurrence. From the results, we revealed that the moderate resistivity could lead to the improvement in flashover voltage.
IEEE, English, International conference proceedings
Web of Science ID：WOS:000355108400075
Measurements of Field Electron Emission Sites Distribution for Oxygen Free Copper Electrodes and Microscopic Observations of Emission Sites KANAI Tomohiro; YAMANO Yasushi; KOBAYASHI Shinichi; SAITO Yoshio
IEEJ Transactions on Fundamentals and Materials,
Volume：132,
Number：11,
First page：958,
Last page：964, Nov. 2012
Electron emission is one of causes leading to electrical breakdown in vacuum. Distributions of field emission sites on a plane electrode before and after current conditioning procedure were investigated by using an Electron Emission Microscope. After the investigation of emission sites distribution, microscopic observation on some of the emission sites were carried out by using an Electron Emission Microscope. The observation revealed that field emission occurs at the foreign particles embedded on the electrode surface. To characterize the emission sites, we observed the absorption current image and analyzed the chemical composition of the emission sites by using an auger electron spectrometer. Observation and analysis suggest that the foreign particle was a semiconducting or insulating material composed of carbon.
The Institute of Electrical Engineers of Japan, Japanese
DOI：https://doi.org/10.1541/ieejfms.132.958DOI ID：10.1541/ieejfms.132.958,
ISSN：0385-4205,
CiNii Articles ID：10031120059,
CiNii Books ID：AN10136312 Analysis of Desorbed Gases from Oxygen-free Copper Stimulated by Irradiation with Single Pulsed Electron Beam KANEKO Hiroki; YAMANO Yasushi; KOBAYASHI Shinichi; SAITO Yoshio
IEEJ Transactions on Fundamentals and Materials,
Volume：132,
Number：11,
First page：951,
Last page：957, Nov. 2012
Desorbed gases from anode stimulated by electron irradiation are regarded as one of causes leading to vacuum breakdown. To understand the vacuum breakdown phenomena, it is important to analyze composition and quantity of electron stimulated desorption gases. Single pulsed electron beam irradiation method was developed for the detailed analysis of the desorbed gas characteristics. It is possible for this method to reduce the modification of surface condition due to electron beam irradiation and enables to measure the transition of gas desorption rate from the virgin surface state to a certain period. Using this method, we investigated the desorbed gases from oxygen-free copper electrode. It was found that electron irradiation caused H
2 gas desorption from copper electrode and the conditioning of the gas desorption. Moreover, a large amount of H
2 gas was desorbed when the first electron beam was irradiated. By using desorbed gases analysis method stimulated by irradiation with single pulsed electron beam, it is possible to observe change of gas desorption rate from virgin surface to a certain number of electron irradiated surface state. Analyzing desorbed gas from the sample in detail can evaluate the electrode material in vacuum.
The Institute of Electrical Engineers of Japan, Japanese
DOI：https://doi.org/10.1541/ieejfms.132.951DOI ID：10.1541/ieejfms.132.951,
ISSN：0385-4205,
CiNii Articles ID：10031120058,
CiNii Books ID：AN10136312 Relationship between Vacuum Surface Flashover and Charging Characteristics for Various kinds of Alumina Ceramics
H. Fukuda; Y. Yamano; S. Kobayashi; S. Michizono; Y. Saito; T. Maeda
25TH INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM (ISDEIV 2012), First page：133, Last page：136, 2012, [Reviewed]
Alumina ceramics is widely used as an insulating material for high voltage devices, because of low outgassing, hardness, low dielectric loss and high bulk breakdown voltage. However, there is serious problem to solve that the flashover voltage along the surface in vacuum is lower than that of a vacuum gap at the same length between electrodes. Many intensive researches have been carried out to improve surface flashover voltage in vacuum. Even so the mechanism of surface flashover is not always clarified yet. One of reason is expected to charging characteristics which depend on the material properties of insulator. In this paper, we focused on the relationship between vacuum flashover characteristics and surface charge caused by high voltage application and surface flashover occurrence for three kinds of alumina ceramics.
IEEE, English, International conference proceedings
ISSN：1093-2941, Web of Science ID：WOS:000315985400036
Vacuum surface flashover characteristics and secondary electron emission characteristics of epoxy resin and FRP insulator Yasushi Yamano; Masahiro Takahashi; Shinichi Kobayashi; Masaya Hanada; Yoshitaka Ikeda
IEEJ Transactions on Fundamentals and Materials,
Volume：130,
Number：12,
First page：3,
Last page：1072, 2010,
[Reviewed]Neutral beam injectors (NBI) used for JT-60 are required to generate negative ions of 500 keV energies. To produce such high-energy ions, the electrostatic accelerators consisting of 3-stage of electrodes and three insulator rings are applied. The insulators are made of Fiberglass Reinforced Plastic (FRP) which is composed of epoxy resin and glass fibers. The surface discharges along the insulators are one of the most serious problems in the development of NBI. To increase the hold-off voltage against surface flashover events, it is necessary to investigate the FRP and epoxy resin insulator properties related to surface discharges in vacuum. This paper describes surface flashover characteristics for epoxy resin, FRP and Alumina samples under vacuum condition. In addition, the measurements of secondary electron emission (SEE) characteristics are also reported. These are important parameters to analyze surface discharge characteristics of insulators in vacuum. © 2010 The Institute of Electrical Engineers of Japan.
Japanese, Scientific journal
DOI：https://doi.org/10.1541/ieejfms.130.1067DOI ID：10.1541/ieejfms.130.1067,
ISSN：0385-4205,
SCOPUS ID：78951483241 Measurement of charged particle current diffused from vacuum arc Masamichi Furesawa; Yasushi Yamano; Shinichi Kobayashi
IEEJ Transactions on Fundamentals and Materials,
Volume：130,
Number：9,
First page：5,
Last page：810, 2010,
[Reviewed]Particles diffused from vacuum arc can be used for thin film formation. Diffusion of particles from vacuum arc influences current breaking properties of a vacuum interrupter. For these application it is essential to clarify the behavior of particles diffused from vacuum arc at around current zero point. In this paper dependence of diffused charged particles current on the crest value of arc current before current interruption point was shown with Faraday cup in case of oxygen-free copper electrodes and CuCr (Cu:Cr=50:50) electrodes. Experimental results were as follows. Ions and electrons diffused from vacuum arc entered into the Faraday cup with pulsive and intermittent states, when vacuum arc of DC 100 A ∼150 A was generated in case of oxygen-free copper electrodes. This phenomenon corresponds to the behavior of cathode spots. Electron current value was about 100 times as large as ion current value. The pulse width is about 1 ∼ 10 μs. When the crest value of arc current were 2,000 A ∼ 10,000 A in case of oxygen-free copper electrodes and CuCr (Cu:Cr=50:50) electrodes, the amount of charged particle current for CuCr before the current interruption point was larger than those for Cu. The ratios of the ion current to the electron current diffused from vacuum arc were calculated by the waveforms of electron and ion currents. The current ratios of 0∼0.02 were taken when the crest value of arc current 2,000 A∼10,000 A. © 2010 The Institute of Electrical Engineers of Japan.
Japanese, Scientific journal
DOI：https://doi.org/10.1541/ieejfms.130.805DOI ID：10.1541/ieejfms.130.805,
ISSN：0385-4205,
SCOPUS ID：78049444015 Effect of Surface Ion Exchange of Machinable Ceramic on Its Flashover Characteristics in Vacuum
Xue-Zeng Huang; Kai-Kun Yu; Guan-Jun Zhang; Nan Zheng; Jie Tian; Guang-Xin Li; Xin-Pei Ma; Yasushi Yamano; Shinichi Kobayashi
ISDEIV 2010: XXIVTH INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM, First page：83, Last page：86, 2010, [Reviewed]
As well known, the surface conditions of solid materials strongly affect the flashover phenomena under high electric field in vacuum. On the basis of the novel low melting temperature machinable glass ceramics for vacuum insulation system, which has excellent machinable performance and good electrical properties, the ion-exchange method was used to change the sample's surface condition, surface electric resistivity and surface trap density. Different alkali metal ions were used in this paper, and this may change the sample's surface microscopic structure. We have measured the different sample's surface flashover in vacuum, and investigated the relationship between the ion-exchange method and sample's surface electricity characteristic. The results indicated that while using suitable ion-exchange method, the sample's surface flashover performance can be improved.
IEEE, English, International conference proceedings
ISSN：1093-2941, Web of Science ID：WOS:000287378600021
Comparison of Surface Charge Distributions under Vacuum and Atmospheric Condition Due to Surface Discharge Events
Yasushi Yamano; Haruki Yamazaki; Shinichi Kobayashi; Yoshio Saito; Guan-jun Zhang
ISDEIV 2010: XXIVTH INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM, First page：95, Last page：98, 2010, [Reviewed]
Surface charging on insulators in vacuum is recognized as one of the important phenomenon related to the occurrence of vacuum surface discharge events. In order to understand the vacuum discharge phenomenon deeply, it is necessary to investigate the influence of the surface charges on surface discharge events. Therefore the research on surface charges on an insulator is requested to measure the charge distribution or progress of charging before and after surface discharge event on the insulator surface.
In this research, the measurement of 2-dimensional surface charge distributions in real time has been carried out in vacuum by Pockels effect. With this measuring method, the charge distributions on a dielectric sample can be measured from the high voltage application to the surface flashover event. This paper describes the comparison of the surface charge distributions in vacuum and those in atmospheric condition on dielectrics under non-uniform ac voltage application. Moreover, using this method, the charge distributions just before and after one flashover event on PET films have been measured. In these experimental results, we found that surface charge distribution in vacuum under negative cycle ac voltage application spread out over the sample surface after a single surface discharge event. On the other hand, surface charges due to negaive streamerlike-discharge are measured under atmospheric condition.
IEEE, English, International conference proceedings
ISSN：1093-2941, Web of Science ID：WOS:000287378600024
Surface Conditions and Vacuum Breakdown Characteristics of Titanium Electrodes Lathed by Different Cutting Tool Bits and Treated by Chemical Polishing Method
Y. Yamano; T. Yoshida; S. Kobayashi; S. Michizono; Y. Saito
ISDEIV 2010: XXIVTH INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM, First page：47, Last page：50, 2010, [Reviewed]
In this paper, we investigated the vacuum breakdown characteristics for some kinds of Ti electrodes which have different surface conditions. We focus on the influence of machining by the use of different tool bit, such as a cemented carbide tool bit and a cubic Boron Nitride (cBN) tool bit when the electrodes are manufactured with a lathing machine. Moreover we investigated the influence of the chemical polishing (CP) using the mixed liquid of nitric acid and hydrofluoric acid on the breakdown characteristics. Surface conditions of the electrodes are investigated by an optical microscope. We report on the comparison of the electrical breakdown characteristics of these processed Ti electrodes and treated with chemical polishing. Additionally we treated some of them with vacuum heat treatment at 200 degree centigrade and made the experiments on them. In these experimental results, it is found that chemical polishing to titanium electrode surface is effective in increasing first breakdown fields and earlier saturation of conditioning. But saturated breakdown fields were almost same value for those of the electrodes which are machined the cemented carbide tool bit and CBN tool bit. Additional vacuum heat treatment showed certainly better effects on them.
IEEE, English, International conference proceedings
ISSN：1093-2941, Web of Science ID：WOS:000287378600012
Estimation of surface charges on dielectric materials for high power rf windows Shinichiro Michizono; Yoshio Saito; Suharyanto; Yasushi Yamano; Shinichi Kobayashi
APPLIED SURFACE SCIENCE,
Volume：256,
Number：4,
First page：950,
Last page：953, Nov. 2009,
[Reviewed]The surface discharges observed at rf windows and vacuum circuit breakers (VCBs) are one of the difficulties faced when developing high-power rf windows or compact VCBs. The surface discharge is considered to take place due to the release of the surface charges. Despite the importance of the surface charging/discharging, these phenomena have not been well evaluated. In this paper, the surface charges are estimated using the multipulse method, where electron beam irradiates a sample up to the saturation condition of surface charges. The amount of surface charges on alumina and TiN coated alumina are compared and the charging mechanism is discussed. (C) 2009 Elsevier B.V. All rights reserved.
ELSEVIER SCIENCE BV, English, Scientific journal
DOI：https://doi.org/10.1016/j.apsusc.2009.07.026DOI ID：10.1016/j.apsusc.2009.07.026,
ISSN：0169-4332,
Web of Science ID：WOS:000272342300007 Energy Spectra of Bremsstrahlung X-Rays Emitted From an FRP Insulator Yutaka Tanaka; Yoshitaka Ikeda; Masaya Hanada; Kaoru Kobayashi; Masaki Kamada; Masashi Kisaki; Noboru Akino; Yasushi Yamano; Shinichi Kobayashi; Larry R. Grisham
IEEE TRANSACTIONS ON PLASMA SCIENCE,
Volume：37,
Number：8,
First page：1495,
Last page：1498, Aug. 2009,
[Reviewed]Energy spectra of X-rays emitted from the surface of a fiberglass-reinforced plastic (FRP) insulator were measured at three different positions and compared with those of the vacuum gap between electrodes. Near the anode, the X-ray spectrum was dominated by monoenergetic electrons. Near the cathode, the spectrum peak shifted to low energy as compared with that near the anode. This result showed that a large amount of low-energy electrons was generated on the surface of the FRP insulator near the cathode.
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, English, Scientific journal
DOI：https://doi.org/10.1109/TPS.2009.2020402DOI ID：10.1109/TPS.2009.2020402,
ISSN：0093-3813,
Web of Science ID：WOS:000268822500024 Characteristics of Voltage Holding Capability in Multi-stage Large Electrostatic Accelerator for Fusion Application
Kaoru Kobayashi; Masaya Hanada; Noboru Akino; Shunichi Sasaki; Yoshitaka Ikeda; Masahiro Takahashi; Yasushi Yamano; Shinichi Kobayashi; Larry R. Grisham
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION, Volume：16, Number：3, First page：871, Last page：875, Jun. 2009, [Reviewed]
Voltage holding capability of a 500 kV, 22 A three-stage electrostatic accelerator, where large-area grids of 0.28 m(2) and large fiberglass reinforced plastic (FRP) insulators of 1.8 in in diameter are used, was examined. High voltage was independently applied to each acceleration stage, where the voltage holding capabilities of 130 kV were obtained. To identify whether the breakdowns occur in the gaps between the grids or the FRP insulators, high voltages were applied to the accelerator with and without the grids. Breakdown voltages without grids, i.e., the FRP insulator itself reached 170 kV of design value for each stage. These results show that the breakdown voltage of the accelerator was mainly determined by the gaps between the large-area grids. In this paper, the influence of non-uniform electric field and multi-stage grids on the voltage holding capabilities was also discussed.
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, English, Scientific journal
ISSN：1070-9878, Web of Science ID：WOS:000267035200038
Measurement of surface and volume resistivity of UV‐irradiated or EB‐irradiated insulator materials for satellites
小宮山丈行; 山納康; 小林信一; 馬場勧; 宮崎英治; 仁田工美
宇宙航空研究開発機構特別資料 JAXA-SP-, Number：08-018, First page：98, Last page：101, Mar. 2009
Japanese
ISSN：1349-113X, J-Global ID：201002277792507136
Observation of Pulse Current Occurring during Spark Conditioning Process of Ultra High Vacuum Gap KAWADA Masashi; YAMANO Yasushi; SAITO Yoshio; KOBAYASHI Shinichi
IEEJ Transactions on Fundamentals and Materials,
Volume：128,
Number：10,
First page：629,
Last page：634, Oct. 2008
It is known that the hold-off voltages of vacuum gaps can be improved by the spark conditioning with repetitive electrical breakdowns. At the early stage of spark conditioning process, small pulse currents (not breakdowns) were observed, and in turn hold-off voltages were improved. To investigate the characteristics of the pulse current occurrences and the reason of the improvement in hold-off voltages, experiments on pulse current observations for a vacuum gap were carried out, and chemical compositions on the electrode surfaces were analyzed before and after the experiments by an X-ray photoelectron spectroscopy (XPS). Pulse current observations confirmed that the currernt peak value decreases with repetitive voltage applications and then the phenomena occurring during the conditioning process change over from pulse current event to breakdowns. The XPS analysis revealed that the electrode surface was cleaned by repetitive pulse current occurrences. This result suggests that cleaning the electrode surface by repetitive pulse current occurrences would be one of causes of the improvement in hold-off voltages of a vacuum gap at the early stage of conditioning process.
The Institute of Electrical Engineers of Japan, English
DOI：https://doi.org/10.1541/ieejfms.128.629DOI ID：10.1541/ieejfms.128.629,
ISSN：0385-4205,
CiNii Articles ID：10024470272,
CiNii Books ID：AN10136312 Recent R&D activities of negative-ion-based ion source for JT-60SA Yoshitaka Ikeda; Masaya Hanada; Masaki Kamada; Kaoru Kobayashi; Naotaka Umeda; Noboru Akino; Noboru Ebisawa; Takashi Inoue; Atsushi Honda; Mikito Kawai; Minoru Kazawa; Katsumi Kikuchi; Masao Komata; Kazuhiko Mogaki; Katsuya Noto; Kuzumi Oasa; Katsumi Oshima; Shunichi Sasaki; Tatsuya Simizu; Tadashi Takenouchi; Yutaka Tanai; Katsutomi Usui; Kazuhiro Watanabe; Larry R. Grisham; Shinichi Kobayashi; Yasushi Yamano; Masahiro Takahashi
IEEE TRANSACTIONS ON PLASMA SCIENCE,
Volume：36,
Number：4,
First page：1519,
Last page：1529, Aug. 2008,
[Reviewed]The JT-60 Super Advanced (JT-60SA) tokamak aims to perform the ITER support and to demonstrate steady-state high-beta plasma project with the collaboration between Japan and EU. To attain these objectives, the negative-ion-based NBI (N-NBI) system is required to inject 10 MW for 100 s at the beam energy of 500 keV. On JT-60U, the present N-NBI ion source has injected 3.2 MW for 21 s at 320 keV; however, three key issues should be solved for the JT-60SA N-NBI ion source. One is to improve the voltage holding capability of the large negative ion source, where the available acceleration voltage has been limited to less than similar to 400 kV due to breakdowns. The accelerator of the JT-60U ion source is composed of large three-stage grids and three fiberglass reinforced plastic (FRP) insulators. Recent R&D tests suggested that the FRP insulators were not the main factor to trigger the breakdowns at the early conditioning stage. The accelerator with a large area of grids and their supporting structure may need a high margin in the design of electric field and a long time for conditioning. The second issue is to reduce the power loading of the acceleration grids. It was found that some beamlets were strongly deflected due to beamlet-beamlet interaction and strike on the grounded grid in the accelerator. Moreover, the electrons generated in the accelerator caused the grid loading and the overheating of the beamline components. The acceleration grids for JT-60SA are to be designed by taking account of the beamlet-beamlet interaction and the applied magnetic field in 3-D simulation. Third is to maintain the D- production for 100 s. Although a constant D- beam power was confirmed on JT-60U for 21 s, an active cooling system is required to keep the temperature of the plasma grid (PG) under optimum condition during 100-s operation. A simple cooling structure is proposed for the active cooled PG, where a key is the temperature gradient on the PG for uniform D- production. In the present schedule, design work, reflecting the latest R&D progress, will continue until similar to 2011. The modified N-NBI ion source will start on JT-60SA in 2015.
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, English, Scientific journal
DOI：https://doi.org/10.1109/TPS.2008.927382DOI ID：10.1109/TPS.2008.927382,
ISSN：0093-3813,
Web of Science ID：WOS:000258618300011 Surface discharge related properties of fiberglass reinforced plastic insulator for use in neutral beam injector of JT-60U Y. Yamano; M. Takahashi; S. Kobayashi; M. Hanada; Y. Ikeda
REVIEW OF SCIENTIFIC INSTRUMENTS,
Volume：79,
Number：2,
First page：02A524-1-02A524-4, Feb. 2008
Neutral beam injection (NBI) used for JT-60U is required to generate negative ions of 500 keV energies. To produce such high-energy ions, three-stage electrostatic accelerators consisting of three insulator rings made of fiberglass reinforced plastic (FRP) are applied. The surface discharges along FRP insulators are one of the most serious problems in the development of NBI. To increase the hold-off voltage against surface flashover events, it is necessary to investigate the FRP insulator properties related to surface discharges in vacuum. This paper describes surface flashover characteristics for FRP and alumina samples under vacuum condition. The results show that the fold-off voltages for FRP samples are inferior to those of alumina ceramics. In addition, measurement results of surface resistivity and volume resistivity under vacuum and atmospheric conditions, secondary electron emission characteristics, and cathodoluminescence under some keV electron beam irradiation are also reported. These are important parameters to analyze surface discharge of insulators in vacuum. (C) 2008 American Institute of Physics.
AMER INST PHYSICS, English, Scientific journal
DOI：https://doi.org/10.1063/1.2828069DOI ID：10.1063/1.2828069,
ISSN：0034-6748,
Web of Science ID：WOS:000254194800056 Investigation of Pulse Current Occurrence Observed for Spark Conditioning Process of Ultra High Vacuum gap
S. Kobayashi; M. Kawada; Y. Yamano; Y. Saito
ISDEIV 2008: PROCEEDINGS OF THE XXIIIRD INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM, VOLS 1 AND 2, First page：39, Last page：+, 2008, [Reviewed]
It is known that the hold-off voltages of vacuum gaps can be Improved by the spark conditioning with repetitive electrical breakdowns. At the early stage of spark conditioning process, small pulse currents (not breakdowns) are sometimes observed, and in turn hold-off voltages were improved. To clarify the mechanism of the pulse current occurrence two experiments were carried out.
First, the polarity effect of the pulse current occurrence was investigated. For the case that the anode was contaminated and the cathode was clean, the number of the pulse current occurrence was very few. On the other hand, many pulse currents occurred for the case that the anode was clean and the cathode was contaminated. As a result, it was found that the cathode of a vacuum gap is more dominant than the anode of that in the pulse current occurrence.
Next, the components of pulse current by using the electrode holder with Faraday cup were analyzed. As a result, It was found that the electronic component Is higher than the ionic component in the pulse current.
IEEE, English, International conference proceedings
ISSN：1093-2941, Web of Science ID：WOS:000261588200010
Measurement of Surface and Volume Resistivity for Alumina Ceramics under Vacuum Condition
Yasushi Yamano; Takeyuki Komiyama; Masahiro Takahashi; Shinichi Kobayashi; Kumi Nitta; Yoshio Saito
ISDEIV 2008: PROCEEDINGS OF THE XXIIIRD INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM, VOLS 1 AND 2, First page：35, Last page：+, 2008, [Reviewed]
This paper reported the surface and volume resistivity of typical insulators under atmospheric condition and vacuum condition. The measured materials are some kinds of alumina ceramics which have different purity of Al2O3 component. It was confirmed that the surface resistivity for almost all of the insulator materials under vacuum condition was higher then that under atmospheric condition. In addition, we checked the dependence of surface resistivity on ambient pressure from the atmospheric condition to the medium vacuum condition. Desorption of moisture vapor from the Insulator surface would be the main cause of the increase of the surface resistivity in vacuum. On the other hand, the volume resistivity had little change between vacuum and atmospheric condition.
IEEE, English, International conference proceedings
ISSN：1093-2941, Web of Science ID：WOS:000261588200009
Real-Time Measurement of Surface Charge Distributions on Insulator before and after Vacuum Surface Discharge Events
Takeshi Ochiai; Yasushi Yamano; Shinichi Kobayashi; Yoshio Saito
ISDEIV 2008: PROCEEDINGS OF THE XXIIIRD INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM, VOLS 1 AND 2, First page：43, Last page：+, 2008, [Reviewed]
It is said that surface charging on Insulator has an influence on vacuum surface discharge. To clarify mechanism of that event, it is necessary to investigate the progress of surface charge distribution on insulator during voltage application. In this research, real-time measurement of surface charge distributions on insulators (Alumina plate and PET film) in vacuum under AC voltage application was carried out with Pockels effect. Moreover, we tried to calculate time dependence of surface charge density near needle electrode on insulator. Especially we focus on time dependence of the surface charge density just before and after surface discharge event. As a result, alumina and PET were not charged just before first surface discharge. After the discharge, they were negatively charged and the negative charge density increased as the negative applied voltage increased.
IEEE, English, International conference proceedings
ISSN：1093-2941, Web of Science ID：WOS:000261588200011
Vacuum Breakdown Characteristics of Oxygen-Free Copper Electrodes with Different Keeping Methods and Terms
Kota Minaminosono; Yasushi Yamano; Shinichi Kobayashi; Yoshio Saito
ISDEIV 2008: PROCEEDINGS OF THE XXIIIRD INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM, VOLS 1 AND 2, First page：227, Last page：+, 2008, [Reviewed]
It has been known that the performance of hold-off voltage of vacuum breakdown for electrodes strongly depends on the surface contamination. Therefore, after manufacturing and cleaning of the electrodes, it is Important to handle and keep them under clean condition until the use of them. In order to investigate the influence of keeping methods and terms on the vacuum breakdown characteristics of oxygen-free copper electrode, we focused on keeping method and terms of electrodes.
Electrodes used for test were kept in atmosphere, in nitrogen and in vacuum for a specific term. Repetitive breakdown tests and the XPS surface analysis before and after repetitive breakdown tests were carried out in vacuum to investigate. Experiment results revealed that the degree of the contamination and the oxidation of test electrode surfaces made some degradation of the breakdown electric field and increased the necessary number of repetitive breakdown to achieve conditioning.
IEEE, English, International conference proceedings
ISSN：1093-2941, Web of Science ID：WOS:000261588200057
Effect of mechanical finishes on secondary electron emission of alumina ceramics
Suharyanto; Yasushi Yamano; Shinichi Kobayashi
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION, Volume：14, Number：3, First page：620, Last page：626, Jun. 2007, [Reviewed]
The effect of surface roughness of insulator on the secondary electron emission (SEE) coefficients was investigated with changing the incident angle of primary electrons. The SEE coefficients were measured using a scanning electron microscope with a single-pulse electron beam (100 pA, 1 ms). As a result, the SEE coefficients increased with the incident angle for smooth surface, while those of rough surface almost did not change with the incident angle. The SEE coefficients of commercial alumina ceramics with three different surface finishes, i.e. as-sintered, as-ground and mirror-finished samples, were also measured before and after annealing treatments. This treatment was carried out in air at 1400 degrees C for 1 h. After annealing, the SEE coefficients were higher than those of unannealed samples. This increase is proposed to be due to the defect recoveries as well as neutralizations of charging, which significantly influence the SEE. For relative low purity (95% or less), the SEE coefficients of annealed alumina became lower after mechanical grinding operations and lower again after mirror-finished operations. The SEE coefficients of 99.7% purity alumina were almost unaffected by the mechanical finishes.
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, English, Scientific journal
ISSN：1070-9878, Web of Science ID：WOS:000246982000015
Secondary electron emission of TiN-coated alumina ceramics Suharyanto; Shinichiro Michizono; Yoshio Saito; Yasushi Yamano; Shinichi Kobayashi
VACUUM,
Volume：81,
Number：6,
First page：799,
Last page：802, Feb. 2007,
[Reviewed]TiN film is often coated on alumina rf windows to suppress multipactor due to high secondary electron emission (SEE) coefficients. In this paper, SEE coefficients of alumina ceramics and sapphire coated with TiN films of various thicknesses are investigated. The SEE coefficients were measured using a scanning electron microscope with a single-pulse electron beam (100 pA, 1 ms). The SEE coefficients of TiN-coated alumina ceramics were lower than those of uncoated ones and nearly unity for TiN thickness of more than 1 nm, even with incident energy of 1 keV. To emulate multipactor-induced surface heating, the SEE coefficients were also measured at high temperature. The results showed a decrease in the SEE coefficients with temperature for TiN thickness of more than 0.5 nm. TiN coating on an rf window should be as thin as possible, and 0.5-1 nm may be the optimum thickness for suppressing multipactor. (c) 2006 Elsevier Ltd. All rights reserved.
PERGAMON-ELSEVIER SCIENCE LTD, English, Scientific journal
DOI：https://doi.org/10.1016/j.vacuum.2005.11.062DOI ID：10.1016/j.vacuum.2005.11.062,
ISSN：0042-207X,
Web of Science ID：WOS:000244816800017 Surface characteristics and electrical breakdown of alumina materials Shinichiro Michizono; Yoshio Saito; Suharyanto; Yasushi Yamano; Shinichi Kobayashi
VACUUM,
Volume：81,
Number：6,
First page：762,
Last page：765, Feb. 2007,
[Reviewed]The electrical breakdown of alumina materials is one of the difficulties in higher electric field applications. This breakdown takes place due to localized excess heating, which is induced by surface defects, multipactor, and surface discharge. These factors were evaluated for several commercial alumina ceramics using a scanning electron microscope and comparing these observations with high-power rf transmission tests. The results indicate that alumina ceramics without F-center defects and lower surface charging are feasible for higher electric field operation. (c) 2005 Elsevier Ltd. All rights reserved.
PERGAMON-ELSEVIER SCIENCE LTD, English, Scientific journal
DOI：https://doi.org/10.1016/j.vacuum.2005.11.058DOI ID：10.1016/j.vacuum.2005.11.058,
ISSN：0042-207X,
Web of Science ID：WOS:000244816800008 Dependence of current interruption performance on the element patterns of etched fuses
Yuzo Ishikawa; Kengo Hirose; Mitsuo Asayama; Yasushi Yamano; Shinichi Kobayashi
ICEFA 2007: EIGHTH INTERNATIONAL CONFERENCE ON ELECTRIC FUSES AND THEIR APPLICATIONS, PROCEEDINGS, First page：51, Last page：56, 2007, [Reviewed]
This paper is about fuses for the protection of semiconductors. The pattern of their current-interruption area is composed of chemically etched copper plated on a ceramic substrate. Interruption tests revealed that the I(2)t characteristics of these fuses are greatly influenced by the numbers P and S of parallel and series interruption points. The I(2)t value of a 6S-32P fuse is 72% that of a 6S-8P fuse, and the I(2)t value of a 24S-8P fuse is 24% that of a 6S-8P fuse. The synergy of these P and S effects reduces the I(2)t value of a 24S-32P fuse to only 8.6% that of a 6S-8P fuse.
LABORATOIRE ARC ELECTRIQUE PLASMAS THERMIQUES, English, International conference proceedings
Web of Science ID：WOS:000253703300008
Vacuum electrical breakdown characteristics and surface condition of Ti electrodes with oxidation conditions Y Ito; Y Yamano; S Kobayashi; Y Saito
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION,
Volume：13,
Number：1,
First page：98,
Last page：104, Feb. 2006
Outgassing from an electrode surface is regarded as a major factor leading to electrical breakdowns in vacuum. Recently oxidation treatment at 200 degrees C was reported as an effective means of reducing Ti outgassing. In this paper, we report our measurement and comparison of the electrical breakdown characteristics of Ti electrodes with different oxidation conditions (without oxidation, oxidation at 200 degrees C, oxidation at 450 degrees C). In addition, we analyzed electrode surfaces before and after breakdown experiments in situ with X-ray photoelectron spectroscopy (XPS). Before oxidation, we machined the electrode's surfaces to the roughness of 0.8 mu m Rmax with diamond turning. Breakdown experiments demonstrated that the breakdown field is highest at the first application of voltage to electrodes with oxidized at 200 degrees C. Before breakdown experiment, surface analysis revealed that all the sample electrodes had a large amount of carbon originating from the hydrocarbons of contaminants, and after the experiments, they revealed that the carbons had disappeared. To obtain breakdown characteristics of electrodes with smoother surfaces, we conducted experiments on electrodes with a surface roughness of 0.05 mu m Ra. For these electrodes, the breakdown field was higher at first breakdown; the repetitions required to achieve saturated breakdown fields were significantly fewer, and the amount of carbon on electrode surfaces before breakdown was less.
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, English, Scientific journal
DOI：https://doi.org/10.1109/TDEI.2006.1593407DOI ID：10.1109/TDEI.2006.1593407,
ISSN：1070-9878,
CiNii Articles ID：120001371240,
Web of Science ID：WOS:000235419200014 Secondary electron emission and surface charging evaluation of alumina ceramics and sapphire Suharyanto; Y Yamano; S Kobayashi; S Michizono; Y Saito
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION,
Volume：13,
Number：1,
First page：72,
Last page：78, Feb. 2006
The breakdown of alumina rf windows is mostly caused by multipactor, as well as by material defects and contamination. Since multipator induces localized surface heating, leading to surface melting, it is necessary to observe secondary electron emission (SEE) coefficients of alumina ceramics under high temperature conditions. The SEE coefficients of commercial alumina ceramics and sapphire were measured by a scanning electron microscopy (SEM) with a single short-pulsed electron beam (100 pA, 1 ms) at room temperature and at 650 degrees C. Additive materials used for sintering alumina, such as SiO2 and MgO, were also investigated. Surface charging evaluations have also become important because the accumulated charges are discharged at the threshold field, resulting in surface discharge. The surface charging evaluations were carried out by multi-pulse measurements with the injection of successive pulses on the sample. As a result, reductions in the SEE coefficients with temperature were confirmed, except for sapphire. The multi-pulse measurement results indicated that surface charging of the sapphire was higher than that of other samples. This may be one of the factors that causes sapphire not to be durable for rf window applications, compared with alumina ceramics. Although there are few exceptions, it was found that the SEE coefficients of alumina ceramics increased with the purity and the average grain size.
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, English, Scientific journal
DOI：https://doi.org/10.1109/TDEI.2006.1593403DOI ID：10.1109/TDEI.2006.1593403,
ISSN：1070-9878,
CiNii Articles ID：120001371239,
Web of Science ID：WOS:000235419200010 Measurement of 2-dimensional surface charge distributions under vacuum flashover events on insulators with sub-milli-second temporal resolution Yasushi Yamano; M. Miyazaki; Shinichi Kobayashi; Yoshio Saito
Proceedings - International Symposium on Discharges and Electrical Insulation in Vacuum, ISDEIV,
Volume：1,
First page：152,
Last page：155, 2006,
[Reviewed]Most studies on a flashover event in vacuum has revealed that the surface charging on insulator has a great influence on the flashover. However, regarding most studies related to the surface charging, their measurements were carried out after high voltage excitation. In this research, the measurement of 2-dimensional surface charge distributions in real time has been carried out in vacuum by Pockels effect With this measuring method, the charge distributions on a dielectric sample can be measured from the high voltage application to the surface flashover event This paper describes the changes of the surface charge distributions on a PET film under non-uniform ac voltage application in vacuum. Moreover, using this method, the charge distribution just before and after a surface discharge event on the PET film has been measured. Especially we focus on the distribution near the triple junction just before and after the surface discharge event. © 2006 IEEE.
English, International conference proceedings
DOI：https://doi.org/10.1109/DEIV.2006.357254DOI ID：10.1109/DEIV.2006.357254,
ISSN：1093-2941,
SCOPUS ID：46649094414 Vacuum breakdown characteristics for electrodes paired with cathodes and with anodes processed by spark conditioning Yasushi Yamano; Takahiro Otsuka; Shinichi Kobayashi; Yoshio Saito
IEEJ Transactions on Fundamentals and Materials,
Volume：126,
Number：8,
First page：775,
Last page：781, 2006
This paper describes vacuum electrical breakdown characteristics for electrodes with spark conditioning process. Two pairs of electrodes processed by spark conditioning were prepared. The conditioning procedure was 500 times repetitive breakdowns by applying positive impulse voltage under ultra-high vacuum condition. Using these processed electrodes, two vacuum gaps were made up by pairing of electrodes used as cathode in spark conditioning process and as anode, respectively. 50 times repetitive breakdown tests were carried out using cathode vs. cathode pair and anode vs. anode pair. As a result, for a pair of cathode vs. cathode, the first breakdown field kept high breakdown field which was almost the same value for the achieved breakdown field by 500 times repetitive spark conditioning. On the other hand, for anode vs. anode pair the first field was much less than that for cathode vs. cathode pair. This is due to the difference of the surface condition between anode and cathode surfaces that were formed by spark conditioning. According to SEM images for anode and cathode after spark conditioning, the profiles had quit difference between anode and cathode surface.
Japanese
DOI：https://doi.org/10.1541/ieejfms.126.775DOI ID：10.1541/ieejfms.126.775,
ISSN：0385-4205,
SCOPUS ID：33746921909 Secondary electron emission from alumina materials used for high-power RF windows Shinichiro Michizono; Yoshio Saito; Suharyanto; Yasushi Yamano; Shinichi Kobayashi
IEEJ Transactions on Fundamentals and Materials,
Volume：126,
Number：8,
First page：751,
Last page：756, 2006
The improvements of the dielectric materials are one of the most important parts for developing the compact and/or higher power insulators. The breakdown of the rf windows, which pass rf power and isolate vacuum, was induced by the multipactor and surface discharge. Both are related to the secondary electron emission (SEE) and surface charigng. The SEE from alumina materials are measured using a scanning electron microscope (SEM). The single-pulse and multi-pulse methods are applied for the SEE coefficients and surface charging measurements, respectively. The TiN coatings for multipactor suppression are also investigated from the view points of SEE and surface charging. Sapphire shows highest surface charging and has higher SEE coefficients with temperature increase. These results lead to the lower threshold of the electrical breakdown observed for the rf windows. It is confirmed that TiN coatings are effective for the decrease in SEE. The multipulse-measurements indicate TiN coatings lower the surface charging probably caused by the lower SEE.
Japanese
DOI：https://doi.org/10.1541/ieejfms.126.751DOI ID：10.1541/ieejfms.126.751,
ISSN：0385-4205,
SCOPUS ID：33746869953 Secondary electron emission from alumina with a multi-pulse irradiation method Shinichiro Michizono; Yoshio Saito; Suharyanto; Yasushi Yamano; Shinichi Kobayashi
Shinku/Journal of the Vacuum Society of Japan,
Volume：48,
Number：3,
First page：145,
Last page：147, 2005,
[Reviewed]Surface flashover on the alumina ceramics is one of the most serious problems for developing the dielectric insulation. The flashover takes place by (1) multipactor, electron multiplication on the surface and/or (2) discharge of the accumulated charges (due to multipactor). Since the multipactor sometimes induces localized surface melting, surface charging is evaluated not only at room but also at high temperature. The alumina ceramics with higher purity show lower surface chargings at room temperature and non-chargings at 650°C. A sapphire (single crystal alumina) disk shows high surface charging even at 650°C. Considering the poor performance of the sapphire for the rf window usage, less charging materials at high temperature is indicated to be the promising candidates for the dielectric insulation.
Vacuum Society of Japan, Japanese, Scientific journal
DOI：https://doi.org/10.3131/jvsj.48.145DOI ID：10.3131/jvsj.48.145,
ISSN：0559-8516,
SCOPUS ID：20444497411 Secondary electron emission of sapphire and anti-multipactor coatings at high temperature Shinichiro Michizono; Yoshio Saito; Suharyanto; Yasushi Yamano; Shinichi Kobayashi
Applied Surface Science,
Volume：235,
Number：1-2,
First page：227,
Last page：230, Jul. 2004,
[Reviewed]Electrical breakdown (surface discharge) is one of the most serious problems for developing compact and/or higher voltage insulation in a vacuum. Electron multiplication (multipactor) due to high secondary electron emission (SEE) yields from an insulator surface is one of the reasons for the discharge. Multipactor induces not only discharging but also excess surface heating, leading to localized surface melting. Thus, SEE at high temperature is important for understanding the actual breakdown process. The SEE yield of single crystal alumina (sapphire) and anti-multipactor coatings, such as TiN and DLC films having low SEE yields, are measured in a scanning electron microscope (SEM). © 2004 Elsevier B.V. All rights reserved.
English, International conference proceedings
DOI：https://doi.org/10.1016/j.apsusc.2004.05.131DOI ID：10.1016/j.apsusc.2004.05.131,
ISSN：0169-4332,
SCOPUS ID：4344564634 Temperature dependence of secondary electron emission on alumina and anti-multipactor coatings Shinichiro Michizono; Yoshio Saito; Suharyanto; Yasushi Yamano; Shinichi Kobayashi
Shinku/Journal of the Vacuum Society of Japan,
Volume：47,
Number：3,
First page：120,
Last page：123, 2004,
[Reviewed]Electrical breakdown (surface discharge) is one of the most serious problems for developing compact and/or higher voltage insulation in a vacuum. High secondary electron emission (SEE) yields result in the multipactor (electron multiplication on the dielectric surface). Multipactor induces not only discharging but also excess surface heating, leading to localized surface melting. Thus, SEE at high temperature is important for understanding the actual breakdown process. The SEE yield of single crystal alumina (sapphire) and anti-multipactor coatings, such as TiN and DLC films having low SEE yields, are measured with a scanning electron microscope (SEM) by pulsed-beam method. In order to examine the surface charging, multi-pulse methods are also carried out for the sapphire disk at high temperature.
Vacuum Society of Japan, Japanese, Scientific journal
DOI：https://doi.org/10.3131/jvsj.47.120DOI ID：10.3131/jvsj.47.120,
ISSN：0559-8516,
SCOPUS ID：33750808900 Secondary electron emission and surface charging from alumina at high temperature S. Michizono; Y. Saito; Suharyanto; Y. Yamano; S. Kobayashi
Proceedings - International Symposium on Discharges and Electrical Insulation in Vacuum, ISDEIV,
Volume：1,
First page：51,
Last page：54, 2004,
[Reviewed]Electrical breakdown is one of the most serious problems for developing compact and/or higher-voltage insulation in a vacuum. High secondary electron emission (SEE) yields result in the multipactor effect (electron multiplication on the dielectric surface). Multipactor induces not only discharging, but also excess surface heating, leading to localized surface melting. Thus, SEE at high temperature is important for understanding the actual breakdown process. The SEE yields of sapphire were measured at high temperature by a single-pulsed beam method with a scanning electron microscope (SEM) so as to avoid surface charging. In general, the effective SEE decreases by multipactor due to surface charging. Since the electrical conductivity becomes higher at a high temperature, effective SEE can be larger due to less surface charging. In order to estimate the surface charging, multi-pulse beams were injected to sapphire disks at room and high temperature. © 2004 IEEE.
English, International conference proceedings
DOI：https://doi.org/10.1109/DEIV.2004.1418598DOI ID：10.1109/DEIV.2004.1418598,
ISSN：1093-2941,
SCOPUS ID：16244364350 Effect of in situ heat treatment on surface flashover characteristic and surface condition of alumina in vacuum
Y Tsukamoto; Y Yamano; S Kobayashi; Y Saito
ISDEIV: XXITH INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM, VOLS 1 AND 2, PROCEEDINGS, Volume：21, First page：118, Last page：121, 2004, [Reviewed]
Flashover along the surface of a solid insulator (surface flashover) prevents minimizing the size of vacuum devices. It has been considered that the emission of electrons from the cathode triple junction region is the first step of initiating the surface flashover, subsequent gas desorption from insulator surface stimulated by electron impact is the second step and finally the surface flashover occurs in the desorbed gases. In addition it has been recognized that conditioning treatment by repetitive surface flashover cleans insulator surface and brings higher flashover voltage. Therefore removal of adsorbed gases and surface contaminants may improve surface flashover voltage. In this experiment, vacuum heat treatment (about 465degrees Celsius) for Alumina samples was employed as a means of removal of adsorbed gases and surface contaminants. After heat treatment, repetitive flashover test was conducted in vacuum without the exposure of sample to atmosphere. Flashover voltages with and without heat treatment were compared.
As a result, flashover voltage for the sample with heat treatment was higher than that for without heat treatment. In particular, an appreciable improvement of first flashover voltage was confirmed for heat treatment samples significant conditioning effect for the sample with heat treatment was obtained as well. In addition the dependence of the flashover voltage on the purity of aluminas with heat treatment was clarified.
IEEE, English, International conference proceedings
ISSN：1093-2941, Web of Science ID：WOS:000226098000029
Secondary electron emission of dielectric materials under high temperature condition
Suharyanto; S Michizono; Y Yamano; Y Saito; S Kobayashi
ISDEIV: XXITH INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM, VOLS 1 AND 2, PROCEEDINGS, Volume：21, First page：21, Last page：24, 2004, [Reviewed]
Secondary electron emission (SEE) coefficients of alumina, sapphire, SiO2, and MgO were measured by using a SEM with short-pulsed electron beam under room and high temperatures. An appreciable reduction in the SEE coefficients with increasing temperature was confirmed, except for sapphire. In addition, it was found that at room and high temperature SEE coefficients of alumina increased with purity and grain size.
IEEE, English, International conference proceedings
ISSN：1093-2941, Web of Science ID：WOS:000226098000006
Vacuum electrical breakdown characteristics and surface chemical compositions of titanium electrodes with oxidation conditions
Y Ito; Y Yamano; S Kobayashi; Y Saito
ISDEIV: XXITH INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM, VOLS 1 AND 2, PROCEEDINGS, Volume：21, First page：80, Last page：83, 2004, [Reviewed]
Outgassing from an electrode is regarded as one of factors leading electrical breakdowns in vacuum. It was already reported that oxidation treatment at 200degreesC for titanium is effective to reduce outgassing because of its thin and fine oxide layer created on the surface. Breakdown characteristics of titanium electrodes with different oxidation conditions (without oxidation, with oxidation at 200degreesC and 450degreesC) were investigated and compared, in order to clarify the dependence of the oxidation treatment on the breakdown characteristics. In addition, chemical composition on the electrode surface was analyzed by X-ray Photoelectron Spectroscopy (XPS) before and after 500 repetitive breakdowns. Experiments clarified that breakdown field at the first voltage application is highest, and conditioning effect is significant for the electrodes at 200degreesC oxidation.
IEEE, English, International conference proceedings
ISSN：1093-2941, Web of Science ID：WOS:000226098000020
Effect of sputtering in vacuum and repetitive breakdowns on field emission characteristic
K Terui; Y Yamano; S Kobayashi; Y Saito
ISDEIV: XXTH INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM, PROCEEDINGS, Volume：20, First page：503, Last page：506, 2002, [Reviewed]
Oxygen-free copper electrodes stored in the atmosphere for long term were used as test samples Changes of field emission characteristics with 500 repetitive breakdowns and He ion beam sputtering were investigated in conjunction with analyses of electrode surface conditions by X-ray Photoelectron Spectroscopy (XPS). Experiments revealed that field emission currents were detected from electrodes used as the anode after 500 breakdowns, while for electrodes that were non-treated and the cathode after 500 breakdowns field emission currents were not detected Anode and cathode surfaces were cleaned up by 500 breakdowns Cathode surfaces were much cleaned up than anode surfaces after repetitive 500 breakdowns.
IEEE, English, International conference proceedings
ISSN：1093-2941, Web of Science ID：WOS:000178625000119
Luminescence spectra emitted at surface flashovers on aluminas in vacuum
S Aoki; Y Yamano; S Kobayashi; Y Saito
ISDEIV: XXTH INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM, PROCEEDINGS, Volume：20, First page：431, Last page：434, 2002, [Reviewed]
The components of desorbed gases from alumina at surface flashover were analyzed by using a monochromator As a result, we found spectra of hydrogen, oxygen and Me material of electrodes (Stainless steel. Fe, Ni, Cr) and component of alumina 60 at surface flashover. The intensity of spectra of hydrogen decreased with the accumulation of the number of surface flashover.
IEEE, English, International conference proceedings
ISSN：1093-2941, Web of Science ID：WOS:000178625000101
Charging characteristics on dielectric surface by different charging processes in vacuum Y Yamano; A Ohashi; K Kato; H Okubo; Y Hakamata
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION,
Volume：6,
Number：4,
First page：464,
Last page：468, Aug. 1999
This paper describes charging characteristics on a dielectric surface in vacuum by electron irradiation, and field emission by a triple junction under negative and positive de Hv applications. We measured the 2-dimensional distribution of electrostatic charging on a dielectric surface in situ. Experimental results revealed that the negative charge distribution caused by the electron beam had a conical shape over the whole surface. On the other hand, for a triple junction, it was an acute distribution around the triple junction. Moreover, we quantitatively investigated the difference of the 2-dimensional charging distribution, using certain shape parameters, between the two charging processes mentioned above. In addition, we examined the time decay characteristics of the surface potential on the dielectric in vacuum.
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, English, Scientific journal
DOI：https://doi.org/10.1109/94.788746DOI ID：10.1109/94.788746,
ISSN：1070-9878,
eISSN：1558-4135,
CiNii Articles ID：30020038289,
Web of Science ID：WOS:000082543000016
Microplasma discharge in ethanol solution: Characterization and its application to the synthesis of carbon microstructures Qiang Chen; Takaya Kitamura; Kenji Saito; Koji Haruta; Yasushi Yamano; Tatsuo Ishikawa; Hajime Shirai
THIN SOLID FILMS,
Volume：516,
Number：13,
First page：4435,
Last page：4440, May 2008
Radio-frequency (rf) microplasma discharge of argon was successfully generated within an ethanol (EtOH) solution and applied for the synthesis of carbon microstructures. The plasma state depends on the flow rate of argon as well as the EtOH concentration. The argon related species are consumed mostly for dissociating EtOH at concentration of over 10%. The carbon related microstructures such as particle and nanotubes (CNTs) were formed directly on c-Si utilizing a microplasma jet of argon generated within ethanol solution, the average size and number density of carbon related products could be controlled by adjusting the ethanol concentration. The determining factor of average size and number density of carbon microstructures are discussed in terms of the surface reaction within ethanol solution. (c) 2007 Elsevier B.V. All rights reserved.
ELSEVIER SCIENCE SA, English
DOI：https://doi.org/10.1016/j.tsf.2007.10.052DOI ID：10.1016/j.tsf.2007.10.052,
ISSN：0040-6090,
Web of Science ID：WOS:000255584800013 Influence of mechanical finishing on secondary electron emission of alumina ceramics Suharyanto; S. Michizono; Y. Saito; Tumiran; Y. Yamano; S. Kobayashi
Proceedings - International Symposium on Discharges and Electrical Insulation in Vacuum, ISDEIV,
Volume：1,
First page：97,
Last page：100, 2006
Secondary electron emission (SEE) coefficients of alumina ceramics with three different surface finishes have been measured using a scanning electron microscope with a single-pulse electron beam (100 pA, 1 ms). SEE coefficients of those aluminas with annealing process became lower after mechanical grinding operations even though its average roughness was almost same as those of as-sintered ones. SEE coefficients of mirror-finished samples were the smallest among the samples. Changes of SEE coefficient with incident angle of primary electrons for smooth and rough surfaces are also discussed. © 2006 IEEE.
English
DOI：https://doi.org/10.1109/DEIV.2006.357240DOI ID：10.1109/DEIV.2006.357240,
ISSN：1093-2941,
SCOPUS ID：46649099104 Development of the high votage etching fuse for protecting semiconductors
浅山三夫; 石川雄三; 広瀬健吾; 小林信一; 山納康
Number：6, First page：67, Last page：70, 2005
We are continuing to develop high voltage etching fuse for protecting semiconductors. Last year fundamental researches to find etching patterns bringing better current breaking capability were conducted, and successfully completed. This year 7.2kV rating etching fuse was developed based on the results of fundamental researches of last year. It was confirmed that this type of etching fuse has good breaking performance and smaller I2t value compared with target value were obtained.Therefore it will be possible to produce a high voltage etching fuse for protecting semiconductors having lower I2t than those of current products.
Japanese
ISSN：1347-4758, CiNii Articles ID：120001371340, CiNii Books ID：AA11808968
高圧半導体保護用エッチングヒューズの開発 (続）
浅山三夫; 石川雄三; 広瀬健吾; 小林信一; 山納康
埼玉大学地域共同研究センター紀要, Number：6, First page：67, Last page：70, 2005
We are continuing to develop high voltage etching fuse for protecting semiconductors. Last year fundamental researches to find etching patterns bringing better current breaking capability were conducted, and successfully completed. This year 7.2kV rating etching fuse was developed based on the results of fundamental researches of last year. It was confirmed that this type of etching fuse has good breaking performance and smaller I2t value compared with target value were obtained.Therefore it will be possible to produce a high voltage etching fuse for protecting semiconductors having lower I2t than those of current products.
Japanese
ISSN：1347-4758, CiNii Articles ID：120001371340, CiNii Books ID：AA11808968
真空沿面放電時のトリプルジャンクションにおける電子放出箇所の微視的観測
山納康
総合研究機構研究プロジェクト研究成果報告書, Volume：16年度, 2005
Erratum to "Secondary electron emission of sapphire and anti-multipactor coatings at high temperature" (vol 235, pg 227, 2004) S Michizono; Y Saito; Suharyanto; Y Yamano; S Kobayashi
APPLIED SURFACE SCIENCE,
Volume：239,
Number：1,
First page：125,
Last page：125, Dec. 2004
ELSEVIER SCIENCE BV, English, Others
DOI：https://doi.org/10.1016/j.apsusc.2004.10.016DOI ID：10.1016/j.apsusc.2004.10.016,
ISSN：0169-4332,
Web of Science ID：WOS:000225140900016 Charging characteristics and electric field distribution on alumina as affected by triple junctions in vacuum Y Yamano; S Ito; K Kato; H Okubo; Y Hakamata
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION,
Volume：9,
Number：2,
First page：173,
Last page：177, Apr. 2002
This paper describes the dependence of the charging characteristics on the electric field distribution on the alumina (Al2O3) surface as affected by the triple junction in vacuum. For HV electrical insulation design of vacuum interrupter, surface flashover in vacuum is very important problem to be solved. Attention should be paid to the fact that the insulation characteristics on the dielectric surface are strongly influenced by field emission of electrons from the triple junction and the accumulated charges on the dielectric surface. In order to clarify the charging mechanism, we measured the charging characteristics for various types of triple junctions. In particular, we focused on the influence of the electric field distribution along the solid dielectrics and near the cathode triple junction (CTJ) on the charging characteristics. The results confirmed that the electric field distribution strongly affected the 2-dimensional (2D) distribution of the surface charge on the dielectric sample. Consequently, it was found that positive charging was generated on alumina, when the incident angle of the electric line of force on the alumina surface became > 60degrees.
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, English
DOI：https://doi.org/10.1109/94.993731DOI ID：10.1109/94.993731,
ISSN：1070-9878,
eISSN：1558-4135,
CiNii Articles ID：80015188876,
Web of Science ID：WOS:000175044500004 真空中の2次電子なだれによる固体絶縁物上の正極性帯電形成条件
山納康; 伊藤慎悟; 加藤克巳; 早川直樹; 袴田好美; 大久保仁
Volume：2000, Number：1, 2000
J-Global ID：201302152014349862
Influence of electric field distribution on charging mechanism on alumina dielectrics by triple junction in vacuum
Y Yamano; S Ito; K Kato; Y Hakamata; H Okubo
ISDEIV: XIXTH INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM, VOLS 1 AND 2, PROCEEDINGS, Volume：19, First page：135, Last page：138, 2000
Surface flashover characteristics in vacuum is very important for HV insulation design of vacuum interrupter It should be paid attention to the fact that the insulation characteristics on the dielectric surface are strongly influenced by field emission of electron at a triple junction and the accumulated charges on the dielectric surface. In order to clarify charging mechanism, we measured the charging characteristics for various types of triple junction configuration. In particular, we focused on the influence of electric field distribution along solid dielectrics and near cathode triple junction (CTJ) on the charging characteristics. Through the discussion on experimental results, we confirmed that electric field distribution strongly affected 2-dimensional (2D) distribution of surface charge on dielectric sample. Consequently, it is found that positive charging is generated on Al2O3, when incident angle of electric line of force on the Al2O3 surface becomes larger than 60 degree.
IEEE, English
ISSN：1093-2941, Web of Science ID：WOS:000166521200036
Investigation of 2-dimensional charge distribution on dielectric surface in vacuum by real-time measurement technique
K Kato; S Ito; Y Yamano; Y Hakamata; H Okubo
ISDEIV: XIXTH INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM, VOLS 1 AND 2, PROCEEDINGS, Volume：19, First page：94, Last page：97, 2000
For the establishment electrical of vacuum insulation technique, electrical insulation characteristics under the existence of the solid insulator need to be paid attention. In particular, a study of a charging mechanism on the solid surface in vacuum is very important. For this reason, we measured a 2-dimensional surface charge distribution using a real-time measurement technique. Under electron beam irradiation to the dielectric surface, we measured the time-transition of surface charge accumulation by electrostatic probes. By varying electron beam current and beam energy, we investigated the dependence of such parameters on the charging process. From the measurement results, we clarified that such a measurement technique allowed us to get the time varying 2D charging characteristics, which resulting in the clarification which of the charging mechanism caused by electron irradiation in vaccuum.
IEEE, English
ISSN：1093-2941, Web of Science ID：WOS:000166521200026
Influence of Electric Field Distribution on Charging Mechanism on Alumina Dielectrics in Vacuum
YAMANO Yasushi; ITO Shingo; KATO Katsumi; HAKAMATA Yoshimi; OKUBO Hitoshi
Volume：1999, Number：183, First page：19, Last page：24, 19 Nov. 1999
Japanese
CiNii Articles ID：10016803461, CiNii Books ID：AN10320559
Illumination Image Characteristics of Laser-Induced Plasma on Solid Target in Vacuum
YAMANO Yasushi; OHASHI Atsushi; KATO Katsumi; OKUBO Hitoshi
The Transactions of the Institute of Electrical Engineers of Japan. A, Volume：119, Number：6, First page：878, Last page：883, 01 Jun. 1999
Japanese
ISSN：0385-4205, CiNii Articles ID：10004540328, CiNii Books ID：AN10136312
Characteristics of Laser-induced Plasma and Laser-triggered Discharge in Low Vacuum
OHASHI Atsushi; YAMANO Yasushi; KATO Katsumi; OKUBO Hitoshi
The Transactions of the Institute of Electrical Engineers of Japan. A, Volume：119, Number：4, First page：469, Last page：474, Apr. 1999
Japanese
ISSN：0385-4205, CiNii Articles ID：10004442458, CiNii Books ID：AN10136312
真空中におけるトリプルジャンクション近傍の電界分布と絶縁物上帯電特性
山納康; 伊藤慎悟; 加藤克巳; 早川直樹; 袴田好美; 大久保仁
Volume：1999, 1999
J-Global ID：200902124211623562
Electric Field Distribution and Charging Characteristics on Solid Dielectric Surface in Vacuum.
山納康; 伊藤慎悟; 加藤克巳; 早川直樹; 袴田好美; 大久保仁
電気学会基礎・材料・共通部門大会講演論文集, Volume：1999, 1999
J-Global ID：200902155187738402
真空中の電子照射による絶縁物上帯電分布の形成機構
山納康; 大橋敦; 加藤克巳; 袴田好美; 大久保仁
電気学会 論文誌A, Volume：119-A, Number：6, First page：841, Last page：847, 1999
ISSN：0385-4205, J-Global ID：200902104443397185
真空中における電子ビームによるアルミナ上帯電分布のビーム照射時間依存性
山納康; 林裕昭; 大橋敦; 加藤克巳; 袴田好美; 大久保仁
Volume：1998, Number：1, 1998
J-Global ID：200902137035121347
Charging characteristics on various insulators by electron beam irradiation in vacuum.
山納康; 大橋敦; 加藤克巳; 早川直樹; 袴田好美; 大久保仁
電気関係学会東海支部連合大会講演論文集, Volume：1998, 1998
J-Global ID：200902169207147369
低真空中における不平等電界下の放電現象
大久保仁; 山納康; 大橋敦; 加藤克巳
Volume：1998, Number：1, 1998
J-Global ID：200902182880661127
Vacuum discharge phenomena under non-uniform field conditions
H Okubo; Y Yamano; A Ohashi; K Kato
ISDEIV: XVIIITH INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM - PROCEEDINGS, VOLS 1 AND 2, Volume：18, First page：93, Last page：100, 1998
For the development of space power applications, it is required to be analyzed the discharge phenomena in low and medium vacuum, in particular, under non-uniform electric field. Although the data under such conditions are very important for the insulation design of space power apparatus, few studies have been reported.
This paper describes the review results of the research activities on discharge phenomena under non-uniform field in low and medium vacuum conditions. Dc discharge inception voltage for various electrode configurations in He gas, Ar gas and air in vacuum range from 10(5) to 10(-1) Pa were measured. In order to discuss quantitatively the change of the discharge characteristics with the vacuum pressure, an image processing method was introduced. Based on the analysis, the dependence on the discharge inception voltage and length of the discharge path on the residual gas pressure under non-uniform field conditions was clarified and agreed well with the dependence formerly obtained for the uniform field condition.
IEEE, English
ISSN：1093-2941, Web of Science ID：WOS:000077494100022
Charging characteristics on dielectric surface by different charging process in vacuum
Y Yamano; A Ohashi; K Kato; Y Hakamata; H Okubo
ISDEIV: XVIIITH INTERNATIONAL SYMPOSIUM ON DISCHARGES AND ELECTRICAL INSULATION IN VACUUM - PROCEEDINGS, VOLS 1 AND 2, Volume：18, First page：174, Last page：178, 1998
This paper describes the charging characteristics on a dielectric surface in vacuum by different types of charging process; electron irradiation by electron beam and field emission by triple junction under negative de high voltage application. We measured 2-dimensional distribution of electrostatic charging on the dielectric surface in-situ. Experimental results revealed that the negative charge distribution by the electron beam had a conical shape all over the surface. On the other hand, for triple junction, it was an acute distribution around the triple junction. Moreover, we quantitatively investigated the difference of the 2-dimensional charging distribution using some shape parameters between above mentioned two charging processes. In addition, we examined the time decay characteristics of the surface potential on the dielectrics in vacuum.
IEEE, English
ISSN：1093-2941, Web of Science ID：WOS:000077494100041
Charging Characteristics on Dielectric Surface by Different Charging Process in Vacuum
OHASHI Atsushi; YAMANO Yasushi; KATO Katsumi; HAKAMATA Yoshimi; OKUBO Hitoshi
Volume：1997, Number：100, First page：31, Last page：36, 30 Sep. 1997
Japanese
CiNii Articles ID：10016817467, CiNii Books ID：AN10320559
Charge generation on alumina sample in vacuum by triple junction.
大橋敦; 山納康; 加藤克巳; 袴田好美; 大久保仁
電気関係学会東海支部連合大会講演論文集, Volume：1997, 1997
J-Global ID：200902131333590394
