Pub Date : 1996-07-21DOI: 10.1109/DEIV.1996.545411
O. Yamamoto, T. Hara, T. Takuma, H. Matsuura, Y. Tanabe, T. Konishi
A Monte Carlo simulation (MCS) method of charge accumulation based on the secondary emission electron avalanche mechanism is applied to the design of effective corrugation on an HV insulator surface. The electric field distribution on the cathode in the vicinity of a triple junction is analysed taking the charge accumulation into account. A considerable relaxation of field strength takes places due to negative charge accumulation with appropriate corrugation. The flashover voltage obtained experimentally increases as the field strength decreases. The result of MCS thus agrees well with the experimental result. This proves that the MCS method is useful for the design of high voltage insulator structures.
{"title":"Numerical design of high voltage insulator structure considering SEEA charge accumulation in vacuum","authors":"O. Yamamoto, T. Hara, T. Takuma, H. Matsuura, Y. Tanabe, T. Konishi","doi":"10.1109/DEIV.1996.545411","DOIUrl":"https://doi.org/10.1109/DEIV.1996.545411","url":null,"abstract":"A Monte Carlo simulation (MCS) method of charge accumulation based on the secondary emission electron avalanche mechanism is applied to the design of effective corrugation on an HV insulator surface. The electric field distribution on the cathode in the vicinity of a triple junction is analysed taking the charge accumulation into account. A considerable relaxation of field strength takes places due to negative charge accumulation with appropriate corrugation. The flashover voltage obtained experimentally increases as the field strength decreases. The result of MCS thus agrees well with the experimental result. This proves that the MCS method is useful for the design of high voltage insulator structures.","PeriodicalId":109221,"journal":{"name":"Proceedings of 17th International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115303579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-07-21DOI: 10.1109/DEIV.1996.545459
J. Mitterauer
Field emission from liquid metal surfaces occurs with different mechanisms such as liquid metal vapor arc cathode spots and liquid metal electron sources. At rather bulk liquid metal coverages, in both cases the emission performance is also affected by hydrodynamic and electrohydrodynamic effects, respectively. Reducing the liquid metal coverage to a relative thin liquid metal film, the field-induced microstructure, as well as the intrinsic microstructure of the liquid metal film on a solid substrate dominates, and new emission modes appear. Representative examples for that are the film emission mode of liquid metal film cathodes (LMFC) and the stationary emission mode of microstructured liquid metal electron sources (MILMES). Both field emission from a cathode spot as well as from a field emitter in vacuum is examined in the scope of prospective applications in pulsed power technology.
{"title":"Field emission from microstructured thin liquid metal films","authors":"J. Mitterauer","doi":"10.1109/DEIV.1996.545459","DOIUrl":"https://doi.org/10.1109/DEIV.1996.545459","url":null,"abstract":"Field emission from liquid metal surfaces occurs with different mechanisms such as liquid metal vapor arc cathode spots and liquid metal electron sources. At rather bulk liquid metal coverages, in both cases the emission performance is also affected by hydrodynamic and electrohydrodynamic effects, respectively. Reducing the liquid metal coverage to a relative thin liquid metal film, the field-induced microstructure, as well as the intrinsic microstructure of the liquid metal film on a solid substrate dominates, and new emission modes appear. Representative examples for that are the film emission mode of liquid metal film cathodes (LMFC) and the stationary emission mode of microstructured liquid metal electron sources (MILMES). Both field emission from a cathode spot as well as from a field emitter in vacuum is examined in the scope of prospective applications in pulsed power technology.","PeriodicalId":109221,"journal":{"name":"Proceedings of 17th International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116979977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-07-21DOI: 10.1109/DEIV.1996.545462
A. Batrakov, C. Popov, D. Proskurovsky
The erosion rate has been measured for capillary-type and needle-type liquid-metal cathode. The erosion drop fraction composition and percentage have been determined. For the capillary-type liquid-metal cathodes, the erosion of the core has been discovered and investigated. To describe this erosion, a simple analytical model has been proposed.
{"title":"Investigation into the erosion of explosive-emission liquid-metal cathodes","authors":"A. Batrakov, C. Popov, D. Proskurovsky","doi":"10.1109/DEIV.1996.545462","DOIUrl":"https://doi.org/10.1109/DEIV.1996.545462","url":null,"abstract":"The erosion rate has been measured for capillary-type and needle-type liquid-metal cathode. The erosion drop fraction composition and percentage have been determined. For the capillary-type liquid-metal cathodes, the erosion of the core has been discovered and investigated. To describe this erosion, a simple analytical model has been proposed.","PeriodicalId":109221,"journal":{"name":"Proceedings of 17th International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121122345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-07-21DOI: 10.1109/DEIV.1996.545327
T. Shioiri, T. Kamikawaji, E. Kaneko, M. Homma
The authors have been studying the conditioning effect characteristic of dielectric breakdowns in a vacuum. Tests were carried out to see the conditioning effect at nonuniform field gaps and the effect of electron beam treatment. The results of the tests with stainless steel electrodes showed that the smaller the cathode electrode area, the sooner the conditioning effect at nonuniform field gaps ended and as with uniform field gaps, the electrode area was also important. The conditioning effect can be ended sooner by allowing a melted layer, having a finer structure, to form on the electrode surface by treating it with an electron beam. This effect is produced probably because the electron beam treatment suppresses prebreakdown currents and removes impurities from the electrode surface and inside it.
{"title":"Influence of electrode shape and electron beam treatment on conditioning in vacuum gap breakdown","authors":"T. Shioiri, T. Kamikawaji, E. Kaneko, M. Homma","doi":"10.1109/DEIV.1996.545327","DOIUrl":"https://doi.org/10.1109/DEIV.1996.545327","url":null,"abstract":"The authors have been studying the conditioning effect characteristic of dielectric breakdowns in a vacuum. Tests were carried out to see the conditioning effect at nonuniform field gaps and the effect of electron beam treatment. The results of the tests with stainless steel electrodes showed that the smaller the cathode electrode area, the sooner the conditioning effect at nonuniform field gaps ended and as with uniform field gaps, the electrode area was also important. The conditioning effect can be ended sooner by allowing a melted layer, having a finer structure, to form on the electrode surface by treating it with an electron beam. This effect is produced probably because the electron beam treatment suppresses prebreakdown currents and removes impurities from the electrode surface and inside it.","PeriodicalId":109221,"journal":{"name":"Proceedings of 17th International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121143944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-07-21DOI: 10.1109/DEIV.1996.545326
V.N. Shrednik
The formation of microprotrusions with droplets as a result of vacuum breakdown on a metal field emitter is well known. These microprotrusions can grow during solidification of a liquid molten phase both on the cathode and on anode. Results of field emission microscopy investigation of the surface of postbreakdown droplets (both on cathode and anode) are summarized and analysed. Taking into account very high rates of cooling of the material at and directly after droplet formation the observed properties of the droplets surfaces (and the bulk) can be explained as disordering and amorphization of their bulk structure and especially the parts near to the surface.
{"title":"Crystal structure of the metal postbreakdown droplets on a nanometric or atomic scale","authors":"V.N. Shrednik","doi":"10.1109/DEIV.1996.545326","DOIUrl":"https://doi.org/10.1109/DEIV.1996.545326","url":null,"abstract":"The formation of microprotrusions with droplets as a result of vacuum breakdown on a metal field emitter is well known. These microprotrusions can grow during solidification of a liquid molten phase both on the cathode and on anode. Results of field emission microscopy investigation of the surface of postbreakdown droplets (both on cathode and anode) are summarized and analysed. Taking into account very high rates of cooling of the material at and directly after droplet formation the observed properties of the droplets surfaces (and the bulk) can be explained as disordering and amorphization of their bulk structure and especially the parts near to the surface.","PeriodicalId":109221,"journal":{"name":"Proceedings of 17th International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127525588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-07-21DOI: 10.1109/DEIV.1996.545401
K. Abramova, G.A. Galechayn, M. Lev, A. Voronin
Results of investigation of rotating plasma in crossed magnetic and electric fields are presented. Combination of efficient heating and confinement in the Tornado closed magnetic trap permits hot, dense, stable, clean hydrogen plasma rotating with a velocity 10 times higher then the critical one to be obtained. This device seems to be important not only for fundamental research but also for practical purposes, such as neutron source, particle centrifuge or accelerator of dense plasma.
{"title":"Rotating plasma in a closed magnetic trap","authors":"K. Abramova, G.A. Galechayn, M. Lev, A. Voronin","doi":"10.1109/DEIV.1996.545401","DOIUrl":"https://doi.org/10.1109/DEIV.1996.545401","url":null,"abstract":"Results of investigation of rotating plasma in crossed magnetic and electric fields are presented. Combination of efficient heating and confinement in the Tornado closed magnetic trap permits hot, dense, stable, clean hydrogen plasma rotating with a velocity 10 times higher then the critical one to be obtained. This device seems to be important not only for fundamental research but also for practical purposes, such as neutron source, particle centrifuge or accelerator of dense plasma.","PeriodicalId":109221,"journal":{"name":"Proceedings of 17th International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124832502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-07-21DOI: 10.1109/DEIV.1996.545978
N. Vogel, V. Skvortsov
The cathode spot formation in laser-induced breakdown in a vacuum was investigated by laser absorption photography with high spatial (0.5 /spl mu/m) and temporal (100 ps) resolution. The discharge was initiated between Cu-electrodes with cathode-anode distance of 25-250 /spl mu/m. The discharge duration was 750 ns and some milliseconds, the current below 10 A. Picosecond momentary absorption photography yielded spatial-temporal density distributions in the ignition phase of the cathode spot. An absolute electron density value >5/spl times/10/sup 26/ m/sup -3/ in narrow plasma fragments with diameter smaller than 5 /spl mu/m was estimated. Principal new physical objects-"shooting solitons"-nonstationary plasma emissive centers, generated at the moving boundary of the expanding cathode spot plasma, obtained during the analysis of computer simulations give a satisfactory explanation of the current transfer in laser-induced breakdown.
{"title":"Plasma parameters within the cathode spot of laser-induced vacuum arcs: experimental and theoretical investigations","authors":"N. Vogel, V. Skvortsov","doi":"10.1109/DEIV.1996.545978","DOIUrl":"https://doi.org/10.1109/DEIV.1996.545978","url":null,"abstract":"The cathode spot formation in laser-induced breakdown in a vacuum was investigated by laser absorption photography with high spatial (0.5 /spl mu/m) and temporal (100 ps) resolution. The discharge was initiated between Cu-electrodes with cathode-anode distance of 25-250 /spl mu/m. The discharge duration was 750 ns and some milliseconds, the current below 10 A. Picosecond momentary absorption photography yielded spatial-temporal density distributions in the ignition phase of the cathode spot. An absolute electron density value >5/spl times/10/sup 26/ m/sup -3/ in narrow plasma fragments with diameter smaller than 5 /spl mu/m was estimated. Principal new physical objects-\"shooting solitons\"-nonstationary plasma emissive centers, generated at the moving boundary of the expanding cathode spot plasma, obtained during the analysis of computer simulations give a satisfactory explanation of the current transfer in laser-induced breakdown.","PeriodicalId":109221,"journal":{"name":"Proceedings of 17th International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"127 1-3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123576136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-07-21DOI: 10.1109/DEIV.1996.545451
H. Okubo, K. Ota, S. Yuasa, N. Hayakawa, M. Hikita
This paper describes the fundamental characteristics of TEA-CO/sub 2/ laser-induced plasma in low vacuum. Experimental results revealed that there existed a threshold pressure for the laser-induced plasma production in He gas and air in low vacuum. The pressure dependence of shape and intensity of plasma was observed and discussed. Laser-triggered breakdown characteristics under uniform field were also measured in atmospheric air.
{"title":"Laser-induced discharge characteristics in low vacuum with residual helium gas and air","authors":"H. Okubo, K. Ota, S. Yuasa, N. Hayakawa, M. Hikita","doi":"10.1109/DEIV.1996.545451","DOIUrl":"https://doi.org/10.1109/DEIV.1996.545451","url":null,"abstract":"This paper describes the fundamental characteristics of TEA-CO/sub 2/ laser-induced plasma in low vacuum. Experimental results revealed that there existed a threshold pressure for the laser-induced plasma production in He gas and air in low vacuum. The pressure dependence of shape and intensity of plasma was observed and discussed. Laser-triggered breakdown characteristics under uniform field were also measured in atmospheric air.","PeriodicalId":109221,"journal":{"name":"Proceedings of 17th International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126759859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-07-21DOI: 10.1109/DEIV.1996.545419
W. Opydo, J. Mila
The paper presents the results of investigations of the electric strength of vacuum insulation systems that were not subjected to conditioning. Plane electrodes with rounded-off edges of Rogowski's profile were used in the investigations. The electrodes with 50 mm diameter, were made of aluminium. The aluminium oxide layer on aluminium electrodes was obtained by electrolytic oxidation of polished and degreased aluminium electrodes. The aluminium oxide layer obtained in such a way was about 15 /spl mu/m thick. The paper shows the influence of fundamental factors defining the conditions of vacuum insulation system on its electric strength, such as: the value of pressure (within the scope of approximately 1 Pa-1 mPa) and at constant value pressure approximately 1 mPa, the length of vacuum gap, and the presence of aluminium oxide layer coating the surfaces of aluminium electrodes. The experiments have shown that the aluminium oxide layer coating the surfaces of aluminium electrodes causes, at the pressure of 2 mPa, 100% increase of electric strength of unconditioned vacuum insulation systems.
{"title":"Effect of coating electrodes with an aluminium oxide layer on the electric strength of unconditioned vacuum insulation systems","authors":"W. Opydo, J. Mila","doi":"10.1109/DEIV.1996.545419","DOIUrl":"https://doi.org/10.1109/DEIV.1996.545419","url":null,"abstract":"The paper presents the results of investigations of the electric strength of vacuum insulation systems that were not subjected to conditioning. Plane electrodes with rounded-off edges of Rogowski's profile were used in the investigations. The electrodes with 50 mm diameter, were made of aluminium. The aluminium oxide layer on aluminium electrodes was obtained by electrolytic oxidation of polished and degreased aluminium electrodes. The aluminium oxide layer obtained in such a way was about 15 /spl mu/m thick. The paper shows the influence of fundamental factors defining the conditions of vacuum insulation system on its electric strength, such as: the value of pressure (within the scope of approximately 1 Pa-1 mPa) and at constant value pressure approximately 1 mPa, the length of vacuum gap, and the presence of aluminium oxide layer coating the surfaces of aluminium electrodes. The experiments have shown that the aluminium oxide layer coating the surfaces of aluminium electrodes causes, at the pressure of 2 mPa, 100% increase of electric strength of unconditioned vacuum insulation systems.","PeriodicalId":109221,"journal":{"name":"Proceedings of 17th International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"500 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115056723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-07-21DOI: 10.1109/DEIV.1996.545504
G.I. Kostiouk, I. Levchenko
A model of thin film condensation have been developed to investigate the film growth regularity and calculate the most important characteristics of thin coating, such as microhardness, roughness, porosity etc. Our model allows calculation of film structure and defines the above-mentioned characteristics. Besides, the model is suitable for calculation of the conditions needed for a film to have a certain structure. The model takes into account all the most important processes on the surface. Some very interesting results were obtained by means of computing experiments.
{"title":"A model of thin film condensation","authors":"G.I. Kostiouk, I. Levchenko","doi":"10.1109/DEIV.1996.545504","DOIUrl":"https://doi.org/10.1109/DEIV.1996.545504","url":null,"abstract":"A model of thin film condensation have been developed to investigate the film growth regularity and calculate the most important characteristics of thin coating, such as microhardness, roughness, porosity etc. Our model allows calculation of film structure and defines the above-mentioned characteristics. Besides, the model is suitable for calculation of the conditions needed for a film to have a certain structure. The model takes into account all the most important processes on the surface. Some very interesting results were obtained by means of computing experiments.","PeriodicalId":109221,"journal":{"name":"Proceedings of 17th International Symposium on Discharges and Electrical Insulation in Vacuum","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115987198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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