Electrical discharge in vacuum is accompanied by X-ray radiation. Knowledge of the generation mechanism of radiation may lead to its practical use. The analysis of this phenomenon indicates that it is only at the discharge development phase until the moment of the anode plasma generation that the proper conditions for X-ray generation are satisfied. The intensity of radiation is dependent on the field current intensity on the cathode surface as well as on the value of the electron current supplying the anode. The anode current at the vacuum discharge development phase has a pulse character, and the pulse amplitude is dependent on the cathode plasma density. The radiation intensity may be increased by increasing the current amplitude, e.g. by artificial plasma generation in the trigger system. >
{"title":"X-ray emission accompanying cathode microdischarge","authors":"B. Mazurek, A. Nowak, A. Tymań","doi":"10.1109/14.231530","DOIUrl":"https://doi.org/10.1109/14.231530","url":null,"abstract":"Electrical discharge in vacuum is accompanied by X-ray radiation. Knowledge of the generation mechanism of radiation may lead to its practical use. The analysis of this phenomenon indicates that it is only at the discharge development phase until the moment of the anode plasma generation that the proper conditions for X-ray generation are satisfied. The intensity of radiation is dependent on the field current intensity on the cathode surface as well as on the value of the electron current supplying the anode. The anode current at the vacuum discharge development phase has a pulse character, and the pulse amplitude is dependent on the cathode plasma density. The radiation intensity may be increased by increasing the current amplitude, e.g. by artificial plasma generation in the trigger system. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":"72 1","pages":"488-493"},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86308789","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}
Reviews surface flashover of insulator, primarily in vacuum, although some comments are made about the effect of ambient gases on surface flashover. It presents theoretical mechanisms of surface flashover and pertinent experimental results. The holdoff voltage of insulators depends upon many insulator parameters, such as material, geometry, surface finish, and attachments to electrodes, but also on the applied voltage waveform (duration, single pulse or repetitive), the process history of the insulator operating environment, and previous applications of voltage. Several suggestions are made regarding choice of the material, geometry, and processing when selecting an insulator for a particular application. Some specific techniques for improving the holdoff voltage of insulators are recommended. >
{"title":"Flashover of insulators in vacuum: review of the phenomena and techniques to improved holdoff voltage","authors":"H. C. Miller","doi":"10.1109/14.231534","DOIUrl":"https://doi.org/10.1109/14.231534","url":null,"abstract":"Reviews surface flashover of insulator, primarily in vacuum, although some comments are made about the effect of ambient gases on surface flashover. It presents theoretical mechanisms of surface flashover and pertinent experimental results. The holdoff voltage of insulators depends upon many insulator parameters, such as material, geometry, surface finish, and attachments to electrodes, but also on the applied voltage waveform (duration, single pulse or repetitive), the process history of the insulator operating environment, and previous applications of voltage. Several suggestions are made regarding choice of the material, geometry, and processing when selecting an insulator for a particular application. Some specific techniques for improving the holdoff voltage of insulators are recommended. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":"154 ","pages":"512-527"},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91447020","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}
Some selected parameters describing microdischarges are examined. The statistical distribution of charge transferred by microdischarges, obtained by means of multichannel pulse-height analysis, is presented. The relations of breakdown voltage to the parameters characterizing microdischarges are defined. The parameters considered are the number N of pulses in count time, maximum charge Q/sub mx/ of a single microdischarge, total charge Q transferred by microdischarges in count time, and summary charge Q/sub 30/ transferred by the most intensive microdischarges with magnitude of 0.7Q/sub mx/ to 1.0Q/sub mx/. >
{"title":"Relation of breakdown voltage and prebreakdown microdischarge parameters in vacuum","authors":"W. Ziomek, H. Mościcka-Grzesiak","doi":"10.1109/14.231529","DOIUrl":"https://doi.org/10.1109/14.231529","url":null,"abstract":"Some selected parameters describing microdischarges are examined. The statistical distribution of charge transferred by microdischarges, obtained by means of multichannel pulse-height analysis, is presented. The relations of breakdown voltage to the parameters characterizing microdischarges are defined. The parameters considered are the number N of pulses in count time, maximum charge Q/sub mx/ of a single microdischarge, total charge Q transferred by microdischarges in count time, and summary charge Q/sub 30/ transferred by the most intensive microdischarges with magnitude of 0.7Q/sub mx/ to 1.0Q/sub mx/. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":"1 1","pages":"481-487"},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89420107","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}
A. Berroung, S. Fayeulle, B. Hamzaoui, D. Tréheux, C. Gressus
The study of ceramics is tackled from the space-charge physics point of view. The role of the polarization and relaxation mechanisms is demonstrated for friction coefficient and wear, as well as for breakdown voltage; therefore these characteristics depend on the permittivity. This result is based on experiments performed with pure or X-irradiated single crystal alumina (sapphire) or polycrystalline alumina. A method called the mirror method is presented, in which the possibility of creating trapped electrical charges in a given material is measured using the electron beam of a scanning electron microscope. This method is based on the fact that X-ray irradiation changes permittivity, Young modulus, and charging properties. Therefore, when a dielectric material is under irradiation, the trap and the bond energies will be modified and consequently changes in electrical and mechanical properties of the material are expected. It is shown that these changes can modify both irradiated and nonirradiated areas. >
{"title":"Effect of X-irradiation and friction on the properties of insulators","authors":"A. Berroung, S. Fayeulle, B. Hamzaoui, D. Tréheux, C. Gressus","doi":"10.1109/14.231535","DOIUrl":"https://doi.org/10.1109/14.231535","url":null,"abstract":"The study of ceramics is tackled from the space-charge physics point of view. The role of the polarization and relaxation mechanisms is demonstrated for friction coefficient and wear, as well as for breakdown voltage; therefore these characteristics depend on the permittivity. This result is based on experiments performed with pure or X-irradiated single crystal alumina (sapphire) or polycrystalline alumina. A method called the mirror method is presented, in which the possibility of creating trapped electrical charges in a given material is measured using the electron beam of a scanning electron microscope. This method is based on the fact that X-ray irradiation changes permittivity, Young modulus, and charging properties. Therefore, when a dielectric material is under irradiation, the trap and the bond energies will be modified and consequently changes in electrical and mechanical properties of the material are expected. It is shown that these changes can modify both irradiated and nonirradiated areas. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":"68 1","pages":"528-534"},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74797523","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}
Conventional HV fuses, which are filled with quartz sand, have an excellent current-limiting capability, but they have a zone of uncertain operation in the low overcurrent range. To overcome this disadvantage, substituting of the quartz sand by a vacuum was considered. In particular, a vacuum fuse can be designed by inserting a fusible element between the fixed butt contacts (electrodes) of a vacuum chamber. Melting curves and the arc quenching capability at current zero are investigated for a simply designed vacuum fuse with flat contacts. Variables are the current amplitude, the electrode material, the diameter of the fuse wire, and the distance between the electrodes. These results show that it is possible to design an operable vacuum fuse with a simplified electrode configuration. The time/current characteristic is strongly influenced by the length of the fuse wire. >
{"title":"Time/current characteristics and breaking capacity of experimental vacuum fuses","authors":"D. Brechtken, D. Konig","doi":"10.1109/14.231547","DOIUrl":"https://doi.org/10.1109/14.231547","url":null,"abstract":"Conventional HV fuses, which are filled with quartz sand, have an excellent current-limiting capability, but they have a zone of uncertain operation in the low overcurrent range. To overcome this disadvantage, substituting of the quartz sand by a vacuum was considered. In particular, a vacuum fuse can be designed by inserting a fusible element between the fixed butt contacts (electrodes) of a vacuum chamber. Melting curves and the arc quenching capability at current zero are investigated for a simply designed vacuum fuse with flat contacts. Variables are the current amplitude, the electrode material, the diameter of the fuse wire, and the distance between the electrodes. These results show that it is possible to design an operable vacuum fuse with a simplified electrode configuration. The time/current characteristic is strongly influenced by the length of the fuse wire. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":"18 1","pages":"642-649"},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86378887","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}
Space vacuum is considered as an insulation component to achieve constructional and operational advantages over totally enclosed designs for the increasing demand for higher levels of electrical power and voltages in spaceborne electrical systems. The dielectric properties of space vacuum insulations are determined mainly by the space environment and local contaminations of the spacecraft structure. Specific aspects of the insulation, such as temperature, pressure, radiation, charged particle flux, outgassing products, and effluents, are discussed. >
{"title":"HV design of vacuum-insulated power supplies for space applications","authors":"M. Gollor, K. Rogalla","doi":"10.1109/14.231550","DOIUrl":"https://doi.org/10.1109/14.231550","url":null,"abstract":"Space vacuum is considered as an insulation component to achieve constructional and operational advantages over totally enclosed designs for the increasing demand for higher levels of electrical power and voltages in spaceborne electrical systems. The dielectric properties of space vacuum insulations are determined mainly by the space environment and local contaminations of the spacecraft structure. Specific aspects of the insulation, such as temperature, pressure, radiation, charged particle flux, outgassing products, and effluents, are discussed. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":"97 1","pages":"667-680"},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78252419","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}
S. Michizono, Yoshio Saito, S. Yamaguchi, S. Anami, N. Matuda, A. Kinbara
The breakdown of RF windows used in high-power klystrons is one of the most serious problems in the development of klystrons. The durability of several dielectric materials used for RF windows is discussed in terms of secondary electron emission (SEE), cathodoluminescence, and dielectric loss. High-power tests of these materials with TiN coatings, thus having low SEE, were also carried out using a traveling wave resonant ring. The results show that alumina ceramics are superior to sapphire and aluminum nitride. The origin of breakdown is investigated, and the requirements for RF window materials are presented. >
{"title":"Dielectric materials for use as output window in high-power klystrons","authors":"S. Michizono, Yoshio Saito, S. Yamaguchi, S. Anami, N. Matuda, A. Kinbara","doi":"10.1109/14.231552","DOIUrl":"https://doi.org/10.1109/14.231552","url":null,"abstract":"The breakdown of RF windows used in high-power klystrons is one of the most serious problems in the development of klystrons. The durability of several dielectric materials used for RF windows is discussed in terms of secondary electron emission (SEE), cathodoluminescence, and dielectric loss. High-power tests of these materials with TiN coatings, thus having low SEE, were also carried out using a traveling wave resonant ring. The results show that alumina ceramics are superior to sapphire and aluminum nitride. The origin of breakdown is investigated, and the requirements for RF window materials are presented. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":"150 1","pages":"692-699"},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77423868","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}
Using an in situ electrode surface cleaning system, the vacuum breakdown strength of vacuum degassed oxygen free copper (VDOFC) electrodes satisfying ASTM-F-68 Class 1, 3, and 5 purity specifications was measured. Breakdown experiments reveal that the breakdown field (breakdown voltage/gap length) depends on the purity of the VDOFC electrodes. The initial breakdown strengths are 1.96*10/sup 7/ V/m for Class 1 copper, 1.89*10/sup 7/ V/m for Class 3, and 1.85*10/sup 7/ V/m for Class 5. After 500 breakdowns, these figures were improved to 18.3*10/sup 7/ V/m for Class 1, 17.5*10/sup 7/ V/m for Class 3, and 11.8*10/sup 7/ V/m for Class 5. It is concluded that the gas content in the electrodes is an important factor relating to the vacuum breakdown strength, provided the electrode surface is properly cleaned. >
{"title":"Vacuum breakdown strength of vacuum-degassed oxygen-free copper electrodes","authors":"S. Kobayashi, Y. Saito, Y. Nagai, Y. Yamamoto","doi":"10.1109/14.231532","DOIUrl":"https://doi.org/10.1109/14.231532","url":null,"abstract":"Using an in situ electrode surface cleaning system, the vacuum breakdown strength of vacuum degassed oxygen free copper (VDOFC) electrodes satisfying ASTM-F-68 Class 1, 3, and 5 purity specifications was measured. Breakdown experiments reveal that the breakdown field (breakdown voltage/gap length) depends on the purity of the VDOFC electrodes. The initial breakdown strengths are 1.96*10/sup 7/ V/m for Class 1 copper, 1.89*10/sup 7/ V/m for Class 3, and 1.85*10/sup 7/ V/m for Class 5. After 500 breakdowns, these figures were improved to 18.3*10/sup 7/ V/m for Class 1, 17.5*10/sup 7/ V/m for Class 3, and 11.8*10/sup 7/ V/m for Class 5. It is concluded that the gas content in the electrodes is an important factor relating to the vacuum breakdown strength, provided the electrode surface is properly cleaned. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":"67 1","pages":"500-506"},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85789557","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}
The reaction of the trigger plasma of triggered vacuum gaps (TVGs) to the main gap voltage changes with the main gap polarity. The trigger polarity has no influence when the main gap voltage exceeds a certain value. The high current-chopping instability in positive TVG mode is investigated in detail, with the influence of the loop parameters and electrode contamination. In the negative mode, a history effect is found in TVG triggering, associated with the surface condition of the main gap cathode. The trigger delay time in the negative mode depends on the trigger plasma density and the plasma buildup. The general TVG triggering is explained, and the reaction of the trigger plasma to the main gap polarity determines the main-gap polarity dependence of TVG. >
{"title":"The properties of triggered vacuum gaps","authors":"W. Shang, G. Damstra","doi":"10.1109/14.231548","DOIUrl":"https://doi.org/10.1109/14.231548","url":null,"abstract":"The reaction of the trigger plasma of triggered vacuum gaps (TVGs) to the main gap voltage changes with the main gap polarity. The trigger polarity has no influence when the main gap voltage exceeds a certain value. The high current-chopping instability in positive TVG mode is investigated in detail, with the influence of the loop parameters and electrode contamination. In the negative mode, a history effect is found in TVG triggering, associated with the surface condition of the main gap cathode. The trigger delay time in the negative mode depends on the trigger plasma density and the plasma buildup. The general TVG triggering is explained, and the reaction of the trigger plasma to the main gap polarity determines the main-gap polarity dependence of TVG. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":"33 1","pages":"650-656"},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85790484","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}
The breakdown voltage between the open contacts of vacuum circuit breakers (VCBs) immediately after manufacturing is low and subject to high scatter. To attain a sufficiently high breakdown voltage, these unknown and undefined surface conditions must be improved by conditioning. Several usual conditioning procedures applied to a large number of 12-kV circuit breakers of a standard design are compared. A large number of conditioning experiments have been made and statistically evaluated. Additional studies have been performed in a vacuum test chamber in which the contacts could be interchanged easily. The aim was to find the most important conditioning parameters and to explain the underlying physical processes. The studies show that the conditioning procedure can be optimized. >
{"title":"Spark conditioning procedures for vacuum interrupters in circuit breakers","authors":"J. Ballat, D. Konig, U. Reininghaus","doi":"10.1109/14.231544","DOIUrl":"https://doi.org/10.1109/14.231544","url":null,"abstract":"The breakdown voltage between the open contacts of vacuum circuit breakers (VCBs) immediately after manufacturing is low and subject to high scatter. To attain a sufficiently high breakdown voltage, these unknown and undefined surface conditions must be improved by conditioning. Several usual conditioning procedures applied to a large number of 12-kV circuit breakers of a standard design are compared. A large number of conditioning experiments have been made and statistically evaluated. Additional studies have been performed in a vacuum test chamber in which the contacts could be interchanged easily. The aim was to find the most important conditioning parameters and to explain the underlying physical processes. The studies show that the conditioning procedure can be optimized. >","PeriodicalId":13105,"journal":{"name":"IEEE Transactions on Electrical Insulation","volume":"75 1","pages":"621-627"},"PeriodicalIF":0.0,"publicationDate":"1993-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79272578","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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