Pub Date : 2019-11-26DOI: 10.1109/ICDL.2019.8796780
T. Stadlbauer, T. Kramer, D. Kontelis, L. Ducimetière, L. Sermeus, D. Woog
Several fast pulsed high voltage kicker systems at CERN use coaxial cables with SF6 gas as dielectric. Leak detection systems are installed and for interventions, the gas is recuperated and re-circulated, reducing emissions to a minimum. Nevertheless due to the high global warming potential of SF6 gas and the efforts of the European Union and CERN to reduce fluorinated greenhouse gas emissions to a minimum, a replacement strategy for the SF6 gas filled coaxial high voltage cables is being developed. New pulse generator technologies as well as different SF6 gas substitutes and also new conventional PE insulated cables are being studied. This paper gives an overview of the studies carried out to replace these cables. A comparison of possible alternatives with liquid, solid and gas dielectrics is given. The properties of the cables with alternative dielectrics are outlined, by either measurement, simulation or calculation.Especially the important parameters for kicker systems are evaluated and compared: breakdown voltage, low attenuation and low impedance change. Possible dimensions and tolerances are given, the expected costs and environmental impact are outlined. In addition an overview of different dielectric liquids used in the complete pulse generator as well as the operational experience, performance and limitations is given.
{"title":"SF6 Gas Replacement in Pulsed High Voltage Coaxial Cables","authors":"T. Stadlbauer, T. Kramer, D. Kontelis, L. Ducimetière, L. Sermeus, D. Woog","doi":"10.1109/ICDL.2019.8796780","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796780","url":null,"abstract":"Several fast pulsed high voltage kicker systems at CERN use coaxial cables with SF6 gas as dielectric. Leak detection systems are installed and for interventions, the gas is recuperated and re-circulated, reducing emissions to a minimum. Nevertheless due to the high global warming potential of SF6 gas and the efforts of the European Union and CERN to reduce fluorinated greenhouse gas emissions to a minimum, a replacement strategy for the SF6 gas filled coaxial high voltage cables is being developed. New pulse generator technologies as well as different SF6 gas substitutes and also new conventional PE insulated cables are being studied. This paper gives an overview of the studies carried out to replace these cables. A comparison of possible alternatives with liquid, solid and gas dielectrics is given. The properties of the cables with alternative dielectrics are outlined, by either measurement, simulation or calculation.Especially the important parameters for kicker systems are evaluated and compared: breakdown voltage, low attenuation and low impedance change. Possible dimensions and tolerances are given, the expected costs and environmental impact are outlined. In addition an overview of different dielectric liquids used in the complete pulse generator as well as the operational experience, performance and limitations is given.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116700612","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 : 2019-06-23DOI: 10.1109/ICDL.2019.8796842
B. Song, Xuze Gao, M. Ren, M. Dong, Tianxin Zhuang
Superconducting DC energy pipeline realizes the mixed transportation of electric energy and liquid natural gas, which is a high efficiency and low energy consumption method of redistribution of energy. Superconducting DC electric termination is one of the cores equipment of superconducting DC energy pipelines which bears various extreme conditions such as electric field, large temperature gradient, mechanical stress, etc. Under the influences of multiphysics, the electrical and thermal properties of the terminal materials will change to varying degrees, and these changes will cause distortion of the physical field in turn. Therefore, in the design of the terminal structure, multiple physical interactions and mutual cooperation methods need to be considered. Under the two-way coupling of multi-physics and terminal material parameters, the physical simulation model of superconducting energy pipeline is established, and the electric field distortion in this model are analyzed.In this article, the physical model of superconducting energy pipeline terminal is established by COMSOL. And we find that the change rule of the material conductivity with temperature counts a great deal in the distribution of the electric field thermal field in the terminal. At the same time, the cooling power of liquid nitrogen influences the temperature distribution, thus affect the electric field indirectly to a certain extent. Therefore, in the optimization design of the terminal, selection of insulation materials, how to control the heat generation should take into consideration. This study provides theoretical support for the insulation optimization design of superconducting energy pipeline terminals.
{"title":"Electrothermal Coupling Simulation of Termination Insulation of Superconducting Energy Pipeline","authors":"B. Song, Xuze Gao, M. Ren, M. Dong, Tianxin Zhuang","doi":"10.1109/ICDL.2019.8796842","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796842","url":null,"abstract":"Superconducting DC energy pipeline realizes the mixed transportation of electric energy and liquid natural gas, which is a high efficiency and low energy consumption method of redistribution of energy. Superconducting DC electric termination is one of the cores equipment of superconducting DC energy pipelines which bears various extreme conditions such as electric field, large temperature gradient, mechanical stress, etc. Under the influences of multiphysics, the electrical and thermal properties of the terminal materials will change to varying degrees, and these changes will cause distortion of the physical field in turn. Therefore, in the design of the terminal structure, multiple physical interactions and mutual cooperation methods need to be considered. Under the two-way coupling of multi-physics and terminal material parameters, the physical simulation model of superconducting energy pipeline is established, and the electric field distortion in this model are analyzed.In this article, the physical model of superconducting energy pipeline terminal is established by COMSOL. And we find that the change rule of the material conductivity with temperature counts a great deal in the distribution of the electric field thermal field in the terminal. At the same time, the cooling power of liquid nitrogen influences the temperature distribution, thus affect the electric field indirectly to a certain extent. Therefore, in the optimization design of the terminal, selection of insulation materials, how to control the heat generation should take into consideration. This study provides theoretical support for the insulation optimization design of superconducting energy pipeline terminals.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131241981","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 : 2019-06-23DOI: 10.1109/ICDL.2019.8796727
P. Leblanc, P. Clermont, T. Paillat, X. Sidambarompoulé, J. Laurentie, P. Notingher
The study of the electrical double layer in transitory regime seems to be a good way to reach a better understanding of its origin. Recent numerical studies have shown the importance of taking into account the thermal dependence of the liquid intrinsic properties, such as the electrical permittivity or ionic mobility. In this paper, a film of dielectric liquid trapped between two metallic plane electrodes is studies via its electrical current response to the thermal step.
{"title":"Numerical Study of the Thermal Excitation Applied to a Dielectric Liquid Film","authors":"P. Leblanc, P. Clermont, T. Paillat, X. Sidambarompoulé, J. Laurentie, P. Notingher","doi":"10.1109/ICDL.2019.8796727","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796727","url":null,"abstract":"The study of the electrical double layer in transitory regime seems to be a good way to reach a better understanding of its origin. Recent numerical studies have shown the importance of taking into account the thermal dependence of the liquid intrinsic properties, such as the electrical permittivity or ionic mobility. In this paper, a film of dielectric liquid trapped between two metallic plane electrodes is studies via its electrical current response to the thermal step.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116280021","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 : 2019-06-23DOI: 10.1109/ICDL.2019.8796534
Yuwei Zhu, S. Acounis, N. Beaupère, J. Beney, J. Bert, S. Bouvier, C. Canot, T. Carlier, M. Chérel, J. Cussonneau, S. Diglio, D. Giovagnoli, J. Idier, F. Kraeber-Bodéré, P. L. Ray, F. Lefèvre, J. Masbou, E. Morteau, J. Stutzmann, D. Thers, D. Visvikis, Y. Xing
An innovative Xenon Medical Imaging System, XEMIS2, designed for small animal 3 $gamma$ preclinical imaging, has been constructed, and it is currently under test and qualification at the SUBATECH laboratory. It consists of a Compton camera, containing nearly 200 kg of liquid xenon, whose main goals are the precise three-dimensional localization of the 44Sc radioactive emitter used to image the small animal and the reduction of the administered radiopharmaceutical activity in cancer diagnosis. The active volume of the XEMIS2 camera is surrounded by a set of PhotoMultiplier Tubes (PMTs) to measure scintillation light. The read-out anodes are segmented in 20000 pixels to measure ionization charges. In order to reduce the electronics dead-time during continuous data taking, a novel DAQ system specifically designed for XEMIS2 has been realized and recently tested. It consists of two independent synchronized scintillation and ionization signal detection chains. The self-triggered scintillation light detection chain has been recently tested and calibrated in XEMIS1, whose experimental results showed a good performance. XEMIS2 will be soon installed at the Center for Applied Multimodal Imaging (CIMA) in the Nantes University Hospital for further preclinical studies. To safely manage a large amount of xenon in a hospital center, a recovery and storage cryogenic subsystem called ReStoX has been conceived, successfully commissioned, and already installed at CIMA.
{"title":"XEMIS2: A liquid xenon Compton camera to image small animals","authors":"Yuwei Zhu, S. Acounis, N. Beaupère, J. Beney, J. Bert, S. Bouvier, C. Canot, T. Carlier, M. Chérel, J. Cussonneau, S. Diglio, D. Giovagnoli, J. Idier, F. Kraeber-Bodéré, P. L. Ray, F. Lefèvre, J. Masbou, E. Morteau, J. Stutzmann, D. Thers, D. Visvikis, Y. Xing","doi":"10.1109/ICDL.2019.8796534","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796534","url":null,"abstract":"An innovative Xenon Medical Imaging System, XEMIS2, designed for small animal 3 $gamma$ preclinical imaging, has been constructed, and it is currently under test and qualification at the SUBATECH laboratory. It consists of a Compton camera, containing nearly 200 kg of liquid xenon, whose main goals are the precise three-dimensional localization of the 44Sc radioactive emitter used to image the small animal and the reduction of the administered radiopharmaceutical activity in cancer diagnosis. The active volume of the XEMIS2 camera is surrounded by a set of PhotoMultiplier Tubes (PMTs) to measure scintillation light. The read-out anodes are segmented in 20000 pixels to measure ionization charges. In order to reduce the electronics dead-time during continuous data taking, a novel DAQ system specifically designed for XEMIS2 has been realized and recently tested. It consists of two independent synchronized scintillation and ionization signal detection chains. The self-triggered scintillation light detection chain has been recently tested and calibrated in XEMIS1, whose experimental results showed a good performance. XEMIS2 will be soon installed at the Center for Applied Multimodal Imaging (CIMA) in the Nantes University Hospital for further preclinical studies. To safely manage a large amount of xenon in a hospital center, a recovery and storage cryogenic subsystem called ReStoX has been conceived, successfully commissioned, and already installed at CIMA.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124808146","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 : 2019-06-23DOI: 10.1109/ICDL.2019.8796598
S. Dujko, J. Atić, D. Bošnjaković, Z. Petrović, J. Urquijo
A multi term theory for solving the Boltzmann equation and a Monte Carlo simulation technique are used to calculate electron transport coefficients in the mixtures of CF3I and SF6 as a function of the applied electric field. The calculated transport coefficients are then used as an input in the fluid equation based models to investigate the transition from an electron avalanche into a streamer and streamer propagation. Electron transport coefficients are also calculated in radio-frequency electric and magnetic fields crossed at arbitrary phases and angles. A multitude of kinetic phenomena induced by the synergism of the magnetic field and electron attachment is observed and discussed using physical arguments.
{"title":"Electron transport coefficients and negative streamer dynamics in CF3I-SF6 mixtures","authors":"S. Dujko, J. Atić, D. Bošnjaković, Z. Petrović, J. Urquijo","doi":"10.1109/ICDL.2019.8796598","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796598","url":null,"abstract":"A multi term theory for solving the Boltzmann equation and a Monte Carlo simulation technique are used to calculate electron transport coefficients in the mixtures of CF3I and SF6 as a function of the applied electric field. The calculated transport coefficients are then used as an input in the fluid equation based models to investigate the transition from an electron avalanche into a streamer and streamer propagation. Electron transport coefficients are also calculated in radio-frequency electric and magnetic fields crossed at arbitrary phases and angles. A multitude of kinetic phenomena induced by the synergism of the magnetic field and electron attachment is observed and discussed using physical arguments.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127753713","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 : 2019-06-23DOI: 10.1109/ICDL.2019.8796643
R. Chassagnoux, O. Lesaint, N. Bonifaci, O. Gallot-Lavallée, P. Legendre, C. Creusot, A. Girodet
An experimental study of breakdown and pre-breakdown phenomena in liquid nitrogen (LN2) is performed in this work, aiming to provide useful knowledge for the design of high voltage superconducting systems. A metallic tape subjected to pulsed heating is used as ground electrode to properly simulate the operating conditions of a quenching superconducting apparatus. Measurements of breakdown voltages between the tape and a plane electrode tied to high voltage show the strong influence of tape polarity, LN2 temperature, and delay between heating and voltage application. Various measurements obtained with either a highspeed camera or an intensified camera allow to characterize the sequence of pre-breakdown events (i.e. liquid boiling, vapor bubble development, and streamer propagation) leading to breakdown.
{"title":"Prebreakdown and Breakdown in Liquid Nitrogen under Pulsed Heating for Superconducting","authors":"R. Chassagnoux, O. Lesaint, N. Bonifaci, O. Gallot-Lavallée, P. Legendre, C. Creusot, A. Girodet","doi":"10.1109/ICDL.2019.8796643","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796643","url":null,"abstract":"An experimental study of breakdown and pre-breakdown phenomena in liquid nitrogen (LN2) is performed in this work, aiming to provide useful knowledge for the design of high voltage superconducting systems. A metallic tape subjected to pulsed heating is used as ground electrode to properly simulate the operating conditions of a quenching superconducting apparatus. Measurements of breakdown voltages between the tape and a plane electrode tied to high voltage show the strong influence of tape polarity, LN2 temperature, and delay between heating and voltage application. Various measurements obtained with either a highspeed camera or an intensified camera allow to characterize the sequence of pre-breakdown events (i.e. liquid boiling, vapor bubble development, and streamer propagation) leading to breakdown.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"129 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133587398","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 : 2019-06-23DOI: 10.1109/ICDL.2019.8796530
U. Khaled, A. Beroual
This paper deals with experimental study of the influence of magnetic nanoparticles namely (Fe3O4) at various concentrations on the dielectric strength of mineral oil, synthetic and natural esters (namely MIDEL 7131 and MIDEL 1204, respectively). A statistical analysis of experimental results is conducted using Weibull probabilistic law. The breakdown voltage with risk of 1%, 10%, and 50% probability are also estimated. Experimental findings reveal that this type of nanoparticles significantly improves AC breakdown voltage of mineral oil and synthetic ester. The enhancement is the highest for mineral oil; the breakdown voltage (BDV) can exceed twice that of mineral oil. With synthetic ester, the enhancement can reach 48%. While the improvement of breakdown voltage of natural ester based Fe3O4 nanofluids does not exceed 7%. The physicochemical mechanisms implicated in this improvement are discussed.
{"title":"Influence of Conductive Nanoparticles on the Breakdown Voltage of Mineral Oil, Synthetic and Natural Ester Oil-based Nanofluids","authors":"U. Khaled, A. Beroual","doi":"10.1109/ICDL.2019.8796530","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796530","url":null,"abstract":"This paper deals with experimental study of the influence of magnetic nanoparticles namely (Fe3O4) at various concentrations on the dielectric strength of mineral oil, synthetic and natural esters (namely MIDEL 7131 and MIDEL 1204, respectively). A statistical analysis of experimental results is conducted using Weibull probabilistic law. The breakdown voltage with risk of 1%, 10%, and 50% probability are also estimated. Experimental findings reveal that this type of nanoparticles significantly improves AC breakdown voltage of mineral oil and synthetic ester. The enhancement is the highest for mineral oil; the breakdown voltage (BDV) can exceed twice that of mineral oil. With synthetic ester, the enhancement can reach 48%. While the improvement of breakdown voltage of natural ester based Fe3O4 nanofluids does not exceed 7%. The physicochemical mechanisms implicated in this improvement are discussed.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133254700","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 : 2019-06-23DOI: 10.1109/ICDL.2019.8796588
N. Pattanadech, Kantitat Sasomponsawatline, Jompatara Siriworachanyadee, Worawich Angsusatra
Dissolved gas analysis (DGA) is an important method and widely used for assessment the conditions of transformer insulations. The dissolved gas interpretation is one of the most significant procedures to identify the failure causes. The objective of this paper is to represent diagnosis of the dissolved gas techniques i.e. IEC ratio, Duval Triangle and Duval Pentagon for interpretation. The data of dissolved gas is received from Metropolitan Electricity Authority (MEA), Thailand during 2016. The DGA test results obtained from 132 transformer units. Due to the transformers have various rated power so providers have made a classification of results by rated transformer power rated of 40, 60, 250 and 300 MVA respectively. Overheating at high temperature is generally found. The results of the data analysis by using Duval Triangle method is the most similar result from observation work. Moreover, the Duval Pentagon method is interested for gas interpretation. However, it needs more research work to guarantee and support this method.
{"title":"The conformity of DGA interpretation techniques: Experience from transformer 132 units","authors":"N. Pattanadech, Kantitat Sasomponsawatline, Jompatara Siriworachanyadee, Worawich Angsusatra","doi":"10.1109/ICDL.2019.8796588","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796588","url":null,"abstract":"Dissolved gas analysis (DGA) is an important method and widely used for assessment the conditions of transformer insulations. The dissolved gas interpretation is one of the most significant procedures to identify the failure causes. The objective of this paper is to represent diagnosis of the dissolved gas techniques i.e. IEC ratio, Duval Triangle and Duval Pentagon for interpretation. The data of dissolved gas is received from Metropolitan Electricity Authority (MEA), Thailand during 2016. The DGA test results obtained from 132 transformer units. Due to the transformers have various rated power so providers have made a classification of results by rated transformer power rated of 40, 60, 250 and 300 MVA respectively. Overheating at high temperature is generally found. The results of the data analysis by using Duval Triangle method is the most similar result from observation work. Moreover, the Duval Pentagon method is interested for gas interpretation. However, it needs more research work to guarantee and support this method.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121720860","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 : 2019-06-23DOI: 10.1109/ICDL.2019.8796776
Qingjiang Xue, I. Timoshkin, M. Given, Mark P. Wilson, S. Macgregor
The mobility of charge carriers in dielectric liquids is not only an intrinsic parameter of the conduction process, but it also can define the pre-breakdown processes in the liquids. The charge carrier mobility also affects the electrostatic behavior of fine and ultra-fine (micrometer and sub-micrometer) particles in -fluids, as the charge induced on dispersed particles is defined by the charge concentration and the velocity of charge carriers in the liquid. In this paper, the charge carrier mobility was obtained by measuring conduction current in different dielectric liquids under DC stress. The investigated liquids included traditional mineral oil, synthetic and natural esters. Both, single polarity and polarity reversal methods were used to obtain the charge carrier mobility in these liquids. The results show significant differences in the mobilities of charge carriers in the mineral oil and in ester liquids. Also, the effects of the electric field on the mobilities has been investigated.
{"title":"Mobility of Charge Carriers in Dielectric Liquids","authors":"Qingjiang Xue, I. Timoshkin, M. Given, Mark P. Wilson, S. Macgregor","doi":"10.1109/ICDL.2019.8796776","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796776","url":null,"abstract":"The mobility of charge carriers in dielectric liquids is not only an intrinsic parameter of the conduction process, but it also can define the pre-breakdown processes in the liquids. The charge carrier mobility also affects the electrostatic behavior of fine and ultra-fine (micrometer and sub-micrometer) particles in -fluids, as the charge induced on dispersed particles is defined by the charge concentration and the velocity of charge carriers in the liquid. In this paper, the charge carrier mobility was obtained by measuring conduction current in different dielectric liquids under DC stress. The investigated liquids included traditional mineral oil, synthetic and natural esters. Both, single polarity and polarity reversal methods were used to obtain the charge carrier mobility in these liquids. The results show significant differences in the mobilities of charge carriers in the mineral oil and in ester liquids. Also, the effects of the electric field on the mobilities has been investigated.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131292841","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 : 2019-06-23DOI: 10.1109/ICDL.2019.8796648
A. Khrapak, S. Bronin
The mobility of electrons injected in the majority of nonpolar dielectric liquids is a few orders of magnitude higher than the mobility of positive ions. However, the behavior of electrons in liquid helium is anomalous. The electron mobility is a few orders of magnitude lower than the value expected according to the classical Langevin theory and even a few times lower than the mobility of positive ions. The reason is that it is energetically favorable for an electron to be localized in nanobubble owing to a strong exchange repulsion from helium atoms. In addition to ordinary electron bubbles, two more types of negative charge carriers were discovered many years ago in superfluid helium: “fast” and “exotic” ions. The mobility of fast ions is approximately seven times higher than the mobility of electron bubbles, whereas the mobility of a family of exotic ions (more than ten members) lies between these two values. In the present work a model according to which fast and exotic negative ions in superfluid helium represent the localized states of electrons in vortex rings is presented. The quantization of radial and longitudinal motions of electrons inside the vortex core and the quantization of the vortex motion of liquid helium around the charged complex lead to the existence of a whole family of excited states of electron vortices with different radii and quanta of vorticity. The proposed simple model of autolocalization of injected electrons in vortex rings allows to understand the nature of fast and exotic ions in superfluid helium.
{"title":"Electron Self-Trapping in Vortex Rings in Superfluid Helium","authors":"A. Khrapak, S. Bronin","doi":"10.1109/ICDL.2019.8796648","DOIUrl":"https://doi.org/10.1109/ICDL.2019.8796648","url":null,"abstract":"The mobility of electrons injected in the majority of nonpolar dielectric liquids is a few orders of magnitude higher than the mobility of positive ions. However, the behavior of electrons in liquid helium is anomalous. The electron mobility is a few orders of magnitude lower than the value expected according to the classical Langevin theory and even a few times lower than the mobility of positive ions. The reason is that it is energetically favorable for an electron to be localized in nanobubble owing to a strong exchange repulsion from helium atoms. In addition to ordinary electron bubbles, two more types of negative charge carriers were discovered many years ago in superfluid helium: “fast” and “exotic” ions. The mobility of fast ions is approximately seven times higher than the mobility of electron bubbles, whereas the mobility of a family of exotic ions (more than ten members) lies between these two values. In the present work a model according to which fast and exotic negative ions in superfluid helium represent the localized states of electrons in vortex rings is presented. The quantization of radial and longitudinal motions of electrons inside the vortex core and the quantization of the vortex motion of liquid helium around the charged complex lead to the existence of a whole family of excited states of electron vortices with different radii and quanta of vorticity. The proposed simple model of autolocalization of injected electrons in vortex rings allows to understand the nature of fast and exotic ions in superfluid helium.","PeriodicalId":102217,"journal":{"name":"2019 IEEE 20th International Conference on Dielectric Liquids (ICDL)","volume":"274 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114025596","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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