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Sasaki, Akira; Kato, Susumu*; Takahashi, Eiichi*; Kishimoto, Yasuaki*; Fujii, Takashi*; Kanazawa, Seiji*
Japanese Journal of Applied Physics, 55(2), p.026101_1 - 026101_10, 2016/02
Times Cited Count:2 Percentile:9.75(Physics, Applied)A percolation model of discharge, which can reproduce stochastic behaviors of initial partial discharge to the growth of a stepped leader, is presented. The model uses macroscopic cells, from which a network of electric circuits is defined, and the spatial and temporal evolutions of the electric field and current in the discharge medium are calculated. For each cell, one of two states, either insulator or conductor, which corresponds to neutral gas or ionized plasmas, respectively, is decided. The decision is made on the basis of probability for each calculation cell at each time step, taking the effects of local electric field and current, which enhance ionization and sustain the discharge channel, respectively, into account. The stochastic behavior of discharge is discussed, in conjunction with the characteristic feature of ionization, that is, the ionization occurs not only ahead of the streamer tip where the electric field is enhanced but randomly in the discharge medium.
Sasaki, Akira; Kato, Susumu*; Takahashi, Eiichi*; Kanazawa, Seiji*
JPS Conference Proceedings (Internet), 1, p.015029_1 - 015029_4, 2014/03
Although streamer discharges have long been studied, the mechanism of sudden formation of the complex discharge path has not been fully understood. We show that a simulation based on the percolation model reproduces such development of the streamer. In the model, the discharge medium is divided into cells and is considered to form an electrical circuit network, which is used to calculate the current. In contrast to the characteristic feature of a single electron avalanche is explained by the Townsend theory, when the size of the system becomes greater, random formation of the avalanche in the medium and connection between them determines the propagation of the steamer, which is analyzed using the percolation model. Figure shows the simulated discharge from the initial pre-discharge activity near the electrode to rapid growth of the stepped leader, which causes breakdown.
Sasaki, Akira; Kishimoto, Yasuaki*; Takahashi, Eiichi*; Kato, Susumu*; Fujii, Takashi*; Kanazawa, Seiji*
Physical Review Letters, 105(7), p.075004_1 - 075004_4, 2010/08
Times Cited Count:10 Percentile:55.4(Physics, Multidisciplinary)A three-dimensional simulation of laser guided-discharges based on the percolation is presented. The model includes both local growth of a streamer due to the enhanced electric field at the tip and propagation of a leader by remote ionization such that caused by runaway electrons. The stochastic behavior of the discharge through preformed plasma channel is reproduced by the calculation, which shows complex path with detouring and bifurcation. The probability of guiding is investigated with respect to the ionized, conductive fraction along the channel.
Yabana, Shuichi*; Kanazawa, Kenji*; Nagata, Seiji*; Kitamura, Seiji; Sano, Takeshi*
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 9 Pages, 2009/07
Shiroya, Seiji*; Misawa, Tsuyoshi*; Unesaki, Hironobu*; Ichihara, Chihiro*; Kobayashi, Keiji*; Nakamura, Hiroshi*; Shin, Kazuo*; Imanishi, Nobutsugu*; Kanazawa, Satoshi*; Mori, Takamasa
JAERI-Tech 2004-025, 93 Pages, 2004/03
In view of the future plan of Research Reactor Institute, Kyoto University, the present study consisted of (1) the transmission experiments of high energy neutrons through materials, (2) experimental simulation of ADSR using the Kyoto University Critical Assembly(KUCA), and (3) conceptual neutronics design study on KUR type ADSR using the MCNP-X code. Through the present study, valuable knowledge on the basic nuclear characteristics of ADSR, which is indispensable to promote the study on ADSR, was obtained both theoretically and experimentally. For the realization of ADSR, it is considered to be necessary to accumulate results of research steadily. For this purpose, it is inevitable (1) to compile the more precise nuclear data for the wide energy range, (2) to establish experimental techniques for reactor physics study on ADSR including subcriticality measurement and absolute neutron flux measurement, and (3) to develop neutronics calculation tools which take into account the neutron generation process by the spallation reaction and the delayed neutron behavior.
Yabana, Shuichi*; Kanazawa, Kenji*; Hirata, Kazuta*; Kitamura, Seiji
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Kanazawa, Kenji*; Nagata, Seiji*; Yabana, Shuichi*; Kitamura, Seiji
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Yabana, Shuichi*; Kanazawa, Kenji*; Nagata, Seiji*; Inaba, Satoru*; Kitamura, Seiji
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Sasaki, Akira; Takahashi, Eiichi*; Kato, Susumu*; Kishimoto, Yasuaki*; Kanazawa, Seiji*; Fujii, Takashi*
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Nagata, Seiji*; Kanazawa, Kenji*; Hirata, Kazuta*; Sano, Takeshi*; Kitamura, Seiji
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Kanazawa, Kenji*; Yabana, Shuichi*; Hirata, Kazuta*; Nakamura, Takashi*; Kitamura, Seiji
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Yabana, Shuichi*; Kanazawa, Kenji*; Hirata, Kazuta*; Umeki, Katsuhiko*; Kitamura, Seiji
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Kanazawa, Kenji*; Nagata, Seiji*; Yabana, Shuichi*; Hirata, Kazuta*; Umeki, Katsuhiko*; Kitamura, Seiji
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Sasaki, Akira; Takahashi, Eiichi*; Kato, Susumu*; Kishimoto, Yasuaki*; Fujii, Takashi*; Kanazawa, Seiji*; Torii, Tatsuo
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Sasaki, Akira; Torii, Tatsuo; Takahashi, Eiichi*; Kato, Susumu*; Kishimoto, Yasuaki*; Kanazawa, Seiji*; Fujii, Takashi*
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Sasaki, Akira; Torii, Tatsuo; Kato, Susumu*; Takahashi, Eiichi*; Fujii, Takashi*; Kanazawa, Seiji*; Kishimoto, Yasuaki*
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Sasaki, Akira; Takahashi, Eiichi*; Kato, Susumu*; Kishimoto, Yasuaki*; Fujii, Takashi*; Kanazawa, Seiji*
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The discharge simulation based on the percolation model is extended to include the dynamics of formation and extincition of the ionized region in the gas, and the temporal evolution of discharge current is calculated taking spatial capacitance and inductance into account. Calculations show prebreakdown activity appears in front of the protrution on the electrode after some delay from a high voltage is applied across the gap, which is followed by the development of the stepped leader and the establishment of a discharge path between the electrondes.
Sasaki, Akira; Kato, Susumu*; Takahashi, Eiichi*; Fujii, Takashi*; Kanazawa, Seiji*; Kishimoto, Yasuaki*
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no abstracts in English
Sasaki, Akira; Kato, Susumu*; Takahashi, Eiichi*; Fujii, Takashi*; Kanazawa, Seiji*; Kishimoto, Yasuaki*
no journal, ,
no abstracts in English
Sasaki, Akira; Torii, Tatsuo; Takahashi, Eiichi*; Kato, Susumu*; Fujii, Takashi*; Kanazawa, Seiji*; Kishimoto, Yasuaki*
no journal, ,
no abstracts in English