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Author Chang, C. ♦ Liu, C. L. ♦ Chen, C. H. ♦ Sun, J. ♦ Liu, Y. S. ♦ Guo, L. T. ♦ Cao, Y. B. ♦ Wang, Y. ♦ Song, Z. M.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY ♦ BREAKDOWN ♦ DESORPTION ♦ ELECTRON DENSITY ♦ ELECTRONS ♦ IONIZATION ♦ JOULE HEATING ♦ METALS ♦ MICROWAVE RADIATION ♦ PLASMA DENSITY ♦ PLASMA SIMULATION ♦ PRESSURE RANGE MEGA PA 10-100 ♦ SECONDARY EMISSION ♦ SPACE CHARGE ♦ SPUTTERING ♦ SURFACES ♦ TRANSMISSION ♦ WAVEGUIDES
Abstract The mechanism of ultrafast breakdown at metal/vacuum interface in the high-power microwave waveguides is studied. In order to realize the nanosecond discharge, the required ambient gas pressure above the metal surface is approximately calculated as high as several Torr due to the low ionization-rate for high-energy electrons and short pulse. The local high pressure may come from the evaporated microscopic protrusions due to Joule heating and gas desorption. Besides, ions accelerated by the ambient space charge field could obtain sufficient high energy to collide and sputter the metal atoms to increase the ambient pressure. The positive feedbacks during the rapid discharge are studied by particle-in-cell simulation. The relatively high-energy ions could generate secondary electrons. It is shown that, as the positive feedback, the secondary electrons induce the gas desorption and stronger ionization, resulting in ion and electron density increasing as well as sheath field further increasing. As a result, more higher-energy ions bombard metal surface, leading to higher secondary electron yield and higher density plasma generated to cut off the microwave transmission finally. These nonlinear courses realize the ultrafast discharge in waveguides.
ISSN 1070664X
Educational Use Research
Learning Resource Type Article
Publisher Date 2015-06-15
Publisher Place United States
Journal Physics of Plasmas
Volume Number 22
Issue Number 6


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