Title :
Polarity effect of density change streamer structure in liquid helium
Author :
Onodera, Koichi ; Mikami, Go ; Yamashita, Hisanao
Author_Institution :
Dept. of Electron. & Electr. Eng., Keio Univ., Yokohama, Japan
Abstract :
The prebreakdown density change streamers and the current pulses in liquid helium were investigated. A point-plane electrode system, consisting of a tungsten needle whose tip radius is 1 μm and a stainless steel plane were used. The streamers under impulse voltage conditions were observed using high-speed photography for both negative and positive polarities. For a negative streamer, the structure was only filamentary and propagates with very high speed. On the other hand, for a positive streamer, the structure was mainly spherical or hemispherical, and a filamentary structure similar to the negative one was rarely observed. Comparing the the propagation speed of filamentary streamer, the negative streamer was two orders of magnitude higher than the positive one
Keywords :
discharges (electric); impulse testing; insulating materials; liquid helium; He; W needle tip radius; current pulses; density change streamer structure; filamentary streamer propagation speed; filamentary structure; hemispherical structure; high-speed photography; impulse voltage conditions; liquid He; negative polarity; point-plane electrode system; polarity effect; positive polarity; prebreakdown density change streamers; spherical structure; stainless steel plane; superconducting power apparatus insulation; Cryogenics; Dielectric liquids; Electric breakdown; Electrodes; Helium; Needles; Pulse measurements; Steel; Streaming media; Voltage;
Conference_Titel :
Electrical Insulation and Dielectric Phenomena, 2000 Annual Report Conference on
Conference_Location :
Victoria, BC
Print_ISBN :
0-7803-6413-9
DOI :
10.1109/CEIDP.2000.885281
