TY - JOUR
T1 - Electric current in dc surface flashover in vacuum
AU - Neuber, A.
AU - Butcher, M.
AU - Hatfield, L. L.
AU - Krompholz, H.
PY - 1999/3/15
Y1 - 1999/3/15
N2 - Dielectric surface flashover in vacuum is characterized by a three-phase development, as shown by current measurements covering the range from 10-4 to 100 A, assisted by x-ray emission measurements, high speed photography, and time-resolved spectroscopy. Further information is gained from a comparison of the flashover dynamics at 77 and 300 K. Phase one comprises a fast (several nanoseconds) buildup of a saturated secondary electron avalanche reaching current levels of 10 to 100 mA. Phase two is associated with a slow current amplification, with a duration on the order of 100 ns, reaching currents in the ampere level. The final phase three is characterized again by a fast (nanoseconds) current rise up to the impedance-limited current on the order of 100 A in this specific apparatus. The development during phase two and three is described by a zero-dimensional model, where electron-induced outgassing leads to a Townsend-like gas discharge above the surface. The feedback mechanism towards a self-sustained discharge is due to space charges leading to an enhanced field emission from the cathode. A priori unknown model parameters, such as field enhancement factors, outgassing rate, and the buildup of the gas density above the surface, are determined by fitting calculated results to experimental data.
AB - Dielectric surface flashover in vacuum is characterized by a three-phase development, as shown by current measurements covering the range from 10-4 to 100 A, assisted by x-ray emission measurements, high speed photography, and time-resolved spectroscopy. Further information is gained from a comparison of the flashover dynamics at 77 and 300 K. Phase one comprises a fast (several nanoseconds) buildup of a saturated secondary electron avalanche reaching current levels of 10 to 100 mA. Phase two is associated with a slow current amplification, with a duration on the order of 100 ns, reaching currents in the ampere level. The final phase three is characterized again by a fast (nanoseconds) current rise up to the impedance-limited current on the order of 100 A in this specific apparatus. The development during phase two and three is described by a zero-dimensional model, where electron-induced outgassing leads to a Townsend-like gas discharge above the surface. The feedback mechanism towards a self-sustained discharge is due to space charges leading to an enhanced field emission from the cathode. A priori unknown model parameters, such as field enhancement factors, outgassing rate, and the buildup of the gas density above the surface, are determined by fitting calculated results to experimental data.
UR - http://www.scopus.com/inward/record.url?scp=0000425774&partnerID=8YFLogxK
U2 - 10.1063/1.369647
DO - 10.1063/1.369647
M3 - Article
AN - SCOPUS:0000425774
VL - 85
SP - 3084
EP - 3091
JO - Journal of Applied Physics
JF - Journal of Applied Physics
SN - 0021-8979
IS - 6
ER -