A semi-empirical expression for the first Townsend coefficient in strong electric fields
1 Institute of Physics, University of Belgrade - P.O. Box 57, 11080 Belgrade, Serbia
2 Department of Experimental Physics, Comenius University - Mlynski dolina F2, 84248 Bratislava, Slovakia
Received: 24 October 2014
Accepted: 28 November 2014
The ionization coefficients for argon, nitrogen, hydrogen, oxygen and air are determined from the measured breakdown voltage curves in microgaps. The obtained values agree very well with the data for the standard size discharges indicating that the Townsend phenomenology does not need extension to describe microdischarges and that the ionization coefficients for such discharges obey the similarity law . In addition, an analytical expression for the ionization coefficients has been derived based on the generalized theory. The appropriate constants in derived expression have been modified by fitting the ionization coefficients obtained from the measured breakdown voltage curves.
PACS: 52.90.+z – Other topics in physics of plasmas and electric discharges (restricted to new topics in section 52) / 52.80.Tn – Other gas discharges / 52.80.-s – Electric discharges
© EPLA, 2014