Electron drift velocity in acetylene and carbon dioxide determined from rf breakdown curves

Abstract

In this work, we measured the breakdown curves of radio-frequency (13.56 MHz) capacitive discharge in acetylene and in carbon dioxide. The electron drift velocity values were determined in the reduced electric field range 319 Td ≤ E/N ≤ 3409 Td (1 Townsend = 10−17 Vcm2) in acetylene and 272 Td ≤ E/N ≤ 6240 Td in carbon dioxide from turning points on the measured breakdown curves. Treating the electron motion equations and the gas breakdown criterion in the rf electric field we have demonstrated that the method of electron drift velocity determination we employed is universal for arbitrary gasses, and a possible dependence of the electron mobility and diffusion on the reduced electric field strength E/N does not affect the drift velocity values obtained with it. We have demonstrated that in the range of E/N values we have studied the ionization rate exceeds the attachment rate considerably therefore one may neglect the effect the attachment of free electrons to gas molecules plays on electron drift velocity. We have explained the reason why the values of the electron drift velocity we have obtained differ from those obtained by other authors.

Transition in radio frequency gas breakdown with a transverse magnetic field

“…The amplitude of the electron displacement is equal to half of the gap at the turning point in rf breakdown curve, i.e. A = L/2, which can be derived from dU rf /dp → ∞ (or dp/dU rf = 0) [50]. It indicates that during one half rf period, half of the electrons on average are absorbed by the boundary and lost, while the other half can be multiplied through ionization processes [35,46].…”