Experimental Study of Tonks-Dattner Resonances in Rare-Gas Plasmas

Abstract

Tonks-Dattner resonances were studied in active discharges of neon, argon, and xenon in the milliTorr pressure region where self-excited moving striations are also present. The observed resonance peaks are fewer and broader than have been reported for mercury vapor discharges. The broadening is considerably greater than expected from Landau damping and Coulomb collisions and is attributed to electron density variations associated with moving striations. Direct measurements of electron densities and electron temperatures under resonance conditions permit comparison with the theory of Nickel, Parker, and Gould with no adjustable parameters. The agreement is satisfactory for argon and xenon but the high operating pressure required for stable operation of the neon plasma invalidates the use of the free fall hypothesis and the experimental resonance frequency peaks in this case lie appreciably above the predictions of the theory.