TRANSPORT PROPERTIES AND DIELECTRIC STRENGTHS OF GAS MIXTURES FOR USE IN DIFFUSE DISCHARGE OPENING SWITCHES.

Gas mixtures for possible use in diffuse discharge switching applications require both high dielectric strength and specific transport properties in the conducting and the opening stages of the operation of the switch. In the conducting stage, the electron drift velocity must be large, and the electron loss processes (e. g. , due to electron attachment and recombination) must be low so as to maximize the efficiency of the current gain in the discharge while maintaining low discharge impedance. In the opening stage, strong electron attachment along with high dielectric strength is required of the gas mixtures in order to extinguish the discharge as quickly as possible to prevent arcing between the switch electrodes due to the high voltages induced across the switch in the opening phase. We present measurements of the electron drift velocity, attachment, diffusion and ionization coefficients, and high voltage dielectric strengths of several gas mixtures proposed for use in diffuse discharge switching applications. These include C//3F//8/Ar, C//3F//8/CH//4, C//2F//6/Ar, C//2F//6/CH//4, CF//4/Ar, CF//4/CH//4, CF//3OCF//3/Ar, and CF//3OCF//3/CH//4.