Modeling of the discharge plasma in a black lighted thyratron

Abstract

The population of atomic levels in a back-lighted thyratron (BLT) plasma with electron density of 1-5*10/sup 15/ cm/sup -3/ and current density of about 10/sup 4/ A/cm/sup 2/ was calculated, and line intensity ratios were compared with spectroscopic measurements. Simple considerations lead to a very small cathode fall width during the conduction phase, and the resulting high electric field can create fast electrons with energies of some 100 eV. From a solution of a Fokker-Planck equation, it was found that fast electrons can penetrate the gap region, which consists of a Maxwellian plasma with electron density of 10/sup 15/ cm/sup -3/ and electron temperature of 1-2 eV. The BLT plasma was modeled assuming a monoenergetic electric beam with a strong anisotropic velocity distribution function, which penetrates a low electric field region of a bulk plasma at thermal equilibrium and neutrals. The numerical solution of the appropriate set of rate equations, which also takes radiative processes into account, yields information about the beam and bulk plasma properties. The principal analysis can also be applied to the similar pseudospark switch.<>