An investigation of non-equilibrium effects in thermal argon plasmas

The parameters and transport properties of a wall stabilized argon arc (40-200 A) at atmospheric pressure with diameters of 5 and 8 mm are studied by spectroscopy and interferometry. The plasma is assumed to be partial local thermal equilibrium and this assumption is verified with the aid of a collisional-radiative model. The departures from Saha-equilibrium of the argon neutral ground state are found to be associated with particle diffusion and the escape of recombination radiation. The measurement of the total excitation rate, from the ground level, including direct ionization, of neutral argon is in reasonable agreement with the literature valu

An argon cascade-arc plasma pulsed with 2200 amperes

In the past several authors have reported on experiments with wall stabilized arcs, to study transport coefficients, deviations from local thermodynamic equilibrium (LTE) and optical properties of these thermal plasmas. Most of these experiments have been performed with continuous arcs in a pressure range of atmospheric to a few 100 atm. In order to get high electron densities, temperatures and to reach higher ionization stages, a current pulse of approximately=2200 A is superimposed on a stationary argon cascade-arc with filling pressures of 1-3 atm. In this way high power densities can be reached, without the need of extensive cooling and power requirements. The rise time of the current pulse approximately=60 mu s and duration time approximately=1.5 m

Plasma flow in an argon cascade arc

A model is described for the plasma flow in an Ar cascade arc which takes into account the heating and pressure effects. As the pressure increases the elec. field increases and the arc temp. decreases. The results agree with exptl. detns. [on SciFinder (R)