Thermal Nonequilibrium of a Free-Burning Argon Arc Plasma

The axial distributions of the electron temperature and number density of a free-burning atmospheric argon arc plasma at 15 Amps have been measured using a Thomson scattering technique. In addition, the excitation temperature of singly ionized argon has been found spectroscopically by relative line intensity method. The results are presented in terms of the degree of electron temperature nonequilibrium as compared with the calculated Saha equilibrium temperature and with the measured ionic excitation temperature along the axis of the arc. The observed temperatures are discussed with respect to the theoretical ion-like particle temperature and to the effect of electrode geometry.