Anode Temperatures and Characteristics of the dc Arc in Noble Gases*†

Abstract

The construction of a gas-tight arcing chamber and continuously recording optical pyrometer is described. The system is reproducible. The current and voltage of the dc carbon arc in noble gases show a sensitive and systematic dependence on the atmospheres employed. A small admixture of a foreign gas, such as air, markedly alters the characteristics of the arc. The arc voltage for fixed current decreases in the order He, Ne, A, and Kr. Thus, the power input decreases in the same order. The anode temperature is linearly related to the power input. The behavior of the cross sections of the gases to electrons in the energy range of the Ramsauer-Townsend effect is suggested as a major contributor to the observed behavior of the dc arc in noble gases.