Some Characteristics of Metal Iodide—Mercury Arcs

Abstract

The spectral characteristics of arcs operated in several kilotorr of mercury vapor with lower pressures of various metal iodides can be explained on the basis of local thermal equilibrium among all components of the plasma except for the radiation itself. The fraction of atoms excited to an electronic state depends only on the excitation energy of the state and the plasma temperature. Conversely, the plasma temperature depends strongly on excitation energy for those transitions responsible for the principal radiative output. Plasma temperature, excitation energies, and number of radiating atoms can be related quantitatively and can lead to calculated plasma temperatures in satisfactory agreement with experimental determinations of temperature.