Electrical Conductivity of Cesium-Seeded Atmospheric Pressure Plasmas near Thermal Equilibrium

Abstract

Measurements have been made of the electrical conductivities of gaseous mixtures formed by the addition of small fractions of cesium vapor to nitrogen, helium, neon, or argon. The mixtures were maintained near thermal equilibrium at temperatures in the 1500°–2000°K range and a total pressure of one atmosphere. The cesium vapor pressures ranged over two decades, from 0.1 to 10 Torr. The apparatus consists, in essence, of two heated zones connected by a slow flow. The first zone is a low‐temperature (200°–400°C) oven where the body‐gas flow picks up the cesium vapor. The second zone is a small electrically heated furnace (1250°–1850°C) containing a diode test section. The principal measurements taken were the seeding temperature, furnace temperature, and voltages and currents in the test section. The results exhibit variations with temperature, seeding pressure, and gas species that correlate reasonably well with simple theory and values for electron collision frequencies and cross sections taken from the literature.