Ionization instability in CO2 laser discharges

Abstract

Criteria are established for calculation of plasma conditions leading to ionization instability in plasmas generally employed in high-power molecular laser applications. Negative ion formation is found to play an important role in causing this instability. For conditions typical of electrically excited CO2 laser mixtures, appearance of an ionization instability requires a negative ion concentration greater than one-tenth that of the electrons, combined with an electron temperature value below approximately 1.5 eV. Satisfactory agreement between theoretically determined stability boundaries and data obtained experimentally confirms the significance of fundamental collisional processes as regards ionization instability in CO2 laser discharges. © 1973 American Institute of Physics.