A comparative value for the lowering of the ionization potential in an argon plasma has been determined from values of the series limits for recombination of free plasma electrons into the $1s$ and $2p$ states of the argon atom obtained from the measured frequency dependence of the electron continuum. The results have been used to compare existing theories which relate the ionization potential lowering to the electron density and temperature.

• Received 10 July 1961

DOI:https://doi.org/10.1103/PhysRev.124.1703