The Lowering of the Ionization Potential of Hydrogen and Carbon in a Plasma.

The lowering of the ionization potentials of hydrogen and carbon atoms immersed in a high temperature and high density thermal plasma generated in a wall stabilized arc was estimated from the advance or shift of their respective series limits in the vacuum ultraviolet region of the spectrum for different electron densities and temperatures. Results show a close agreement with those theoretical calculations in which the effects of both microfield and polarization terms are added. However, electron densities are lower by about two orders of magnitude than the critical electron densities required by theory for the inclusion of the microfield term. The question of validity of a critical electron density is discussed. Author