Continuous emission, lowering of the ionization potential and total excitation cross-sections of an atmospheric thermal plasma

The authors present a Partial LTE (PLTE) model in which the ground state is overpopulated with respect to the other excited states. The relative overpopulation of the ground state as a function of the electron temperature, T/sub e/, is fairly sensitive to small variations in both the transition probability, A, and the value for the lowering of the ionisation potential, Delta chi /sub 0/. The total cross-section for excitation from the neutral ground state was derived from the measured degree of overpopulation. The authors calculated the emissivity of the free-bound UV recombination radiation, which proved to be quite large in the 70-80 nm spectral range. Some results for the continuum radiation and for the Stark parameters at lambda approximately=700 nm were also given