Radiative continua of noble gas plasmas

A simple completely analytical method for the calculation of the plasma radiation continuum in the visible and neighbouring regions is derived. It is based on the semi-classical quantum defect theory. In spite of the simplicity the accuracy of the method is found to be comparable with those of Schluter and Hofsaess calculations, but its main advantage is the reasonable description of the plasma density (weak coupling) effects in the near-threshold region. Thus, our calculation does not show the sharp threshold of the photoionization continuum and a correct comparison with experiment in the whole wavelength range under consideration can be made. A good agreement with experimental data on the continuous radiation of neon, argon, krypton and xenon plasmas is found. The calculation scheme presented may be useful for moderately dense plasma diagnostics and looks as reasonable basis for incorporation of strong-coupling effects. (C) 1998 Elsevier Science Ltd. All rights reserved.