Density-dependent Lines of One- and Two-electron Ions in Diagnostics of Laboratory plasma. I. The rates of collision relaxation of excited levels

Abstract

Plasma devices with inertial plasma confinement such as laser produced plasmas, exploding wires, plasma focus, etc., which have been rapidly developed during recent years, appear to be very intensive sources of spectral line radiation in far UV and X-ray regions. Analysis of this radiation provides a good tool for plasma diagnostics with very high electron densities up to 1022 cm-3. In this work, consisting of two parts, we consider the mechanism of the formation of spectral lines in hot and dense plasma. The key point for density diagnostics is the fact that for some ion levels the rate of collisional relaxation has the same order of magnitude as the radiative decay. Thus the intensities of spectral lines arising from these levels show a strong dependence on electron density which makes diagnostics possible.In the first paper, emphasis is laid on the calculation of rates of transition between close ion levels induced by electron or ion impact, which usually gives the main contribution to the collisional relaxation constants. The influence of plasma polarization effects on the collision frequency in a dense plasma is also considered.In a second paper, the formation of spectral lines of hydrogen-like, helium-like and oxygen-like ions will be considered for electron density 1018 cm-3 ⩽ N ⩽ 1024 cm-3 and the ion charge 10 ⩽ Z ⩽ 19.