The populations of excited levels of hydrogen-like and helium-like ions in plasmas traversed by neutral hydrogen beams

Abstract

This paper examines the populations of excited levels of impurity ions in a spatially homogeneous plasma containing primarily thermal electrons and protons and monoenergetic neutral hydrogen atoms. Of special concern is the role of recombination which may include the radiative, three-body and dielectronic processes together with charge exchange capture from neutral hydrogen beams. The influence of these primary processes on the populations is modified by radiative transitions and redistributive transitions due to collisions with electrons and protons in the plasma. The behaviour of the populations of the ions C 5+, C 4+ and Ar 16+ with variation of plasma parameters is explored in the present work. A bundled principal quantum level picture and a more elaborate LS resolved picture are used which allow investigation of the expected spectral emission and its sensitivity to uncertainty in the primary rates. The variation of the impurity ion spectrum in transiently recombining or ionising conditions is also considered.