A theory for the ion impact broadening of fine-structure sublevels

It is shown that for a wide class of plasma experiments the spectral line broadening caused by ions has to be described in the impact approximation. The theory of ion impact broadening (IIB), taking place against a background of electron impact broadening, is developed. It is demonstrated that broadening at the expense of interaction with the ion subsystem can depend on parameters characterising the electron subsystem. Detailed calculations are made for IIB of the resonance doublet of hydrogen-like ions Ar XVIII, Br XXXV, Kr XXXVI, I LIII, Xe LIV, which may be added to a DT mixture for diagnostics in experiments on an inertial fusion programme. The results of calculations show that, below subthermonuclear and thermonuclear temperatures, the Stark broadening of the red component of the resonance doublet of the indicated ions can be used. (author)