On radiative power from impurities in plasmas

Processes for radiative power loss in optically thin high temperature plasmas due to electronic transitions in the field of an impurity ion are summarised. The theoretical calculation of the net power arising from these various radiative loss mechanisms is reviewed and a theory for the frequency distribution of radiated power presented. The description of radiative power loss from elements in dynamic states of ionisation is then addressed. Formal generalisation of current collisional-radiative theory is made to accomodate low metastable levels consistently. This is proposed as the basis for the most reliable power loss calculations. The state of practical calculations of the important collisional-dielectronic recombination and ionisation coefficients is briefly reviewed and suggestions made for the practical implementation of the metastable generalisation. Illustrative examples are given of power loss coefficients and functions, together with important intermediate quantities.