On radiative power from impurities in plasmas

Ionization state, excited populations and emission of impurities in dynamic finite density plasmas: I. The generalized collisional–radiative model for light elements

“…Energy levels for high bundle-nS levels and their A-values, Maxwell averaged collision strengths, radiative recombination coefficients, dielectronic recombination coefficients and ionisation coefficients are generated from a range of parametric formulae and approximations described in earlier works (Burgess and Summers, 1976;Summers, 1977;Summers and Hooper, 1983;Burgess and Summers, 1987;Summers, 2004). High quality specific data when available are acccessed from archives and substituted for the default values.…”

“…The most powerful theoretical methods used for excitation, namely R-matrix with pseudostates (RMPS) (Bartschat and Bray, 1996;Ballance et al , 2003) and convergent-close-coupling (CCC) (Bray and Stelbovics, 1993), have some capability for ionisation, but at this stage are limited to very few electron systems as is the time-dependent-close-coupling (TDCC) (Pindzola and Robicheaux, 1996;Colgan et al , 2003) ionisation method. For GCR calculations, we have relied on the procedures of Summers and Hooper (1983) for initial and final state resolution of total ionisation rate coefficients and on the distorted wave approximation. The distorted wave method is our main method for extended GCR studies for many elements and most stages of ionisation.…”

Dielectronic recombination data for dynamic finite-density plasmas

“…We now consider a projection-condensation approach that allows for the effect of the high-level populations (n ≡ n > n c ) on the low-level populations (n ≤ n c ) -see Summers & Hooper (1983) and Burgess & Summers (1969). We work in the bundled-n picture.…”

“…Finally, we note that use of total zero-density ground-state recombination rate coefficients is, in principle, quite unsafe for the collisional-radiative modelling of dynamic finite-density plasmas -see Burgess & Summers (1969), Summers & Hooper (1983), Badnell et al (1993) and Sect. 4 below.…”

“…This means that such metastables are the starting point for recombination events, and so the time-evolution of their populations must be tracked in the same manner as for the ground states. We call this the generalized collisional-radiative (GCR) picture (Summers & Hooper 1983). Even if the metastable populations are in quasi-static equilibrium with the ground state, they are significant and so are still a source term for dielectronic recombination which cannot be ignored.…”