Effect of microscopic electric fields on dielectronic recombination in plasmas

The effect of the quasistatic electric fields excited in a plasma on the rate of dielectronic recombination, k/sub d/, is studied. On the one hand, these fields cause a redistribution in angular momentum of the highly excited states of the outer electron (which increases k/sub d/); on the other, they limit the levels to which capture can occur. Analytic expressions are derived for the field dependence of k/sub d/ in the linear Stark approximation and under the assumption of a complete mixing of states with various values of l for highly excited levels. In a field E/sub asterisk/(V/cm) = 1.4 x 10-3 x√ZDelta-barE0 the dielectronic recombination coefficient reaches a maximum and exceeds the corresponding coefficient in vacuum, k/sub d/0, by a factor of about 10Z/sup 1/12/E/sup -3/8/0 (E0 is the energy of the stabilizing transition, in electron volts, Z is the ion charge, and Δ is the characteristic quantum defect of the highly excited levels with lapprox.3). The equations derived are compared with the results of a numerical calculation. This effect is important in a plasma with a highly developed low-frequency turbulence. The range of conditions under which it may occur in the equilibrium case has also been found. It may be necessary to take this effect into account when dielectronic satellites are used for diagnostic purposes