We present a basic theory of the link between the low and high gas-density limits to ion-ion recombination under a general interaction V which now depends on the ion density and which is determined self-consistently with the recombination Increase in ion density up to lOI cmT3 causes littlc change to the recombmation rates in direct contrast to that obtained in recent computer simulations.
Not only IS the ion
-ion recombination process * X++y-tZ-+[XY] +Z (1) of basic theoretical significance [l] in its own right, but it plays a key role in populating [2] the upper molecular electronic states of inert gas-halide lasers which operate not only at high densities N (G-10 atm) of the background gas 2 but aIso at moderateIy high densitiesN* x 1012-1014 cm-3 of the positive and negative ions X+ and Y-. Reliable laboratory experiments are difficult and are as yet not forthcoming_ Al! previous [3] theoretlcal treatments and experiments pertain tacitly to dilute ionization for which a coulombic ion-ion interaction is correct. The purpose of this letter is to briefly outlme a basic theory of the recombination rate o[ (cm3 s-l) of (1) versus gas and ion densities, N and N*, respectively and then to illustrate the key effects by appeal to a model version. In so doing, we will raise an interesting issue on the validity at all N of the ab initio adoptlon [4] of the Debye-Hrickel interaction as a means of incorporating plasma sheathing effects whenN' is raised. Bates [S] has recently argued that this procedure is invalid at high N. Recombination rate CL Let the negative ions of density n-(R, t) at time t stream across spheres of radius R each centered at each positive ion distributed lV% * The square brackets denote that the product may not remain bound.