PLASMA RECOMBINATION AND DIVERTOR DETACHMENT

We consider the influence on plasma recombination of the formation of negative and molecular ions in a divertor plasma. We take into account different atomic processes (vibrational excitation of molecular hydro gen, electron dissociative attachment, ion conversion, charge exchange and dissociative recombinations, dissociation and ionization, etc.) a nd find the expression for the effective plasma recombination rate con stant from a suitably reduced set of coupled rate equations. We estima te the influence of the recombination process on divertor plasma behav ior and find that for AlcatorC-MOD-like parameters plasma recombinatio n due to negative and molecular ions becomes significant in the temper ature range below a few eV. We conclude that plasma recombination is a strongly contributing mechanism for the explanation of divertor plasm a detachment in low temperature plasmas.