Electron-Ion Recombination in Dense Plasmas

The rate of recombination and the characteristics of the afterglow line emission have been measured in magnetically confined plasmas of helium and hydrogen, with electron densities of the order of 10^13 cm^-3 and degree of ionization initially of the order of 50%. Electron densities and temperatures are deduced from absolute intensity measurements of spectrum line intensities originating from highly excited states, in good agreement with those obtained from microwave phase shift and plasma conductivity measurements. The results are explained in terms of an electron-electron-ion three-body recombination process. The recombination coefficient for this process is calculated as a function of electron temperature and density.