Collisional-radiative recombination of Ar+ ions with electrons in ambient helium at temperatures from 50 K to 100 K
Abstract
Ternary electron-assisted collisional radiative recombination (E-CRR) and neutral-assisted radiative recombination (N-CRR) have very strong negative temperature dependencies and hence dominate electron recombination in some plasmas at very low temperatures. However, there are only few data for molecular ions and almost none for atomic ions at temperatures much below 300 K.
In this experimental study we used a cryogenic afterglow plasma experiment (Cryo-FALP II) at temperatures from 50 K to 100 K to measure ternary recombination rate coefficients for Ar+ ions in ambient helium gas. The measured magnitudes and the temperature dependencies of the ternary recombination rate coefficients for electron-assisted and neutral-assisted collisional radiative recombination agree well with theoretical predictions (KE-CRR similar to T-4.5 and KHe-CRR similar to T-2.5 to T-2.9) over a broad range of electron and He densities.