Kinetics of Hydrogen Molecules in MAGNUM-PSI

摘要

Results from simulations of plasma and neutrals under conditions predictively char-acterizing the detached plasma regime in the linear machine MAGNUM-PSI are presented.Therelaxation of the vibrationally excited hydrogen molecules is investigated in order to establish arelation between their relaxation and dwell times,and the role of the various mechanisms of themolecular vibrational kinetics.The results obtained show that the individual vibrational stateshave to be included in the transport code for neutrals as distinct species,since the relaxation timeof the vibrational states is sufficiently longer than the typical dwell time of hydrogen molecules inthe detached plasma region.The parameters of plasma and neutrals are affected by the transport.of the vibrationally excited hydrogen molecules.Furthermore,the rate of molecular recombinationis overestimated by a factor of～5 provided that the transport of hydrogen molecules only in theirground vibrational state is considered,The role of the various processes of vibrational kineticsis studied.The vibrational excitation through singlet electronic states has a strong influence onthe molecular densities for levels with vibrational quantum numbers v≥5.Vibration-vibration(V-V) collisions between vibrationally excited hydrogen molecules and vibration-translation (V-T)collisions between vibrationally excited hydrogen molecules and ground state molecules and atomsare of minor importance in MAGNUM-PSI.