NUMERICAL STUDY ON COOLING OF ELECTRONS OF AN ARGON PLASMA JET IN COLLISION WITH HYDROGEN MOLECULE Katsuhiro Kano and Hiroshi Akatsuka Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology Effect of gas-contact cooling in a recombining argon plasma is studied numerically based on energy balance equations and the argon collisional-radiative model. Incidence of hydrogen molecules into the argon plasma is proved to be effective for cooling of electrons and generation of population inversion.