Low energy heavy particle collisions relevant to gas divertor physics

Cross sections for rotational and vibrational excitations of H2 molecules caused by impact of electron, proton, H atom, H2, H2+, or H- are compared with one another and reviewed for rotational excitations by examining an interaction potential between collision partners. It is pointed out what are difficulties in theoretical approaches to collision of atoms with H2 molecules initially in vibrationally and rotationally excited states. A theoretical approach developed by our group, which aims quantum mechanically to investigate vibrationally inelastic scattering, exchange reaction, or dissociation of molecule in vibrationally excited states collided with an atom or its ion, is presented. Newly obtained dissociation cross sections of H2 in vibrationally excited states by He impact are presented and compared in magnitude with those of H2 caused by electron impact. (author)