Numerical study on production processes of vibrationally excited molecules in hydrogen negative ion sources

Production processes of vibrationally excited hydrogen molecules and their effects on H− production are studied theoretically by using a set of particle balance equations in a steady-state hydrogen plasma. For vibrational excitation, three processes, i.e., fast-electron collisional excitation, neutralization of moleculer ions, and atom-surface recombination, are taken into account. Enhancement of vibrational excitation including vibrational distribution and H− production is obtained as a function of three different excitation processes.