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.