Reaction processes of molecular activated recombination leading to detachment of divertor simulation plasma in GAMMA 10/PDX

•Dependence of Balmer line emissions and vibrational temperature of hydrogen molecular on the neutral pressure indicates that the dissociative recombination reaction of triatomic ion produces vibrationally excited molecules and it caused the increase of production of negative ion enhancement due to dissociative attachment process.•Sudden increase in Balmer line emissions from highly excited atoms (Hβ, Hγ and Hd) intensities and population inversion was observed when neutral pressure was higher than a certain value.•The population inversion and suddenly increase of Balmer line emission seems to be caused by the mutual neutralization reaction between molecular ion and negative ion (MN2).•The negative ions for the MN2 reaction can be produced by resonant ionization process of H(2s).