Spectroscopic study of hydrogen particle behavior in attached and detached divertor plasmas of JT-60U

Hydrogen particle behavior, especially H2 molecule behavior, has been studied spectroscopically in attached and detached divertor plasmas of JT-60U. The decay lengths of the H2 Fulcher line intensity in attached and detached divertor plasmas were roughly 1 cm and 4 cm, respectively. The fall in intensity of the H2 Fulcher lines with distance from the divertor plates was reproduced by calculation using a neutral transport and a collisional radiative model code. Molecular assisted recombination was estimated to be as important as H+–e recombination in a detached divertor plasma.