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 1cm and 4cm, 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.