Hydrogen neutral transport code which includes 112 vibrational excitation and H radiation trapping for evaluation of molecular assisted recombination in fusion edge plasmas

点击翻译按钮获取中文摘要

In fusion edge plasmas, molecular processes play important role in particle, momentum and energy balances. The molecular assisted recombination (MAR) in detached diverter plasmas is one of them. We have estimated the effective reaction rate coefficient of the molecular processes by constructing collisional-radiative models of atomic hydrogen and molecular hydrogen. We have found the rate coefficient of the MAR depends strongly on the initial vibrational levels of molecular hydrogen.We have constructed a neutral transport code in which molecules in different vibrational states are traced as independent species.In the neutral transport code, the populating process of excited hydrogen atom by the radiation trapping of Lyman series has been included using newly developed iteration method in this study.The neutral transport code was applied to our RF plasmas and LHD plasmas. Calculated population of atomic hydrogen with principal quantum number 3, 4, 5 in the RF plasmas has well reproduced experimental values which were determined by spectroscopic method. Calculated Line profile of Ha in LHD plasmas was compared with experimental line profile. The calculation indicates the dominant process of production of the excited atoms is the electron impact excitation of the ground state atom which are produced by processes of H_2(v) + e^->H_2^+ + 2e; H_2^+ +e → H + H^+ + e and H_2(v)→ H + H^* → H + H.