Neutral particle transport under strong hydrogen recycling condition in the GAMMA 10 central cell

• Published in: Journal of nuclear materials Vol. 266; pp. 566 - 570
• Main Authors: Kobayashi, S., Nakashima, Y., Shoji, M., Tsuchiya, K., Hasegawa, Y., Islam, M.K., Yamaguchi, N., Yoshikawa, M., Mase, A., Tamano, T., Yatsu, K.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-03-1999
• Subjects: DEGAS code; GAMMA 10; Neutral transport; Recycling; Tandem mirror; GAMMA 10; Neutral transport; Tandem mirror; Recycling; P05; DEGAS code
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/S0022-3115(98)00673-4

In order to understand the behavior of neutral hydrogen in ICRH plasmas of the GAMMA 10 tandem mirror, we tried new simulations of neutral transport by using the DEGAS Monte Carlo code in which the effects of hydrogen recycling were taken into account. This simulation has been performed by introducing a multiplication coefficient in DEGAS to control the amount of desorbed test particles, which enables us to simulate the neutral transport for the first time under the conditions in which the recycling coefficient exceeds unity. By using the multiplication coefficient, it was found that the axial profile of the atomic hydrogen density obtained from the simulation changed significantly. On the other hand, there is little influence on the radial profile of the simulated hydrogen density. The simulation result, taking the axial variation of the multiplication coefficient into consideration, well predicted the result of the H
α-emission measurements. This indicates that strong hydrogen recycling is localized near the midplane. These calculation results are discussed from the view point of the wall-reflux coefficient deduced from the DEGAS simulation.