Neutralization Effect on Energetic Proton Gonfinement in LHD

The neutralization effect for energetic protons in Large Helical Device (LHD) was estimated from the high energy neutral flux measured by Natural Diamond Detectors (NDD). The neutral- and partiallyionized-particle-distributions are calculated with a code for the incoming H0, Heo transport (Analytical Calculation of Helium Neutral, ACHEN-Code). The electron density dependence of the effective He+ density at the ICRF resonance region derived from measured neutral flux of high energy particles is well reproduced by the neutral-transport calculation with the incoming neutral temperature of about 10 eV and the neutral density at the Last Closed Flux Surface (LCFS) of 10-3 x n". The estimated loss rates are consistent in factors with the saturation level of decaying time of tail temperature after the termination of the ICRF heating.