A benchmark of the eigenfunction method and the 5D simulation on the fast ion slowing down velocity distribution in the NBI-heated helical plasmas

Recently, the eigenfunction method for the fast ion slowing down velocity distribution in NBI-heated and/or burning plasmas [1,2] was generalized to general stellarator/heliotron configurations. It is already applied to calculations of momentum input [3] and the fast ions’ anisotropic pressure [4] in NBI-heated stellarator/heliotron plasmas. However, complicated guiding center motions in the perpendicular direction are basically neglected in this semi-analytical method. Another tool for investing the NB-produced fast ions that has been used for the LHD (Large Helical Device) experiment is a 5D simulation code GNET. [5] In this presentation, a benchmark of these contrasting methods for the LHD configuration is shown. [1] C.T.Hsu, P.J.Catto, and D.J.Sigmar, Phys.Fluids B 2, 280 (1990)[2] M.Taguchi, Nucl.Fusion 32, 143 (1992) [3] S.Nishimura, et al., Phys.Plasmas 22, 092505 (2015) [4] S.Nishimura, Phys.Plasmas 25,042509 (2018) [5] H.Yamaguchi and S.Murakami, Plasma Fusion Res. 9, 3403127 (2014)