TY - JOUR T1 - A Code that Simulates Fast-Ion D_Alpha and Neutral Particle Measurements JO - Communications in Computational Physics VL - 3 SP - 716 EP - 741 PY - 2011 DA - 2011/10 SN - 10 DO - http://doi.org/10.4208/cicp.190810.080211a UR - https://global-sci.org/intro/article_detail/cicp/7458.html KW - AB -

A code that models signals produced by charge-exchange reactions between fast ions and injected neutral beams in tokamak plasmas is described. With the fastion distribution function as input, the code predicts the efflux to a neutral particle analyzer (NPA) diagnostic and the photon radiance of Balmer-alpha light to a fastion Dα (FIDA) diagnostic. Reactions with both the primary injected neutrals and with the cloud of secondary "halo" neutrals that surround the beam are treated. Accurate calculation of the fraction of neutrals that occupy excited atomic states (the collisional-radiative transition equations) is an important element of the code. Comparison with TRANSP output and other tests verify the solutions. Judicious selection of grid size and other parameters facilitate efficient solutions. The output of the code has been validated by FIDA measurements on DIII-D but further tests are warranted.