THEORETICAL EVALUATIONS OF NEUTRAL BEAM INJECTION EFFICIENCY FOR THE TJ-II HELICAL-AXIS STELLARATOR

Theoretical evaluations of neutral beam injection (NBI) efficiency for the TJ-II helical-axis stellarator have been done for several expecte d scenarios using the FASOLT code, an adaptation of the FAFNER three-d imensional NBI Monte Carlo code to the peculiar geometry, vacuum vesse l, and helical indented magnetic surfaces of TJ-II. The code is used i n combination with another one-dimensional flux coordinates transport code (PLASMATOR). Results for I-MW injected power, comparing co-inject ion and counterinjection, as well as 2- and 4-MW balanced injection, a re discussed with emphasis on fast ion losses and wall loads. Some pre liminary results, including radial electric field effects, are also pr esented.