Optic diagnosis of neutral beam injection on HL—1M

During the operation of a high-power neutral beam injection (NBI) system on the H L-1M tokamak, an optical diagnostic means using CCD camera was developed to characterize the NBI performance. The vacuum valve opening process and NBI period in the HL-1M experiment were displayed by a lot of photos taken with this means. Thus, the Hα emission profiles of the neutral beam (NB) and its interaction with plasma were given. Finally, the reason possible for plasma breakdown during NBI mode Ⅱ discharge was investigated. Therefore, this in-situ diagnosis can provide more information of the NBI.