Observation of Plasma Behavior During the ECRH Injection by Using a High-Speed Camera in GAMMA 10

A new high-speed camera (MEMRECAM GX-1, NAC Inc.) has been installed at the GAMMA 10 central-cell. This camera observes two directions through vertical and horizontal ports by using dual optical fiber bundles. This paper describes the results of 2-D image of visible emission observed from the central-cell plasma during Supersonic Molecular Beam injection (SMBI) in the C-ECRH experiments. Observational results showed that the instability of plasma light-emission on the central-limiter was suppressed during SMBI and the plasma sustainability increased along the SMBI plenum pressure. Relationship between plasma sustainability and power of C-ECRH and/or the quantity of SMBI is also investigated.