Measurement of NSTX divertor plasma using fast camera

NISHINO Nobuhiro, ROQUEMORE Lane1), BREWER Theodore1), KAITA Robert1), ZWEBEN Stewart J.1), JOHNSON David1), KUGEL Henry W1), MAQUEDA Recald3) , MAINGI Rajesh4), SOUKHANOVSKII Vlad2) and NSTX team1)

Graduate school of Engineering, Hiroshima University, Hiroshima 739-8527, Japan
1) Princeton Plasma Physics Laboratory, Princeton, NJ 08543-0451, USA
2) Los Alamos National Laboratory, Los Alamos, NM 87545, USA
3) Fusion Phys. Technol. Inc., Torrance, CA, USA
4) Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA

To measure divertor plasma in NSTX, a fast camera with some optical filters was installed. The camera viewed the divertor region, which is included in X-point, tangentially through a hole of passive plate (inner wall). Using this measurement we found several interesting phenomena in divertor plasma with lower null configuration as follows,
1. Upward flow of visible light emission was found in the inner separatrix region.
2. Strong downward flow in the inner separatrix region was observed during ELM
3. Many filaments were observed to go downward in outer separatrix region.
4. There seems to be no correlation behavior between the private region and outer separatrix region.
5. Sometimes there were concentric circular multiple legs on the divertor plates.
In this paper, these interesting phenomena are presented.

This study is supported by US-JAPAN collaborative activity.