First Observation of RF-Induced Visible Light Fluctuations
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In order to detect rf modulation of visible light emitted from plasma, a high-speed photodiode measurement system was developed. The system is located outside the vacuum vessel of the TST-2 spherical tokamak and measures visible light emissions through a quartz window. A dedicated amplifier for the photodiode was made. Care was taken to reduce the rf pickup noise. The frequency spectrum of the light signal detected during high harmonic fast wave (HHFW) heating showed modulation by HHFW. This is the first measurement of visible light modulation induced by HHFW, and shows promise for measurement of the rf electric field in the plasma core.
- Plasma and Fusion Research
Plasma and Fusion Research (2), 023-023, 2007
The Japan Society of Plasma Science and Nuclear Fusion Research