A new diagnostic method is proposed for direct measurements of electromagnetic field patterns of fast waves in toroidal plasmas. The fluctuations of the ponderomotive potential at the beat wave frequency between two fast waves with different frequencies produces the actual potential fluctuations via electron and ion motions. A heavy ion beam probe detected the potential fluctuation patterns at the beat wave frequency during the fast wave pulse. The amplitude of the potential fluctuations decreases with increasing electron temperature in fast wave current drive experiments in JFT-2M, owing to the improvement of wave absorption via electron Landau damping. The measured potential fluctuations do not contradict the prediction using full wave code calculations.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- Condensed Matter Physics