High frequency magnetic fluctuations in the lower hybrid frequency range were observed in the upstream region of reconnection site during counter-helicity merging experiment in TS-4. In contrast, no high frequency fluctuation was observed during co-helicity merging which contains considerable toroidal guide field at the X point. Toroidal electric field measured in counter-helicity merging was larger than that measured in co-helicity merging. These observations indicate the fluctuations might contribute to the fast reconnection in counter-helicity merging.
- Counter-helicity plasma merging
- Field-reversed configuration
- Magnetic fluctuation
- Magnetic reconnection