Measurement of low frequency plasma fluctuations with a visible light detector in GAMMA 10

Low frequency fluctuations of a plasma in the central cell of the GAMMA10 tandem mirror have been observed with electrostatic probes (ESPs) installed at the peripheral region of the plasma. Typical plasma parameters for a hot ion mode operation are ne∼2×1012 cm−3, Ti∼4 keV, Te∼100 eV, B=4 kG, and rp=18 cm. Although the ESP is an effective tool to measure local plasma parameters and fluctuations, it can be damaged with the higher electron temperature. Here, a new visible light detector was introduced, which could measure the plasma fluctuations without contacting the plasma. The obtained results were compared with those of ESPs. It is found that the visible light detector is applicable when the electron temperature becomes much higher in the future experiment.