Plasma potential fluctuations and large quasi-coherent modes observed by a heavy ion beam probe on the JIPP T-IIU tokamak

We observed, in the signals of the plasma potential fluctuation, large-scale oscillations of large energy change in the secondary beam of an HIBP on the JIPP T-IIU tokamak. The frequency is around 10–40 kHz and the amplitude is 10–100 V. It is also found that the coherence of the energy change and the toroidal deflection is very high (0.6), implying that they are; caused by the magnetic oscillations. In spite of the oscillations, we obtained stable values for the correlation between the density and local electric field, which are proportional to the turbulence-driven particle flux.