Large-amplitude oscillations of soft X-rays in a high current density plasma on TPE-1RM15 reversed field pinch

Abstract

In the high current density plasma on TPE-1RM15 reversed field pinch, large-amplitude oscillations with m=0, n=0 are observed in soft X-ray (SXR) emission for a wide range of theta values, even at low- theta ( theta <1.55) discharges. Another small-amplitude oscillation with m=1 is observed quasicontinuously for almost all the discharge. The burst of high-energy soft X-rays is observed in the channels of the SBD array looking at the electron drift side of a metal limiter and seems to correlate with the crash of the large-amplitude oscillation. This SXR burst indicates the existence of energetic electrons flowing along the field lines near the plasma surface in the dynamo phase. These large-amplitude SXR oscillations are mainly due to the variations in the electron temperature and are roughly in antiphase with the oscillation of ion temperature.