Radial transport of the nonthermal electrons in runaway discharges in the SINP tokamak from analysis of hard x-ray fluctuations

摘要

X-ray bursts from nonthermal electrons (～10 keV to 1 MeV) emanating from the core plasma and the limiter are measured simultaneously in runaway dominated discharges in the SINP tokamak using a tangentially viewing Nal(T1) detector and a detector that views the limiter areas. The radial transport coefficient of the nonthermal electrons has been derived from the cross-correlation function of the two x-ray intensities. Two phases of the plasma discharges with distinct transport of the nonthermal electrons are found in these experiments. The stochastic magnetic field fluctuations obtained from the transport coefficients are found to have a relationship with the autocorrelation functions of the x-ray emissivity signals.