Biased Limiter and RHF Effects on X-Ray Intensity and Mirnov Oscillations

We have calculated and investigated the runaway electron generation in IR-T1 tokamak. For this purpose, we used the hard X-ray spectroscopy. Hard X-ray emission produces due to collision of the runaway electrons with the plasma particles or limiters. Runaway electrons in tokamaks can cause serious damage to the first wall of the reactor and decrease its life time. In addition, hard X-ray emission generated from high-energy runaway electrons lead to plasma energy loss. Therefore, suggesting methods to minimize runaway electrons in tokamaks are very important. Applying external resonant field is one of the methods for controlling the magnetohydrodynamic (MHD) activity. This paper attempts to investigate the effects of limiter biasing and resonant helical magnetic field on the generation of runaway electrons. For this purpose, plasma parameters, such as plasma current, MHD oscillation, loop voltage, emitted hard X-ray intensity, H_α impurity, and safety factor in the presence and absence of external fields, were measured. Frequency activity was investigated with fast Fourier transform analysis. The results show that applying resonant fields can control the MHD activity, and then hard X-ray emitted from the runaway electrons.