Effects of Externally Applied Magnetic Perturbation in a Spherical Tokamak Plasma Produced by ECH on the LATE Device

摘要

In toiroidally confined fusion plasmas, transport of particle and energy caused by externally applied magnetic perturbation (MP) fields and/or therefore stochastic fields is very important for controlling the plasma performance and MHD instabilities. For example, modifications of edge localized modes (ELMs) have been observed by controlling the edge pressure gradient by application of resonant magnetic perturbations (RMPs) in various tokamak plasmas such as DIII-D [1] and JET [2]. On the other hand, losses of runaway electrons (can reach high energies of several tens of megaelectronvolts) in ergodized plasmas with RMPs are investigated in JFT-2M [3] and TEXTOR [4]. Loss of high energy electrons is smaller than that of thermal electrons, because the large shift of the drift surface of high energy electrons from the magnetic surface causes a significant reduction in transport with RMPs. Among these studies on RMPs in various tokamaks, the major difference is the MP spectra, which includes not only the mode number but also the ratio of the resonant to the non-resonant components. Therefore, it is important to clarify the effects among these qualitatively different RMPs, especially possible effects by non-resonant components on both bulk plasmas and high-energy particles.