Impact of Sheath Boundary Conditions and Magnetic Flutter on Evolution and Distribution of Transient Particle and Heat Fluxes in the Edge-Localized Mode Burst by Experimental Advanced Superconducting Tokamak Simulation

To study the evolution and distribution of the transient particle and heat fluxes during the edge-localized modes(ELMs) burst on the experimental advanced superconducting tokamak(EAST), the BOUT++six-field two-fluid model with sheath boundary conditions(SBCs) and magnetic flutter terms in the parallel thermal conduction is used to simulate the evolution of the profiles and growing process of the fluxes at divertor targets. Although SBCs hardly play a role in the linear phase, in the nonlinear phase both SBCs and magnetic flutter can change the dominant toroidal mode. SBCs are able to broaden the frequency distribution of the turbulence. The magnetic flutter increases the ELM size from 2.8% to 8.4%, and it doubles the amplitudes of the radial heat and particle transport coefficients at outer midplane(OMP), at around 1.0 m~2 s~(-1). It is then able to increase the particle and heat flux at the divertor targets and to broaden the radial distribution of the parallel heat flux towards the targets.     

SUNIST球形托卡马克的外加n=1磁场系统

为在SUNIST球形托卡马克上进行MHD不稳定性控制研究,建立了一套外加n=1径向磁场系统。此径向磁场系统的电源能确保在1ms内达到电流峰值并维持3ms以上的电流平台,并且有快速关断功能。测试表明,此套径向磁场系统可以稳定可靠地提供在真空室中心产生以n=1模式为主的径向磁场,为开展控制MHD不稳定性研究奠定了基础。