Simulation Of Runaway Electrons Transport Affected By J-TEXT Resonant Magnetic Perturbation

Runaway electrons in tokamak may carry tens of MeV energy which may deposit in the first wall with fearful damage to it, resonant magnetic perturbation(RMP) is applied for the mitigation of runaway electrons. This thesis studies the effect of resonant magnetic perturbation(RMP) on the confinement of runaway electrons via simulating their drift orbits. The main content of this thesis is:And a real-shot J-TEXT equilibrium is used here with a limiter configuration, which is reconstructed by EFIT code. The topology of the magnetic field affected by RMP can be obtained by tracing the trajectory of field line. Both the DRMP and SRMP of J-TEXT can form magnetic islands in the plasma center where q is rational. The overlap of the islands wrecks the magnetic surface and thus the field lines become chaotic and open to the wall, which leads to the formulation of a stochastic layer. The layer is thin and the magnetic field is partially chaotic. With bigger RMP current, the stochastic layer are more severe, the formed center islands are larger, the field lines on the edge are more chaotic.This paper studies the effect of resonant magnetic perturbation(RMP) on the confinement of runaway electrons via simulating their drift orbits in the magnetic perturbation field The model adopted is based on Hamiltonian guiding center equations for runaway electrons, and the J-TEXT magnetic turbulences and RMP are taken into account. The drift surfaces for co-passing electrons are shifted outwards while counter-passing electrons are shift inward. Outside the shrinkage region of the runaways are lost rapidly since their drift orbits intersected with the vessel wall; that is to say, more and more runaway electrons will lose very fast due to the shrinkage of confinement volume if they possess higher energy.The transport of runaway electrons are studied by calculating the orbit losses for different runaway initial energies and different runaway electrons initial locations. The simulation indicates that the loss rate of runaway electrons is sensitive to the radial position of electrons. The loss of energetic runaway beam is dominated by the shrinkage of the confinement region. The experimental result on the response of runaway transport to the application RMP indicates that the loss of runaway electrons is dominated by the shrinkage of the confinement region, other than the external magnetic perturbation.