Explanation for Marfe Formation and Subsequent Evolution into a DetachedSymmetric Plasma Edge

摘要

An explanation is proposed for the experimentally onserved tokamak phenomenon ofa symmetric radiating edge evolving with increasing density into a multifaceted asymmetric radiation from the edge (MARFE) condition and then cooling into a detached plasma with a symmetric edge. The thermal stability impurity density limits increase with the poloidal mode number, m, of the edge plasma distribution. When the edge impurity density exceeds the m equal to 0 mode density limit, the edge plasma evolves into a mixture of m greater than O modes which becomes more highly asymmetric as the density increase further and exceeds the density limits of successively higher modes, forcing the plasma into the remaining stable higher-m modes-the stable MARFE.