MARFE onset conditions and stability
Abstract
The MARFE stability is considered on closed magnetic field lines in a configuration having an Xpoint. The model incorporates both perpendicular and parallel transport and takes into account the flux expansion in the vicinity of the Xpoint. The stability analysis can be reduced to a standard eigenvalue problem for the temperature perturbation. The ballooning representation of the perturbation is shown to be essentially a method to separate radial and poloidal variables and to reduce the twodimensional heat conduction equation with periodic metric coefficients to a onedimensional equation in a ballooning space. The effect of the toroidal magnetic topology on the marfe stability is investigated. It is shown that the flux expansion near the Xpoint has a destabilizing effect. The competing stabilizing effect is associated with the `steepening' of the ballooning perturbation both in radial direction (between the magnetic surfaces) and perpendicular to the magnetic field lines on the magnetic surfaces. The main result of the work argues that in the stability analyses both parallel and perpendicular heat fluxes must be taken into account and can not be omitted without change in the spectrum of the anisotropic heat conduction equation.
 Publication:

Journal of Nuclear Materials
 Pub Date:
 1999
 DOI:
 10.1016/S00223115(98)00614X
 Bibcode:
 1999JNuM..266..837I