Bifurcation of temperature in 3-D plasma equilibria

This paper discusses some general aspects of MARFE formation and bifurcation of temperature in stellarators. The starting point is the three-dimensional heat conduction equation with a conduction matrix depending on temperature and position. The existence, uniqueness and stability of steady state solutions are discussed. Marfes in stellarators predominantly exist on rational magnetic surfaces if the shear is low. Outside the last magnetic surface bifurcation of temperature can arise on flux bundles between two divertor target plates. The number of solutions depends on the non-linearity of the boundary conditions and the details of the radiation function, especially its dependence on the temperature. Numerical solutions of the one-dimensional heat conduction equation in a slab and a cylindrical fusion plasma, using the shooting method, illustrate the various aspects of bifurcation. (orig.)Available from TIB Hannover: RA 71(2/342) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman