MARFE FORMATION IN DIVERTED TOKAMAKS

The equilibrium and stability of MARFEs are considered. It is demonstrated that important aspects of the two dimensional problem can be illustrated by a one dimensional treatment. A stability analysis indicates that MARFE formation requires low temperature, high impurity content and low cross-field transport. Additionally, MARFEs tend to form on flux surfaces that contain an X point. It is observed that the transition to a MARFE-like solution can result from a fluctuation induced jump from a neighbouring constant temperature solution.