Energy balance in plasma detachment

Abstract

Divertor plasma detachment is analyzed from the viewpoint of energy and particle balance in the edge plasma. It is shown that volumetric recombination and impurity radiation losses are responsible for the transition to the detached plasma regime, whereas “momentum removal” plays although important, but auxiliary role providing conditions necessary for the first two to become efficient. A criterion of the local (on an isolated flux tube) detachment onset is studied for both pure and impurity-seeded plasmas.