Anomalous ion heating from ambipolar-constrained magnetic fluctuation-induced transport

A kinetic theory for the anomalous heating of ions from energy stored in ma gnetic turbulence is presented. Imposing self-consistency through the const itutive relations between particle distributions and fields, a turbulent Ki rchhoff's Law is derived that expresses a direct connection between rates o f ion heating and electron thermal transport. This connection arises from t he kinematics of electron motion along turbulent fields, which results in g ranular structures in the electron distribution. The drag exerted on these structures through emission into collective modes mediates an effective amb ipolar constraint on transport. Resonant damping of the collective modes by ions produces the heating. In collisionless plasmas the rate of ion dampin g controls the rate of emission, and hence the ambipolar-constrained electr on heat flux. The heating rate is calculated for both a resonant and nonres onant magnetic fluctuation spectrum and compared with observations. The the oretical heating rate is sufficient to account for the observed twofold ris e in ion temperature during sawtooth events in experimental discharges. (C) 2001 American Institute of Physics.