INWARD TRANSPORT OF ENERGY DURING OFF-AXIS HEATING ON THE DIII-D TOKAMAK

Inward transport of energy is observed on the Dill-D tokamak during of f-axis electron cyclotron heating (ECH) experiments under a variety of operating conditions. Power balance analysis of steady state discharg es shows that the electron heat flux can be negative (inward) interior to the ECH resonance location with a certainty of up to three times t he experimental error bars. The ion heat flux is always positive (outw ard), as is the total heat flux. The electron heat flux becomes increa singly negative as the plasma density is increased. A detailed error a nalysis of the energy transport is performed as well as an independent verification of the measured plasma profiles. These results contradic t purely diffusive models of radial heat transport, since energy in th e electron channel is observed to flow in the direction of increasing temperature.