NONLOCAL COMPONENT OF ELECTRON HEAT-TRANSPORT IN TFTR

The electron temperature profile response in ohmically heated Tokamak Fusion Test Reactor (TFTR) discharges to temporally and spatially shar p edge cooling from laser ablation of trace impurities is studied. The profile response is found to exhibit transport behaviour which cannot be described by transport coefficients that depend solely on local pa rameters. Thus, the transport behaviour is 'non-local'. This non-local behaviour manifests itself as a core electron temperature rise in res ponse to localized edge cooling as well as transient modification of s awteeth. A phenomenological model demonstrating overlapping non-local and non-linear effects is presented in the context of some alternative transport theories. Carbon flakes falling from the TFTR wall into a l ow power deuterium-tritium supershot produce this same core electron t emperature rise. This paper complements observations by Gentle et al. (Gentle, K.W., et al., Phys. Rev. Lett. 74 (1995) 3620).