Heatpulse Propagation Studies on DIII-D and TFTR
Authors: E.D. Fredrickson, M.E. Austin, R. Groebner, J. Manickam, B. Rice, G. Schmidt, and R. Snider
Date of PPPL Report: April 2000
Published in: Phys. of Plasmas 7 (December 2000) 5051-5063. (Title changed to: Heat Pulse Propagation Studies on DIII-D and the Tokamak Fusion Test Reactor.)
Sawtooth phenomena have been studied on DIII-D and TFTR. In the experiments, with high power neutral beam injection the sawtooth characteristics were studied with fast electron temperature (ECE) and soft x-ray diagnostics. A strong ballistic electron heat pulse is found on DIII-D, stronger than was previously reported on TFTR. Evidence is presented in this paper that the ballistic effect is related to the sawtooth precursor. Fast, 2 msec interval, measurements on DIII-D were made of the ion temperature evolution following the sawtooth to document the ion heat pulse characteristics. It is found that the ion heat pulse does not exhibit the very fast, ̉ballisticÓ behavior seen for the electrons. Further, both the electron and ion heat pulses from partial sawtooth crashes and similar events are seen to propagate at speeds close to those expected from the power balance calculations of the thermal diffusivities. These results suggest that the fast sawtooth induced heat pulse propagation is not a feature of non-linear transport models, but that MHD events can have a strong effect on thermal transport.