Non-Local Model Analysis of Heat Pulse Propagation and Simulation of Experiments in W7-AS

Abstract

A new model equation which includes the non-local effectin the heat flux is introduced to study the transient transportphenomena. A non-local heat flux, which is expressed in terms of theintegral equation, is superimposed on the conventional form of theheat flux. This model is applied to describe theexperimental results from the power switching [U. Strothet al.: Plasma Phys. Control. Fusion 38 (1996) 1087] and thepower modulation experiments [L. Giannone et al.:Nucl. Fusion 32 (1992) 1985] in the W7-AS stellarator.A small fraction of non-local component in the heat fluxis found to be very effective in modifying the response against anexternal modulation. The transient feature of the transport property, which are observed in the response of heat pulse propagation, arequalitatively reproduced by the transport simulations based on thismodel. A possibility is discussed to estimate thecorrelation length of the non-local effect experimentally by use ofthe results of transport simulations.