Non-local model analysis of heat pulse propagation and simulation of experiments in W7-AS

A new model equation which includes the non-local effect in the heat flux i s introduced to study the transient transport phenomena. A non-local heat A ux, which is expressed in terms of the integral equation, is superimposed o n the conventional form of the heat flux. This model is applied to describe the experimental results from the power switching [U. Stroth et al.: Plasm a Phys. Control. Fusion 38 (1996) 1087] and the power modulation experiment s [L. Giannone et al.: Nucl. Fusion 32 (1992) 1985] in the W7-AS stellarato r. A small fraction of non-local component in the heat flux is found to he very effective in modifying the response against an external modulation. Th e transient feature of the transport property: which are observed in the re sponse of heat pulse propagation, are qualitatively reproduced by the trans port simulations based on this model. A possibility is discussed to estimat e the correlation length of the non-local effect experimentally by use of t he results of transport simulations.