Asymmetry of radial heat pulse propagation at TEXTOR
It is usually assumed that electron heat transport is governed by a diffusive process across the entire magnetic surface, and consequently that X(e)(r) is a useful characteristic quantity. Experimentally X(e)(r) is derived from the (quasi-)stationary energy balance. Complementing this standard procedure, perturbation methods have been applied to calculate the X(e)-values from the radial propagation of transients on the T(e)- and n(e)-profiles. The present paper reports on the simultaneous observation of heat pulse propagation along two opposite radial directions, i.e. along both the high field side (HFS) and the low field side (LFS). Much faster heat pulse propagation was observed towards the LFS than towards the HFS. The time delay between HFS and LFS increases with increasing isobar radius, suggesting that the predominant heat transport is localised at the LFS, and that the HFS is subsequently fed from the LFS by parallel heat equilibration along the connecting magnetic field lines. This questions the concept of a simple diffusive transport across the entire surface, and the use of X(e)(r) to characterise the process.
Bibliographic Reference: Article: Proceedings of the 19th Conference on Controlled Fusion and Plasma Physics, Vol. 1 (1992) pp. 95-98
Record Number: 199211312 / Last updated on: 1994-11-29
Original language: en
Available languages: en