Transport in toroidal devices - the experimentalist's view
This paper summarises the present state of experimental tokamak confinement studies. Where possible, tokamak results are compared with those from stellarators, in particular with those from W7-AS. Such a comparison is meaningful because stellarators and tokamaks share many transport aspects. In both cases transport is generally anomalous, degrades with heating power and increases towards the edge. Bifurcations such as the tokamak H-mode transition are also observed in the W7-AS stellarator. Transport in stellarators, although anomalous, seems to be less confused by additional complexities such as large off-diagonal contributions, profile resilience, disparities between steady-state and perturbatively determined transport coefficients and an isotopic mass dependence in energy and particle transport. Differences in magnetic field and minor radius scaling seem to be introduced by operational restrictions: the rotational transform iota is constant in stellarator field or size scans whereas q(a) generally varies with current, field or size in tokamaks.
Bibliographic Reference: Article: Plasma Physics and Controlled Fusion, Vol. 35 (1993) pp. 1321-1371
Record Number: 199311508 / Last updated on: 1994-11-28
Original language: en
Available languages: en