Application of dimensionless parameter scaling techniques to the design and interpretation of magnetic fusion experiments

Abstract

A review of the application of dimensionless parameter scaling techniques to magnetic fusion experiments is presented. Because the methods of this type of analysis are not generally known, a detailed discussion of the basis for these techniques is given, including examples. The primary applications and successes of these methods in magnetic fusion research are in the area of transport of energy and particles across surfaces of constant magnetic flux. The experimental justification for the use of these techniques to describe transport is given, and the applications are reviewed. The two key applications of these techniques, the identification of the underlying physical mechanisms that cause transport and the projection of the transport in future devices from presentday experiments, are extensively discussed. Comparison of the results of dimensionless parameter scaling experiments with the regression analysis of multi-machine databases points to limitations in the databases and the analysis of them as the source of the discrepancies. These discrepancies have significant implications for the design optimization of tokamaks, which are discussed here. Finally, the application of dimensionless parameter scaling techniques to plasma stability, to the boundary region between closed and open field lines and to divertor operation in the open field line region are reviewed and discussed.

Development of advanced inductive scenarios for ITER

“…€ E × B shearing of turbulence, and magnetic shear [17]. While no information on magnetic shear is available in the database, it is possible to test if either of the other two effects have a dominant influence on confinement by looking at data supplied in the original datasets.…”

Multi-device studies of pedestal physics and confinement in the I-mode regime

“…reviews [27,28,29]. If the match over the whole radius is perfect, B T   , where   is the global energy confinement time, also has the same value in the two devices, in this case AUG and C-Mod.…”

Validation metrics for turbulent plasma transport

“…but matched dimensionless parameters. [23][24][25] In this context, basic plasma physics and smaller-scale experiments focused on specific plasma dynamics play a key role in MFE plasma model validation, by enabling access to parameter regimes significantly different than those obtainable in large high-power fusion experiments. Such experiments also often allow use of diagnostic approaches and measurement techniques not available on larger devices, enabling testing of predictions of phenomena which cannot otherwise be measured easily, if at all.…”