A Bayesian approach to the global confinement time scaling in W7-AS

摘要

A recently assembled W7-AS stellarator database, consisting of 143 electron cyclotron resonance (ECR) heated discharges, 51 discharges heated by neutral beam injection (NBI), and five discharges using combined ECR and NBI heating, is used to test three scaling models for the energy confinement time in terms of the other physical parameters. The three models are: the Lackner-Gottardi model, the ion plateau neoclassical transport model and the ITER 89-P model. The analysis employs Bayesian reasoning. On the basis of these data, Lackner-Gottardi scaling is 37 dB more likely to be correct than ITER 89-P in W7-AS and is over 21 dB more probable than the ion plateau neoclassical transport model. Values for the scaling exponents are given taking these data into account.