MAXIMUM-ENTROPY BASED RECONSTRUCTION OF SOFT-X-RAY EMISSIVITY PROFILES IN W7-AS

Citation
K. Ertl et al., MAXIMUM-ENTROPY BASED RECONSTRUCTION OF SOFT-X-RAY EMISSIVITY PROFILES IN W7-AS, Nuclear fusion, 36(11), 1996, pp. 1477-1488
Citations number
39
Categorie Soggetti
Phsycs, Fluid & Plasmas","Physics, Nuclear
Journal title
ISSN journal
00295515
Volume
36
Issue
11
Year of publication
1996
Pages
1477 - 1488
Database
ISI
SICI code
0029-5515(1996)36:11<1477:MBROSE>2.0.ZU;2-6
Abstract
The reconstruction of 2-D emissivity profiles from soft. X ray tomogra phy measurements constitutes a highly underdetermined and ill-posed in version problem, because of the restricted viewing access, the number of chords and the increased noise level in most plasma devices. An unb iased and consistent probabilistic approach within the framework of Ba yesian inference is provided by the maximum entropy method, which is i ndependent of model assumptions, but allows any prior knowledge availa ble to be incorporated. The formalism is applied to the reconstruction of emissivity profiles in an NBI heated plasma discharge to determine the dependence of the Shafranov shift on beta, the reduction of which was a particular objective in designing the advanced W7-AS stellarato r.