X-Ray Tomography: A MaxEnt Approach

W.v.d.Linden, K.Ertl, and V.Dose
Max-Planck-Institut für Plasmaphysik
EURATOM Association
D-85740 Garching b. München, Germany


Soft X-ray emission tomography has become standard diagnostic equipment to analyze the formation and time-evolution of the plasma cross-section on tokamaks and stellerators. X-ray tomography measures the integrated emissivity along different, overlapping chords through the plasma at one toroidal position. For a unique reconstruction of the two-dimensional poloidal emissivity profile an infinite number of exact line-integrals is required.

However, viewing access in most plasma experiments is strongly limited leading to a highly underdetermined inversion problem which is aggravated by the fact that the experimental data suffer from noise of unknown distribution.

The applicability of MaxEnt to this problem is analyzed guided by synthetic data as well as by measured data from Wendelstein 7AS stellerator. The features of MaxEnt-Tomography are discussed.

MaxEnt 94 Abstracts / mas@mrao.cam.ac.uk