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
Abstract
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