Reconstruction of m=1 MHD modes from projections

Fluctuations with a dominant poloidal structure involving the intact displacement of the center of the discharge play a significant role in tokamak discharges. A technique for the deductive analysis of their structures, which involve multiple harmonics due to the multipole moments, is desired. This paper describes (1) a method for the inversion of line integral data from a single view of a rotating plasma based on a harmonic decomposition of the poloidal structure, and (2) some techniques for determining critical parameters by inspection. A simulation program generates sample data based on the assumption of a slowly evolving plasma with a displaced central hot spot and a plateau near the radius of the ‘‘q=1’’ surface. The sample data are decomposed into time windows to permit reconstruction of the profiles every few rotations. Results of the reconstructions are compared to the source data. Applicability of the techniques to experimental tokamak data is discussed.