MAXIMUM ENTROPY SPECTRAL ANALYSIS IN MICHELSON INTERFEROMETRY
A Rapid Scan Michelson Interferometer is used to measure the spectrum of Electron Cyclotron Emission from the plasma in the DITE Tokamak at the Culham Laboratory. Instruments of this type can only be used to measure the autocorrelation function up to a certain maximum value of the time delay in one of the wave trains; this is determined by the maximum path difference which can be introduced. If conventional Fourier methods are then used to invert the data, false sidelobe structures often appear on the transformed spectra. The application of an alternative method of analysis, the Maximum Entropy Method is described. The method gives a positive valued spectrum having the maximum spectral resolution consistent with the given autocorrelation data set but has the minimum of sidelobes and false structures. Because the numerical algorithm is non-linear, it is possible to "bootstrap' the data inversion scheme in order to self-calibrate it with respect to the "zero path difference" correction. Electron Cyclotron Emission spectra from the DITE Tokamak plasma and compared results with those obtained from the conventional method are presented.
Bibliographic Reference: WORKSHOP ON DIAGNOSTICS FOR FUSION REACTOR CONDITIONS, VARENNA, COMO (ITALY), SEPT. 6-17, 1982, PP. 177-187 351 P., 1983, ISBN 0-08-031161-X WRITE TO PERGAMON PRESS LTD., HEADINGTON HILL HALL, OXFORD OX3 OBW (ENGLAND), PRICE: UKL 47, (EUR 8351 EN).
Record Number: 1989123101400 / Last updated on: 1987-01-01
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