Tomography of fast-ion velocity-space distributions from synthetic CTS and FIDA measurements.

We compute tomographies of 2D fastion velocity distribution functions from synthetic collective Thomson scattering (CTS) and fastion Dα (FIDA)1Dmeasurements using a newreconstruction prescription. Contradicting conventional wisdom we demonstrate that one single 1D CTS or FIDAviewsuffices to compute accurate tomographies of arbitrary 2D functions under idealized conditions. Under simulated experimental conditions, single-view tomographies do not resemble the original fastion velocity distribution functions but nevertheless show their coarsest features. For CTS or FIDA systems with many simultaneous views on the same measurement volume, the resemblance improves with the number of available views, even if the resolution in each view is varied inversely proportional to the number of views, so that the total number of measurements in all views is the same. With a realistic four-view system, tomographies of a beam ion velocity distribution function at ASDEX Upgrade reproduce the general shape of the function and the location of the maxima at full and half injection energy of the beam ions. By applying our method to real many-view CTS or FIDA measurements, one could determine tomographies of 2D fastion velocity distribution functions experimentally. [ABSTRACT FROM AUTHOR]