Hosted by Michiel Hochstenbach

Abstract

In this inverse problem, we compute the velocity distribution of fast ions in a small volume of a tokamak plasma from measurements of the Doppler shift of photons emitted from the plasma. This inverse problem is severely underdetermined, and there is a demand for incorporating prior information about the solution to stabilize the inverse problem. A successful way to do this is to express the solution in a physics-based basis consisting of so-called slowing-down functions that reflect the statistical behavior of fast ions in the plasma. We demonstrate the usefulness of this approach, and that it is equivalent to using a general-form Tikhonov regularization term that dampens undesired high-frequency components.