Soft X-ray tomography on tokamaks using flux coordinates

Abstract

Methods of inverting line integrated data using coordinates, which are adapted to problems arising from Hamiltonian flows, are presented. They are exemplified for measurements of soft X-rays on tokamaks with widely arbitrary poloidal cross section. Boundary conditions can be met and cause fewer 'ghosts' for most of the present day tokamaks. The soft X-ray measurements are then used to improve the flux function Psi as obtained from codes using magnetic measurements as input. We investigate oscillatory phenomena such as sawtooth crash precursors on tokamaks by decomposing the profiles into space-like eigenfunctions and their time dependencies.