A maximum likelihood tomographic method applied to JET gamma ray emission during the current quench

Abstract In recent years, a new inversion method has been adapted to JET tomographic diagnostics. It is based on the Maximum Likelihood (ML) approach and has been applied to most systems of interest: the neutron, gamma ray and bolometric tomographies. In addition to its accuracy and reliability, the main competitive advantage of the ML inversion is the fact that it can provide reliable estimates of the uncertainties in the reconstructions. Recently the same approach has been deployed for the investigation of the hard X-rays and gamma rays, emitted by beams of runaway electrons during disruptions. This application is a particularly challenging proposition, given the potential detrimental effects of the errors in the magnetic topology, during the current quench. In this perspective, particular attention has been devoted to producing good quality, high time resolution equilibria. The ML inversion technique has given promising results and the developed routines have the potential of constituting a good complement to the other diagnostics, such as the infrared cameras, typically used to investigate the runaway electrons.