München 2019 – wissenschaftliches Programm
P 18.95: Poster
Donnerstag, 21. März 2019, 16:30–18:30, Foyer Audimax
Bayesian modelling of reflectometers at Joint European Torus using the Minerva framework — •Sehyun Kwak1,2, Jakob Svensson2, Joe Abbate3, Lynton Appel3, Jon Hillesheim3, Felix Parra Diaz3, and Luis Meneses3 — 1Department of Nuclear and Quantum Engineering, KAIST, Daejeon 34141, Republic of Korea — 2Max-Planck-Institut für Plasmaphysik, 17491 Greifswald, Germany — 3Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB, UK
A Bayesian model for the JET reflectometers has been developed to infer electron density profiles using the Minerva framework. The reflectometry system consists of six channels covering four different bands between 44 and 150 GHz by the fast-sweeping frequency with ordinary and extraordinary mode wave. It measures electron density profiles from the edge to the centre, up to electron density of ~1020 m-3 with the temporal resolution about 10 microseconds. The forward model predicts optical path length that the waves travel and reflect back to the antenna, given electron density, temperature profiles, and magnetic field. The electron temperature profiles and magnetic field are taken from high resolution Thomson scattering diagnostics and equilibrium fitting (EFIT) code respectively. The electron density profiles are modelled by Gaussian processes to constraint profiles with length scale without any specific parameterisation. The posterior distribution is explored by Markov chain Monte Carlo (MCMC) sampling and the results include electron density profiles as well as their associated uncertainties.