Tomographic capabilities of the new GEM based SXR diagnostic of WEST

A. Jardin (1) , D. Mazon (1) , Martin O'Mullane (2) , J. Mlynar (3) , V. Loffelmann (3) , M. Imrisek (3) , M Chernyshova (4) , T. Czarski (4) , G. Kasprowicz (5) , A. Wojenski (5) , C. Bourdelle (1) , P. Malard (1)

1 IRFM - Institut de Recherche sur la Fusion par confinement Magnétique
2 Department of Physics [Glasgow]
3 IPP PRAGUE - Institute of Plasma Physics, Association EURATOM
4 IPPLM - Institute of Plasma Physics and Laser Microfusion [Warsaw]
5 Warsaw University of Technology [Warsaw]

The tokamak WEST (Tungsten Environment in Steady-State Tokamak) will start operating by the end of 2016 as a test bed for the ITER divertor components in long pulse operation. In this context, radiative cooling of heavy impurities like tungsten (W) in the Soft X-ray (SXR) range [0.1 keV; 20 keV] is a critical issue for the plasma core performances. Thus reliable tools are required to monitor the local impurity density and avoid W accumulation. The WEST SXR diagnostic will be equipped with two new GEM (Gas Electron Multiplier) based poloidal cameras allowing to perform 2D tomographic reconstructions in tunable energy bands. In this paper tomographic capabilities of the Minimum Fisher Information (MFI) algorithm developed for Tore Supra and upgraded for WEST are investigated, in particular through a set of emissivity phantoms and the standard WEST scenario including reconstruction errors, influence of noise as well as computational time.

Keywords: Tokamaks; GEM; Soft X-Ray Tomography; Plasma diagnostics

Domains: Physics [physics]; Physics [physics]; Plasma Physics [physics.plasm-ph]; Physics [physics]; High Energy Physics - Experiment [hep-ex]

A. Jardin, D. Mazon, Martin O'Mullane, J. Mlynar, V. Loffelmann, et al.. Tomographic capabilities of the new GEM based SXR diagnostic of WEST. Journal of Instrumentation, 2016, 11, pp.C07006. ⟨10.1088/1748-0221/11/07/C07006⟩. ⟨cea-01394591⟩