Validation of a planar probe diagnostics for plasmatron VISIONI and its application for the study of deuterium retention in tungsten

With ITER, the proof that the magnetic confinement concept allows to gain energy from thermonuclear fusion should be demonstrated. However, long term operation requires a sufficient lifetime of wall components. Erosion, redeposition, deuterium and tritium retention are key PWI issues. The main aspects for the selection of plasma facing materials are the requirements of plasma performance, engineering integrity, component lifetime and safety. Tungsten is considered a possible first-wall material for ITER. The plasmatron VISIONI at the Belgian Nuclear research center SCK-CEN is a high flux, low temperature plasma simulator dedicated to investigation of plasma wall interactions. Research is focused on hydrogen isotopes retention in tungsten and tungsten alloys under fusion-relevant conditions. A planar probe system, to monitor the relevant plasma parameters in term of plasma surface interactions, has been developed. The main concept is to use the investigated tungsten specimen itself as electrostatic probe. This master thesis project is dedicated to the validation of the potential of this planar probe as diagnostic tool. Current-voltage characteristics were analysed to measure plasma parameters in the vicinity of the sample. Then, first exposure of tungsten samples to deuterium plasma was performed. The deuterium retention was determined by thermodesorption spectroscopy.