Determination of Hydrogen and Deuterium Inventory of Pre-Treated Targets Using Laser-Induced Desorption

Abstract

Laser-Induced Desorption-Quadrupole Mass Spectrometry (LID-QMS) is a diagnostic method in which a quadrupole mass analyzer is used to measure the amount of material that is desorbed from a sample by firing a spot laser on the surface. An LID-QMS system has been set up at the Target Exchange and Analysis Chamber (TEAC) of the plasma generator Magnum-PSI in order to investigate the first principles of laser-induced desorption of hydrogen isotopes from plasma facing component (PFC) materials. Two LID-QMS experiments with pre-treated targets were conducted in which the local hydrogen and deuterium concentration of the samples was determined. The most important uncertainty in the observed concentrations resulted from the determination of the desorbed area. This area is essential for obtaining the D and H concentrations of the targets but is difficult to determine. Furthermore, a first attempt to perform an absolute calibration of the LID-QMS system at the TEAC was unsuccessful. Fulfilment of this absolute calibration is a priority for further research. The experimental work was supported by theoretical modeling in TMAP7. TMAP7 analysis showed that, for a single 3.0 ms laser pulse on a tungsten (W) surface, desorption percentages are higher than 90% for maximum surface temperatures > 1300 K.