Influence of heating rate and storage condition on thermal desorption of deuterium in tungsten

The retention of hydrogen isotopes in tungsten has been a critical issue in future fusion facilities. Thermal desorption spectroscopy (TDS) is a common method for the studies of hydrogen isotope retention. To explore the effect of heating rate in TDS measurement, a series of deuterium (D) desorption experiments with different heating rates were conducted. The results were compared with TMAP7 (Tritium Migration and Analysis Program, version 7) simulations and Kissinger's theory. An empirical expression for the analysis of desorption spectra with different heating rates was derived. The expression was verified in another set of experiments on helium (He) desorption. Furthermore, the formation of molecules containing D atoms during TDS measurements was investigated. Specimens exposed to D plasma were stored in air and vacuum respectively for three months prior to desorption experiments. Signals of H, H2, HD, D2, HDO and D2O were detected. The reasons for the formation of these species were explored.