Demonstrating the use of Multiple Experimental Techniques to Investigate Helium-Hydrogen Synergies in Tungsten

Polycrystalline W sample discs measuring 6 mm by 0.5 mm have been exposed to a low-energy (70 eV) He plasma using a low flux ( ) [1.3 times 10 to the 17 Helium per meter squared per second] ECR source located at the University of Tennessee in Dr. Donovan's laboratory. The samples were exposed to three different He fluences ( ) [5 times 10 to the 19 Helium per meter squared, 5 times 10 to the 20 Helium per meter squared, 5 times 10 to the 21 Helium per meter squared] at surface temperatures of ~300 K, 600 K and 900 K. These He fluences and temperatures provide a systematic study to evaluate the deuterium permeation behavior in W, as a function of He fluence and sample surface temperature. Laser-Induced Breakdown Spectroscopy (LIBS) and Laser Ablation Mass Spectrometry (LAMS) experiments were subsequently performed to determine the location and quantity of He present within the W material. Deuterium was introduced into the W using the Wirth group upstream gas permeation system located at Oak Ridge National Laboratory. LIBS/LAMS experiments were once more performed, to determine the location and quantity of deuterium and He, and to construct spatial profiles of deuterium and He within W. The results of these experiments give insight into existing synergies between H and He in W and the effects of He fluence and W surface temperature on deuterium retention and permeation.