Mechanism of PDP in Ni membrane

To investigate the interaction between the wall of a fusion device and the low energy plasma like scrape-off, the experiment had been carried out using a RF discharge plasma device. In this work, plasma driven permeation (PDP) was paid attention to and many permeation rate data on various kind of conditions were obtained. The PDP process model in which a high diffusion rate was occurred on upstream side was introduced and it was able to explain the result well. It was remarkable that larger hydrogen isotope permeation rate was expected than ever estimated on condition that hydrogen isotope was highly atomized in low energy plasma and that metal as a device wall was exposed to such plasma. (author)