Characteristic of a pdCu membrane as atomic hydrogen probe for QUEST

A permeation probe is a useful device for detecting the atomic hydrogen flux to plasma-facing walls. Recently, we developed a new type of probe using 60Pd-40Cu alloy (PdCu) as the permeation material. The deuterium behaviors in PdCu samples were investigated using nuclear reaction analysis (NRA) and permeation observations, and the diffusion coefficient and recombination coefficients were determined from these observations. It was found that the sensitivity of a 0.02-mm-thick probe was as high as 0.5 below 473 K and was independent of the incident flux. The response time at 473 K was 0.41 s and 1.3 s under an incident flux of 1020 m−2s−1 and 1019 m−2s−1, respectively. Thus, we concluded that the new PdCu probe can effectively detect the incident atomic hydrogen with high sensitivity and a suitable response time.