Neutron elastic recoil detection for hydrogen isotope analysis in fusion materials

Kubota, Naoyoshi; Kondo, Keitaro; Ochiai, Kentaro; Nishitani, Takeo

The Neutron Elastic Recoil Detection Analysis (NERDA) using a neutron beam was proposed to extend the analyzing depth of hydrogen isotopes up to several hundreds micrometers. The 14.1 MeV neutrons beam produced by the Fusion Neutronics Source facility in Japan Atomic Energy Agency entered a sample from the normal direction. Emitted particles from the sample were measured using a E-E counter telescope detector. Incident neutron fluence was monitored with a U fission chamber located behind the target chamber. The proof-of-principle experiment was performed using a standard sample of deuterated polyethylene film containing a known concentration of deuterium with the thickness of 100 m. The depth resolution was evaluated to be 99 m corresponding to 12% of the maximum probing depth of 801 m for the sample. For a carbon-based Plasma Facing Component (PFC) sample the depth resolution was expected to be 61 m, which was enough to reveal hydrogen isotope distributions of co-deposited layers. Also, we applied NERDA to analyses of hydrogen isotope distributions in PFCs of JT-60U.