RTNS-II - a fusion materials research tool

Abstract

Rotating Target Neutron Source-II (RTNS-II) is a national facility for fusion materials research. It contains two 14 MeV neutron sources. Deuterons are accelerated to ∼ 400 keV and transported to a rotating titanium tritide target. Present source strength is greater than 1 × 10 13 n/s and source diameter is 1 cm fwhm. An air-levitated vacuum seal permits rotation of the target at 5000 rpm with negligible impact on accelerator vacuum system gas load. Targets are cooled by chilled water flowing through internal channels in a copper alloy substrate. Substrates are produced by solid-state diffusion bonding of two sheets, one containing etched cooling channels. An electroforming process is being developed which will reduce substrate cost and improve reliability. Titanium tritide coating thickness is ∼ 10 μm giving an initial tritium inventory for the present 23 cm diameter targets of 3.7 × 10 7 MBq. Operating interval between target changes is typically about 80 h. Thirteen laboratories and universities have participated in the experimental program at RTNS-II. Most measurements have been directed at understanding defect production and low-dose damage microstructure. The principal diagnostic tools have been cryogenic resistivity measurements, mechanical properties assessment and transmission electron microscopy. Some engineering tests have been conducted in support of near-term magnetic confinement experiments and of reactor materials which will see small lifetime doses.