A fusion relevant neutron source is a more than three decades long pending step for the successful development of fusion energy. In DEMO, like in future fusion power plants, the deuterium-tritium nuclear fusion reactions will generate neutron fluxes in the order of 1018m-2s-1 with an energy of 14.1 MeV that will collide with the first wall of the reactor vessel, which provides the physical boundary for the plasma and contributes to the thermal and nuclear shielding of the external machine components such as the superconducting magnets. [Further reading]
IFMIF, the International Fusion Materials Irradiation Facility, will generate, thanks to two parallel deuteron accelerators, a neutron flux with a broad peak at 14 MeV by Li(d,xn) nuclear reactions that will collide in a liquid Li screen with a footprint of 20 cm x 5 cm. The energy of the beam (40 MeV) and the current of the parallel accelerators (2 x 125 mA) have been tuned to maximize the neutrons flux to get irradiation conditions comparable to those of a fusion reactor in a volume of 0.5 l that will house around 1000 small specimens. The successful validation of the small specimens test technique under the Broader Approach Agreement between Japan and EURATOM will allow the full mechanical characterization of suitable materials, and allow the understanding of the degradation that will lead to the design of constituents better tolerant to radiation.
