Estimation of 14 MeV neutron rate from triton burn‐up in future W7‐X deuterium plasma campaigns

Fast ion confinement is of major importance for the ignition of a burning fusion plasma. In future deuterium plasma campaigns of the Wendelstein 7‐X stellarator, W7‐X, the amount of triton burn‐up is one possible measure for fast ion confinement. A well‐established technique to observe triton burn‐up is the 14 MeV neutron rate. In this paper, it is estimated whether an existing scintillating fibre neutron detector is also suited to measure triton burn‐up in W7‐X with sufficient accuracy. An estimation is presented, which can be applied to any tokamak or stellarator design and is one‐dimensional in the minor radius. The inputs are profiles of density, temperature, and differential volume element as well as the triton slowing‐down time. The estimation calculates the thermal deuteron fusion rate and the associated deuteron‐triton fusion rate; thus, the triton burn‐up generated 14 MeV neutron rate. It neither takes triton diffusion nor explicit losses into account. This thermally generated fusion rate is compared to the neutral beam injection heating induced beam‐plasma fusion rate.