Neutron production rates during four transitions from DT to D3 He ignited plasmas in a compact tokamak

Neutron production rates due to DT, DD, TT, and T³He reaction rate during four transitions from DT to D³He ignited plasmas (characterized by different evolutions of ion densities and temperature) in a compact tokamak have been calculated. For each transition, the results are reported in graphical form and discussed. The main feature is the predominance of 14-MeV DT neutrons, whose production rate does not appear to be negligible. It is therefore concluded that, while acceptable in experiments of D³He ignition, tritium assistance may not be suitable for routine startup of D³He fusion power plants, in which plasma temperature will probably have to be raised to ignition level by other means. A program aimed at measuring cross sections of some neutron-lean fusion reactions is also mentioned