Additional Beta due to Fast Fusion Products in D-³He Fusion Plasma

An analytical formula for the additional beta due to fast fusion-born ions is derived by using the slowing-down approximation from the Fokker-Planck equation under the assumption of negligible loss term. It is found that the fast ion beta in a D-³He fusion plasma at a typical temperature of 55 keV is about 20% of the thermal beta, which is the same ratio as that obtained in a D-T plasma at 20 keV.