The nuclear reaction of deuterium–tritium (D–T) fusion by the usual magnetic or inertial confinement suffers from a number of difficulties and problems caused by tritium handling, neutron damage to materials and neutroninduced radioactivity, etc. The study of the nuclear synthesis reaction of deuterium–helium-3 (D–3He) at low collision energies (below 1 keV) is of interest for its applications in nuclear physics and astrophysics. Spherical tokamak (ST) reactors have a low aspect ratio and can confine plasma with β≈1. These capabilities of ST reactors are due to the use of the alternative D–3He reaction. In this work, the burn condition of D–3He reaction was calculated by using zerodimensional particles and power equations, and, with the use of the parameters of the ST reactor, the stability limit of D–3He reaction was calculated and then the results were compared with those of D–T reaction. The obtained results show that the burn conditions of D–3He reaction required a higher temperature and had a much more limited temperature range in comparison to those of D–T reaction
