Comparative Analysis of D-T and D-He<sup>3</sup> Fusion for Mars-Bound Spacecraft

The feasibility of fusion propulsion for Mars-bound spacecraft depends on the selection of an optimal fuel, with Deuterium-Tritium (D-T) and Deuterium-Helium-3 (D-He3) being the primary candidates. This study presents a comparative analysis of these fuels under vacuum conditions, focusing on reaction efficiency, neutron radiation hazards, and fuel availability. The energy partitioning and neutron production rates of both reactions are examined, highlighting the shielding and structural integrity challenges posed by D-T fusion due to its relatively high neutron flux. Furthermore, specific impulse and thrust calculations are conducted to precisely assess the propulsion capabilities, considering mass flow rate constraints and fuel availability. The results indicate that while D-He3 fusion offers advantages in reduced radiation exposure and direct energy conversion potential, its fuel scarcity and ignition challenges pose significant obstacles. Conversely, D-T fusion provides higher reaction efficiency and greater thrust but requires extensive radiation shielding and thermal management. The study concludes that while neither fuel is currently viable for near-term spacecraft propulsion, advancements in fusion reactor miniaturization, cryogenic fuel storage, and thermal regulation systems could bridge existing technological gaps. Future research should focus on experimental validation of fusion propulsion systems, reactor optimization for space conditions, and improved He3 acquisition methods.