Engineering Considerations for the Self-Energizing Magnetoplasmadynamic (MPD)-Type Fusion Plasma Thruster

Abstract : Feasibility studies Of dense plasma focus (DPF) device as a fusion propulsion thruster have been performed. Both conventional and spin-polarized D- 3He fuels were used. Three modes of operation were identified and each was investigated for its usefulness in space travel with special attention paid to a manned Mars mission. Using fusion products to directly produce thrust resulted in specific impulse, Isp (i.e., the ratio of the rocket thrust to the propellant weight flow rate), around 10(6) sec, but produced system thrust-to-weight ratios (F/W) less than 10(-5). This F/W is many orders of magnitude less than a typical value of 0.2 for a manned Mars mission which is presently possible with chemical and nuclear thermal rockets. Using large quantities of propellant to burn impulsively gave Isp's of 4,000 sec with F/W equal to 0.05 for one thruster and 0.132 if five thrusters are used. The spin-polarized D-3He studies provided increased values of F/W and Isp over conventional D-3He fuel which was due to the increased fusion power and decreased radiation losses for the spin-polarized case. Thus, the DPF provides attractive plasma conditions as a space propulsion thruster, though uncertainties remain in the validity of scaling laws on capacitor mass at high current beyond 1 MA. Fusion Propulsion, Dense Plasma Focus, Magnetoplasmadynamic Thruster, Advanced Fuel, D-3He Fusion, Spin-Polarized Fusion.