2. Course Summary Session: Trajectories, Chemical Rockets, Plasma Propulsion, Fusion Propulsion John F Santarius Lecture 43 Resources from Space NEEP 533/ Geology 533 / Astronomy 533 / EMA 601 University of Wisconsin

3. Efficient Solar-System Travel Requires High-Exhaust-Velocity, Low-Thrust Propulsion Electric power can be used to drive high-exhaust-velocity plasma or ion thrusters, or fusion plasmas can be directly exhausted. Electric power can be used to drive high-exhaust-velocity plasma or ion thrusters, or fusion plasmas can be directly exhausted. – Allows fast trip times or large payload fractions for long-range missions. Uses relatively small amounts of propellant, reducing total mass. Uses relatively small amounts of propellant, reducing total mass. Fusion rocket (   specific power ) 2 JFS 1999 University of Wisconsin

4. 3 JFS 1999 University of Wisconsin Plasma Thrusters Give High Exhaust Velocity Electrostatic thruster Electrodynamic thruster From University of Stuttgart’s web page: www.irs.uni-stuttgart.de/RESEARCH/ EL_PROP/e_el_prop.html EL_PROP/e_el_prop.html Electrothermal thruster From Robert Jahn, Physics of Electric Propulsion (1968)

5. D- 3 He Fusion Would Outperform D-T Fusion for Space Applications High charged-particle fraction allows efficient direct conversion to thrust or electricity. High charged-particle fraction allows efficient direct conversion to thrust or electricity. – Increases useful power. – Reduces heat-rejection (radiator) mass. – Allows flexible thrust and specific-impulse tailoring. Low neutron fraction reduces radiation shielding. Low neutron fraction reduces radiation shielding. D-3He eliminates need for a tritium-breeding blanket. D-3He eliminates need for a tritium-breeding blanket. 4 JFS 1999 University of Wisconsin

6. Field-Reversed Configurations Appear Attractive for Fusion Space Propulsion From Univ. of Washington web page for the Star Thrust Experiment (STX): www.aa.washington.edu/AERP/RPPL/STX.html JFS 1999