Antiproton-Driven Fusion Propulsion System for OTV Applications

Abstract

[Abstract] It has often been argued that fusion propulsion systems are strictly suitable for deep space missions such as those to the outer planets or interstellar space due to the large specific impulses they are capable of producing. It is intriguing however to find out how suitable they may be for near Earth missions such as orbit transfers from low Earth orbits (LEO) to geosynchronous orbits (GEO). We examine these cases using an antiprotondriven fusion system consisting of a Gasdynamic Mirror (GDM) magnetic confinement chamber connected to an antiproton “trap”. Taking LEO to be at an altitude of 200 km and GEO to be at approximately 36,000 km, we follow Cassenti’s analysis 1 of Hohmann transfers to establish the required ∆v for a basic mission of transferring a vehicle from LEO to GEO and back. It is found that ∆v = 5.5 km/sec. The vehicle in question is the DT burning fusion propulsion system noted above where plasma heating in the device is achieved by the fission fragments and annihilation products resulting from the “at rest” annihilation of antiprotons in U 238 targets. It is found that such a system will produce an Isp of 2×10 5 seconds and a thrust of 1.2×10 6 Newtons for a total mass of approximately 23×10 3 mT. Assuming a continuous burn acceleration/deceleration type of trajectory, we find that the orbital transfer noted above can be undertaken in about 8 hours, and the amount of antiprotons needed is about 4 µg. The propulsion system will have a specific power of about 40 and a thrust to weight ratio of about 5×10 -3 .