8-8. A High Specific Power Aneutronic Space Reactor J. NORWOOD, Jr., J. NERING, B. C. MAGLICH & C. POWELL Summary A nuclear reactor may be defined as aneutronic if less than 1% of its energy is carried by neutrons. Aneutronic reactors are most likely to be fueled with nonradioactive D + 3He. Such a reactor would produce very little radioactive waste, with most of the energy released carried by charged particles. The reactions utilizing these fuels have ignition temperatures 10-100 times higher than that of the D+T neutronic reaction pursued by the mainline fusion effort. A practical means of utilizing the aneutronic fuels came about in 1982 with the laboratory demonstration of the colliding beam fusion device known as the self-collider (Migma IV). In it the average fuel density exceeded the maximum density attainable in accelerators (the space charge limit) by a factor of 10; 3 X 10'° cm~3 of 700 keV deuterons were stored and collided for 20 seconds. (US Patent #4,788,024 (1988)). For aerospace application, an aneutronic reactor has the following attractive features: (1) due to lack of radiation, the reactor is compact and requires little shielding; (2) energy release in the form of charged particles allows the possibility of efficient direct conversion, which for low output reactors promotes high specific power. In an Air-Force sponsored joint study with Bechtel, we established a point design of a 2 MWe continuously operating space power system with specific power 20 kWe/Mg. Subsequently, a breakthrough was achieved in the magnet configuration that allows vastly increased power output without concomitant increase in system mass. On the basis of this new configuration (Exyder) we may now be able to project a space power system with a specific power approaching 1 MWe/Mg in continuous operation. 1. Introduction Space power reactors, assuming that they are well conceived, can be judged largely on the basis of their specific power: MWe/Mg. This is especially true for electric propulsion. Plasma thrusters typically have exhaust velocities of ten to a few hundred kilometers per second. For burn times limited by political realities to 100-1000 days, the specific power required for optimal operation [1] ranges from 10~3 to 10 MW/Mg, taking into account the rocket plus payload as well as the reactor. If the space power system is to be a reasonably small fraction of the rocket mass (less fuel), then clearly we must contemplate space power reactor specific masses on the order of 1 MW/Mg. It is the lack of availability of such systems that has precluded the deployment of plasma thrusters for other than attitude adjustment. The authors are with Advanced Physics Corp., 14 Washington Rd., Bldg. 6, Princeton Jet., NJ 08550, USA. Paper number IAF-ICOSP89-8-8.
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