Antimatter Induced Fission for Nuclear Rocket Propulsion

Abstract

A propulsion device in which antiprotons induced fission can be used to heat a suitable propellant to very high temperatures is presented. It is based on recent research which demonstrated that "at rest" annihilation of antiprotons in Uranium-238 nuclei induces fission at nearly 100% efficiency. The proposed device consists of an antiproton trap connected to a magnetic confinement system of the mirror configuration which will contain the pre-ionized propellant while being heated by the fission fragments and the annihilation products, namely the pions and muons. When an antiproton annihilates on a U 238 nucleus, fission fragments with a total mass of 212 amu and total energy of 160 MeV are ejected nearly isotropically and interact almost instantly with the electrons of the propellant plasma transferring energy to them. The electrons subsequently transfer energy to the ions, and this energy exchange time dictates the plasma confinement time in the mirror. We use a U 238 propellant since it is effectively hazardless, and can provide sizable thrust because of its massive nucleus. When heated to one keV temperature by the fission fragments and the annihilation products, it is shown that such a system is capable of producing about 3000 seconds of specific impulse at a thrust of about 48 kilo-Newtons. When applied to a round trip mission to Mars, it is shown that it can be accomplished in about 127 days consisting of 2.2 days of thrusting and the rest in coasting. It is also shown the trip would require one gram of antiprotons.