The Possibility of Micro-fission Chain-reactions and their Application to the Controlled Release of Thermonuclear Energy

Abstract

It had been shown 1, 2 recently that it may be possible to reach densities up to 103 g/cm3 by imploding a solid hydrogen pellet with the aid of a symmetric arrangement of multiple laser beams irradiating the pellet simultaneously from all sides. The purpose of this proposed scheme was to reduce the energy input requirements for the controlled release of thermonuclear energy delivered by laser ignited T - D micro-explosion systems. It is shown in this paper that by applying the foregoing concept of high density compression to a pellet consisting of fissionable material such as U235, Pu239, or U223, the critical mass for the initiation of a fission chain reaction in these materials can be reduced by many orders of magnitude raising the possibility of micro-fission-explosions with laser energy inputs for compression within the expected reach of laser technology. Alternatively, the pellet compression may be also achieved by the employment of intense relativistic electron beams. In addition, by surrounding the fis­sionable pellet with a layer of dense T - D material to be compressed together with the pellet, the minimum pellet size can be furthermore reduced by neutron reflection from the high neutron albedo T - D shell. For fissionable pellets without a reflector the critical mass can be as small as ∼ 0.3 g requiring a laser energy input for compression of several megajoule. For a pellet surrounded by a T - D reflector the critical mass can be reducel down to ∼10-3g with a laser energy input for compression of several 105 joule. In addition to the neutron albedo effect of the T - D shell there is a bootstrap mechanism where­by the T - D mantle achieves thermonuclear temperatures resulting in the emission of thermo­nuclear reaction neutrons into the fissionable pellet causing more fission reactions and thereby raising the temperature of the pellet. This then in turn will lead to an additional heating of the T - D blanket resulting in an increased flux of thermonuclear neutrons raising the fission rate even further. Because of the greatly increased material density, a fission chain reaction initiated in it will grow in proportion much faster than in uncompressed fissionable material as it is being used in conventional fission bombs. The system described may have important usefulness as a small fission power plant especially for space propulsion applications but also for a more effective burn in a thermonuclear micro-bomb reactor as a fission supported fusion reaction.