Fission-fragment rocket

By physically arranging the fuel into very thin layers or particles, the fragments of a nuclear reaction can escape from the surface.

The axial magnetic field is too weak to affect the motions of the dust particles but strong enough to channel the fragments into a beam which can be decelerated for power, allowed to be emitted for thrust, or a combination of the two.

Fission-fragment rocket using 242mAm was proposed by George Chapline[7] at Lawrence Livermore National Laboratory in 1988, who suggested propulsion based on the direct heating of a propellant gas by fission fragments generated by a fissile material.

Ronen et al.[8] demonstrate that 242mAm can maintain sustained nuclear fission as an extremely thin metallic film, less than a micrometer thick.

Ronen's group at Ben-Gurion University of the Negev further showed that nuclear fuel based on 242mAm could speed space vehicles from Earth to Mars in as little as two weeks.

Another report claims that 242mAm can sustain a chain reaction even as a thin film, and could be used for a novel type of nuclear rocket.

[16] In 2000, Carlo Rubbia at CERN further extended the work by Ronen[6] and Chapline[7] on fission-fragment rocket using 242mAm as a fuel.

[20] Preliminary results were very satisfactory and it has been observed that a propulsion system with these characteristics could make the mission feasible.

The aerogel matrix (and a strong magnetic field) would allow fission fragments to escape the core, while increasing conductive and radiative heat loss from the individual fuel particles.