Fission Thrust sail as booster for high {\Delta}v fusion based   propulsion
  The fission thrust sail as booster for nuclear fusion-based rocket propulsion for future starships is studied. Some required aspects of these systems such as neutron moderation and sail regeneration are discussed. First order calculations are used together with Monte Carlo simulations to assess system performance. When the fusion rocket has relatively low efficiency (~30%) in converting fusion fuel to a directed exhaust, adding a fission sail is shown to be beneficial for obtainable delta-v. Also, this type of fission-fusion hybrid interstellar propulsion has the potential to improve acceleration. Other advantages are discussed as well. 
Frederik Ceyssens, Kristof Wouters, Maarten Driesen
physics.ins-det astro-ph.IM