Developing the Pulsed Fission-Fusion (PuFF) Engine

Abstract

In September 2013 the NASA Innovative Advanced Concept (NIAC) organization awarded a phase I contract to the PuFF team. Our phase 1 proposal researched a pulsed fission-fusion propulsion system that compressed a target of deuterium (D) and tritium (T) as a mixture in a column, surrounded concentrically by Uranium. The target is surrounded by liquid lithium. A high power current would flow down the liquid lithium and the resulting Lorentz force would compress the column by roughly a factor of 10. The compressed column would reach criticality and a combination of fission and fusion reactions would occur. Our Phase I results, summarized herein, review our estimates of engine and vehicle performance, our work to date to model the fission-fusion reaction, and our initial efforts in experimental analysis. NomenclatureA = Target Surface Area B = Magnetic Field pressure E = Electric Field f = fractional deposition of alpha particles h = smoothing length H = Magnetic Field J = current density k = thermal conductivity, Boltzmann's constant m = mass n = number density P = Pressure Q = fusion reaction energy Qi = thermal equilibrium term r = position Re = friction tensor 1 Aerospace Engineer, ER24/Advanced Propulsion and Technology, Associate Fellow. 2 t = time T = Temperature u = velocity V = Volume W = kernel Z = ion charge  = permittivity  = conductivity  = viscous stress tensor  = magnetic permeability  = density <> = velocity averaged fusion cross section

Preliminary Analysis of the Gradient Field Imploding Liner Fusion Propulsion Concept

“…The propulsion system is sized using an alpha of 17.6 kW/kg, which is the specific power used in the Magnetized Target Fusion (MTF) concept in [37]. This value is somewhat pessimistic, as the current system will be significantly less complex and presumably less massive than the referenced MTF system.…”

“…Because calculations of the actual performance were concurrently being developed during the study, the system was initially modeled parametrically with values based on the PUFF fusion system [37], specifically using Pj = 1 GW, α = 16 kW/kg, and varying Isp from 10,000 to 50,000 seconds. Using the equivalent length method described above, a calculation of initial mass and trip time could be performed for varying payloads, initial masses, and Isp.…”

Propulsion Research and Academic Programs at the University of Alabama in Huntsville - 2018

“…Fission/fusion hybrid 65 and pulsed fusion propulsion, 66 have been shown to significantly reduce the trip times for space travel. The specific approach being pursued at UAH PRC is called "z-pinch."…”