The pulsed fission fusion propulsion (PuFF) system envisions using a pulsed z-pinch to compress a fission-fusion target. The resulting deflagration expands against a magnetic nozzle to produce thrust and generate recharge energy for the next pulse. A z-Pinch is a device that is commonly used to compress laboratory plasmas to high pressures (~1 Mbar) for very short timescales (~100 ns). An electrical discharge produces a high axial current along the outer surface of a column of plasma; this current in turn generates a very strong toroidal magnetic field. This self-generated magnetic field interacts with the axial current via the Lorentz force and radially compresses the plasma column, bringing it to very high densities and temperatures. This team is exploring a modified Z-pinch geometry as a propulsion system by encasing the fission- fusion target in a sheath of liquid lithium, providing a current return path. Numerical results have been promising, the level of compression is sufficient to reach fission criticality. The fission energy boosts the fusion reaction rate, generating more neutrons which boost the fission process. This concept will potentially reach specific impulses of 30,000 sec with thrust levels sufficient to travel to Mars in a month and to interstellar space in a few decades.
Above – Graphic depiction of Pulsed Fission-Fusion (PuFF) Propulsion Concept. Credits: R. Adams