John. Slough of the Plasma Dynamics Lab at the University of Washington has been developing Pulsed High Density Fusion systems for many years. He has also been working on adapting the technique for space propulsion and has won a couple of grants from the NASA Innovative Advanced Concepts (NIAC) program. The Fusion Driven Rocket: Nuclear Propulsion through Direct Conversion of Fusion Energy – NASA
The Fusion Driven rocket (FDR) represents a revolutionary approach to fusion propulsion where the power source releases its energy directly into the propellant, not requiring conversion to electricity. It employs a solid lithium propellant that requires no significant tankage mass. The propellant is rapidly heated and accelerated to high exhaust velocity (> 30 km/s), while having no significant physical interaction with the spacecraft thereby avoiding damage to the rocket and limiting both the thermal heat load and radiator mass. In addition, it is believed that the FDR can be realized with little extrapolation from currently existing technology, at high specific power (~ 1 kW/kg), at a reasonable mass scale (<100 mt), and therefore cost.
If realized, it would not only enable manned interplanetary space travel, it would allow it to become common place. The key to achieving all this stems from research at MSNW on the magnetically driven implosion of metal foils onto a magnetized plasma target to obtain fusion conditions. A logical extension of this work leads to a method that utilizes these metal shells (or liners) to not only achieve fusion conditions, but to serve as the propellant as well. Several low-mass, magnetically-driven metal liners are inductively driven to converge radially and axially and form a thick blanket surrounding the target plasmoid and compress the plasmoid to fusion conditions.
Virtually all of the radiant, neutron and particle energy from the plasma is absorbed by the encapsulating, metal blanket thereby isolating the spacecraft from the fusion process and eliminating the need for large radiator mass. This energy, in addition to the intense Ohmic heating at peak magnetic field compression, is adequate to vaporize and ionize the metal blanket. The expansion of this hot, ionized metal propellant through a magnetically insulated nozzle produces high thrust at the optimal Isp. The energy from the fusion process, is thus utilized at very high efficiency.
His team has made progress on individual components of the system and this summer they will test the entire system:
- Rocket powered by nuclear fusion could send humans to Mars – University of Washington Today
- Full nuclear fusion tests this summer which would enable propulsion for 30 day trips to Mars – NextBigFuture.com
Here is a slide from the presentation: Nuclear Propulsion through Direct Conversion of Fusion Energy: The Fusion Driven Rocket, John Slough et al, NIAC Spring 2012 Symposium – Mar.2012 (pdf)
Update April.6.13: Alan Boyle has some additional background about the project: Scientists develop fusion rocket technology in lab – and aim for Mars – Cosmic Log.
See also Slough’s company MSNW LLC.
