New spacecraft engine: nuclear slapshots?

[rhoenix]

Scientists at UAHuntsville have proposed a scheme that could see a spacecraft propelled through space by using a pulsed nuclear fusion system. To do so, a series of "nuclear slapshots" would apply magnetic pulses in order to slam nuclei into each other inside a hockey puck like structure made of a special lightweight salt. Should it work, this hot gas-propulsed "flying tea kettle" would get us to Mars in weeks rather than months.

Physicists at The University of Alabama in Huntsville's Department of Mechanical and Aerospace Engineering are developing the "Z-pinch" – a small, lightweight propulsion system. Jason Cassibry, an associate professor of engineering at UAHuntsville, and his team are attempting to drive a hollowed-out puck in on itself, fusing lithium and hydrogen atoms. In other words, nuclear fusion – the process where four hydrogen atoms combine to make one helium atom in which a small amount of matter is converted into pure energy.

The "pucks" themselves are about two inches wide and an inch thick, smaller than a regulation three-inch hockey puck. They are made of lithium deuteride, the lightest metal combined with the middleweight form of the lightest element. And like a sharpshooter in hockey, the idea is to dig the blade of the hockey stick into the ice to bend the shaft, storing energy for a quicker, more powerful snap against the puck.

But to get it to work, the researchers will need to get heavy hydrogen (one proton plus one neutron) to fuse with each other or with lithium – something that's easier said than done as getting nuclei to meet is a monumental task. To that end, the researchers will experiment with the Decade Module Two, or DM2, a pulsed power design used by the Department of Defense for weapons effects testing in the 1990s.

The DM2 is comprised of banks of capacitors that store an electrical charge for release on demand. It strips the target into an electrified gas or plasma. The Z-pinch effect happens when electricity flowing through it generates a magnetic field that compresses the plasma – what is equivalent to 20% of the world's power output in a tiny bolt of lightning no bigger than a finger. This is the power slapshot, a tremendous amount of energy in a tiny fraction of time, just a hundred billionths of a second.

The tests at DM2 will serve as proof of concept, which would allow researchers to progress to the next level of development. At the end of the day, the researchers are hoping to "break-even", producing more energy than is consumed – the magic that is fusion power.

The researchers clarify that this is not some kind of "warp drive" as portrayed in science fiction. It is a pulsed fusion engine not unlike any other rocket engine. Cold material goes in, it gets energized, and hot gas pushes out. Ideally, their spacecraft would see their pellets fired up to 10 times per second and produce up to 10,000 Newtons of thrust – about 2% of what a Space Shuttle main engine does. So when in space, the propulsion would feel like a soft nudge.

It's also worth noting that the system is only meant for space, and not launch purposes. The Z-pinch will run continuously for weeks at a time to quickly spiral a spacecraft out of Earth's orbit where it could set course for another planet. Once there, the engines would fire for another week or two to decelerate into orbit around the destination planet.

And interestingly, the system could be attached to an asteroid and run for months to gently nudge its trajectory away from Earth. He shoots, he scores!

So. A fusion-based engine. It's meant only for use in space, and has less power than the space shuttle's current engines - but, this is an impressive idea coming to fruition nonetheless.

[Josh]

Sweeeeeeeeeeeeeeeet. This is the kind of thing that, if pursued, could see a lot of improvements in the base design. Sure, the current version offers a fractional amount of thrust compared to conventional rocket, but the first steam engine wasn't exactly that impressive either.