Nuclear fusion could power a rocket to take humans to Mars
same energy content as one gallon of rocket fuel.
To power a rocket, the team has devised a system in which a powerful magnetic field causes large metal rings to implode around this plasma, compressing it to a fusion state. The converging rings merge to form a shell that ignites the fusion, but only for a few microseconds. Even though the compression time is very short, enough energy is released from the fusion reactions to quickly heat and ionize the shell. This super-heated, ionized metal is ejected out of the rocket nozzle at a high velocity. This process is repeated every minute or so, propelling the spacecraft.
In this YouTube video simulation, the plasma (purple) is injected while lithium metal rings (green) rapidly collapse around the plasma, creating fusion.
The UW-MSNW team has successfully demonstrated the metal-crushing process in the UW Plasma Dynamics Laboratory in Redmond.
The video, taken from a 3-D computer simulation, shows three lithium rings as they collapse around plasma material.
The team had a sample of the collapsed, fist-sized aluminum ring resulting from one of those tests on hand for people to see and touch at the recent NASA symposium.
“I think everybody was pleased to see confirmation of the principal mechanism that we’re using to compress the plasma,” Slough said. “We hope we can interest the world with the fact that fusion isn’t always 40 years away and doesn’t always cost $2 billion.”
The release notes that now, the team is working to bring it all together by using the technology to compress the plasma and create nuclear fusion. Slough hopes to have everything ready for a first test at the end of the summer.
The Plasma Dynamics Lab — where Slough and colleagues, including UW graduate students, build and conduct experiments — is filled wall-to-wall with blue capacitors that hold energy, each functioning like a high-voltage battery. The capacitors are hooked up to a giant magnet that houses the chamber where the fusion reaction will take place. With the flip of a switch, the capacitors are simultaneously triggered to deliver 1 million amps of electricity for a fraction of a second to the magnet, which quickly compresses the metal ring.
The mechanical process and equipment used are reasonably straightforward, which Slough said supports their design working in space.
“Anything you put in space has to function in a fairly simple manner,” he said. “You can extrapolate this technology to something usable in space.”
In actual space travel, scientists would use lithium metal as the crushing rings to power the rocket. Lithium is very reactive, and for lab-testing purposes, aluminum works just as well, Slough said.
Nuclear fusion may draw concern because of its application in nuclear bombs, but its use in this scenario is very different, Slough said. The fusion energy for powering a rocket would be reduced by a factor of one billion from a hydrogen bomb, too little to create a significant explosion. Also, Slough’s concept uses a strong magnetic field to contain the fusion fuel and guide it safely away from the spacecraft and any passengers within.
