Thruster Graphic
PPPL physicist Fatima Ebrahimi in front of an artist's conception of a fusion rocket. (Photo by Elle Starkman, PPPL Office of Communications, and ITER)

A new type of rocket thruster was developed at the DOE’s Princeton Plasma Physics Laboratory (PPPL) that could take humankind to Mars and beyond. It applies magnetic fields to cause particles of plasma – electrically charged gas also known as the fourth state of matter – to shoot out the back of a rocket and because of the conservation of momentum, propel the craft forward.

Current plasma thrusters that use electric fields to propel the particles can only produce low specific impulse, or speed. The new plasma thruster concept can generate exhaust with velocities of hundreds of kilometers per second – ten times faster than those of other thrusters. That faster velocity at the beginning of a spacecraft’s journey could bring the outer planets within reach of astronauts.

While other thrusters require heavy gas made of atoms like xenon, in this concept, any type of gas may be used. Scientists might prefer light gas in some cases because the smaller atoms can get moving more quickly.