For years, scientists have dreamed of the idea of a nuclear propulsion system for rockets that would be much faster than solid propellants, because it could dramatically reduce travel time to the Moon and even to Mars. But safety and radiation hazards have prevented this idea from being applied to a rocket. Up to now.
A physicist at the US Department of Energy’s Princeton Plasma Physics Laboratory (PPPL), Fatima Ebrahimi, has designed a new rocket that uses magnetic fields to shoot plasma particles (electrically charged gas) into the vacuum of space. and propel the ship through the cosmos. With it we could one day take humans to Mars (and further afield).
Using magnetic fields allows scientists to adjust the amount of thrust needed for a particular mission, and astronauts could change the amount of thrust as they navigate to distant worlds. This new type of fusion energy rocket would get us 10 times faster to Mars compared to current rocket boosters that use electric fields to propel the particles. For while today’s space-tested plasma propulsion engines use electric fields to propel the particles, the new rocket design would accelerate them through magnetic reconnection.
Practical nuclear fusion
Fusion is the power that drives the Sun and the stars, and combines elements of light in the form of plasma. Plasma is the hot and charged state of matter made up of free electrons and atomic nuclei that represents 99% of the visible universe and is capable of generating massive amounts of energy . Take as an example what happens on the surface of the Sun: when the magnetic field lines converge, before separating and then reconnecting, they produce an enormous amount of energy.
“I’ve been cooking up this concept for quite some time. I had the idea in 2017 while sitting on a deck and thinking about the similarities between car exhaust and high-velocity exhaust particles created by the National Spherical Torus Experiment (NSTX). During its operation, this tokamak produces magnetic bubbles called plasmoids that move at about 20 kilometers per second, which seemed very similar to an impulse “, comments Ebrahimi, whose study has been published in the Journal of Plasma Physics. .
Today’s plasma thrusters that use electric fields to propel the particles produce very low momentum or velocity. But computer simulations conducted at PPPL and the National Center for Scientific Computing for Energy Research showed that the new plasma propellant concept can generate exhaust gases with speeds of hundreds of kilometers per second, 10 times faster than those of other thrusters.
“Long-distance trips take months or years of duration because the specific impulse of chemical rocket engines is very low, so it takes time for the spacecraft to catch up,” explains the researcher. “But if we make thrusters based on magnetic reconnection, then we could possibly complete long-distance missions in a shorter period of time.”
The three keys to the new rocket
- Changing the strength of the magnetic fields can increase or decrease the amount of momentum / speed.
- The new thruster produces motion by expelling both plasma and plasmoid particles, adding power to the propulsion.
- Magnetic fields allow plasma to be either heavy or light atoms.
This means that if implemented, astronauts could reach the outer planets much more quickly. The thrusters would significantly boost the start of the trip and ultimately reduce the entire trip time.
“The next step is to build a prototype,” concludes the expert.
Referencia: Fatima Ebrahimi, An Alfvenic reconnecting plasmoid thruster, Journal of Plasma Physics (2020). DOI: 10.1017/S0022377820001476
