Fusion could power space travel in the future

Science fiction is full of futuristic sources of power, such as dilithium crystals, which help the crew of Star Trek’s USS Enterprise explore the depths of space at warp speed.

Unfortunately for Star Trek fans and anyone with an interest in space exploration, dilithium is a fictional substance, and warp speed space ships are still a dream. However, in the real world, we are seeing incredible experiments to increase the efficiency of rockets.

We may be a while away from charging boldly into the unknown, but we’re close to seeing rockets which could be powered by the propulsion of particles by using magnetic fields, according to American physicist Dr Fatima Ebrahimi. The technique could borrow from the way the Sun expels particles through solar flares, and create rockets with a much higher amount of thrust.

The thrust of the argument

Dr Ebrahimi has been working hard at the US Department of Energy, to create a new way of propelling rockets. Unveiling a design in the Journal of Plasma Physics, Dr Ebrahimi revealed that it could be possible to take plasma particles, apply the forces of a magnetic field to them, causing them to propel outwards. The process is termed as magnetic reconnection, and is found in nature, as something which occurs on the Sun’s surface.

I had the idea in 2017 while sitting on a deck and thinking about the similarities between a car’s exhaust and the high-velocity exhaust particles created by PPPL’s National Spherical Torus Experiment (NSTX)

– Dr. Fatima Ebrahimi, Principal Research Physicist, Princeton Plasma Physics Laboratory (PPPL)

Magnetic reconnection involves the breaking up and reconnection of opposing magnetic field lines within a highly conductive plasma, producing a high quantity of kinetic and thermal energy.

Dr Ebrahimi had observed how fusion reactors called tokamaks created plasma bubbles which could move at speeds of 20km per second, and reasoned that the fusion process could produce a source of great thrust, if modified.

When a simulation was fed into a computer, based on Dr Ebrahimi’s specifications, her new plasma thruster concept produced readings suggesting the process could produce thrusters with exhaust velocities 10 times faster than more conventional thruster designs.

In short – the process of travelling across vast distances could get a whole lot shorter.

Fusion as the future of rockets

It seems only right that scientists should look to nature to create a cleaner, more powerful source of energy, to design the rockets of the future. Fusion-powered rockets are still a theoretical concept than a workable reality at present. By switching to fusion in place of sources such as fission, rockets would need less shielding, but fusion reactions might only be possible, within a bulky reactor.

Long-distance travel takes months or years because the specific impulse of chemical rocket engines is very low, so the craft takes a while to get up to speed. But if we make thrusters based on magnetic reconnection, then we could conceivably complete long-distance missions in a shorter period of time.

– Dr. Fatima Ebrahimi, Principal Research Physicist, Princeton Plasma Physics Laboratory (PPPL)

While manned missions into space using fusion might be somewhat remote at present, the possibility of propelling smaller objects such as probes could be closer than you think. By 2028, a Direct Fusion Drive-powered vehicle the size of a minivan could be ready to launch. It could have the capabilities of transporting a space probe to Saturn in the space of just two years – compared to the 6.75-year journey NASA’s Cassini probe undertook.

The DFD method of propulsion would take helium and mix it with a form of hydrogen as a plasma, generating a large amount of heat, which will help warm up a cool propellant. The propellant would then be siphoned out through a nozzle in the engine, pushing the craft forwards.

Photo’s by Elle Starkman, PPPL Office of Communications, and ITER

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