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Boeing has patented a laser powered propulsion system for airplanes. A number of sites reported on the patent, with eye-rubbing headlines that told the story. BusinessInsider headline read, "Boeing just patented a jet engine powered by lasers and nuclear explosions." Benjamin Zhang said the US Patent and Trademark Office approved Boeing's application for a laser and nuclear-driven airplane engine.
Zhang noted that presently the Boeing Dreamliner is powered by multiple turbofan engines with their fans and turbines in place to compress air and ignite fuel to provide thrust. The engine presented in Boeing's patent application takes another route. Zhang said the laser engine may also be used to power rockets, missiles, and spacecraft.
The new engine would work "by firing high-power lasers at radioactive material, such as deuterium and tritium," said BusinessInsider. "The lasers vaporize the radioactive material and cause a fusion reaction—in effect a small thermonuclear explosion," said the article. "Hydrogen or helium are the exhaust byproducts, which exit the back of the engine under high pressure. Thrust is produced."
In this approach the inside wall of the engine's thruster chamber coated in uranium 238 reacts with the neutrons from the nuclear reaction and generates immense heat. "The engine harnesses the heat by running coolant along the other side of the uranium-coated combustion chamber," said Zhang. "This heat-energized coolant is sent through a turbine and generator that produces electricity to power the engine's lasers."
Three inventors named in the patent application are Robert Budica, James Herzberg and Frank Chandler of California. The applicant is listed as The Boeing Company in Chicago. The patent was filed in 2012.
Original Submission
(Score: 2) by Immerman on Monday July 13 2015, @09:55PM
I would think it would tend to be a self-correcting problem: Space is full of ionized particles, especially around planets with magnetic fields to capture them. Your positively ionized graphene "sponge" would tend to "soak up" ambient electrons from those ion clouds until it reached equilibrium.
Of course that would likely mean that your thruster might only be really useful for minor course adjustments near planets, but the solar wind is blowing past at several hundred km/s, so there's probably always a decent influx of new electrons to capture, so long as you don't spend them too quickly.