Here's a better view of the same thing: https://www.google.com/patents/US7808353 https://www.google.com/patents/US7808353 Note that this coil essentially is th

Here's a better view of the same thing: https://www.google.com/patents/US7808353 https://www.google.com/patents/US7808353 Note that this coil essentially is the thruster. You put gas (from a compressed tank) in one end and it fires out the back, creating thrust from electricity + the gas. It's not quite a massless thruster, but very close! This represents a major improvement over the ion propulsion on Deep Space 1.