Relativistic Electron Beam Rocket. Companion to the fusor proposed by R.W. Bussard. Uses megavolt-class relativistic electron beams to blast a suitable propellant to plasma, which is then directed through a nozzle. It works well with a fusor burning a boron-11/proton fuel mixture. A fusor burning this mix can convert the reaction energy directly to DC current at 1.5 megavolts, perfect for the electrical input of an REB rocket. The really cool thing is that this combination could be used to build a rocket that was Single Stage to Anywhere, i.e. you could go straight from the surface of Earth to the surface of the Moon or even Mars.