re: Bussard Ramjet is the stuff of dreams
I agree, but any compact source of large amounts of energy could have a variety of propulsion applications, from an electric ion drive to a fusion-powered NERVA-type rocket (fusion instead of fission heats up liquid hydrogen or some other fluid). Perhaps even some form of direct use of the exhaust of the fusion power plant as a propellant could be employed, yielding extremely high specific impulse. None of these would qualify as the classic Bussard Ramjet, because the working fluid would be carried aboard the vehicle and not harvested from space. It all depends on the power/mass ratio of the propulsion system that could be achieved by the Bussard system (if it actually can be demonstrated to work).