Gasdynamic fusion propulsion system for space exploration

Abstract

An open-ended fusion system in which a high-density plasma is confined and heated to thermonuclear temperatures is examined as a potential high specific power propulsion device that can be used for space exploration. With a collision mean free path much smaller than a characteristic dimension of the system, the plasma behaves much like a continuous medium (fluid) for which the confinement time is drastically different from that which characterizes a typical fusion power reactor. Noting that fact and using an appropriate set of balance equations we derive an expression for the length of the rocket in terms of the plasma parameters required for certain propulsive capabilities. We find that a moderately sized system can produce large values of specific impulse and thrust that would allow a massive rocket to make a round-trip to Mars in months instead of years. By carrying out a preliminary engineering design we also identify those technological areas that must be developed before such a system can become practical. Many of these technologies are surprisingly not out of reach today.