Plasma and Engineering Parameters for a Fusion Powered Rocket

With the advent of hard superconductors, thermonuclear fusion reactors can be seriously considered as a continuous power source for high-powered interplanetary missions. Assuming a solution will be forthcoming to solve the plasma instability and confinement problems, a preliminary study is presented showing the relationship of pertinent plasma parameters. The set of equations describing these pertinent parameters indicates a typical 25 megawatt net power motor could be expected to operate at a plasma ion density of ~1014/cm3 and an average ion temperature of ~105 kev. The plasma would be confined by a magnetic field of approximately 50 kilogauss, with a total motor weight of approximately 25,000 lbs. The reacting plasma is assumed within a multipolar magnetic confinement geometry. The power lost to neutrons by most fusion reactors shows that 3He-D is the unique fusion reaction suitable for space propulsion. The relationship of plasma particle density, ion temperature, and confining magnetic field to total fusion power is presented. The significant plasma losses of bremsstrahlung and gyromagnetic radiation are discussed and equations describing their relationship to the plasma parameters are calculated. The consequences resulting from different values of ß (the ratio of plasma to magnetic confinement pressures) are investigated. All equations are derived with ß as a dependent variable. Necessary average plasma containment time is studied to indicate the magnitude of required average plasma confinement time. The rate of generation of both DD and DT neutrons is investigated over the range of interest.