Single port electro-thermal propulsion - Design factors

This paper discusses a nozzle geometric design allowing unobstructed beam passage while maintaining high area ratio for both chamber flow and exit flow. This design has efficient energy conversion using volume absorption providing high specific impulse and thrust. Extension of operating frequency to existing gyrotron range is possible and allows device test in the near future. Chamber pressure must be below one atmosphere at these frequencies to limit beam intensity and avoid breakdown. For this reason, device operation below 25 kilometers is not possible. However, with launch assist, use of earth-based beam source may be feasible. the nozzle design permits IR and optical waveband entrance so that plasma and internal surface heating can also be considered as combustion options. Lunar-based source options are considered using lunar refuel to lower cost of return-to-earth and moon-to-Mars missions.