State of the art Orbital Transfer Vehicle systems require the demanding combined requirements of both high Thrust-to-Power (greater than 120 mN/kW) and high specific impulse (greater than 3000 s), all at constant power. The 25 kW PROTEAN system is a two-stage plasmoid thruster which adds an secondary auxiliary Neutral Entrainment (NE) stage to the ElectroMagnetic Plasmoid Thruster (EMPT) to dramatically increases the total Thrust-to-Power. The NE stage injects neutral propellant into the preformed plasmoids path. Through resonant charge exchange collisions mass is added to the plasmoid at no additional ionization cost. Kinetic energy is then efficiently added to the engorged plasmoid through Peristaltic Dynamic Acceleration, in which sequenced theta-pinch coils provide a large magnetic pressure gradient. In total, this system allows for very efficient acceleration of light as well as heavy plasmoids, all without significant further ionization or plasma frozen flow losses. By simply varying the auxiliary propellant input flow rate, thrust and specific impulse can be dynamically varied at constant input power and without affecting the initial plasma formation. PROTEAN is therefore a thruster system with an unprecedented frozen flow loss of less than 5 eV/ion providing mission designers an almost infinitely variable Isp and thrust range.
Benefit: The PROTEAN thruster system is able to provide greater than 160 mN/kW and operate from 800-5000 s of specific impulse. In addition, this system is extremely lightweight, with a specific power of greater than 1 kW/kg, and designed to operate at constant power across an infinitely variable range of specific impulse conditions. At peak performance this thruster has the ability to operate with lower than 5 eV/ion, dramatically less than any Electric Propulsion system in existence. These combined abilities yield a thruster system that has numerous mission benefits, and thus, commercial benefits. The 25 kW PROTEAN system operating on Xenon would enable any number Orbital Transfer Vehicle mission architectures. A PROTEAN operating on lightweight or chemically reactive gases would allow for a true, fully dynamic, high thrust-to-power multi-mode system. For non-DOD missions, PROTEAN provides the unique ability to efficiently use In-Situ Resources at tremendous benefits to interplanetary missions.
Keywords: FRC, Thrust-to-Power, Electric Propulsion, Electromagnetic, Neutral Entrainment, PROTEAN, ELF
