Experimental Study of Air Breathing Ion Engine Using Laser Detonation Beam Source

The basic properties of an air breathing ion engine, which uses upper atmospheric gases as a propellant, were experimentally investigated. The environment in a sub-low Earth orbit (altitude of 140–200 km) was simulated by a laser detonation beam source, which has been previously used in studies on atomic oxygen-induced material degradation. The basic properties of the air breathing ion engine were studied using a hyperthermal beam. It is suggested that the hyperthermal molecules thermalized by scattering at the reflector surface in the air breathing ion engine. The efficiency of the collimator was experimentally investigated and the collimator was found to maintain the pressure inside the air breathing ion engine. An ion beam current of 16 mA at an acceleration voltage of 200 V provided a thrust of 0.13 mN for both hyperthermal and atomic oxygen beams. The maximum ion beam current was found to be limited by the space-charge effect. The experimental results strongly indicated the recombination of atomic oxygen into molecules inside the air breathing ion engine.