An atomic hydrogen propulsion system

Abstract

P ERFORMANCE characteristics of a space propulsion system utilizing atomic hydrogen as a propellant are calculated. This thruster could be utilized for missions which require reliable long life operation, such as attitude correction, stationkeeping, and orbit change. A schematic diagram of the atomic hydrogen space propulsion thruster is shown in Fig. 1. An important feature of the engine is that atomic H is used as soon as it is produced by the discharge, thus eliminating the difficult problem of storage.' A mathematical model which describes the reaction chamber is presented; however, details of the microwave discharge, connecting regions, and other parts of the propulsion system are not discussed. The H2 is assumed to be completely dissociated by the microwave discharge with no impurities. The mathematical model is formulated in terms of a derived set of coupled nonlinear, first-order, differential equations governing the rate of formation and collisional dissociation of H2 and various energy loss mechanisms. These, in addition to the rate equation governing the density of atomic hydrogen in the chamber, are solved using iterative procedures. Based upon a specified flow rate of atomic hydrogen into the reaction chamber, values are given for the thrust, specific impulse, reaction chamber pressure and gas temperature, and the densities of H and H2 inside the reaction chamber for a spherical reaction chamber geometry.