New Concept of Laser-Augmented Chemical Propulsion

Abstract

The applications of laser propulsions to explore space have been discussed for long time. The laser ablation or laser plasma propulsions by high-power laser are discussed in terms of launching, orbit keeping, and attitude controlling for microsatellites and vehicles. The advantage of laser ablation propulsion is higher specific impulse than other conventional propulsions, but a lightweight and high-power laser is required. A new concept of laser-augmented chemical propulsion (LACP) is proposed to control variable thrust and to turn on/off thrust easily by a low-power laser. The principle of laser-augmented chemical propulsion is based on the solid propellant combustion under thermal radiation, in which the burning rate of solid propellant depends linearly on the radiation strength of a continuous wave (CW) laser. Some photosensitive and lower energetic propellants are used for the laser-augmented chemical thrusts, such as ammonium nitrate (AN), guanidine nitrate (GN), carbamide, and 5-aminotetrazole (5-ATZ), in which the propellants can burn under laser radiation, but flame off when turning off laser radiation. The propulsion energy comes from chemical reaction heat and laser energy. The feasibility and ballistics of laser-augmented chemical propulsion are discussed in experimental and theoretical analysis in the paper. The specific impulse and the thrust depend on the irradiation strength. The specific impulse equation ${\mathrm{I}}_{\mathrm{s}}\propto 1/\sqrt{{\uprho \mathrm{b}\mathrm{A}}_{\mathrm{r}}\mathrm{q}}$ shows that the specific impulse will decrease with increase of radiant flux (q) and radiation sensitivity coefficient (b), but the thrust ${\mathrm{F}}_{\mathrm{cp}}\propto \sqrt{{\uprho \mathrm{b}\mathrm{A}}_{\mathrm{r}}\mathrm{q}}$ will increase with the increase of radiant flux and radiation sensitivity coefficient.