A laser-ignition micro solid rocket for application as propulsion on a 1-10 kg-class microspacecraft was proposed and designed. The laser-ignition micro solid rocket uses boron/potassium nitrate as propellant, and a number of solid propellant blocks are ignited by irradiating their surface with a 1 W diode laser through a laser-incident window. According to previous experiments, contamination of the laser-incident window can cause ignition failure to as high as 39% (7 thrusters out of 18) as a result of the gas generated at the initial phase of the laser irradiation. To reduce this contamination, the distance between propellant and laser-incident window is the parameter of interest in this study. The ignition probability was measured using a newly designed propellant stand with variable distance between propellant and laser-incident window, and an optimized window-to-propellant distance was applied to the thrusters. As a result, the ignition probability reached 100% (26 thrusters out of 26) while maintaining the specific impulse.
2014 The Japan Society for Aeronautical and Space Sciences