Development and performance evaluation of the laser ignition device for micro thruster systems

To meet the requirements for micro thruster system in microsatellites and solve the integration problems caused by large laser ignition devices, this study developed a miniature laser ignition device using a 2 × 2 VCSEL(vertical-cavity surface-emitting laser) chip array. The device incorporates dual-aspheric lenses system for beam shaping. The device’s spot characteristics and power output were systematically characterized. A three-dimensional ignition model that includes heat transfer, chemical reaction heat, and laser energy effects was established. This model simulates the heating process of the propellant under multi-spot laser irradiation and examines factors affecting ignition delay time. Ignition tests using B/KNO₃ propellant showed 100% reliable ignition at laser output powers between 3.55 and 6.23 W. As the laser power density increases, the propellant surface rapidly reaches its decomposition temperature. This increase in burning rate leads to shorter burn duration. The connection between burn rate and ignition delay time confirms the accuracy of the ignition model. The compact laser ignition device proposed in this paper enables reliable ignition of microsatellite thruster systems.