Thermal Management for Space Based High Energy Lasers

In the proposed SBIR effort RTI will investigate an innovative cooling approach to dissipate the high heat fluxes generated by diode-pumped solid-state laser (SSL) systems. SSL systems require efficient heat transfer techniques that are capable of managing high heat fluxes and high transient loads (laser "on" vs laser "off"). Existing water-based micro-channel cooling technology is not suited for deployment of high-power SSL's in space due to high system weight. Existing space-qualified heat pipe cooling technologies are not capable of handling the heat fluxes of 100-350W/cm2 generated by the laser diodes. RTI's cooling approach dissipates the high heat flux with Evaporative Spray Cooling (ESC) technology and transports the heat via a pump loop to a thermal energy storage (TES) unit featuring enhanced phase change material encapsulated in a porous graphite matrix. TES is the key technology that enables a laser operating heat load an order of magnitude greater than the ultimate heat rejection rate to space. RTI will perform sub-scale demonstrations to determine feasibility, and provide a conceptual design for a 1kWo SSL system with traceability to a 100kWo system. If shown to be feasible, the proposed cooling techniques can provide high heat flux thermal management to space based solid-state lasers with acceptable weight impacts to the spacecraft.