Heat Storage and Temperature Amplification for Space-Based Laser Diode Cooling

Solid-state lasers are attractive for space-based and airborne applications such as target illumination and weapons, but heat must be removed for continuous operation. Laser cooling involves three problems: (1) heat removal from the laser diode, (2) heattransport for rejection, and (3) heat rejection to space. High-power lasers require heat removal capability equal to maximum reject power, although this capability is underutilized for most of the mission. High peak-to-average heat rejection ratiossuggest the use of thermal storage and raising of rejection temperature to minimize system mass.Pumped liquid loops work well for removal of heat from the diode package and do not rely on gravity. The immediate problem for nonterrestrial lasers is heat transport and rejection. The proposed development is focused on these two aspects. The systemwill utilize absorption and desorption of ammonia from a coordinative complex compound to remove heat from the laser cooling fluid and raise heat rejection temperature > 100¿F to reduce radiator area.Savings in radiator mass will be ~70 pounds per kW rejected, with added hardware for the heat transport system of ~27 pounds/kW for net savings of 40 pounds/kW. The enhanced system weight will be less than 80% of the baseline. The primary market for theproposed development is the U.S. military. Modified versions of the proposed system can meet industrial and commercial applications for thermal energy storage. Many industrial processes have short-duration peak heat loads, and operating and capital costscan be reduced by load leveling.