High Temperature Lightweight Heat Pipes for Solid-State Power Amplifier (SSPA) Thermal Management

Current Gallium Nitride (GaN)-based solid state power amplifiers (SSPAs) are limited in their operational capabilities due to the limitations of the overall thermal management system in dissipating the high heat fluxes. However, GaN based SSPAs are desirable for satellite communication due to their superior linearity, built-in redundancy, reliability, power density and energy efficiency as compared to current technologies such as traveling wave tube amplifiers (TWTAs). In order to enable higher power GaN amplifiers and next generation phased arrays, it is critical to reduce the heat flux on the thermal management system by spreading the heat efficiently across a larger area, as well as develop heat pipes that can operate at higher temperatures than copper/water and aluminum/ammonia pipes. This paper presents a novel, low-cost and low-mass thermal management system (TMS) which is capable of handling power densities and temperatures of next generation GaN power amplifiers and phased arrays on satellites. The design is based on titanium-water heat pipes with several novel features designed to ensure cooling of GaN devices during start-up or operation in space (vacuum and zero gravity) as well as earth environments. Two prototype 3D printed titanium/water heat pipes were designed, fabricated, and tested. The heat pipes transmitted the required power, and survived multiple freeze/thaw cycles.