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Solid-State Power Amplifier Thermal Management


TECHNOLOGY AREA(S): Space Platforms

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 5.4.c.(8) of the solicitation and within the AF Component-specific instructions. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. Please direct questions to the AF SBIR/STTR Contracting Officer, Ms. Gail Nyikon,

OBJECTIVE: Develop low-cost, low-mass thermal management solutions to address the high heat flux and temperature of next generation GaN power amplifiers or phased arrays.

DESCRIPTION: Current thermal management of solid-state power amplifiers (SSPAs) in space is limited in its ability to spread power densities from the channels of active power amplifier devices to the large area thermal radiators required for ultimate rejection of heat to space. Current power densities at the bottom of the power amplifier device can exceed 62 W/cm2 and are expected to climb to values greater than 1400 W/cm2 in the next five to six years. At these extreme heat fluxes and temperatures, it is apparent that a new generation of thermal management is required to bridge the gap between future requirements and the capabilities of our current systems.

The introduction of GaN power amplifiers affects the thermal control system from source-to-sink, and innovative tech solutions at any point in the thermal control system will be considered. GaN technology provides a number of system level benefits (e.g., reduced volume/mass) if the thermal subsystem design can take advantage of the increased operating powers and temperatures.

Future GaN power amplifier devices will operate at temperatures in excess of 150 degrees C and will exceed power densities of 1400 W/cm2 (600W over 0.635 cm x 0.635 cm). Current spacecraft thermal management systems are not currently able to handle these extreme temperatures and power densities. Traditional heat transport devices are limited to approx. 6W/cm2 and temperatures below 80 degrees C. Proposed technology solutions should seek to minimize the resultant temperature drop such that the radiator operates at peak efficiency. Due to the biquadratic nature of radiation heat transfer an increase in radiator temperature directly equates to reduced radiator volume and mass.

Proposed tech solutions shall operate in a space environment (vacuum and no gravity), as well as on Earth in any orientation with respect to gravity for ground testability. The solution must operate over the temperature range of -20 to150 degrees C and must survive a temperature range of -60 to 150 degrees C. In addition, please be sure to address the thermal induced stress on the tech solution after thermal cycles in a specific application as this will vary depending on the mission. The solution shall be a passive design, no power required to meet performance requirements.

PHASE I: Develop conceptual designs of the hardware based on preliminary analysis. Demonstrate by analysis and/or test the feasibility of such concepts and that the approach can meet all of the performance requirements stated above in the Phase II development effort.

PHASE II: Demonstrate the technology developed in Phase I. Tasks shall include, but are not limited to, a demonstration of key technical parameters that can be accomplished and a detailed performance analysis of the technology. The culmination of the Phase II effort shall be at least one prototype delivery for validation testing. Teaming with a prime contractor is highly recommended, as it speeds tech transition.

PHASE III DUAL USE APPLICATIONS: Thermal control technologies developed for use aboard DoD satellites are equally applicable for use on commercial satellites, as well as any number of terrestrial electronics.


    • Gilmore, D. G., “Spacecraft Thermal Control Handbook Volume I: Fundamental Technologies,” 2nd Ed, The Aerospace Press, El Segundo, CA, 2002.


    • Wertz, J. R., and Larson, W. J. (eds.), “Space Mission Analysis and Design,” 3rd Ed, Microcosm, 1999.


  • Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITHERM) Proceedings,

KEYWORDS: thermal management, thermal control, GaN power amplifiers, heat spreader, high power, space platform

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