Sandia Labs FY21 LDRD Annual Report

FY21 ANNUAL REPORT

Bridging modern power concepts into weapons systems. To enhance the nation’s ability to iterate and optimize systems used in select space and defense applications, this LDRD team investigated the use of optimization tools in the design of power conversion and distribution architectures. Researchers studied the deployment of power conversion components and circuits for specific use cases, subject to constraints on volume, weight, and extreme environment specifications. By computing the benefits of select power architectures, and evaluating these in trade- spaces, these approaches will help teams identify the best design for a given application or set of applications and quantify the performance limits based on existing or forthcoming technologies.

Optimizations can also be applied across several mission scenarios to identify power architectures that offer the best mission agility. This optimization work utilized and extended the capabilities of the Sandia- developed Whole System Trades Analysis Tool. Beginning in FY22, this tool with extended capabilities will be adapted for use in designing power distribution systems for a high-consequence military application. (PI: Jason Neely) The Pareto Optimal Front includes the set of non-dominated designs in a design space; the Performance Metrics for Power Architectures may include Size, Electrical Performance, Cost, Environmental Resilience, and Upgradeability.

Digital logic gates for extreme environment applications. Ultra-wide bandgap (UWBG) aluminum-rich gallium nitride (AlGaN) transistors and high electron mobility transistor (HEMT) logic gates may be candidates for use in extreme environments, particularly ones with high temperatures (up to 500°C) and radiation. Because of the UWBG of AlGaN, these semiconductors offer potential immunity to environmentally harsh conditions where conventional semiconductors cannot operate, including automotive, aerospace, military, petroleum, and geothermal well applications. The key results were a demonstration of AlGaN inverters operating from room temperature to approximately 500°C and GaN SRAM operating from room temperature to 300°C. Academic partner, Georgia Tech, developed a Finite Element Method (FEM) model which compared different thermal management solutions specific to AlGaN HEMTs, and those findings are already contributing to new designs for other AlGaN projects at Sandia. For applications where environmental shielding is unavailable, ultra-wide bandgap AlGaN’s superior electrical performance at elevated temperatures and high intrinsic material radiation tolerance can be exploited to insert digital logic directly into extreme environments. This project’s work has laid a foundation to support more advanced high-temperature circuitry maturation in the future. (PI: Brianna Klein)

(A) AlGaN high electron mobility transistor, (B) inverter with combined enhancement- and depletion-mode transistors, and (C) inverter electrical performance over temperature with devices tested from 25°C to 491°C.

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LABORATORY DIRECTED RESEARCH & DEVELOPMENT

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