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Commonwealth Fusion Systems is seeking a Senior R&D Test Engineer to design and develop novel fluid systems for research and development test stands, with a primary focus on supporting magnet testing for fusion energy applications. This role combines mechanical and chemical engineering fundamentals across a broad range of process fluids including liquid, gaseous, cryogenic, supercritical, and molten salt systems.
You will design fluid systems for test stands ranging from smaller-scale rapid prototypes to larger, complex projects supporting SPARC and ARC fusion reactor programs. Responsibilities include performing hand calculations and system-level analyses, building ANSYS structural and thermal simulations, procuring off-the-shelf and custom components, managing vendor relationships, and actively commissioning systems alongside test engineers and operators.
The ideal candidate brings 7+ years of experience with integrated fluid and mechanical systems, including full lifecycle thermofluid system development. Required expertise spans component selection (tanks, pumps, valves, heat exchangers, compressors), design documentation (PFDs, P&IDs), instrumentation design and integration, and hands-on experience with specialized environments (pressurized, cryogenic, vacuum, elevated-temperature applications). Strong proficiency with engineering tools such as ANSYS, COMSOL, Python, and MATLAB is essential.
This role requires cross-functional collaboration with production, R&D, procurement, and SPARC teams. You will occasionally flex into adjacent disciplines such as structures or materials engineering to retire technical risks. The position demands resourcefulness, creative problem-solving on tight timelines, and the ability to challenge requirements for design simplicity and efficiency. Physical requirements include occasional lifting up to 50 lbs and dedication to safety protocols around industrial hazards including cryogenics, high voltage, strong magnets, and extreme temperatures.
