Mechanical Engineer, RF Systems

Commonwealth Fusion Systems•Devens, MA

1d•$90,000 - $145,000•Onsite

About The Position

Commonwealth Fusion Systems (CFS) is on a mission to deliver the urgent transition to fusion energy by designing and building commercially viable fusion power plants. Combining decades of research, top talent, and new technologies, CFS is working with policymakers, suppliers, and others to build the energy industry of the future. Since 2018, CFS has raised $4 billion of capital, making it the largest and leading fusion company in the world. The SPARC project sustains fusion reactions by feeding over 25MW of 120MHz RF power into the tokamak to heat the plasma to 100 million Kelvin. This role is critical for designing the physical infrastructure that routes this massive power, from coax transmission lines to the intricate cooling plates required for high-power electronics. The Mechanical Engineer will own the physical design and integration of robust mechanical systems, translating requirements into manufacturing-ready hardware, covering designs from ideation and CAD modeling through fabrication and direct plant integration.

Requirements

Bachelor’s degree in Mechanical Engineering, Physics, or a related field.
5+ years of hands-on mechanical design experience in industrial, heavy machinery, high-power electronics, electric vehicle, or aerospace environments.
Demonstrated experience as the primary creator and owner of mechanical design architectures, operating as a core design engineer.
Direct experience performing structural loads analysis and thermal analyses to validate mechanical designs.
High proficiency in 3D CAD software and creating detailed manufacturing drawings utilizing GD&T standards.
Strong fundamental understanding of heat transfer, structural mechanics, and fluid dynamics.
Ability to lift up to 50lbs.
Perform activities such as stooping, climbing, standing, typing or sitting for extended periods of time.
Willingness to travel or work required nights/weekends/on-call occasionally.
Work in a facility that contains industrial hazards including heat, cold, noise, fumes, strong magnets, lead (Pb), high voltage, high current, pressure systems, and cryogenics.
Compliance with U.S. laws concerning the export of controlled or protected technologies or information.

Nice To Haves

Experience using Siemens NX for 3D modeling and Teamcenter for product lifecycle management and drawing release workflows.
Background decomposing complex system requirements into clear mechanical hardware specifications.
Experience designing large-scale pipe routing, coaxial transmission lines, flanges, bellows, or active water and air cooling systems.
Experience with complex electronics assemblies and the thermal management of such assemblies.
Deep familiarity with sheet metal fabrication processes, machining capabilities, and communicating directly with contract manufacturers.

Responsibilities

Design specialized RF Heating plant components working closely with RF Engineers, including large-diameter coaxial transmission lines, stub tuners, and RF testing loads.
Decompose high-level system requirements into actionable mechanical specifications, owning the mechanical designs for the RF Heating system.
Collaborate daily with a dedicated CAD drafting team, providing clear guidance to detail, rigorously review, and release designs.
Partner cross-functionally with RF engineers, electronics engineers, process engineers, and other disciplines.
Architect thermal management solutions by integrating complex water and air cooling loops directly into high-power electronics enclosures and plant systems.
Develop large sheet metal components, precise mounting hardware for custom printed circuit board assemblies, cold plates, and more.
Perform structural loads analysis and thermal analyses to ensure design viability.