Mechanical Engineer, RF Systems

About the role

Commonwealth Fusion Systems is seeking a Mechanical Engineer to design and integrate the physical infrastructure for its high‑power RF heating plant. The role focuses on coaxial transmission lines, cooling plates, and other mechanical components that deliver >25 MW of 120 MHz RF power to the SPARC tokamak.

Key responsibilities

• Design specialized RF heating plant components, including large‑diameter coaxial lines, stub tuners, and testing loads, in close collaboration with RF engineers.
• Translate system requirements into detailed mechanical specifications, create 3D CAD models, and produce GD&T‑based manufacturing drawings.
• Develop thermal‑management solutions by integrating water and air cooling loops into high‑power electronics enclosures.
• Perform structural loads and thermal analyses to validate designs and ensure reliability.
• Partner with CAD drafting teams, electronics, process, and other engineering disciplines throughout the design‑to‑fabrication cycle.

Required profile

• Bachelor’s degree in Mechanical Engineering, Physics, or a related field.
• 5+ years of hands‑on mechanical design experience in industrial, high‑power electronics, aerospace, or similar environments.
• Proven ownership of mechanical design architectures and experience delivering manufacturing‑ready hardware.
• Ability to conduct structural and thermal analyses to certify design viability.

Required skills

• High proficiency in 3D CAD software (e.g., Siemens NX) and GD&T drawing standards.
• Experience with structural loads analysis and thermal analysis.
• Strong understanding of heat transfer, fluid dynamics, and structural mechanics.
• Knowledge of sheet‑metal fabrication, machining, and contract‑manufacturer communication.
• Familiarity with PLM tools such as Teamcenter is a plus.

What we offer

• Competitive salary range $90,000‑$145,000 USD plus equity.
• 13 company‑wide holidays, flexible vacation and sick days, generous parental leave.
• Health, dental, and vision insurance, 401(k) with employer match.
• Professional growth opportunities and team‑building activities.