Senior Mechanical Engineer

About Commonwealth Fusion Systems

Commonwealth Fusion Systems (CFS) is on a mission to deliver the urgent transition to clean, limitless fusion energy. Born as a spin-out from MIT’s Plasma Science and Fusion Center, CFS combines decades of rigorous research with the speed and agility of the private sector. Since our founding in 2018, we have raised over $2 billion in capital to build SPARC, the world’s first commercially relevant, net-energy fusion device.

At CFS, we don’t just design; we build. Our team is a diverse group of "thinkers, doers, and makers" dedicated to solving the world’s toughest energy challenges. We operate in a fast-paced environment where safety, scientific integrity, and rapid execution are our core values.

Job Summary

We are seeking a Senior Mechanical Engineer to join our SPARC Project team. In this role, you will be a lead technical contributor responsible for the design, analysis, and integration of critical mechanical subsystems within the tokamak. You will bridge the gap between complex physics requirements and manufacturable hardware, ensuring that our systems can withstand the extreme thermal and electromagnetic environments of a fusion plasma. This role requires a "first principles" engineering approach and the ability to lead cross-functional teams through the full product lifecycle, from concept to commissioning.

Key Responsibilities

- System Design & Ownership: Own the end-to-end design of complex mechanical components (such as vacuum vessel internals, support structures, or cryogenic interfaces).

- High-Fidelity Analysis: Perform and review structural, thermal, and electromagnetic Finite Element Analysis (FEA) to validate designs against rigorous fusion-specific safety codes.

- Cross-Functional Collaboration: Act as the primary technical interface between the Science, Vacuum, and Superconducting Magnet teams to manage complex hardware interfaces and tolerances.

- Manufacturing Support: Collaborate with the production floor and external vendors to resolve "shipside" technical issues, ensuring that hardware is built to spec and on schedule.

- Technical Leadership: Lead formal design reviews (PDR, CDR) and mentor junior engineers, fostering a culture of technical excellence and self-critique.

- Project Management: Develop and maintain project schedules and budgets for your assigned subsystems, ensuring transparent reporting to project leadership.

Requirements

- Education: Bachelor’s degree in Mechanical Engineering, Aerospace Engineering, or a related field (Master’s or PhD preferred).

- Experience: 7+ years of professional experience in a high-tech hardware industry (e.g., aerospace, semiconductor, or large-scale scientific facilities). - Technical Proficiency: * Expertise in 3D CAD modeling (SolidWorks or Siemens NX preferred).

- Strong background in computational structural mechanics (ANSYS or COMSOL).

- Experience with high-vacuum systems, cryogenics, or high-voltage environments.

- Regulatory Knowledge: Familiarity with industry codes and standards such as ASME BPVC (Boiler and Pressure Vessel Code).

- Physical Requirements: Ability to work in an industrial environment, which may include proximity to high-strength magnets and cryogenic systems; ability to lift up to 50 lbs.

Job Type: Full-time

Pay: $3,800.00 - $4,100.00 per month

Benefits:

- 401(k)

- Dental insurance

- Flexible schedule

- Health insurance

- Paid time off

- Vision insurance

Work Location: In person