Intern - Mechanical Engineer - Fall Co-op 2026

About Commonwealth Fusion Systems: Commonwealth Fusion Systems is on a mission to deliver the urgent transition to fusion energy. Combining decades of research, top talent, and new technologies, we’re designing and building commercially viable fusion power plants. And we're working with policymakers and suppliers to build the energy industry of the future. We’re in the best position to make it happen. Since 2018, we’ve raised nearly $3 billion in capital, making us the largest and leading private fusion company in the world. Now we’re looking for more thinkers, doers, builders, and makers to join us. People who’ll bring new perspectives, solve tough problems, and thrive as part of a team. If that’s you and this role fits, we want to hear from you. Join the power movement as a Mechanical Engineering Intern We are looking for a talented Mechanical Engineering Intern to join our team! CFS interns are highly valued within the organization and placed into meaningful and challenging roles. Program Details 26 week internship 40-50 hours per week with set hourly salary based on year in school Opportunities on site in Devens, MA. If an intern is going to be on site, you will be responsible for your own transportation and housing Specific project assignments and required technical skillset will vary based on the team’s existing need. Opportunities available for currently enrolled college students in all levels of schooling from bachelor’s degree to PhD Interns must be authorized to work in the United States for any employer What you'll do Design and build tooling used for integration and assembly of complex hardware Development of workflows to reverse engineer hardware or adjust installation to meet final system tolerances Supporting in-field integration of hardware into a tokamak fusion device Design of actuated systems to remotely install and remove large structural components What we’re looking for Pursuing an engineering degree with focus in the fields of Mechanical, Electrical or Aerospace Curious, high-initiative, and bias towards execution Approaches problems from a fundamental physics perspective Crisp communication paired with technically dense documentation Ideally, background in design, build, and test of highly-loaded hardware or large tooling assemblies Ideally, experience with CAD systems to design parts and release drawings for manufacturing Understanding of GD&T Ideally design review experience in a technical environment Ideally experience running simple testing to validate designs A commitment to a safe working environment Must-have Requirements Willingness to travel or work required nights/weekends/on-call occasionally Perform activities such as typing, standing, or sitting for extended periods of time Dedication to safety to mitigate industrial hazards that may include heat, cold, noise, fumes, strong magnets, lead (Pb), high voltage, and cryogenics $23 - $35 an hour Rates are aligned to your current year in school, ensuring equitable and consistent pay across our intern program. For BS interns, the hourly rate is $23–$29 For MS/PhD interns, the rate is $32–$35 Benefits included for full-time interns 40 hours of sick time Health, dental, and vision insurance 401(k) with employer matching (must be 21 years of age to enroll) Professional growth opportunities Team-building activities #LI-Onsite At CFS, we excel in fast-paced environments, driven by our values of integrity, execution, impact, and self-critique. As we grow, we’re eager to bring on mission-driven folks who offer diverse perspectives and fresh ways to tackle challenges. We value diversity deeply and are proud to be an equal opportunity employer by choice. We consider all qualified applicants equally, regardless of race, color, national origin, ancestry, citizenship status, protected veteran status, religion, physical or mental disability, marital status, sex, sexual orientation, gender identity or expression, age, or any other basis protected by law. This role requires compliance with U.S. laws concerning the export of controlled or protected technologies or information (collectively, “Export Control Laws”). Any offer of employment will be contingent on the need for compliance with such Export Control Laws. #J-18808-Ljbffr Commonwealth Fusion Systems