Intern - R&D Test Engineer - Summer 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 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 an R&D Test Engineering Intern

The R&D Intern will work with the TF R&D team primarily at CFS-1, to de-risk SPARC TF magnet components. Responsibilities include supporting engineers in designing and building test stand components/fixtures for testing, as well as conducting tests and analysis to obtain high quality data that informs actionable recommendations on an aggressive schedule supporting magnet technology development.

Program Details:

• 12-16 week internship program
• 40-50 hours per week with set hourly salary based on year in school
• Opportunities vary between onsite in Somerville, MA and 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:

• Support engineers in building test stands, executing tests and/or projects
• Responsible for obtaining high quality data and performing high quality data analysis
• Responsible for the design, build, and commissioning of key pieces of equipment and/or software in support of development, qualification, and production test objectives
• Work with test engineers in close collaboration across manufacturing, R&D, procurement, and SPARC teams to achieve their test objectives
• Support design reviews, and test readiness reviews as needed

What we’re looking for:

• Pursuing an engineering degree with focus in the fields of Mechanical, Electrical or Aerospace OR pursuing a degree in Physics or Applied Physics
• Hands-on experience through academic research, project teams, machine shops, hackathons, or industry internships
• Mechanical design (structural focus), electrical design, instrumentation and control, experience with cryogenics, high currents, high voltage, experimental design, rapid prototyping and testing is a plus
• Ansys, COMSOL, Python for data analysis, 3D CAD is a plus
• Demonstration of exceptional results through a range of different pursuits
• High self-motivation and drive to execute quickly with excellent troubleshooting/problem-solving skills

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

F or 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.