Commonwealth Fusion Systems

Senior Mechanical Engineer

Join Commonwealth Fusion Systems in Devens, Massachusetts as a Senior Mechanical Engineer. Lead manufacturing equipment commissioning and optimization in fusion energy production. Enjoy competitive pay, equity, flexible vacation, and comprehensive benefits in a mission-driven team.
Commonwealth Fusion Systems
Commonwealth Fusion Systems
Devens, Massachusetts, United States On-site Full time USD 110k–185k yearly UTC-05:00

Commonwealth Fusion Systems

Company Overview

Commonwealth Fusion Systems (CFS)

Cambridge, MA, United States

2018

Approximately 430 employees (source: zoominfo.com). Revenue figures vary, with reports indicating $211.3 million or $31.7 million, though as a pre-revenue fusion developer focused on R&D, these may reflect funding or operations rather than sales.

What They Do

Commonwealth Fusion Systems (CFS) is a pioneering private fusion energy company that specializes in tokamak-based magnetic confinement fusion. Founded as a spinout from MIT's Plasma Science and Fusion Center, CFS focuses on utilizing high-temperature superconducting magnets to achieve commercial net energy production (source: cfs.energy). The company has made significant strides in its technology, particularly with the development of compact fusion machines that leverage decades of tokamak science. Their flagship projects, SPARC and ARC, aim to demonstrate net energy gain and commercial viability in the coming years (source: cfs.energy).

Projects & Track Record

CFS is currently engaged in several groundbreaking projects, most notably the construction of SPARC, which is set to be the world's first net-energy fusion machine. Located at their Fusion Energy Campus in Devens, Massachusetts, SPARC aims to demonstrate net energy gain by the late 2020s (source: cfs.energy). Additionally, CFS is planning the ARC project, a 400 MW-class grid-scale tokamak power plant designed for commercial deployment in the early 2030s. These projects are underpinned by significant technological advancements, including the successful testing of the central solenoid magnet module (CSMC) in November 2024, which confirmed the manufacturability of critical components for SPARC (source: zoominfo.com).

Recent Developments

In the past two years, CFS has made remarkable progress, including the opening of its Devens Fusion Energy Campus on February 10, 2023, which was attended by notable figures such as U.S. Secretary of Energy Jennifer Granholm (source: cfs.energy). The company has also secured substantial funding, raising $863 million in August 2024, building on a previous $1.8 billion round in May 2023, bringing total funding to over $2 billion (source: wbjournal.com). Furthermore, CFS announced its first commercial power plant site in Chesterfield County, Virginia, which will be independently financed and operated, with plans for grid connection in the early 2030s (source: zoominfo.com).

Working There

CFS offers a range of roles across various disciplines, including fusion science, engineering, manufacturing, and materials science. The majority of their workforce is based at the Devens campus, which has grown to over 430 employees (source: cfs.energy). The company culture emphasizes rapid execution and transparency, attracting top talent from the fusion and manufacturing sectors. Key executives include Co-Founder and CEO Bob Mumgaard, along with other leaders in operations and science, indicating a strong demand for expertise in tough tech and physics (source: nasdaqprivatemarket.com). While specific benefits are not detailed, the scale-up and investor backing suggest competitive packages for high-caliber roles in a mission-driven environment (source: cfs.energy). Job seekers are encouraged to monitor their careers page for openings related to SPARC and ARC advancements.


Last updated on Feb 23, 2026 | Report an issue

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 Senior Mechanical Engineer

We are seeking a highly motivated and experienced Mechanical Engineer to join our manufacturing team. In this role, you will be responsible for providing technical expertise during the commissioning, implementation, and integration of manufacturing equipment. You will work closely with our production team to ensure that our manufacturing processes are optimized for efficiency, quality, and safety.

What you'll do

  • Provide technical expertise during the commissioning, implementation, and integration of manufacturing equipment
  • Support Factory Acceptance Testing (FAT) and Site Acceptance Testing (SAT) of equipment
  • Troubleshoot mechanical issues and provide solutions to ensure equipment operates efficiently
  • Collaborate with production and engineering teams to optimize manufacturing processes and improve equipment performance
  • Drive continuous improvement initiatives for manufacturing equipment to increase efficiency, reduce downtime, and improve quality.
  • Conduct root cause analysis and implement corrective actions to resolve manufacturing issues
  • Ensure compliance with all safety requirements
  • Work with external vendors and suppliers to ensure the timely delivery of equipment and materials
  • Conceptualize and detail new manufacturing equipment for scaled up manufacturing processes
  • Run experiments to determine the feasibility of new manufacturing processes and translate those learnings into practical designs

What we're looking for

  • Bachelor's degree in Mechanical Engineering or a related field
  • 7+ years of experience in mechanical engineering, with a focus on manufacturing equipment
  • 5+ years of manufacturing equipment and tooling design
  • Strong knowledge of mechanical systems, including hydraulics, pneumatics, and motion control
  • Experience with 3D CAD packages and 2D drawings
  • Experience with Factory Acceptance Testing (FAT) and Site Acceptance Testing (SAT) of equipment
  • Understanding of GD&T and its application
  • Excellent problem solving and analytical skills
  • Strong communication and interpersonal skills, with the ability to collaborate effectively with cross-functional teams
  • Experience with commissioning and startup of manufacturing equipment

Bonus points for

  • Strong knowledge of mechanical systems, including hydraulics, pneumatics, and motion control
  • Experience developing manufacturing equipment and tooling for a novel process
  • Experience with production ramp-up and optimization of manufacturing processes
  • Experience with automated equipment and robotics

Must-have requirements

  • Ability to lift up to 50 lbs occasionally
  • Perform activities such as typing, standing, stooping, and sitting, for extended periods of time
  • Willingness to occasionally travel or work required nights/weekends/on-call
  • Dedication to safety to mitigate hazards that may include heat, cold, noise, fumes, strong magnets, lead, high voltage, and cryogenics

$110,000 - $185,000 a year

Salary range for this full-time position + equity + benefits. The actual salary will depend on level, location, qualifications, and experience. The range displayed on each job posting reflects new hire salaries for the position across all US locations. Benefits include:

  • Competitive compensation with equity
  • 13 Company-wide Holidays
  • Flexible vacation days
  • 10 sick days
  • Generous parental leave policy
  • Health, dental, and vision insurance
  • 401(k) with employer matching
  • Professional growth opportunities
  • Team-building activities

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.

Apply now

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About the role

April 16, 2026

Full time

Company

April 16, 2026

On-site

USD 110k–185k yearly

Hydrogen

Commonwealth Fusion Systems

cfs.energy

  •  Devens, Massachusetts, United States

7+ years in mechanical engineering

UTC-05:00