Commonwealth Fusion Systems

R&D Test Engineer - Fluid Systems

Join Commonwealth Fusion Systems in Devens, Massachusetts as an R&D Test Engineer developing advanced fluid systems for fusion energy test stands. This role involves design, build, and commissioning with a focus on magnet testing. Enjoy competitive pay, equity, flexible vacation, and comprehensive benefits in a mission-driven environment.
Commonwealth Fusion Systems
Commonwealth Fusion Systems
Devens, Massachusetts, United States On-site Full time USD 90k–145k 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 an R&D Test Engineer

The role of an R&D Test Engineer is to develop novel fluid systems for R&D test stands, with a major focus on supporting magnet testing. The range of process fluids is broad (liquid, gaseous, cryogenic, supercritical, molten salt, etc.), requiring strong mechanical and chemical engineering fundamentals. The ideal candidate will be resourceful-combining industry best practices, off-the-shelf and customized hardware, and creativity to deliver these fluid systems on tight timelines.

Projects will be on varying scales, from smaller-scale test stands and deep system analysis to larger, complex projects as needed for SPARC and ARC. In addition to designing and building, the engineer will actively operate as a test engineer to commission systems and design automation alongside a team of test/software engineers and operators. You must work collaboratively across production, R&D, procurement, and the SPARC team. Various projects will also require flexing outside of traditional fluids engineering into other disciplines, such as structures and materials engineering, to successfully retire risks for SPARC and ARC.

What you'll do

  • Design fluid systems for test stands that meet test objectives/requirements, soliciting feedback from interfacing teams as necessary
  • Challenge requirements as necessary to achieve simplicity in design and develop efficient de-risking strategies and plans
  • Perform hand calculations and system level analyses demonstrating sufficient margin for fluid system requirements; build and run Ansys structural and thermal simulations on components and assemblies
  • Procure off-the-shelf process fluid components, manage relationships with vendors, draft specifications for speciality parts and design custom fluid system components as needed
  • Manage the build and commissioning of fluid systems, coordinating engineers and technicians to safely bring systems to operational status
  • Design system instrumentation and automation for safe operations

What we're looking for

  • Bachelor's degree in mechanical, chemical, process engineering, or a closely related field
  • 5+ years of experience in the engineering of integrated fluid/mechanical systems (experience with both small-scale rapid R&D and large-scale systems is highly desired)
  • Full-lifecycle fluid systems:
    • Hands-on experience executing the entire lifecycle of large-scale thermofluid systems
  • Component expertise:
    • Experience developing specifications, sizing and working with tanks, process piping, pumps, valves, compressors, purification stages, circulators, heat exchangers, etc.
  • Design documentation:
    • Strong background in establishing system requirements, generating process flow diagrams (PFDs), and developing piping and instrumentation diagrams (P&IDs)
  • Instrumentation:
    • Experience in the design, integration, and troubleshooting of system instrumentation
  • Software and analysis tools:
    • Experience utilizing engineering tools such as ANSYS, COMSOL, 1D compressible flow codes, Python and MATLAB
  • Extreme environments:
    • Practical experience designing, building, and commissioning fluid systems for specialized pressurized, cryogenic, vacuum, and/or elevated-temperature applications
  • Vendor relations:
    • Experience sourcing complex components, drafting technical specifications, and managing relationships with specialized vendors and suppliers
  • Cross-functional communication:
    • Strong ability to distill complex fluid system details and effectively communicate to non-experts and interfacing teams across R&D, production, and procurement
  • Problem solving:
    • Highly driven to challenge assumptions, make efficient technical decisions, and develop innovative solutions on tight timelines

Bonus points for

  • Adaptability:
    • Ability to flex into adjacent engineering disciplines, such as structures or materials, when required to help retire risks for SPARC and ARC
  • Process optimization:
    • Strong aptitude for identifying bottlenecks and improving throughput during system designs, builds, and commissioning operations

Must-have requirements

  • Ability to occasionally lift up to 50 lbs
  • Perform activities such as stooping, climbing, 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
  • Willingness to travel or work required nights/weekends/on-call occasionally

$90,000 - $145,000 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

July 8, 2026

July 8, 2026

Full time

On-site

Company

USD 90k–145k yearly

Hydrogen

Commonwealth Fusion Systems

cfs.energy

  •  Devens, Massachusetts, United States

5+ years

UTC-05:00