Diagnostician
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.
Contact
Last updated on 2026-01-02 | Report an issue
Job Description
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 a Diagnostician
Commonwealth Fusion Systems is assembling the high-field SPARC tokamak, which aims to be the first magnetic fusion device to achieve net fusion energy, and is predicted to be able to achieve high gain and fusion power up to 140MW. We are completing the design and beginning the assembly and installation of diagnostic systems that will be used to control the plasma and deliver the scientific data necessary to complete the design of ARC. These include approximately 40 sub-systems covering magnetics, interferometry, neutral pressure, x-ray to visible spectroscopy, camera imaging, bolometry, neutrons, Thomson scattering, electron cyclotron emission, reflectometry, Langmuir probes and structural temperature and strain sensing. A more detailed overview can be found at: https://pubs.aip.org/aip/rsi/article/95/10/103518/3317155.
CFS is looking to grow the SPARC team in order to complete back-end design and move diagnostics through fabrication, assembly, commissioning and utilization. Presently the diagnostics team has enough expertise to support all major diagnostic systems, but we are looking to add a generalist who has experience in multiple diagnostics to ensure our team can deliver measurements on SPARC's fast timeline. Candidates will work as part of an integrated diagnostic team along with MIT-PSFC partners and fusion community collaborators from around the world to demonstrate net energy from a tokamak for the first time. CFS encourages applications from both senior and early career fusion scientists and those interested in cross-industry career changers to help us build a diverse team to meet our mission goals.
What you'll do
- Shepherd SPARC diagnostic sub-systems through final design, working with a team of scientists, designers, analysts and engineers
- Integrate technical input from experts in the SPARC team to ensure diagnostic designs will be usable to achieve SPARC's mission goals
- Develop the diagnostic's assembly, installation, calibration and commissioning plans to ensure SPARC is able to achieve first plasma on-schedule
- Integrate the diagnostic into the plant-level and real-time plasma control systems
- Participate in the testing and operation of diagnostic systems that balances learning how to operate SPARC with obtaining physics results as quickly as possible
- Contribute to a strong safety culture
- Collaborate with CFS designers and analysts as well as provide feedback to academic partners providing input to SPARC diagnostic designs
What we're looking for
- Bachelor's degree in a relevant engineering field (mechanical, aerospace, civil or nuclear)
- Participated in the design of a new or upgraded scientific instrument of the scale and complexity of those used in magnetically confined fusion
- Demonstrated examples of using scientific instruments to support an operational and/or research mission
- Developed software using Python, Matlab, C++ or equivalent for analysis of experimental data and automation of lab equipment
- Relevant hands-on knowledge/skills specific to diagnostic systems listed in summary (e.g. vacuum systems, lasers, calibration sources, etc.)
- Ability to understand concepts and tradeoffs that bridge engineering and physics
Bonus points for
- Participated in the design and implementation of a plasma diagnostic for a magnetically confined fusion experiment at University-scale or above
Must-have requirements
- Ability to occasionally lift up to 50 lbs
- Perform activities such as climbing, typing, standing, or sitting for extended periods of time
- Willingness to travel or work required nights/weekends/on-call occasionally
- Work in a facility that contains industrial hazards including heat, cold, noise, fumes, strong magnets, lead (Pb), high voltage, high current, pressure systems, 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
- 12.5 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.
Get Job Alerts
Get alerts for Energy Storage jobs in Devens, Massachusetts, United States
About the role
November 24, 2025
Full Time
Company
January 2, 2026
On-site
USD 110k–185k yearly
- Devens, Massachusetts, United States
Bachelor's degree and relevant experience in engineering or scientific instrumentation.
UTC-05:00
Apply now
Job expired?Please let Commonwealth Fusion Systems know you found this job on Rejobs. This will help us grow and get more people to work on renewable energy!
Discover how you’re connected
View connectionsSee your contacts at Commonwealth Fusion Systems on LinkedIn to leverage your network in applying for this position.
Similar jobs near Devens, Massachusetts, United States
Share with Friends
The stakes are high, and the time for talk has passed. Now is the time for action. Help a friend accelerate the shift to a sustainable future.
Share this job - Diagnostician - with your folks, and help them find a career to be proud of.