Principal Scientist - Radio Frequency Plasma Heating
Devens, MA, USA
Posted on Aug 21, 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, suppliers, and many others to build the energy industry of the future.
We’re in the best position to make it happen. Since 2018, we’ve raised $4 billion of capital, making us the largest and leading 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 Principal Scientist - Radio Frequency Plasma Heating
CFS is looking for an enthusiastic experimental RF Scientist/Engineer to join the team to operate the SPARC ion cyclotron heating system and study RF physics/engineering in SPARC and ARC.
The SPARC tokamak aims to be the first magnetic confinement device to achieve net energy and is predicted to have up to Q=11 in DT, producing up to 140 MW of fusion power. The sole auxiliary heating for SPARC is a 120 MHz, 25 MW (coupled) Ion Cyclotron Resonance Heating (ICRH) system that will launch into SPARC via an array of 14 4-strap ICRH antennas. The novel, solid-state 120 MHz sources and the ICRH antennas are already in production.
The Ion Cyclotron Discharge Cleaning (ICDC) System provides one of several mechanisms to clean and condition the exposed surfaces within the Tokamak confinement vessel, including boronization of plasma facing components. The ICDC System is similar in design but wholly distinct from the ICRF, with its own transmitter, transmission network, and antennas.
The Scientist – Radio Frequency Plasma Heating will be vital to the successful commissioning and operation of both the ICRH and ICDC systems. They will prepare for commissioning via simulations of the antennas and the plasmas and then will be a key part of the team to operate SPARC and to design ARC.What you'll do:
- Simulate the SPARC ICRH antennas and RF network system to inform commissioning and operation
- Contribute to testing of ICRH/ICDC components
- Inform the implementation of the RF control system and operator interfaces
- Contribute to the development of commissioning and operation plans and procedures for the ICRH/ICDC system
- Commission the SPARC ICRH/ICDC system into early plasmas
- Operate the SPARC ICRH system during Q>1 and high power DT plasmas
- Study the physics of radio frequency waves in SPARC
- Provide input to ARC design through simulation and modeling efforts
- Work with multi-institutional team of collaborators from universities and national labs
What we’re looking for:
- PhD in plasma physics or a closely related discipline
- 7+ years experience (post degree) working with radio frequency heating, current drive or discharge cleaning systems in fusion plasmas (this may include ion cyclotron, lower hybrid, helicon, or other similar wave systems)
- Experience running experiments on tokamaks, stellarators, or similar plasma confinement devices
- Experience developing hardware for plasma physics experiments
- Experience working with COMSOL, ANSYS HFSS, CST, or similar finite element tools
- A desire for active participation in tokamak design and operations
- A drive toward practical solutions to integrated physics and engineering challenges
- Expertise in ICRF, plasma physics, fusion engineering, and fusion power plant design
Bonus points for:
- 10+ years experience in operating and/or simulating RF heating of plasmas
- Experience with Python
- Experience designing ICRH system, RF diagnostics, control and operation tools and procedures for radio frequency heating
- Experience modelling ICDC physics
Must-have Requirements:
- Perform extended activities such as typing, standing, sitting, etc.
- Willingness to travel or work required nights/weekends/on-call regularly; expected to travel 1-2 times per year for conferences
- 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
#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.
150000 - 225000 USD 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