Senior RF Test Engineer

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 Senior RF Test Engineer

SPARC sustains fusion reactions by feeding >25MW of 120MHz RF power into the tokamak to heat the plasma to 100 million Kelvin. We need an RF Test Engineer to play a pivotal role in validating and testing the electronics and control systems that power the most ambitious RF plant in the world.

At this level, you are a hands‑on executor and technical problem solver. You will be directly responsible for taking newly architected RF and power electronics from the benchtop to full‑scale operation. Your day‑to‑day will span board‑level bring‑up, operating high‑power RF transmitters, and integrating hardware with software controls to ensure SPARC achieves net energy.

For more information on the SPARC RF plant, see the SPARC journal papers here:

• Overview of the SPARC tokamak
• Physics basis for the ICRF system of the SPARC tokamak

What you’ll do:

• Execute Board‑Level Bring‑Up: Lead the initial power‑on, debugging, and validation of custom printed circuit board assemblies (PCBAs), embedded digital controllers, and low‑level electronics, focusing heavily on the integration of these boards into working modular solid‑state RF systems
• Operate RF Transmitters & High Voltage Systems: Safely run and test high‑power RF transmitters with a primary focus on validating and troubleshooting complex RF behaviors. You will also safely interface with, and occasionally troubleshoot, the supporting high‑voltage infrastructure and large‑scale supercapacitor banks
• Drive Hardware/Software Integration: Bridge the gap between physical electronics and control software, ensuring that measurement circuits, timing systems, and sensors interface seamlessly with SPARC’s central data collection and control networks
• Oversee FAT Fixturing & Operation: Design, assemble, and manage the fixturing for Factory Acceptance Testing (FAT). You will oversee the execution of these tests to validate that incoming hardware meets stringent performance and safety criteria
• Develop Procedures & Hand‑Off: Translate complex engineering validation steps into clear, repeatable test procedures, ultimately training and handing off routine testing and steady‑state operations to engineering technicians

What we’re looking for:

• Bachelor’s degree in Electrical Engineering, Physics, or a related field
• 7+ years of hands‑on experience testing high‑power RF systems, radar, particle accelerators, electric vehicles, or heavy industrial power electronics
• Proven hands‑on experience safely working with high voltage components, energy storage (e.g., supercapacitors), and troubleshooting complex analog and digital circuits at the component level
• Exceptional skills in reading RF circuit designs (Altium or similar) and setting up automated test environments to validate sensitive timing and RF detection circuits within extreme high‑power, high‑noise environments (EMI/EMC mitigation)
• Proficiency in C++ and Python, with the ability to read code and thoroughly understand software deployments before testing them
• Proven intuition for high‑power RF environments

Bonus points for:

• Experience designing test fixtures, writing comprehensive FAT protocols, and setting up automated data acquisition systems in high‑noise environments, utilizing EMI/EMC mitigation techniques to ensure circuits operate reliably
• Hands‑on experience measuring forward and reflected RF power, diagnosing RF arcs, and validating the timing and electronics designed to mitigate them
• Proven experience writing custom test software to automate lab equipment and validate system functionality
• A strong systems‑level understanding of modern high‑performance embedded digital controllers, high‑speed communications, and fundamentals of mechanical/thermal design to safely execute tests and interface effectively with cross‑functional teams

Must‑have Requirements:

• Ability to lift up to 50lbs
• Perform activities such as stooping, climbing, standing, typing 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

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.