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Salary
$150k – $225k per year
Location
In office (Devens)
Seniority
Principal · 15+ years exp
Employment
Full-Time

Confirmed on the employer's own hiring board on Sep 26, 2026. First seen by Alion on Aug 6, 2026. Commonwealth Fusion Systems scores A on the Alion truth index.

Overview
Company
Impact
Profile match
Commonwealth Fusion Systems is a commercial fusion energy company headquartered in Devens, Massachusetts, and founded in 2018. The firm specializes in the development of high-temperature superconducting magnets and compact tokamak devices, specifically the SPARC net-energy machine and the ARC commercial power plant. It operates through a strategic partnership with the Massachusetts Institute of Technology and focuses on scaling fusion technology to provide carbon-free, baseload power to global energy markets.

Join the power movement as a Principal RF Systems 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 a Principal RF Systems Engineer to play a pivotal role in building the most powerful RF plant in the world.

At this level, you are a highly influential architect of the system. You will help drive the high-level technical direction while remaining deeply hands-on, taking a central role in the integration of high-power electronics, solid-state amplification, and complex transmission networks to ensure SPARC achieves net energy.

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

What you'll do:

  • Shape System Architecture: Play a critical role in the end-to-end design and integration strategy for RF plants for tokamaks, collaborating with other senior engineers to ensure seamless interaction between RF sources, matching networks, and the dynamic plasma load
  • Guide Solid-State & Electronics Integration: Act as a key driver in the architecture and design of the electronics ecosystems required to integrate massive, distributed RF systems, with a heavy emphasis on solid-state amplifier technology and associated power supplies
  • Spearhead Instrumentation & Control (I&C): Take the initiative in designing and integrating advanced RF signal detection, measurement circuits, and embedded digital controllers that interface seamlessly with SPARC’s central data collection systems
  • Tame High-Power Delivery: Serve as a central figure in the hands-on design, integration, and optimization of critical high-power transmission components, specifically large-diameter coax lines and dynamic impedance matching networks
  • Hands-on Technical Mentorship: Act as a senior technical authority on the floor. You will be actively involved in commissioning equipment, troubleshooting the most complex system-level hardware discrepancies, and organically mentoring junior engineers to elevate the entire RF team's capabilities

What we’re looking for:

  • Education: Bachelor’s degree in Electrical Engineering, Physics, or a related field (Master’s or Ph.D. strongly preferred for this level)
  • Experience: 15+ years of hands-on experience in high-power RF systems, radar, particle accelerators, or heavy industrial power electronics
  • RF Fundamentals Expertise: Proven intuition for high-power RF environments, specifically hands-on experience measuring forward and reflected RF power, diagnosing RF arcs, and designing the timing and electronics to mitigate them
  • Electronics & Design: Exceptional skills in RF circuit and electronics design (Altium or similar) specifically geared toward instrumentation, sensing, control, and system integration. Experience in EMI/EMC mitigation to ensure sensitive timing and RF detection circuits operate reliably within extreme high-power, high-noise environments
  • Advanced Simulation: High proficiency in RF/Microwave simulation software (CST, HFSS, etc.) to validate architectural decisions before physical integration
  • Cross-Disciplinary Fluency: A strong systems-level understanding of modern high-performance embedded digital controllers, high speed communications, and fundamentals of mechanical/thermal design to interface effectively with cross-functional teams

Must-have Requirements:

  • Perform activities such as stooping, 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
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