Principal Experimental Scientist - RF

About Helion We are a fusion power company based in Everett, WA, with the mission to build the world's first fusion power plant, enabling a future with unlimited clean electricity. Our vision is a world with clean, reliable, and affordable energy for everyone. Since Helion's founding in 2013, we have raised over $1 billion from long-time investors such as Sam Altman, Mithril, and Capricorn Investment Group as well as new investors SoftBank and Lightspeed to propel us forward. Our last prototype, Trenta, completed 10,000 high-power pulses and reached plasma temperatures of 100 million degrees Celsius (9 keV). We are now operating Polaris, our next prototype on the path to the world's first fusion power plant. This is a pivotal time to join Helion. You will tackle real-world challenges with a team that prizes urgency, rigor, ownership, and a commitment to delivering hard truths – values essential to achieving what no one has before. Together, we will change the future of energy, because the world can't wait. What You Will Be Doing: Helion is hiring a Principal Experimental Scientist to lead the development of our RF pre-ionization capability for Helion’s fusion generators. In this role, you will own the strategy, technical direction, and execution of RF plasma source development for our FRC system, translating plasma physics goals into robust experimental hardware and operational capability. You will develop, optimize, and validate high-performance RF systems to achieve target plasma density, stability, and coupling efficiency, while defining the diagnostic and experimental approach needed to measure and improve performance. As a principal-level scientist, you will integrate cross-functional input from plasma physics, controls, machine operations, electrical engineering, and data science to mature RF pre-ionization from experimental concept into reliable platform capability. You will also help establish Helion’s long-term technical roadmap and internal best practices for RF-driven plasma startup and next-generation machine development. This is an onsite role reporting directly to our Director of Plasma and Nuclear Science in Everett, WA. You Will: - Own the end-to-end technical development of Helion’s RF pre-ionization capability for FRC startup, including concept development, experimental design, execution, validation, and performance improvement - Lead hands-on experimental work spanning RF hardware, antenna and coupling design, plasma diagnostics, and operational procedures to deliver repeatable plasma startup performance - Develop and optimize high-performance RF plasma source systems to achieve targeted plasma density, stability, and coupling efficiency - Define and deploy the diagnostic strategy needed to characterize RF-driven plasma formation, coupling behavior, and startup performance, ensuring high-fidelity data and actionable insight - Integrate cross-disciplinary technical input across plasma physics, machine operations, controls, electrical engineering, and data science to align RF development with Helion’s machine roadmap - Partner with technical leadership on strategic planning, long-range roadmap development, and identification of new RF/plasma startup concepts for future Helion systems Required Skills: - Ph.D. in physics, plasma physics, electrical engineering, aerospace engineering, or a related discipline with strong relevance to RF plasma systems, plasma sources, or fusion experimentation - 10+ years of experience in advanced laboratory or R&D environments, including substantial hands-on work with plasma generation systems, RF hardware, vacuum systems, and experimental campaign execution - Deep expertise in RF plasma source development, antenna/coupling design, RF-plasma interactions, or related high-energy plasma hardware - Strong background in plasma diagnostics and data interpretation, with experience using measurement systems to evaluate plasma parameters such as density, temperature, stability, coupling,