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 Senior Experimental Scientist to support and advance the plasma diagnostics capability for Helion’s fusion generators. In this role, you will be a key technical contributor for the design, deployment, calibration, and interpretation of plasma diagnostics across experimental campaigns and testbeds. This is an onsite role that reports directly to our Director of Plasma and Nuclear Science at our Everett, WA office. You Will: * Lead the design, build, deployment, calibration, and commissioning of plasma diagnostic systems for Helion’s fusion generators, with guidance from senior technical leadership on broader priorities and roadmap alignment * Serve as a go-to technical contributor for a defined diagnostics scope, helping evaluate plasma parameters such as density, temperature, current profiles, and other key performance indicators * Partner cross-functionally with plasma physics, machine operations, controls, mechanical engineering, electrical engineering, and data science teams to align diagnostic capabilities with experimental and operational needs * Develop foundational expertise in pre-ionization plasma diagnostics, establishing best practices and internal methodologies that inform next-generation fusion device development optimized for energy gain and power conversion * Analyze diagnostic data in real time to extract actionable insights about plasma behavior, inform operational tuning, and identify opportunities for performance optimization and system redesign * Contribute to best practices, documentation, and internal methods for plasma diagnostics, helping improve consistency, reliability, and scalability across Helion’s experimental programs Required Skills: * Ph.D. in physics, electrical engineering, aerospace engineering, or a related discipline, with a focus on plasma science, diagnostics, or high-vacuum instrumentation * 3+ years of relevant experience with plasma systems, advanced laboratory environments, high-vacuum systems, pulsed-power systems, or complex experimental hardware * Hands-on experience designing, building, calibrating, troubleshooting, or operating plasma diagnostics such as interferometry, spectroscopy, Langmuir probes, magnetic coils, electrostatic diagnostics, optical diagnostics, or related measurement systems * Demonstrated ability to independently lead complex technical workstreams while collaborating with cross-functional stakeholders across science and engineering teams Benefits Our total compensation package includes benefits, including but not limited to: • Medical, Dental, and Vision plans for employees and their families • 31 Days of PTO (21 vacation days and 10 sick days) • 10 Paid holidays, plus company-wide winter break • Up to 5% employer 401(k) match • Short term disability, long term disability, and life insurance • Paid parental leave and support (up to 16 weeks) • Annual wellness stipend Helion is an equal opportunity employer and value diversity at our company. We do not discriminate based on race, religion, color, national origin, gender, sexual orientation, age, marital status, veteran status, or disability status. If you need assistance or an accommodation during the interview process, please let us know.