Senior Mechanical Engineer, Plasma Diagnostics

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: As a Diagnostics Engineer on the Science team at Helion, you will help advance the design and development of next-generation diagnostic instrumentation that supports our mission to achieve fusion energy. Sitting at the intersection of mechanical design, prototyping, and scientific exploration, you'll transform early-stage concepts into robust mechanical systems that enable groundbreaking plasma diagnostics and research. This is an onsite role that reports directly to the Director of Plasma and Nuclear Science at our Everett, WA office. You Will: - Collaborate with interdisciplinary teams that include scientists, engineers, and product designers, to develop novel mechanical solutions for experimental diagnostic devices - Own the mechanical design of diagnostic systems: define and refine requirements, troubleshoot hardware issues, and drive continuous improvements - Design, prototype, and iterate mechanical components and assemblies using CAD tools (e.g., NX, SolidWorks); perform structural and thermal analysis (e.g., ANSYS); and lead design reviews - Conduct experimental testing, collect and analyze performance data, and support root-cause analyses of mechanical failures or performance deviations - Apply lessons from historical designs, develop innovative hardware, and integrate your solutions into ongoing fusion research experiments - Continuously expand your skills and domain knowledge by learning from Helion’s technical experts and engaging with cutting-edge science and engineering Required Skills: - Advanced degree in Mechanical Engineering with experience in plasma, laser, aero, or similar specialty - 5+ years of hands-on industry experience with diagnostic equipment, laboratory instrumentation, precision sensing, or similar technologies - 5+ years of experience with CAD software (e.g. NX, SolidWorks) and FEA software (e.g. ANSYS, FEMAP) - Experience applying engineering first-principles and method-based thinking to challenging first-of-a-kind designs - Hands-on exposure to a variety of engineering disciplines (mechanical, electrical, fluids) #LI-ONSITE #LI-AM1 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.