Senior Mechanical Engineer

About Pacific Fusion Pacific Fusion was founded in 2023 with the mission to power the world with abundant, affordable, clean energy. We are rapidly designing and building a pulser-driven inertial fusion system to achieve net facility gain (more fusion energy output than stored energy input). In parallel, we are developing the key components required to build affordable fusion systems. Our plans are ambitious. We have raised over $900M so far from incredible investors, resourcing us to deliver on these plans. We are bringing together the best scientists, engineers, and operators from the fusion community, hard tech industry, and other sectors. We are united by a shared sense of urgency to provide clean power for the world, particularly managing climate change while meeting growing global energy demand. You can read more about us in this letter from our founders . Why This Role Matters Pacific Fusion is seeking an exceptional Senior Mechanical Engineer to help create the path to commercial fusion energy. You will help with the design, analysis, integration, and validation of mechanical systems and components across our advanced fusion energy platform. This role sits at the intersection of precision engineering and first-of-kind technology, demanding both deep technical expertise and the creative problem-solving mindset needed to tackle challenges no one has solved before. You will lead collaborative projects, mentor junior engineers, and play a vital role in driving our overall development effort. What You'll Do Own assigned mechanical scope end-to-end, providing technical direction to multidisciplinary teams to translate system requirements into robust, deliverable designs Provide subject matter expertise in mechanical design and analysis for advanced diagnostic instrumentation, from concept through release Develop precision motion and thermal management solutions compatible with high-vacuum and radiation environments Define and verify mechanical alignment requirements for optical and detector systems, coordinating with metrology and assembly teams Apply optomechanical design principles for mirrors, lenses, and optical mounts to ensure precision alignment and performance of diagnostic systems Create and maintain 3D CAD models and 2D fabrication drawings with GD&T for machined, sheet-metal, and additive-manufactured components Perform FEA (structural, thermal) to validate designs against shock, vibration, and thermal loads expected in pulsed fusion experiments Drive hardware from prototype through delivery, installation, and commissioning, working with vendors and in-house shops in a rapid-turn laboratory setting Maintain rigorous revision control and configuration management in PDM/PLM systems: part numbering, BOMs, ECOs, and CAD library maintenance Mentor early-career engineers and contribute to the technical development of the broader team Perform other duties as assigned What You Bring Bachelor’s degree in mechanical engineering or related field; advanced degree a plus Strong first-principles engineering instincts and problem-solving skills 5+ years’ experience in mechanical design for vacuum-compatible instrumentation, ideally with radiation or high-energy diagnostics Expert proficiency in a professional 3D CAD platform (Creo, NX, or SolidWorks), GD&T, and producing detailed manufacturing drawings Significant experience with FEA tools (ANSYS, COMSOL) for structural and thermal analysis Demonstrated ability to navigate competing design constraints simultaneously: vacuum compatibility, radiation tolerance, thermal management, and tight geometric envelopes internally and between neighboring subsystems Proven ability to operate as an effective individual contributor: self-directed and accountable for assigned deliverables end-to-end Comfortable driving cross-functional stakeholders — vendors, technicians, and peer engineers — to keep mechanical deliverables on schedule Excellent verbal and written communication skills for tech…