Senior Mechanical Engineer, Accelerator Technology

Senior Mechanical Engineer, Accelerator Technology Madison, WI

Help design the high-performance hardware powering the future of fusion energy. This Senior Mechanical Engineer will lead the mechanical design and integration of ion sources, high-voltage systems, and RF hardware supporting Realta’s technology development roadmap. This role will be a critical contributor to Realta’s first-of-a-kind fusion pilot plant, Hammir. The ideal candidate will work shoulder-to-shoulder with physicists, engineers, and technicians to commission and operate first-of-a-kind fusion experiments in a fast-moving environment. Realta Fusion is a rapidly growing start-up developing compact magnetic mirror fusion energy systems to address the biggest challenge of our time – tackling global climate change while ensuring a sufficient energy supply for at least ten billion people on (and off) earth. We are building a team with diverse talents dedicated to making fusion energy a real solution to humanity’s most pressing problem. Responsibilities

• Lead the mechanical design and integration of beamline components, ion source assemblies, extraction/acceleration grids, and associated accelerator equipment from concept through fabrication and commissioning.
• Design and specify high-voltage (HV) hardware – insulators, feedthroughs, HV power supplies, and ultra-high vacuum-compatible HV structures – ensuring reliable standoff and minimal breakdown risk.
• Own the mechanical design of RF components for accelerator systems, working closely with RF engineers to meet electromagnetic, thermal, and vacuum requirements.
• Perform thermal, structural, electromagnetic, and vacuum analysis (e.g., using Ansys or COMSOL) to validate designs against operational loads and performance targets.
• Design for ultra-high vacuum (UHV) compatibility, including material selection, bakeout procedures, and joint/seal design for ion source and beamline subsystems.
• Develop detailed mechanical drawings, tolerances, and specifications suitable for precision machining, vendor quoting, and in-house fabrication.
• Lead or support assembly, integration, troubleshooting, and testing of ion sources and accelerator subsystems, including HV conditioning and RF commissioning.
• Collaborate cross-functionally with physicists, RF/electrical engineers, and controls teams to translate physics requirements into manufacturable mechanical designs.
• Support design for manufacturability (DFM) and drive iterative improvements across prototype, first-build, and production phases.
• Contribute to technical documentation, safety protocols (HV and radiation safety), and design reviews.
• Mentor junior engineers and contribute to the technical growth of the mechanical engineering team.

Required Qualifications

• Education: BS in Mechanical Engineering or a related field, or equivalent experience
• Experience: 5–10+ years of relevant industry or national-lab experience, with demonstrated experience designing and building ion sources or particle accelerator components (linacs, cyclotrons, synchrotrons, or similar)
• Proficiency with CAD (SolidWorks, NX, or equivalent) and simulation tools (Ansys, COMSOL, or equivalent) for structural, thermal, and EM analysis
• Hands-on experience with UHV design practices, vacuum hardware, and vacuum system troubleshooting
• Familiarity with precision fabrication methods and GD&T for tight-tolerance, high-reliability hardware
• Ability to work in a fast-paced, multidisciplinary, and results-driven start-up environment
• Collaboration: Exceptional interpersonal and communication skills (written, verbal, public presentation) to collaborate effectively with colleagues, external partners, and stakeholders

Preferred Qualifications

• Master’s Degree or higher in Mechanical Engineering or related field
• Professional Engineering (PE) license
• Experience in designing for and working within radiation environments
• Experience with cryogenic systems for ultra-high vacuum applications
• Experience with high-voltage systems, megawatt-scale heating and cooling systems, and specialty materials for fusion or particle accelerator applications

Applicants who do not meet the entire job specification are encouraged to apply. Compensation & Benefits What we are working on is hard… and hugely important. Realta Fusion is assembling a talented team bound together by a passion to solve humanity’s biggest challenge with first-of-a-kind technology. Additionally, Realta offers:

• Competitive compensation package, including equity stock options
• Comprehensive benefits including health, dental, and vision insurance, plus a 401(k)
• Flexible paid time off (PTO) to support work-life balance
• Work and live in Madison, Wisconsin — one of America’s most livable and vibrant cities

We value diversity as a critical factor in innovation and believe a diverse team is necessary to solve the toughest problems. We aim to create an inclusive environment that unleashes the full creativity of our team members from a wide variety of backgrounds and experiences. We provide equal employment opportunities to all individuals based on merit and without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, disability, veteran status, or any other protected status under applicable laws.