Senior Mechanical Engineer - Test Infrastructure

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 a Senior Mechanical Engineer to lead the mechanical design, structural analysis, and physical implementation of core components and assemblies for our nuclear fusion demonstration system. In this role, you will take ownership of complex hardware from concept through detailed 3D CAD modeling, rigorous structural analysis, and final system integration. Working closely with physics, systems engineering, and manufacturing teams, you will tackle high-impact, high-precision engineering challenges to turn physics requirements into robust, high-performance hardware. What You'll Do

• Lead the end-to-end mechanical design, 3D CAD modeling, and detail engineering of complex high-performance components and assemblies.
• Perform hand calculations, first-principles mechanical design, and advanced finite element analysis.
• Translate high-level physics requirements, spatial constraints, and boundary conditions into robust engineering models and hardware specifications.
• Conduct detailed tolerance stack-up analyses and impact assessments on part variances to ensure strict design interface requirements are met.
• Apply Design for Manufacturability (DFM) and Design for Assembly (DFA) best practices to optimize performance, weight, cost, and lead times.
• Interface with cross-functional teams (physics, system integration, manufacturing) to resolve complex design trade-offs and mitigate technical risk.
• Prepare and maintain comprehensive engineering documentation, including fully dimensioned detail drawings (GD&T), and design review packages.

What You Bring

• Bachelor’s Degree in Mechanical Engineering required; Master’s or PhD is a plus.
• 5+ years of hands-on experience in mechanical design and structural/thermal analysis for complex hardware systems.
• Advanced proficiency in 3D CAD modeling software (e.g., Creo, SolidWorks).
• Extensive practical experience applying Finite Element Analysis software (e.g., ANSYS, Abaqus, or Creo Simulate) to evaluate stress, fatigue, thermal effects, and structural integrity.
• Deep understanding of GD&T (ASME Y14.5), tolerance stack-up analysis, and material selection for demanding environments.
• Strong knowledge of advanced manufacturing techniques (machining, additive manufacturing, precision welding) and DFM/DFA principles.
• Strong problem-solving capabilities with a solid foundation in engineering fundamentals.
• Excellent written and verbal communication skills, with a track record of cross-functional technical leadership.

Pay Range: $138,100—$263,800 USD

TOTAL COMPENSATION AND BENEFITS FOR ELIGIBLE EMPLOYEES

• Industry-competitive salary

• Equity plan

• 6% employer 401k matching

• Generous paid time off (including sick leave, vacation, paid family leave)

• Medical, Dental, and Vision insurance

Actual base salary offered will be determined by: experience, skills, and work location. This range is for base salary, our total compensation includes equity and benefits. We welcome you to apply even if your expectations are outside our listed range. EQUAL OPPORTUNTITY Pacific Fusion is committed to creating a diverse environment and is proud to be an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, gender, gender identity or expression, sexual orientation, national origin, genetics, disability, age, or veteran status. Pacific Fusion is committed to providing reasonable accommodations for qualified individuals with disabilities in our job application procedures and throughout employment. If you need assistance or any accommodation, please let us know. U.S. EXPORT CONTROL COMPLIANCE This position may require access to information or technology that is subject to U.S. export control laws, such as ITAR or EAR. Under these regulations, we are required to ensure that such access is provided only to individuals who are classified as 'U.S. Persons.'This status includes U.S. citizens, U.S. nationals, lawful permanent residents (green card holders), and asylees and refugees with such status granted, not pending.

RECRUITING AGENCIES Pacific Fusion does not accept unsolicited resumes from recruiters or employment agencies without a fully executed recruitment agreement in place. In the absence of such agreement, Pacific Fusion reserves the right to pursue and hire any candidates without an obligation to pay fees. Agencies are requested not to contact Pacific Fusion hiring managers or employees regarding recruiting services.