Senior Mechanical Engineer, Thermal

About the role

Helion is developing fusion power technology at its Everett facility to provide clean, reliable energy. This role owns the thermal and mechanical design of critical hardware for our fusion generators as we advance toward the Orion power plant. You will drive the technical specifications for thermal, fluid, and structural subsystems while applying first-principles thinking to complex engineering challenges. The position requires you to analyze past engineering efforts and conduct original testing to develop novel hardware solutions for demanding fusion environments. You will leverage advanced 3D CAD tools to create detailed fusion hardware designs and lead rigorous design reviews with cross-functional teams. Collaboration with floor technicians is essential as you implement and assemble your designs into physical systems. You will diagnose and resolve performance issues on integrated fusion generators to ensure hardware reliability and operational success.

Key facts

What you'll do

• Take ownership of thermal, fluid, and structural subsystem designs and refine their technical specifications to meet fusion power requirements.
• Develop novel hardware solutions by analyzing past engineering efforts and conducting original tests that validate performance under extreme conditions.
• Create fusion hardware designs using 3D CAD software like NX, ensuring geometric accuracy and manufacturability for complex components.
• Execute 1D, 2D, and 3D analyses using tools such as ANSYS to evaluate thermal, fluid, and structural behavior of fusion systems.
• Lead design reviews to iterate on systems, presenting findings and recommendations to engineering stakeholders for decision making.
• Collaborate with technicians on the floor to implement and assemble your designs, translating digital models into physical hardware.
• Diagnose and resolve hardware performance issues on integrated fusion generators using data analysis and root cause investigation methods.
• Apply first-principles engineering to evaluate thermal pathways, heat transfer coefficients, and material behavior in high-flux environments.
• Manage schedule responsibility for mechanical engineering projects, ensuring deliverables align with program milestones and technical goals.
• Utilize advanced proficiency with CAD software such as NX or Solidworks to produce detailed drawings and assemblies for manufacturing.
• Partner with cross-functional teams to align thermal and mechanical designs with electrical, vacuum, and control system requirements.
• Support the development of testing protocols that validate thermal and mechanical performance of fusion hardware prototypes.
• Document design decisions, analysis results, and test outcomes in comprehensive engineering reports for internal and external review.
• Mentor junior engineers by providing technical guidance on thermal analysis methods and mechanical design best practices.

Requirements

• Bachelor degree in engineering from an accredited institution is required for this role.
• Minimum 7 years of professional experience managing full-scope engineering projects, including schedule responsibility and delivery against timelines.
• Demonstrated ability to apply first-principles and method-based thinking to complex technical challenges in a fusion or advanced energy environment.
• Practical experience across mechanical, thermal, and fluid engineering disciplines with a proven track record of successful implementation.
• Advanced proficiency with CAD software such as NX or Solidworks, including the ability to create detailed models and assemblies.
• Strong background in thermal analysis, including heat transfer mechanisms, thermal stress, and high-temperature material behavior.
• Experience with fluid engineering principles such as fluid flow, pressure drop, and heat transfer in closed and open systems.
• Familiarity with structural design methods for mechanical components subjected to dynamic and static loading conditions.
• Ability to execute and interpret results from 1D, 2D, and 3D analyses using ANSYS or similar engineering simulation tools.
• Commitment to maintaining rigorous documentation standards and adhering to engineering best practices and company procedures.
• Willingness to work onsite at the Everett facility, collaborating closely with multidisciplinary teams in a fast-paced environment.
• Capacity to manage multiple priorities and deliver high-quality engineering solutions under tight project schedules.
• Alignment with Helion's mission to develop fusion power technology as a clean, reliable energy source for the future.

Practical notes

This role requires onsite presence at the Everett, WA facility due to the hands-on nature of hardware development and collaboration with production technicians. The position is full-time and offers comprehensive benefits including medical, dental, and vision coverage for families, 31 days of PTO (21 vacation, 10 sick), 10 paid holidays plus a winter break, a 5% 401(k) match, disability and life insurance, and 16 weeks of paid parental leave. An annual wellness stipend is also provided to support personal health and fitness goals. Helion is an equal opportunity employer, welcoming diverse candidates who share a passion for advancing fusion energy technology. Applicants must submit current contact information and relevant documentation as part of the hiring process, and hiring decisions will be based on qualifications and demonstrated ability to meet the outlined responsibilities.