About Marathon Fusion

Marathon Fusion is building the technologies needed to make fusion practical. Our work spans high-flux fusion neutron sources for radioisotope production, fuel cycle technologies, and plant-level systems that will enable fusion power at climate-relevant scale.

We are developing compact, beam-driven fusion systems to produce radioisotopes for targeted cancer therapies and to test materials for future fusion power plants. Alongside this work, we develop stable isotope enrichment, tritium processing and recycling, and advanced blanket technologies to close the fusion fuel cycle and enable both energy generation and high-value co-products.

Founded in 2023, Marathon Fusion is advancing near-term applications of fusion in medicine and materials development while building the foundation for abundant, reliable energy in the 21st century.

Culture at Marathon Fusion

We are a startup environment characterized by a need for focus, adaptability and prioritization in a shifting landscape. Thriving in this environment requires excellent proactive communication across roles and backgrounds, the ability to build and maintain trust between team members, and the willingness to learn and develop new skills on the job. We place particularly high weight on each team member's ability to be self-directed.

Please review these points carefully before applying:

• This application is exclusively for the Engineering Physics - Ion Beam role.

• We provide both Internship and Co-op placements through this single posting.

• Application Deadline: December 2nd, 2026

Role Description:

You will join our R&D engineering team working on ion-beam development for neutron production and radioisotope transmutation. We are currently scaling neutron gun prototypes into a high-flux reactor, and will be upgrading our beam design and capabilities.

Role Responsibilities:

• Assisting with the development and implementation of a high-power ion beam.

• Designing components and assemblies for high-voltage operation while mitigating vacuum breakdown and improving beam optics

• Integrating fabricated and acquired components

• Building and modifying high-power electrical systems (corona-rings, diagnostic systems, and controls hardware) as well as control system software

Minimum Requirements:

• Studying mechanical/electrical engineering, physics, or engineering physics

• Or studying a related engineering/technical field and have exceptional work ethic, eagerness to learn, and autonomy

• Proficient with 3D CAD software (SolidWorks preferred)

• Have meaningful applied experience in areas such as fabrication, test engineering, vacuum systems operation, or similar

Preferred Requirements:

• Proficient at basic machine shop fabrication (lathe, mill, etc.)

• Proficient with basic electrostatic modeling

• Experience with high voltage electrical systems

• Experience with high vacuum systems

• Small-scale experiment development

Soft Skills:

• Ability to creatively and independently diagnose and solve issues

• Excellent written and oral communication

• Ability to think holistically about systems

• Capacity to learn new technical subjects quickly, collaborate cross-functionally, and consider problems from inter-disciplinary perspectives

• Organization and project management

• A high degree of conscientiousness and integrity

• Long-term vision while executing short-term goals

• Comfort with the inherent uncertainty of breakthrough technology

• Experimental mindset, ability to form and test hypotheses

Additional Desired Skills:

• Plasma physics

• High-power battery systems

• Fabrication for scientific applications

Compensation

Undergraduate interns are paid $27.88/hour. More experienced interns can earn up to $40.87/hour depending on qualifications.

Marathon Fusion considers all qualified applicants equally for employment. We do not discriminate on the basis of race, color, national origin, ancestry, citizenship status, protected veteran status, religion, physical or mental disability, marital status, sex, sexual orientation, gender identity or expression, age, or any other basis protected by law, ordinance, or regulation.