Please review these points carefully before applying:

• This application is exclusively for the Optical Diagnostics/Experimental Physics track.

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

• Application Deadline: April 7, 2026

About Marathon Fusion

Marathon Fusion is building the engineering technologies needed to scale fusion from breakeven experiments into real power plants. While much of the industry is focused on proving new fusion devices, our focus is on the practical systems that will make fusion deployable at climate-relevant scale.

We develop core fuel cycle and plant-level technologies for stable isotope production, fuel cycle closure, and advanced blanket systems that enable both energy generation and high-value co-products.

Founded in 2023, Marathon Fusion is building the components and systems that will help fusion become a practical, abundant, and reliable energy source for 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.

Technical Roles at Marathon Fusion

We are primarily interested in interns who are:

• Studying physics, and have meaningful hands-on experience in experimental physics, optical diagnostics, electro-magnetic probes, vacuum systems operation, or similar.

• Studying applied physics or electrical engineering, and have had meaningful exposure to physics, optical diagnostics and electro-magnetic probes through coursework, internships and projects.

• Studying a combination of both in a physics / engineering program, double major or similar and have exceptional work-ethic, eagerness to learn, and autonomy.

Optical Diagnostics/Experimental Physics Intern Role

This track combines optical/electro-magnetic diagnostics with hands-on experimentation on a plasma centrifuge apparatus. Successful candidates will work with optical, spectroscopic and electro-magnetic diagnostics to characterize plasma centrifuge.

Core Responsibilities and Focus Areas

• Experimental Physics: Setting up experiments and coordinating with relevant sub-systems owners: diagnostics, data acquisition and control systems, gas and vacuum equipment, for measurements of plasma properties.

• Diagnostics: Preparing optical and electro-magnetic diagnostics systems and experimental controls for measurements on plasma centrifuge.

• Testing and Iteration: Conducting measurements, collecting and analyzing data, and clearly communicating these results with the team to contribute to the development of plasma diagnostics systems.

Example Projects

Interns and Co-ops in this role have previously been involved in:

• Optical measurements of atomic or molecular spectra using spectrometers or interferometers.

• Electro-Magnetic measurements of plasma parameters using Langmuir probe.

• Alignment, calibration and testing of optical and imaging systems

Preferred (But Not Required) Experience

We don't expect, but would be particularly excited about any candidates with experience in the following: plasma physics, optics, spectroscopy, vacuum systems.

For all roles, important soft skills include:

• 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

Compensation

Undergraduate interns are paid $27.88/hour. More experienced interns can earn up to $43.27/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. If you need assistance or an accommodation during the interview process, please let us know.