Senior R&D Test Engineer - Fluid Systems

Commonwealth Fusion Systems; Harvard (MA); On-site; USD 90,000 - 145,000; Full time

Benefits offered by this job

Health, dental, and vision insurance

401(k) with employer matching

Parental leave

Flexible vacation days

Team-building activities

Job summary

Commonwealth Fusion Systems is seeking an Senior R&D Test Engineer to develop novel fluid systems for R&D test stands, focused on supporting magnet testing. You will work on liquids, gases, cryogenics, or molten salts, using off‑the‑shelf and custom hardware with tight timelines.

The role involves designing, building, and operating test systems, collaborating across production, R&D, procurement, and the SPARC team, with opportunities to apply structures and materials ideas to mitigate risks.

Qualifications

• Bachelor's degree in mechanical, chemical, process engineering, or closely related field.
• 7+ years of experience in engineering of integrated fluid/mechanical systems.
• Hands‑on experience with full lifecycle of large-scale thermofluid systems.

Responsibilities

• Design fluid systems for test stands meeting objectives and requirements.
• Develop de-risking strategies to simplify designs.
• Perform hand calculations and run ANSYS simulations for components and assemblies.
• Procure off-the-shelf components and design custom fluid system parts.
• Manage build and commissioning of fluid systems with engineers and technicians.
• Design instrumentation and automation for safe operations.

Skills

Fluid systems design

Test engineering

Cross-functional teamwork

Problem solving

Education

Bachelor's degree in mechanical or chemical engineering

Tools

ANSYS

COMSOL

Python

MATLAB

Job description

About Commonwealth Fusion Systems:

Commonwealth Fusion Systems is on a mission to deliver the urgent transition to fusion energy.

Combining decades of research, top talent, and new technologies, we’re designing and building commercially viable fusion power plants. And we're working with policymakers, suppliers, and many others to build the energy industry of the future.

We’re in the best position to make it happen. Since 2018, we’ve raised $4 billion of capital, making us the largest and leading fusion company in the world.

Now we’re looking for more thinkers, doers, builders, and makers to join us. People who’ll bring new perspectives, solve tough problems, and thrive as part of a team.

If that’s you and this role fits, we want to hear from you.

Join the power movement as an Senior R&D Test Engineer

The role of an Senior R&D Test Engineer is to develop novel fluid systems for R&D test stands, with a major focus on supporting magnet testing. The range of process fluids is broad (liquid, gaseous, cryogenic, supercritical, molten salt, etc.), requiring strong mechanical and chemical engineering fundamentals. The ideal candidate will be resourceful—combining industry best practices, off-the-shelf and customized hardware, and creativity to deliver these fluid systems on tight timelines.

Projects will be on varying scales, from smaller-scale test stands and deep system analysis to larger, complex projects as needed for SPARC and ARC. In addition to designing and building, the engineer will actively operate as a test engineer to commission systems and design automation alongside a team of test/software engineers and operators. You must work collaboratively across production, R&D, procurement, and the SPARC team. Various projects will also require flexing outside of traditional fluids engineering into other disciplines, such as structures and materials engineering, to successfully retire risks for SPARC and ARC.

What you’ll do:

• Design fluid systems for test stands that meet test objectives/requirements, soliciting feedback from interfacing teams as necessary
• Challenge requirements as necessary to achieve simplicity in design and develop efficient de-risking strategies and plans
• Perform hand calculations and system level analyses demonstrating sufficient margin for fluid system requirements; build and run Ansys structural and thermal simulations on components and assemblies
• Procure off-the-shelf process fluid components, manage relationships with vendors, draft specifications for speciality parts and design custom fluid system components as needed
• Manage the build and commissioning of fluid systems, coordinating engineers and technicians to safely bring systems to operational status
• Design system instrumentation and automation for safe operations

What we’re looking for:

• Bachelor’s degree in mechanical, chemical, process engineering, or a closely related field
• 7+ years of experience in the engineering of integrated fluid/mechanical systems (experience with both small-scale rapid R&D and large-scale systems is highly desired)
• Full-lifecycle fluid systems:
  • Hands‑on experience executing the entire lifecycle of large-scale thermofluid systems
• Component expertise:
  • Experience developing specifications, sizing and working with tanks, process piping, pumps, valves, compressors, purification stages, circulators, heat exchangers, etc.
• Design documentation:
  • Strong background in establishing system requirements, generating process flow diagrams (PFDs), and developing piping and instrumentation diagrams (P&IDs)
• Instrumentation:
  • Experience in the design, integration, and troubleshooting of system instrumentation
• Software and analysis tools:
  • Experience utilizing engineering tools such as ANSYS, COMSOL, 1D compressible flow codes, Python and MATLAB
• Extreme environments:
  • Practical experience designing, building, and commissioning fluid systems for specialized pressurized, cryogenic, vacuum, and/or elevated-temperature applications
• Vendor relations:
  • Experience sourcing complex components, drafting technical specifications, and managing relationships with specialized vendors and suppliers
• Cross-functional communication:
  • Strong ability to distill complex fluid system details and effectively communicate to non‑experts and interfacing teams across R&D, production, and procurement
• Problem solving:
  • Highly driven to challenge assumptions, make efficient technical decisions, and develop innovative solutions on tight timelines

Bonus points for:

• Adaptability:
  • Ability to flex into adjacent engineering disciplines, such as structures or materials, when required to help retire risks for SPARC and ARC
• Process optimization:
  • Strong aptitude for identifying bottlenecks and improving throughput during system designs, builds, and commissioning operations

Must-have requirements:

• Ability to occasionally lift up to 50 lbs
• Perform activities such as stooping, climbing, typing, standing, or sitting for extended periods of time
• Dedication to safety to mitigate industrial hazards that may include heat, cold, noise, fumes, strong magnets, lead (Pb), high voltage, and cryogenics
• Willingness to travel or work required nights/weekends/on‑call occasionally

$90,000 - $145,000 a year

Benefits include:

• Competitive compensation with equity
• 13 Company-wide Holidays
• Flexible vacation days
• 10 sick days
• Generous parental leave policy
• Health, dental, and vision insurance
• 401(k) with employer matching
• Professional growth opportunities
• Team-building activities

#LI-Onsite

At CFS, we excel in fast-paced environments, driven by our values of integrity, execution, impact, and self-critique. As we grow, we’re eager to bring on mission-driven folks who offer diverse perspectives and fresh ways to tackle challenges.

We value diversity deeply and are proud to be an equal opportunity employer by choice. We consider all qualified applicants equally, regardless 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.

This role requires compliance with U.S. laws concerning the export of controlled or protected technologies or information (collectively, “Export Control Laws") Any offer of employment will be contingent on the need for compliance with such Export Control Laws.