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Salary
$140k – $165k per year
Location
In office (Denver)
Seniority
Middle · 3+ years exp
Employment
Full-Time

Confirmed on the employer's own hiring board on Oct 4, 2026. First seen by Alion on Sep 29, 2026. Xcimer Energy scores A on the Alion truth index.

Overview
Company
Impact
Profile match
Xcimer Energy is a Denver-based company developing laser-driven inertial fusion power and high-energy laser systems for air defense, built around large electron-beam-pumped excimer lasers. In 2024 it began building Phoenix, its first high-energy laser system, in its Denver laser bay, it has had a fusion power plant preconceptual design milestone approved by the US Department of Energy, and RTX has invested in it to develop directed energy technology. It hires optical, laser, pulsed power and nuclear engineers, physicists and materials scientists, scientific software and data engineers, technicians, quality and supply chain leaders, and summer interns.

Xcimer Energy leverages decades of research on Inertial Fusion Energy (IFE) combined with groundbreaking new laser architecture. Our mission is to deploy fusion power plants to meet global decarbonization goals as fast as possible. Xcimer has assembled a team of leaders in tough tech, fusion science, and manufacturing with a track record of rapid execution. Supported by leading investors, Xcimer is uniquely positioned to deliver limitless, clean, fusion power to combat climate change. Join us in powering a better world with inertial fusion!

This is a full-time, onsite role based at our headquarters in Denver, CO.

We are welcoming applicants for a Cryophysicist position on Xcimer’s Fill and Injection Station Team. The successful candidate will join a growing group of engineers and scientists aimed at developing the processes and technologies to build a first of its kind Inertial Fusion Energy fueling station for Xcimer’s fusion reactor plant. In this role, you will lead the experimental and theoretical design, characterization, and optimization of physical systems operating at ultra-low temperatures. You will manage relations and work closely with collaborators from national labs and universities to drive research objectives that will critically impact future system design and architecture. This is an entry- to mid-level role focused on experimental and theoretical R&D.

Responsibilities

    Experimental Research

    • Design, build, and iterate on experiments aimed at advancing target filling processes and technologies.
    • Evaluate, analyze, and improve system designs aimed at streamlining rapid target throughput.
    • Own the documentation and management of internal test stands and their experiments.
    • Partner with a varied team of scientists, engineers, and designers to translate experience into realizable products.
    • Modeling and Simulation

      • Advance the team’s predictive capabilities utilizing COMSOL Multiphysics to model physical systems.
      • Leverage Python to develop in-house simulations for thermal transport, fluid flow, and materials interactions.
      • Provide insight into results from collaborators and internal experiments using analysis and modeling methods.
      • Own documentation and artifacts for developed models and simulations.
      • Work Share Rotation

        • Split your time between the Xcimer Fill and Injection Station team and our external collaborators.
        • Serve as the primary contact for the knowledge transfer between our collaborators and Xcimer.
        • Balance the role of being both mentor and mentee to both teams.
        • Research and Development

          • Provide fresh perspectives on challenging engineering problems concerning high pressure, high vacuum, and cryogenic environments.
          • Own research tasks which will help push the team’s understanding of system capabilities and risks.
          • Integrate into an agile team focused on advancing technologies through rapid prototyping and reliance on the build-test-fail-repeat methodology.

Qualification

    • Education: Master’s + 3 years experience or PhD in applied physics, engineering physics, mechanical engineering, aerospace engineering, vacuum engineering, or related field
    • Experience: 0 - 3+ years of experience in the fields of cryophysics, thermodynamics, superconducting magnetics, or similar background
    • Expertise in ultra low temperature engineering and design with a focus on thermal transport, mechanical compatibility, or liquefaction
    • Demonstrated experience on system design and integration teams.
    • Demonstrated experience working in laboratory environments and hands-on experience with ultra-low temperature installations.
    • Demonstrated experience building thermal, fluid flow, and materials models.
    • Experience with both wet and dry cryogenic systems.
    • Experience collaborating with a multidisciplinary team of engineers, scientists, and non-domain experts supporting system design.
    • Highly self-motivated, with the ability to work independently without guidance.
    • Advanced verbal and written communications skills.
    • Must be a U.S. citizen or national, U.S. permanent resident (current Green Card holder), or lawfully admitted into the E.S. as a refugee or granted asylum.

Desired

    • Familiarity with instrumentation controls and scripts, specifically PyVISA and SCPI commands.
    • Familiarity with project life-cycle management and the AGILE structure.
    • Cryogenics handling safety training.
    • Experience with vendor interactions and supply management.
    • Experience working in a start-up or quick paced environment.
    • Background supporting team expansion and providing mentoring to junior contributors.
    • Experience working on R&D teams or developing low TRL products.
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