Xcimer Energy
Develops inertial fusion power using laser
Mechanical Engineer - Pulsed Power
Onsite role based at the headquarters in Denver.
About the job
- A Bachelor of Science degree in Mechanical Engineering, Nuclear Engineering, Aerospace Engineering, or a related field.
- At least 3 years of mechanical engineering experience focused on high-voltage pulsed power design for complex hardware.
- Proficiency with 3D computer-aided design software, with NX preferred.
- Working knowledge of Finite Element Analysis.
- Experience designing simple printed circuit boards or flex circuits.
- Experience with complex integrated system design involving pulsed power, lasers, high-voltage systems, fusion energy, aerospace, or defense.
- Hands-on problem-solving, troubleshooting, and testing experience.
- U.S. citizenship or nationality, U.S. permanent residency, or lawful admission as a refugee or person granted asylum.
- Develop and specify pulsed power generator components to meet pulsed power requirements.
- Design equipment using NX CAD.
- Work with vendors for custom and off-the-shelf devices and instruments.
- Ensure functional integration of Marx and generator architecture and subsystems through analysis, documentation, and machine testing.
- Design and document generator parts, assemblies, lifting structures, oil plumbing and pumping, and structural supports using NX.
- Analyze designs with Finite Element Analysis to map external influences on components and assemblies.
- Create and maintain interface control documents.
- Lead design efforts for prototype systems and subsystems, including preliminary and final designs.
- Troubleshoot escalations and derive practical recommendations for improvements.
- Collaborate with mechanical, laser, controls, pulsed power, and optical engineering teams throughout the design and development process.
- Support procurement of hardware for laser amplifiers and support equipment.
- Oversee and assist with assembly, shakedown, testing, and failure analysis of pulsed power systems, laser amplifiers, and ancillary equipment.
- Provide operational support for pulsed power systems and equipment.
- Contribute to scaling designs for power-producing inertial fusion energy reactors and participate in concept studies for inertial fusion energy applications and beyond.
- Interdisciplinary engineering experience.
- Start-up experience.
- Electrostatic Finite Element Analysis.
About the company
Xcimer Energy develops inertial fusion energy technology aiming to generate fusion-powered electricity. Its system uses a 10+ megajoule KrF laser to ignite a hydrogen fusion target inside a HYLIFE-style liquid-wall chamber, which absorbs fusion energy and shields reactor walls for long life. The approach combines a high-energy laser, a consumable fusion target, and a liquid-wall chamber to pursue scalable, laser-driven inertial confinement fusion for power generation. The company’s goal is to make commercial fusion power a reality for utilities within the next decade.
Company Size
51-200
Company Stage
Series A
Total Funding
$117.8M
Headquarters
Denver, Colorado
Founded
2021
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Simplify's Take
What believers are saying
- Xcimer raised $100 million in June 2024 and nearly $200 million total.
- The company expanded Denver in May 2026 and planned to double headcount.
- DOE funding, June 2026 approval, and RTX backing improve financing and recruiting access.
What critics are saying
- Vulcan site selection slipped past 2025; further delays push commercialization beyond 2035.
- Athena needs multi-megajoule lasers, tritium breeding, and grid integration before any revenue.
- Any Phoenix-to-Anvil performance miss would strand Xcimer’s capital-intensive laser platform.
What makes Xcimer Energy unique
- Xcimer’s June 2026 DOE-approved Athena roadmap validates its KrF inertial-fusion architecture.
- Phoenix started operations June 3, 2026, proving 1-kJ excimer amplification and 38-meter SBS compression.
- RTX partnered September 9, 2026, giving Xcimer defense-market validation beyond fusion alone.
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Benefits
Health Insurance
Dental Insurance
Vision Insurance
Life Insurance
Disability Insurance
401(k) Company Match
Paid Vacation
Paid Sick Leave
Paid Holidays
Company Equity
Growth & Insights and Company News
6 month growth
↓ -3%1 year growth
↓ -3%2 year growth
↓ -3%RTX Ventures has made a minority investment in Xcimer Energy Corporation to support development of scalable pulsed-laser technologies. Xcimer has raised nearly $200 million from investors including Hedosophia and Breakthrough Energy Ventures. The companies signed a teaming agreement to explore integrating Xcimer's laser technology into RTX's defence systems for defeating airborne threats. Xcimer's fusion pilot power plant design was approved by the US Department of Energy in June as part of the Milestone-based Fusion Development Program. The excimer laser system aims to deliver longer-range performance at lower cost than current directed energy systems. Xcimer expects to deliver fusion energy to the grid by the mid-2030s. RTX's chief technology officer Juan de Bedout said the partnership will explore integrating Xcimer's technology with RTX's expertise in advanced sensing and air defence.
Xcimer Energy has secured US Department of Energy approval for its preconceptual design and technology roadmap for Athena, its fusion power plant architecture. The milestone, part of the DOE's Fusion Milestone Development Program, positions the Denver-based startup amongst frontrunners to commercialise fusion energy. Xcimer's 724-page submission detailed plant performance targets, economics, engineering requirements, safety analyses and development pathways. Athena integrates the company's proprietary excimer laser platform with target delivery, fusion chamber, tritium breeding and power generation systems designed for industrial scale. The approval follows Xcimer's launch of Phoenix, the world's largest privately owned laser system, at its 74,000-square-foot Denver facility. Founded in 2022, Xcimer is developing laser fusion technology targeting costs under $100 per joule with a chamber design requiring no first-wall replacement.
Fusion startup Xcimer Energy has activated its Phoenix laser system, which the company claims is the world's largest privately owned laser. The system uses excimer amplification to generate over one kilojoule of energy through a 38-metre-long krypton-fluoride laser core. Xcimer's approach mirrors the National Ignition Facility, which in December 2022 demonstrated a controlled fusion reaction producing more power than required to ignite it. The company aims to improve upon this concept using more powerful, less complex lasers that compress fuel targets in nanoseconds rather than microseconds. Phoenix represents an early step towards a commercial fusion power plant, which Xcimer estimates would require lasers exceeding 12 megajoules. The company plans to complete a prototype by 2028 and build its first commercial-scale power plant in the mid-2030s.
Xcimer Energy has hired Doug Kunzman as Vice President of Defence as the Denver-based fusion startup scales towards commercial operations. Kunzman brings extensive military and aerospace experience, including commanding US Navy warships and leading operations at Blue Origin and Astra. The company, which now employs nearly 200 people, plans to double its workforce over the next year to advance Vulcan, its next-generation laser fusion facility. Xcimer is developing excimer-laser architecture for scalable inertial fusion energy with applications in energy resilience and national security. Recent leadership additions include Brad Appel as Chief Engineer for Vulcan, previously CTO at Ursa Major and SpaceX; Justin Brynestad as Senior Vice President overseeing Vulcan programme execution; and Rachel Konrad as Senior Vice President of Strategic Communications. Founded in 2022, Xcimer has secured Department of Energy funding.
Xcimer Energy Inc. today announced that it has raised $100 million in Series A financing led by Hedosophia, with participation from investors includin