Mechanical Engineer
About the job
- A B.S. in Mechanical, Nuclear, or Aerospace Engineering, or a related field.
- Three to five years of mechanical engineering experience focused on industrial equipment design; preferred industries include semiconductor, solar, research and development, nuclear, fusion energy, lasers, and defense.
- Proficiency with 3D computer-aided design software; NX is preferred.
- Working knowledge of finite element analysis.
- Experience taking design projects through completion, build, and qualification.
- Strong problem-solving skills and a hands-on approach to troubleshooting and testing.
- Must be a U.S. citizen or national, U.S. permanent resident with a current Green Card, or lawfully admitted into the U.S. as a refugee or granted asylum.
- Create 3D models, detail part drawings and assemblies, and prepare P&IDs and interface control documents.
- Design structures and pressure vessels, and perform proof tests to code standards.
- Communicate and document designs with mechanical, systems, laser, optical engineering, and manufacturing team members.
- Support procurement of hardware for prototype laser amplifiers and optical conditioning equipment.
- Select sensors and instruments, and work with the controls team on integration.
- Oversee and assist a team of interdisciplinary technicians with assembly.
- Support ongoing operation of the equipment and systems.
- Continue these responsibilities through subsequent amplifier scale-up for a power-producing inertial fusion energy reactor.
- Participate in concept studies for using the lasers in a power-producing inertial fusion energy reactor and other applications.
- Contribute to authoring work instructions, test plans, specifications, and other documentation for integration and operation of complex systems of systems.
- Provide manufacturing and production support and support first-time engineering builds.
- Participate in design reviews and help streamline engineering processes.
- Work with cross-functional teams selecting materials, manufacturing processes, and suppliers to produce hardware.
- Plan, coordinate, and conduct tests, and review test data.
- Maintain and report on activity schedule, budget, and technical status.
- Identify opportunities for improvements and operational cost savings.
- Interdisciplinary engineering experience is a plus.
- Start-up experience is preferred.
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