Xcimer Energy is an inertial fusion energy company based in Denver, Colorado. Founded in 2022 by MIT alumni Conner Galloway and Alexander Valys, Xcimer is building the world’s most powerful laser to commercialize laser fusion — the only fusion approach that has ever achieved scientific breakeven in the laboratory.
Laser fusion — also called inertial confinement fusion (ICF) or inertial fusion energy (IFE) — uses powerful laser beams to compress and ignite a small fuel capsule containing hydrogen isotopes, triggering a fusion reaction. It is the only fusion approach that has ever achieved scientific breakeven in a laboratory setting, demonstrated at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory in December 2022.
Xcimer’s system has three primary elements: (1) a 10+ MJ krypton-fluoride excimer laser driver; (2) a fusion fuel capsule containing deuterium-tritium (DT) hydrogen fuel, larger and more robust but using the same fusion physics as NIF’s capsules; and (3) a HYLIFE-III fusion chamber, which uses a flowing lithium salt to absorb fusion energy and protect the chamber walls from neutrons — minimizing maintenance and reducing waste.
An excimer laser uses a mixture of noble gases (in Xcimer’s case, krypton and fluorine) as the lasing medium. Excimer lasers have been commercially proven at scale in semiconductor manufacturing and other industrial and medical applications for decades. Xcimer’s electron-beam-pumped excimer architecture provides unique advantages in output energy, scalability and industrialization compared to conventional solid-state laser designs — at a fraction of the cost.
Yes. Xcimer built its first electron-beam excimer laser in 2024, and a second larger system in 2025. Both systems are the first e-beam-pumped excimer lasers built in the private sector, and the first built anywhere in the world in over 20 years. Both systems have achieved record-setting results and are operating in Xcimer’s Denver facility.
Xcimer is building toward commercial fusion energy through four major milestones:
Phoenix (2026, Denver): Demonstration of core laser technology and laser architecture.
Anvil (2028, Denver): 200 kJ, two-sided inertial fusion energy (IFE) excimer beamline demonstrator. Anvil will use Argos laser modules, the largest laser amplifiers in the world and the first production units that will be used in a commercial laser fusion facility.
Vulcan (2031, site TBD): An engineering (wall-plug) breakeven demonstration – combining many Argos laser modules to achieve 4 MJ of laser light on-target and demonstrate net energy gain from laser fusion for the first time. Vulcan will be the world’s largest laser, and upgradeable up to 12 MJ of laser energy (6x larger than NIF).
Athena (2035, site TBD): The first laser fusion power plant, delivering 400 MW of electricity to the grid.
Wall-plug breakeven means a fusion machine produces more electricity than it consumes to operate — including all the energy used to power components like a laser. NIF achieved scientific breakeven (more energy from the fusion fuel than laser energy input), but not yet wall-plug breakeven. Xcimer’s Vulcan system is designed to achieve this milestone by 2031.
Xcimer’s economics are driven by several interrelated advantages: a 30x reduction in laser cost per joule versus NIF; larger, higher-gain fuel capsules; lower repetition rates; and a self-protecting liquid lithium salt chamber that minimizes maintenance. Together these make a commercial fusion power plant economically competitive with fossil fuels and superior to intermittent renewables.
Xcimer’s roadmap to wall-plug breakeven by 2031 and grid power by 2035 is among the most aggressive in the industry — and uniquely grounded in experimentally validated science. Xcimer builds on NIF’s proven ignition results rather than unproven plasma confinement physics, which reduces technical risk significantly.
The National Ignition Facility uses solid-state glass lasers, which are expensive to build and operate. Xcimer uses a krypton fluoride (KrF) gas excimer laser architecture — the same technology that powers semiconductor lithography equipment. This reduces cost per joule by more than 30x compared to NIF, while enabling a much higher-energy laser with a smaller optical footprint.
Yes. Xcimer’s laser technology has significant national security applications, including Nuclear Weapons Effects Testing (NWET) and stockpile stewardship. The Xcimer laser is expected to contribute to full-system survivability testing that will rival the capability of pre-1992 underground nuclear tests — without returning to underground testing. Directed energy applications are also in development.
Yes. Each fuel capsule contains only a few milligrams of hydrogen fuel, and only one capsule is in the chamber at a time. Laser fusion requires precise conditions to ignite and burns for only a few billionths of a second. There is no possibility of an uncontrolled or runaway reaction.
Laser fusion uses deuterium and tritium — isotopes of hydrogen. Deuterium is derived from seawater; tritium is produced from lithium. Both are effectively limitless: humanity has enough of these resources to last millions of years. A single gram of hydrogen isotopes yields the same energy as 11 metric tons of coal.
Xcimer was co-founded by Conner Galloway (CEO, CSO) and Alexander Valys (CTO, President). They were undergraduate roommates at MIT and later worked together at Los Alamos National Laboratory. Conner has worked in inertial fusion since 2009, with deep expertise in radiation hydrodynamics and laser system architecture. Alex has built early-stage technology startups since 2002 across fusion, healthcare, and AI.
Xcimer is headquartered in Denver, Colorado, with manufacturing operations in Tucson, Arizona. We partner with numerous national labs, universities, and corporations, including Los Alamos National Laboratory, Lawrence Livermore National Laboratory, Oak Ridge National Laboratory, the Naval Research Laboratory, MIT, University of Rochester, the Naval Research Laboratory, General Atomics, Westinghouse, and others.
More than 150 people work for Xcimer, including engineers, scientists, technicians, and other professionals. The team spans expertise in laser physics, fusion science, pulsed power, optics, materials science, operations, and manufacturing — drawn from national laboratories, aerospace, semiconductor lithography, and academia worldwide.
Open positions are posted on our frequently refreshed Careers page. Send inquiries to careers@xcimer.energy.
Yes. Xcimer runs one of the most competitive internship programs in the energy sector, giving the next generation hands-on experience in fusion science and engineering. And we have a track record of hiring many interns into full-time roles after graduation or completion of their academic studies. More information about our competitive internship program: xcimer.energy/internships
Yes. As we expand, we are increasingly hiring world-class employees in non-technical business roles, including HR, finance, government relations, and business development.
Xcimer’s culture is built around four core values:
Respectful Critique (we invite debate and require honesty, but never tolerate disrespect);
Humble Ambition (we aim to do great things while acknowledging we stand on the shoulders of giants);
Accountable Trust (we give each other real ownership and hold each other to commitments);
Rigorous Urgency (we move fast without compromising standards in an unforgiving discipline).
All full-time employees receive competitive pay, equity compensation, and comprehensive benefits including health, dental, and vision insurance; flexible spending accounts; short- and long-term disability; life and AD&D insurance; employer-matched 401K; up to 12 weeks paid parental leave; 13 paid company holidays; generous sick leave and vacation; relocation assistance; professional growth opportunities; free lunch Tuesdays and Thursdays; and a dog-friendly workplace.
Xcimer is headquartered in Denver, Colorado, with manufacturing operations in Tucson, Arizona.
Xcimer has raised nearly $200 million in its seed and Series A rounds from leading technology and climate investors including Hedosophia, Breakthrough Energy Ventures, Lowercarbon Capital, Prelude Ventures, Emerson Collective, Starlight Ventures, Wireframe Ventures, Leitmotif Ventures, and Gigascale Capital.
Xcimer is backed by nearly $200M from the world’s leading energy and technology investors. We occasionally make room for partners who bring strategic value beyond capital. investors@xcimer.energy