Mechanical Engineer

Xcimer Energy

200

Denver, CO

Posted on: 2026-10-01

Category: energy

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Employment type:

Full time

Experience required:

Intermediate

Salary

$127,500.00 - $150,000.00

About the company:

Xcimer Energy is a fusion energy company focused on commercializing laser-driven inertial confinement fusion, which it describes as the only scientifically validated form of fusion energy. The company is developing high-energy excimer laser systems designed to ignite fusion reactions using fuel derived from seawater and lithium, with the goal of delivering safe, clean, and affordable electricity that is cost-competitive with fossil fuels and renewables. Its mission centers on decarbonizing energy-intensive sectors such as artificial intelligence infrastructure, desalination, and industrial processes that require firm, always-on, carbon-free power. Xcimer's technical approach relies on electron-beam-pumped excimer lasers combined with a pulse compression technique called Stimulated Brillouin Scattering (SBS), which compresses microsecond laser pulses to nanosecond durations without damaging optics. In 2024 the company broke ground on Phoenix, its first prototype high-energy laser system, located in Denver, Colorado, and announced the start of its operations in June 2026. Phoenix is the first electron-beam-pumped excimer laser built in the private sector in more than two decades and validates key elements of the company's low-cost laser fusion architecture. Xcimer's longer-term target is Athena, which it describes as the world's first laser fusion power plant, expected to deliver 400 megawatts of continuous clean energy by 2035. The company has received a U.S. Department of Energy approval of its fusion power plant preconceptual design and technology roadmap milestone, and collaborates with industrial partners such as TRUMPF Laser SE. With a team of nearly 200 engineers, physicists, and business professionals, Xcimer positions itself as the most technically mature private laser fusion company.

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.

As a Mechanical Engineer, you will play a critical role in the design, analysis, build, and operation of laser, pulsed power, vacuum vessel, and ancillary mechanical systems that are central to Xcimer’s excimer‑laser‑based IFE technology. You will contribute across the full product lifecycle—from early prototype systems through the design and demonstration of a power‑producing inertial fusion reactor. We are seeking engineers who bring strong technical depth, hands‑on problem-solving skills, and a passion for building high‑performance hardware that will redefine the future of energy.

Equal Employment Opportunity

Xcimer Energy is proud to be an Equal Opportunity/Affirmative Action Employer and is committed to attracting, retaining, and developing a highly qualified, diverse, and dedicated work force. Xcimer Energy hires and promotes people on the basis of their qualifications, performance, and abilities. We support the establishment and maintenance of a workplace that fosters trust, equality, and teamwork, in which all employees recognize and appreciate the diversity of individual team members. We provide all qualified applicants for employment and employees with equal opportunities for hire, promotion, and other terms and conditions of employment, regardless of their race, color, religion, gender, sexual orientation, gender identity, national origin/ethnicity, age, physical or mental disability, genetic factors, military/veteran status, or any other status or characteristic protected by federal, state, and/or local law. Xcimer Energy will consider for employment qualified applicants with criminal histories in a manner consistent with applicable federal, state, and local laws. For more information on “EEO Is the Law,” please see here and here.

Benefits

Xcimer offers a comprehensive benefits package designed to support employee health, well-being, and long-term success. Benefits include medical, dental, and vision coverage; basic and supplemental life insurance; short- and long-term disability; paid parental leave for employees at the time of birth or adoption; and a 401(k) with a company match of up to 6%. Eligible employees also receive equity, allowing them to share in the company’s long-term success.

Xcimer operates under a flexible Paid Time Off (ATO) approach. Rather than a fixed number of vacation days, employees are trusted to take the time they need to rest and recharge while meeting the expectations of their role and team. In addition, employees receive paid sick time, 13 company-paid holidays, and an annual paid company shutdown. Benefits are available to regular employees, including part-time and fixed-term roles, as well as interns, with eligibility varying by benefit.

Responsibilities

Create 3D models, detail part drawings, assemblies, P&ID’s and interface control documents.

Design structures and pressure vessels, perform proof-tests to code standards.

Communicate and document design with mechanical, systems, laser and optical engineering and manufacturing team members.

Support procurement of the hardware for the prototype laser amplifiers and optical conditioning equipment.

Selection of sensors and instruments, work with controls team for integration

Oversee and assist assembly by a team of interdisciplinary technicians.

Support ongoing operation of the subject equipment and systems.

Continue above roles and responsibilities to participate in subsequent amplifier up-scaling leading to that which is needed for a power-producing IFE reactor.

Participate in concept studies supporting the use of these lasers in a power-producing IFE reactor, and other applications.

Contribute to authoring work instructions, test plans, specifications, and other documentation for the integration and operation of complex systems of systems

Provide manufacturing and production support and first-time engineering builds

Participate in design reviews and help to streamline engineering processes

Work with cross-functional teams that are responsible for selecting materials, manufacturing processes, and suppliers to produce world class hardware.

Plan, coordinate, conduct tests, and review test data

Maintain and report on activity schedule, budget and technical status

Identify opportunities for improvements and operational cost savings

Qualifications

Education: B.S. in Mechanical, Nuclear, Aerospace Engineering, or related field.

Experience: 3-5 years in mechanical engineering, with a focus on industrial equipment design (preferred industries include semiconductor, solar, R+D, nuclear, fusion energy, lasers, defense).

Proficiency with 3D CAD software (NX preferred).

Working knowledge of Finite Element Analysis (FEA).

Experience getting design projects over the finish line, built, and qualified.

Strong problem-solving skills and a hands-on approach to troubleshooting and testing.

Interdisciplinary engineering experience is a plus.

Must be a U.S. citizen or national, U.S. permanent resident (current Green Card holder), or lawfully admitted into the U.S. as a refugee of granted asylum 

Desired

Start-up experience preferred

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