Director of Fusion Nuclear Science

Xcimer Energy

200

Denver, CO

Posted on: 2026-08-25

Category: energy

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Employment type:

Full time

Experience required:

Director

Salary

$220,000.00 - $260,000.00

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.

The Director of Fusion Nuclear Science provides strategic, technical, and organizational leadership for the scientific disciplines that enable the realization and industrialization of practical fusion power systems. This leader will define and execute the long‑term scientific roadmap supporting fusion chamber dynamics, blanket multi-physics, tritium science, and other critical fusion nuclear science domains needed to deliver Xcimer’s next‑generation fusion energy platform.

The successful candidate will recruit, build, and mentor multidisciplinary world‑class scientific teams; establish long-term scientific roadmap; and ensure that cutting‑edge research translates into validated models, experimental data, and actionable design guidance. This role partners closely with program and engineering leadership, and other science department directors, while serving as the company’s primary authority for fusion nuclear science.

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

Build, lead and grow the Fusion Nuclear Science department, including hiring, onboarding, mentoring, and professional development of scientific staff.

Define and own the scientific roadmap for fusion chamber dynamics, blanket multi-physics, tritium science, and supporting fusion nuclear science domains.

Develop the strategy for scientific tools, modeling frameworks, experimental capabilities, and validation infrastructure.

Oversee scientific analysis, modeling, code development, and experimental programs with strong emphasis on reproducibility, uncertainty quantification, and model credibility.

Translate scientific insights, experimental data, and validated models into design guidance for engineering teams responsible for fusion system architecture.

Collaborate closely with the engineering and operations divisions, and with other science departments, to ensure strong communication and alignment.

Evaluate emerging scientific opportunities and integrate advances from academia, national laboratories, and international fusion programs.

Manage relationships with external laboratories, university collaborators, and vendors providing modeling tools, experimental facilities, or other fusion nuclear science scope.

Establish department‑wide scientific best practices, documentation standards, review processes, and quality expectations appropriate for industrial fusion systems.

Identify key scientific risks across fusion nuclear science programs and drive mitigation strategies supporting execution and long‑term scalability.

Support system troubleshooting, root‑cause investigations, and scientific review of failures or anomalies encountered in development or experimental operations.

Align fusion nuclear science priorities with company strategy, program schedules, resource constraints, and commercialization goals in partnership with executive leadership.

Qualifications

Education: PhD in Nuclear Science, Nuclear Engineering, Nuclear Physics, or a closely related field.

Experience: 12+ years of experience in analysis, simulation, experimental R&D, or technology development for complex nuclear or fusion systems under extreme thermal and radiation environments.

Leadership: 6+ years in leadership of multidisciplinary scientific or R&D organizations.

Deep experience with nuclear analysis tools (e.g., MCNP), multi‑physics simulation software (e.g., COMSOL, ANSYS), and reactor thermohydraulic codes (e.g., RELAP, MELCOR).

Experience designing and executing experiments that raise component or system technology readiness.

Proven record of mentoring and growing high-performing technical teams.

Strong publication and scientific leadership record.

Ability to operate effectively within a rapidly evolving organization transitioning from startup to industrial scale.

Ability to balance hands‑on scientific leadership with high‑level strategic direction and organizational oversight.

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 or granted asylum.