Digital Twin Principal Scientist (f/m/d)

About Focused Energy Focused Energy is building the future of clean energy through laser-driven inertial fusion. Backed by our $240M Series A - the largest fully secured Series A in the global fusion industry - we are scaling rapidly across multiple geographies. Based in Germany and the US, we have brought together the top scientific and engineering minds using proven technologies to unlock fusion power at commercial scale. Focused Energy is working to realize game-changing scientific innovation that promises to deliver a clean, sustainable and abundant source of power globally. Your Role Focused Energy is advancing laser-driven inertial fusion energy (IFE) toward commercial power generation, and the credibility and velocity of that mission depend on our ability to model how the full IFE system behaves, where the physics risks lie, and what each subsystem must achieve for the plant to be economically viable. This role exists to and lead and participate in that capability. We are seeking a Principal Scientist to serve as the most senior technical authority on the Digital Twin team to bring together an integrated IFE system modeling environment which will be at the center of Focused Energy’s IFE plant design efforts. You will lead a team of scientists who develop and own the simulation codes for each major subsystem - laser, target, fusion chamber, target injection and tracking, and target manufacturing - and drive the synthesis of those subsystem models into a comprehensive, self-consistent plant-level simulation framework. That framework enables rigorous trade-off analysis across competing point design candidates and allocates quantitative performance budgets back to each subsystem, forming the physics foundation from which engineering requirements are derived. What You'll Do - Integrate the physics modeling efforts across all IFE subsystems — laser, target, chamber, target injection/tracking, and manufacturing. - Validate that subsystem code accurately captures the physics, with model uncertainty rigorously quantified and reported. - Set the scientific direction, modeling standards, and validation philosophy for the Digital Twin team. - Lead development of a comprehensive, integrated IFE plant model. - Work directly with the Science team on trade-off analyses across design candidates, identifying which design choices and parameters most affect plant viability. - Work with experimental physics teams to validate simulation codes against real shot data (our own, plus NIF, OMEGA, ELI, etc.). - Partner with the Digital Twin team and external collaborators (national labs, the broader IFE community) to keep our modeling at the frontier. - Present the modeling team's work to executive leadership, program management, and investors. Who You Are Must-haves - Master’s degree in Physics (with a specialization in Plasma, Laser, Nuclear, or related field); a Ph.D. is strongly preferred. - Deep expertise in IFE/ICF physics - e.g. target implosion design, laser-plasma interaction, hydrodynamic instability, burn physics, or chamber/neutronics - Track record developing, validating, and publishing physics simulation codes (hydrodynamic, radiation-hydrodynamics, PIC, ray tracing, Monte Carlo neutronics, etc.) - Strong programming skills (Python, Fortran, C++, or equivalent) and experience with HPC/large-scale simulation workflows. - Experience with integrated, systems-level modeling - coupling physics domains, managing code interfaces, uncertainty propagation, sensitivity analysis. Nice-to-haves - Strong scientific leadership - sets high standards and builds team confidence. - Clear communicator - can translate complex physics for execs, engineers, and external partners. - Systems-level thinker - sees how subsystem trade-offs affect the whole design. - Collaborative across physics, engineering, and software disciplines. - Comfortable making decisions under uncertainty and being transparent about confidence levels. - Familiarity with Digital Twin methods, reduced-order modeling, or physics-informed ML. - Published or patented work in IFE/ICF or related plasma/laser physics. - Experience with requirements flow-down, performance budgeting, or margin analysis. - Entrepreneurial, self-directed, energized by building things from scratch. - Comfortable engaging with execs, program managers, academics, and investors. - Genuinely mission-driven and energized by startup pace and ambiguity. What We Offer - Innovative Technology & Mission: Be part of a cutting-edge company working on groundbreaking research in clean energy and scientific discovery. - Career Development: We invest in our people. This is an opportunity to join an early, growing company at the forefront of new technology, where you’ll have the opportunity to develop and grow your career. - Collaborative Culture: Work with great people in a dynamic, international environment with top-tier scientists, engineers and professionals passionate about solving global challenges. - Ownership: Take ownership from day 1 and drive impact by making decisions, solving challenges and shaping the future of our company. - Your Success is our Success: We offer a competitive salary and company ownership in the form of stock options, giving you a direct stake in our success and ownership in what we build together. - Medical, Dental, Vision: Multiple great plans to pick from that are active come the 1st Day of employment for you and any enrolled dependents. - Vacation Days: We support your work-life-balance by granting you Unlimited PTO. - Snacks and Drinks: Our office fridges are never empty. Enjoy our healthy snacks and drinks. - Retirement Plan: If you decide to enroll in our 401k plan, we will match up to 4% on top of the employee contribution. - Equipment: We offer state-of-the-art Windows or Apple Laptops. In addition, you will receive a keyboard, mouse and headset so you are fully equipped from day 1. - Events: We organize regular events to foster team bonding, encourage collaboration, and build a strong, supportive company culture. Connect with colleagues across departments, share ideas, and have fun together, both in and outside of the workplace. Focused Energy is an equal opportunity employer committed to creating an inclusive environment. Qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender perception or identity, national origin, age, marital status, protected veteran status, or disability status. Pursuant to the San Francisco Fair Chance Ordinance, Focused Energy will consider for employment qualified applicants with arrest and conviction records. Compensation offered will be determined by factors such as location, level, job-related knowledge, skills, and experience. Certain roles may be eligible for incentive compensation, equity, benefits.