Postdoc (all genders) – Development of Simulation Codes for High-Energy Laser Systems for Fusio[...]

The GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt operates one of the world’s leading particle accelerator facilities for fundamental research. Together with international partners, GSI is currently building FAIR (Facility for Antiproton and Ion Research), one of the largest research projects worldwide. GSI and FAIR offer the opportunity to work in an international environment within a dedicated team committed to scientific excellence.

Within the framework of the research project LASE-FUSE, we are seeking at the earliest possible date: Postdoc (all genders) – Development of Simulation Codes for High‑Energy Laser Systems for Fusion . Reference number: 26.75‑1700.

Project Context (LASE-FUSE)

Nuclear fusion has long been pursued as a sustainable and virtually inexhaustible energy source. Despite significant breakthroughs—such as the net energy gain achieved at the National Ignition Facility (NIF) through inertial confinement fusion (ICF)—the path toward an economically viable fusion power plant remains highly challenging. A key limitation of current approaches, particularly those based on indirect laser drive of fusion fuel capsules (“indirect drive”), is the inefficient conversion of laser energy into fusion‑relevant conditions. Direct‑drive concepts promise to overcome this limitation by eliminating the intermediate step of X‑ray conversion. However, they place exceptionally high demands on existing and future laser technologies. Given the complexity of such laser systems—strongly nonlinear and coupled processes along the entire laser chain, from amplification and beam shaping to pulse modulation—the development of predictive, holistic simulation tools is essential.

At the core of LASE‑FUSE is the development of a comprehensive simulation platform in the sense of a digital twin for a high‑energy laser facility. This platform virtually maps the behavior of real laser systems and serves as a predictive tool for system analysis, optimization, and rapid testing of new laser concepts developed and evaluated within the project. The goal is to create a flexible framework that integrates all stages of the laser chain and provides a realistic representation of system dynamics.

The advertised position plays a central role in the development and integration of advanced numerical models for realistic simulation of high‑energy laser systems within LASE‑FUSE.

Your Responsibilities

• Further development of the simulation software OPOSSUM ( for modeling complete high‑energy laser systems as a digital twin.
• Integration and optimization of amplification and transport models for pulses/beams in complex laser architectures.
• Implementation, maintenance, and further development of fusion‑specific codes—for example, for spectrally incoherent pulses and focal zooming—developed in the context of LASE‑FUSE PhD projects.
• Implementation of realistic detector system models and interfaces for experimental benchmarks.
• Design, construction, and support of experimental test setups to validate simulation approaches.
• Data analysis for validation and benchmarking of optical simulation models.
• Supervision and scientific mentoring of PhD students.
• Close collaboration with internal project partners (group leaders, postdocs, PhDs) and external partners from research and industry.
• Documentation and maintenance of developed codes in Git repositories.
• Publication of results in scientific journals and at international conferences.

Your Profile

• PhD in Physics, ideally with a focus on laser physics, optics, photonics, or a related field.
• Solid knowledge in numerical simulation, high‑energy laser technologies, and experimental implementation.
• Experience in the development and integration of scientific software.
• Strong programming skills, ideally in Rust, Python, or C++.
• Practical experience with optical laboratory systems desirable.
• Independent, structured working style, as well as teamwork and communication skills.
• Experience in supervising and mentoring junior researchers is advantageous.
• Good command of English, both written and spoken; knowledge of German or willingness to acquire it is a plus.

We Offer

• Employment at GSI within the LASE‑FUSE project, in close collaboration with national and international partners at FAIR and beyond.
• A central role in further developing a digital twin for high‑energy laser systems in the context of fusion.
• Participation in a highly topical research area in laser‑driven nuclear fusion.
• Freedom to contribute your own scientific concepts and ideas within the project structure.
• Opportunities for publication and participation in international conferences.
• Close collaboration with leading research institutions and industrial partners in the field of fusion energy.
• Flexible working conditions, including up to two days of remote work per week (depending on current tasks), and a good work–life balance.
• Access to a unique experimental environment and modern research infrastructures at GSI/FAIR.

The duration of the position is limited to 4.5 years (54 months).

GSI supports the vocational development of women. Therefore, women are especially encouraged to apply for this position. Handicapped persons will preferentially be considered when equally qualified.

For questions, please contact Dr. Yannik Zobus ( , Tel. ).