Title: Digital Twins for Laser-Plasma Wakefield Acceleration
Abstract: Laser-plasma wakefield acceleration compresses tens of meters of conventional accelerator into several centimeters of plasma, but progress is complicated by the complex, multi-physics nature of the problem, making prediction, design, and control difficult. As part of a DOE Genesis Mission Phase I effort, we are building a digital twin of a 10 GeV acceleration process spanning gas ionization, plasma channel formation, and wakefield acceleration, learning from multi-fidelity simulation ensembles and multi-modal datasets. The methodological problems this raises include deploying sampling strategies when simulation cost varies by four orders of magnitude across coupled stages, propagating uncertainty through a chain of learned models, handling models whose inputs and outputs are fields and images rather than scalars, and solving the inverse problem of recovering unmeasurable plasma parameters from the diagnostics an experiment actually records. Training on simulations rather than on experimental data alone encodes our physics understanding into the model, so we can interpret results and identify where missing physics drives discrepancies. By the end of Phase I we will have a digital twin aimed at design optimization of novel acceleration configurations to be deployed at experimental facilities in Phase II.
Bio: Blagoje Djordjević is a Staff Scientist in the Design Physics Division at Lawrence Livermore National Laboratory (LLNL), where he studies short-pulse laser-plasma interactions, inertial confinement fusion, and machine learning for high-energy-density (HED) physics. His work spans kinetic to hydrodynamic scales, from particle-in-cell modeling of laser-driven particle acceleration to integrated radiation-magnetohydrodynamic hohlraum calculations. He builds simulation ensembles to train neural-network surrogate models that design and optimize high-repetition-rate HED experiments. He joined LLNL in 2020 after earning his Ph.D. in physics from the University of California, Berkeley, where he studied laser wakefield acceleration. He also holds M.S. degrees from Luleå University of Technology and Université Toulouse III and B.A. and B.S. degrees from the University of Texas at Austin.
Notes: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, as part of the Genesis Mission National Science and Technology Challenges under Award Number 294844. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344