Plasma-based accelerators now reliably produce high-energy electron beams at laser facilities in Sweden (Lund Laser Facility, Umeå Relativistic Attosecond Physics Lab) and elsewhere in Europe (Extreme Light Infrastructure, DESY, Apollon, Vulcan). The same infrastructure could be employed for “photon acceleration”, where the frequency and intensity of a laser pulse is upshifted while copropagating with a relativistic plasma wave. Photon acceleration will be the focus of upcoming experimental campaigns at the Extreme Light Infrastructure and Stanford Linear Accelerator starting next year, which we will support with the simulations performed here. Coherent XUV light has a variety of applications in basic science and industry, from attosecond spectroscopy to materials characterization and lithography (semiconductor manufacturing). Intense XUV laser light from a photon accelerator would open up a new quantum-mechanical regime for laser-plasma interactions, paving the way for more compact particle accelerators, coherent x-ray sources, and circularly polarized gamma-ray sources with applications in nuclear and particle physics. The collision of intense XUV laser light with ultrarelativistic electrons would reach a higher center-of-mass energy than currently available with optical lasers, indicating the onset of higher-order effects in strong-field Quantum Electrodynamics (QED) such as electron-positron pair cascades, radiative (loop) corrections, and the conjectured breakdown of perturbative QED, which has yet to be observed. Mattias Marklund, Tom Blackburn and Arkady Gonoskov have a long track record developing theory and numerical tools for high-intensity laser-plasma interactions. This project is a continuation of their research by Michael Quin, a postdoctoral researcher in the same group, with a focus on GPU-accelerated simulations. This project will focus on the following work packages (WPs): 1. Parameter scans of photon acceleration 2. Plasma-wakefield acceleration in solid targets 3. Collision simulations