Intensity and dimensionality-dependent dynamics of laser-proton acceleration in 1D, 2D, and 3D particle-in-cell simulations

Due to the high computational cost of 3D particle-in-cell (PIC) simulations, lower dimensional (2D or 1D) simulations are frequently used in their place. Our work shows that when modeling high-intensity laser ion acceleration, simulation dimensionality interfaces with laser intensity in the dynamics of ion acceleration at every step of the process, from laser absorption through particle acceleration. We expand on previous studies by comparing the behavior of 1D and 2D simulations (of different polarization) with 3D PIC simulations at high resolutions across five orders of magnitude of laser intensity, enabling us to study multiple regimes of laser-proton acceleration. We find that key output metrics such as maximum proton energy depend on a complex interplay of both simulation dimensionality and laser intensity regime. Differences between simulation predictions generally increase for higher laser intensity regimes, making 3D simulations especially important for quantitative predictions of next-generation laser experiments.