PIConGPU modeling of nanoplasma formation in helium nanodroplets irradiated by intense femtosecond laser pulses

Helium nanodroplets provide a unique and versatile platform for investigating strong-field-driven nanoplasma dynamics. In this work, we present large-scale, GPU-accelerated particle-in-cell simulations using $\text{textsc}PIConGPU$ to study the interaction of pure helium nanodroplets containing up to ${10}^6$ atoms with intense near-infrared femtosecond laser pulses, and compare the results with single-shot velocity-map electron imaging and ion measurements. The simulations describe the plasma evolution from the first ionization events to collective electron motion, nanoplasma formation, and early expansion. We show that the calculated electron and ion observables reproduce the main features of the measured spectra in systems with similar cluster sizes and laser intensities. Our results demonstrate that $\text{textsc}PIConGPU$ captures the essential physics of nanoplasma formation previously addressed mainly with molecular-dynamics or TDDFT approaches, while remaining computationally efficient and applicable to much larger systems. This establishes $\text{textsc}PIConGPU$ as a powerful and scalable tool for connecting nanoplasma theory with experimentally accessible observables.