Optimal Beam Loading in a Laser-Plasma Accelerator

Applications of laser-plasma accelerators demand low energy spread beams and high-efficiency operation. Achieving both requires flattening the accelerating fields by controlled beam loading plasma wave. Here, we optimize generation an electron bunch via localized ionization injection, such that combination injected current profile averaged acceleration dynamics results in optimal conditions. This enables reproducible production 1.2% rms bunches with 282 MeV 44 pC at estimated energy-transfer efficiency $\ensuremath{\sim}19%$. We correlate shot-to-shot variations to reveal phase space train a neural network predicts quality as function drive laser.