Simulated electron pulse properties. (a) and (b) Transverse electron beam emittance and energy width depending on the number of emitted electrons and the initial pulse durations. A linear scaling with the charge density is found. (c) Aspect ratio (longitudinal relative to transverse pulse width) of the electron pulse depending on the delay after arrival of the photoemission laser pulse at the tip apex. After photoemission, the pulse evolves from a conical to a disk-like shape. Blue curve: intensity profile of the photoemission laser. (d) Distribution of tangential electron velocities (i.e., velocity components perpendicular to the radius vector from the center of the spherical emitter apex) at a radial distance of $315$μm from the emitter for the space-charge-free regime (gray curve) and with Coulomb interactions (black curve, considering 2000 electrons/pulse and an initial pulse duration of $100 fs$⁠).