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Ion bursts, accelerated by an ultrafast (40 fs) laser-assisted target normal sheath acceleration mechanism, can be adjusted so as to deliver a nearly pure proton beam. Such laser-driven proton bursts have predominantly a low transverse emittance and a broad kinetic spectrum suitable for continuous probing of the temporal evolution of spatially extended electric fields that arise after laser irradiation of thin foils. Fields with a strength of up to 10^10 V/m were measured with a new streaklike proton deflectometry setup. The data show the temporal and spatial evolution of electric fields that are due to target charge-up and ion-front expansion following intense laser-target interaction at intensities of 10^17-10^18 W/cm^2. Measurement of the field evolution is important to gain further insight into lateral electron-transport processes and the influence of field dynamics on ion beam properties.

Laser-accelerated ion sources have exceptional properties and could stimulate development of compact ion accelerators. For many applications beam control is an essential requirement. A new and interesting technique to control proton beam characteristics has been recently developed. It consists in using an ultrafast laser-triggered micro-lens, which provides simultaneous energy selection and focusing of the incoming ion beam and is tunable. Particle-in-cell simulations coupled with particle tracing are used to model the focusing and energy selection mechanisms, and to study the symmetry of the expanding plasma inside the micro-lens. The model developed is able to reproduce and explain the experimental results obtained at the Laboratoire pour l'Utilisation des Lasers Intenses in France.