Proton acceleration: New developments in energy increase, focusing and energy selection

In the last few years, intense research has been conducted on laser-accelerated ion sources and their applications. These sources have exceptional properties, i.e. high brightness and high spectral cut-oft high directionality and laminarity, short burst duration. These proton sources open new opportunities for ion beam generation and control, and could stimulate development of compact ion accelerators for many applications. We have studied the variations of the proton acceleration characteristic time with target and laser parameters. We used these variations to correct one of the model recently developed to predict maximum energies of laser-accelerated protons for low energy, short duration laser pulses. We have also developed an ultra-fast laser-triggered micro-lens that allows tunable control of the beam divergence as well as energy selection, therefore solving two of the major problems that these proton beams were facing. We used PIC simulations to explain the focusing and energy selection mechanisms, and to study the symmetry of the expanding plasma inside the cylinder.