Collimated proton beams from laser interaction with a slab having a hole on its backside are investigated using particle-in-cell simulation. The hot target electrons driven by the laser expand rapidly into the hole. However, at the hole's corners the electrons are strongly compressed and an intense electron jet is emitted from each corner, tightly followed by the ions. The plasma jets focus and collimate along the axis of the hole and can propagate without divergence within the hole. The effect of the hole diameter on the collimated proton beam is considered.

We study proton acceleration from a foil target with a transversely varying density using multi-dimensional Particle-in-Cell (PIC) simulations. In order to reduce electron heating and deformation of the target, circularly polarized Gaussian laser pulses at intensities on the order of 1022 Wcm−2 are used. It is shown that when the target density distribution fits that of the laser intensity profile, protons accelerated from the center part of the target have quasi-monoenergetic spectra and are well collimated. In our two-dimensional PIC simulations, the final peak energy can be up to 1.4 GeV with the full-width of half maximum divergence cone of less than 4°. We observe highly efficient energy conversion from the laser to the protons in the simulations.

Cylindrical cryogenic targets are required to carry out the Laboratory Planetary Science scheme of the experiments of the High Energy Density matter Generated by Heavy Ion Beams collaboration at FAIR. In this paper, for the first time a thorough analysis of the problem of such targets' fabrication, delivery and positioning in the center of the experimental chamber has been made. Particular attention is paid to the issue of a specialized cryogenic system creation intended for rep-rate supply of the High Energy Density matter Generated by Heavy Ion Beams experiments with the cylindrical cryogenic targets.