Synchronized off-harmonic probe laser with highly variable pulse duration for laser-plasma interaction experiments

This paper presents the development and experimental utilization of a synchronized off-harmonic laser system designed as a probe for ultra-intense laser±plasma interaction experiments. The system exhibits a novel seed-generation design,allowing for a variable pulse duration spanning over more than three orders of magnitude, from 3.45 picoseconds to 10 nanoseconds. This makes it suitable for various plasma diagnostics and visualization techniques. In a side-view configuration, the laser was employed for interferometry and streaked shadowgraphy of a laser-induced plasma while successfully suppressing the self-emission background of the laser±plasma interaction, resulting in a signal-to-self-emission ratio of 110 for this setup. These properties enable the probe to yield valuable insights into the plasma dynamics and interactions at the PHELIX facility and to be deployed at various laser facilities due to its easy-to-implement design.

Ultra-compact post-compressor on-shot wavefront measurement for beam correction at PHELIX

In order to reach the highest intensities,modern laser systems use adaptive optics to control their beam quality.Ideally,the focal spot is optimized after the compression stage of the system in order to avoid spatio-temporal couplings.This also requires a wavefront sensor after the compressor,which should be able to measure the wavefront on-shot.At PHELIX,we have developed an ultra-compact post-compressor beam diagnostic due to strict space constraints,measuring the wavefront over the full aperture of 28 cm.This system features all-reflective imaging beam transport and a high dynamic range in order to measure the wavefront in alignment mode as well as on shot.

Enhancement of the laser-driven proton source at PHELIX

We present a study of laser-driven ion acceleration with micrometre and sub-micrometre thick targets,which focuses on the enhancement of the maximum proton energy and the total number of accelerated particles at the PHELIX facility.Using laser pulses with a nanosecond temporal contrast of up to 10^-12 and an intensity of the order of 1020 W/cm^2,proton energies up to 93 MeV are achieved.Additionally,the conversion efficiency at 45°incidence angle was increased when changing the laser polarization to p,enabling similar proton energies and particle numbers as in the case of normal incidence and s-polarization,but reducing the debris on the last focusing optic.

High-energy laser facility PHELIX at GSI:latest advances and extended capabilities

The high-energy/high-intensity laser facility PHELIX of the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt,Germany,has been in operation since 2008.Here,we review the current system performance,which is the result of continuous development and further improvement.Through its versatile frontend architecture,PHELIX can be operated in both long-and short-pulse modes,corresponding to ns-pulses with up to 1 kJ pulse energy and sub-ps,200 J pulses,respectively.In the short-pulse mode,the excellent temporal contrast and the control over the wavefront make PHELIX an ideal driver for secondary sources of high-energy ions,neutrons,electrons and X-rays.The long-pulse mode is mainly used for plasma heating,which can then be probed by the heavy-ion beam of the linear accelerator of GSI.In addition,PHELIX can now be used to generate X-rays for studying exotic states of matter created by heavy-ion heating using the ion beam of the heavy-ion synchrotron of GSI.