Fig. 1. The location of the PHELIX building on the GSI campus allows for using both high-energy laser pulses and the heavy-ion beam in combination at the Z6 experimental area downstream of the linear accelerator section, the UNILAC and at HHT, downstream of the heavy-ion synchrotron SIS18.

Fig. 2. Digital mock-up of the experimental hall (ESR hall) downstream of the SIS18 heavy-ion synchrotron, showing the PHELIX beamline (green/grey tube) as it traverses several experimental areas on its way to HHT. The total length of the beam transport is of the order of 65 m.

Fig. 3. Schematic floor plan of PHELIX. The laser amplifier chain is situated in the PHELIX laser bay, together with the grating compressor and the petawatt target area (PTA) for the short, highest-intensity pulses. The PHELIX long pulse can be directed to the Z6 and HHT experiment areas, where it can be combined with the heavy-ion beams from UNILAC and SIS18, respectively. In addition, the Z6 area has the possibility to use the sub-aperture, short-pulse beam of PHELIX. This figure is based on the original version by Ohland^[20] and its modification by Malki^[21].

Fig. 4. Build-up of wavefront aberrations in high-repetition-rate operation of the preamplifier. The peak-to-valley value of the wavefront distribution as a function of time is shown after the 45-mm preamplifier module with 45 s between laser shots, starting at 6 min. After about 20 min an equilibrium is reached, in which the aberrations remain constant over time. At 51 min (red dashed line) the aberrations, which mostly consist of defocus, are compensated by moving a lens in the Kepler telescope of the preamplifier setup.

Fig. 5. Typical temporal pulse shape of the compressed PHELIX sub-ps pulse, measured with a high-dynamic-range third-order cross-correlator. On top of a very low ASE background limited by the noise of the measurement device, the peaks before the main pulse are mainly due to artifacts^[30,31].

Fig. 6. Layout of the petawatt target area sensor (top). The leakage of the last turning mirror before the target chamber is used to monitor the beam quality as close as possible to the laser–matter interaction experiment. A closed loop with a full-aperture deformable mirror allows for the maximization of the focused intensity on the target. The focal spots without (bottom left) and with (bottom right) this optimization loop are shown. Note that we quantify the spot quality in absolute terms of intensity instead of a relative Strehl ratio due to high-order spatial frequencies on the surface of the focusing optic, which is still to be characterized. This figure is reproduced from Ohland et al.^[40] with the permission of the authors.

Fig. 7. Example of the PCS graphical user interface. The different parts of the laser chain and diagnostics can be accessed on different tabs. In the picture the preamplifier stage is shown.

Fig. 8. 3D-model of the petawatt target area served by PHELIX. The target chamber has two entrance possibilities for the laser beam(s), which allows one to accommodate very diverse and highly complex experimental setups.

Fig. 9. Photograph of the HHT experiment area downstream of the SIS18 heavy-ion synchrotron, showing the target chamber and the PHELIX beamline.

Fig. 10. Second-harmonic generation in the PHELIX-HHT beamline showing the conversion efficiency at the HHTS. The inset shows a typical temporal shape of the PHELIX narrowband pulse.

Fig. 11. Intensity distribution in the focal spot of the PHELIX beam at HHT area.

Fig. 12. X-ray line-emission spectra from different mid-Z metal targets generated at HHT using the PHELIX ns-pulse.

Fig. 13. Schematic representation of the timing signals used for synchronization of the SIS18 ion bunch to the PHELIX laser pulse.