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.

This work presents first insights into the dynamics of free-surface release clouds from dynamically compressed polystyrene and pyrolytic graphite at pressures up to 200 GPa, where they transform into diamond or lonsdaleite, respectively. These ejecta clouds are released into either vacuum or various types of catcher systems, and are monitored with high-speed recordings (frame rates up to 10 MHz). Molecular dynamics simulations are used to give insights to the rate of diamond preservation throughout the free expansion and the catcher impact process, highlighting the challenges of diamond retrieval. Raman spectroscopy data show graphitic signatures on a catcher plate confirming that the shock-compressed PS is transformed. First electron microscopy analyses of solid catcher plates yield an outstanding number of different spherical-like objects in the size range between ten(s) up to hundreds of nanometres, which are one type of two potential diamond candidates identified. The origin of some objects can unambiguously be assigned, while the history of others remains speculative.

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.

Post-compressor beam transport becomes a challenge in Chirped Pulse Amplification lasers if a surface shall be imaged. We developed an easy and repeatable alignment procedure for off-axis parabola telescopes to fit these needs.

Temporal pulse profile characterization is necessary to ensure and quantify the quality of short pulse laser systems. Yet it remains challenging to measure the temporal behavior of a pulse in all of its comprehensiveness. In this manuscript we present results which encourage to perform more ambitious pulse characterizations with optimized scanning cross-correlators. Several temporallaser pulse profile measurements in multiple nanosecond time scale with high dynamic range are shown. The measurements were taken by our in-house third-order cross-correlator EICHEL (Schanz et al. in Opt Express 25:9252, 2017), which is able to resolve the intensity dynamics down to the level of amplified spontaneous emission. With this device we show for the first time the onset of the plateau of the amplified spontaneous emission in the laser profile and investigate the origin of several side-pulses created early in the laser system.

In 2013, the upgrade of the PHELIX high-energy target area, dedicated to laser-only experiments in the PHELIX Laser Hall (PLH), has been completed. Due to this effort, the experimental possibilities could be broadened, experiment setup became simpler and radiation protection has been optimized. In April, the new chamber was commissioned by an internal beam-time testing the radiation shielding. Since then, eight experimental beam-times have been realized [1].

General overview PHELIX, a high-energy short-pulse laser, allows for combined ion-laser experiments to support the science programs of the Plasma Physics and Atomic Physics departments of GSI. 2009 was the first year of full nominal operation, in which the laser delivered high-energy pulses in the sub-kilojoule range to various target areas. In spite of its relatively low repetition rate, the 1000 documented shot was delivered near the end of the year. In 2009, PHELIX was used in combination with the ion beam. It was shot simultaneously with the nhelix laser to uniformly heat carbon foils to a plasma state, which was then probed using the ion beam from the UNILAC. This new setup led to a significant increase in the quality of the recorded data. Other experiments were done using the laser alone to study the generation of an x-ray laser at wavelengths shorter than 10 nm. In this experiment, a new setup yielded a reduction of the pump-laser energy, required to reach the lasing threshold, to values compatible with existing high repetition-rate facilities. This makes the setup ideally suited for high-average-energy short-wavelength x-ray laser systems. Another significant scientific result was obtained in proton acceleration by use of hemispherical targets. Here, a significant shift of the proton spectrum to higher energies was observed. Furthermore, about one third of the time was devoted to maintenance and improvements of the facility, which are reviewed in the last part of this report.

PHELIX (Petawatt High Energy Laser for Heavy Ion Experiments) is a hybrid Ti:Sapphire / Nd:Glass laser system using large aperture amplifiers from the former Nova and Phebus laser systems at Livermore and Limeil, respectively, designed to offer pulse energies in access of 2 kJ and output power in the petawatt range. It is aiming mainly on combined experiments in plasma physics [2] and atomic physics [3] together with the GSI accelerator facility, and in preparation for the new FAIR facility for antiproton and ion research. Both nanosecond and sub-picosecond pulses can be supplied. Presently pulse energies up to 500 J are used, at pulse durations between 2 and 25 ns. Compressed pulses down to 500 fs are achieved after full amplification. The maximum output energy after the pulse compressor is limited by the damage threshold of the final grating. For 20 to 50 ps pulses, the maximal throughput energy is 300 J. For the pulses around 500-fs duration, it is reduced to 230 J. A special arrangement allows for the preparation of pulse pairs, where the duration of the pulses can be individually controlled between 2 and 200 ps. Recent experiments included the preparation of a plasma target for the interaction with energetic heavy ions [3], and the pumping of a plasma x-ray laser [4].

At the Helmholtz center GSI, PHELIX (Petawatt High Energy Laser for heavy Ion eXperiments) has been commissioned for operation in stand-alone mode and, in combination with ions accelerated up to an energy of 13 MeV/u by the heavy ion accelerator UNILAC. The combination of PHELIX with the heavy-ion beams available at GSI enables a large variety of unique experiments. Novel research opportunities are spanning from the study of ion–matter interaction, through challenging new experiments in atomic physics, nuclear physics, and astrophysics, into the field of relativistic plasma physics.

PHELIX is a Petawatt high-energy laser for heavy-ion experiments that can deliver 1-10 ns long pulses at 1053 nm with energies up to 1 kJ to the ion beam target chamber at the Z6 experimental area or 200 TW in subpicosecond pulses to the target chamber in the laser bay. Near-term upgrades comprise frequency doubling of the ns pulses to 527 nm and a power increase of the short pulse to 500 TW with the larger compressor gratings obtained from the Lawrence Livermore National Laboratory (LLNL) in the USA PHELIX was built in close cooperation with LLNL and the Commissariat à l’Energie Atomique (CEA) in France. In the following, the major achievements in 2008 are reported.

K. Witte 1 , V. Bagnoud 1 , A. Blazevic 1 , S. Borneis 1 , C. Bruske 1 , J. Caird 2 , S. Calderon 3 , U. Eisenbarth 1 , J. Fils 1,4 , S. Götte 1 , T. Hahn 1 , H.-M. Heuck 1,5 , D. H. H. Hoffmann 4 , D. Javorkova 1 , G. Klappich 1 , F. Knobloch 1 , Th. Kühl 1,6 , M. Kugler 1,7 , S. Kunzer 1 , M. Kreutz 1 , B. LeGarrec 8 , T. Merz-Mantwill 1 , E. Onkels 1 , S. Radau 9 , M. Rebscher 1 , D. Reemts 1 , R. M. Richard 10 , M. Roth 1,4 , A. Roussel 8 , Andreas Tauschwitz 1 , Anna Tauschwitz 11 , R. Thiel 1 , U. Thiemer 1 , D. Ursescu 1 , U. Wittrock 5 , B. Zielbauer 1,12 , D. Zimmer 1,6

We report the major achievements of the construction of the Petawatt High-Energy Laser for Heavy-Ion Experiments (PHELIX) that will be capable of producing pulses up to the peak power of one PW (10 W) in 500 fs and 4 kJ in 10 ns. In July and August, the commissioning of the main amplifier (MA) of PHELIX was started employing the stretched pulses of the fs-front-end (FE) which were amplified in the pre-amplifier (PA) up to 7 J. The MA was run in single-pass. The results verified the expected gain-voltage characteristics of all five 315-mm aperture Nova amplifiers and demonstrated the full functionality of all mechanical and optical components, the pulsed power, the control system, as well as the timing. We also gained first data of the beam pointing stability and the wave-front aberrations of the chain. In December, the MA was run in double-pass for the first time. To minimize the risk of damage during these first shots, the PA and MA were adjusted for generating the output energy of 133 J corresponding to 27% of the expected maximal output energy of 500 J for the 0.5 ns amplified stretched pulse. First experiments aiming at the charge-state characterization of plasmas suited for transient collisionally excited x-ray lasers were performed with 50 J. Another important milestone was the completion of the fabrication of the PW compressor vacuum chamber that was cleaned to clean room 100-standard and stored in the PHELIX laser bay in August. The large-size multi-layer dielectric gratings were also delivered. A new single-shot autocorrelator with a dynamic range of 60-dB was developed and successfully tested [1]. The design of the beam transport to the Z6 experimental area is almost completed. For the two 520-mm diameter, 85-mm thick BK7 periscope mirrors in the laser bay tower, a six-point whiffletree back support was designed to effectively counteract the gravity sag and unavoidable deformations introduced by conventional mirror mounts. Furthermore, the requirement document of the beam line to the PW compressor at the HHT cave was completed. Two experimental campaigns with the PA output were carried out, one investigating the proton acceleration from the rear side of micro-structured thin foils and the other continuing the soft X-ray laser program. A major success is the demonstration of the nickel-like silver laser enabling the spectroscopy of high-Z Li-like ions in the storage ring.

The high-energy high-power laser system PHELIX (Petawatt High Energy Laser for heavy Ion eXperiments) [1] is currently under construction at the Gesellschaft fuer Schwerionenforschung mbH (GSI) Darmstadt. With PHELIX GSI will offer the unique combination of a high-current, high-energy (GeV/u) heavy-ion beam with an intense laser beam. This will open the door to a variety of fundamental science issues in the field of atomic physics, plasma physics and nuclear physics. The project will gain further interest in the near future by the dramatic increase of the accelerator performance with the starting FAIR project at GSI [2]. This paper reports the current status of the project as well as the laser architecture. The proposed physics program and a first experiment carried out with PHELIX, the realization of a transient collisionally excited x-ray laser [3], will also be reviewed briefly.

This paper reports on the status of the PHELIX petawatt laser which is built at the Gesellschaft fuer Schwerionenforschung (GSI) in close collaboration with the Lawrence Livermore National Laboratory (LLNL), and the Commissariat l'Energie Atomique (CEA) in France. First experiments carried out with the chirped pulse amplification (CPA) front-end will also be briefly reviewed.

With PHELIX (Petawatt High Energy Laser for heavy Ion EXperiments) a high energy/ultra-high intensity laser system is currently under construction at the GSI (Gesellschaft für SchwerIonenforschung, Germany). In combination with the high current high energy ion accelerator facility this will provide worldwide unique experimental opportunities in the field of dense plasma physics and inertial fusion research. In the long pulse mode the laser system will provide laser pulses of up to 5 kJ in 1-10 ns pulses. In the high intensity mode pulse powers in excess of 1 PW will be achieved. For this the well known technique of chirped pulse amplification (CPA) will be implemented. A new CPA stretcher-compressor setup for the PHELIX laser was calculated and designed. A 4-pass single-grating stretcher and a 4-pass single-grating test compressor, both with a full transmission bandwidth of 16 nm, as well as the compact single-pass compressor for the final pulse compression will be presented. Spatial chirp and spectral phase aberrations of the stretcher were optimized. We discuss the dependence of critical alignment tolerances on the angle of incidence and show the effects on the temporal pulse shape.

S. Borneis, R. Bock, E. Brambrink , H. Brand, C. Bruske, J. Caird, R. Fuchs, S. Götte, T. Hahn, H.-M. Heuck, D. H. H. Hoffmann, D. Javorkova, H. J. Kluge, Th. Kühl, S. Kunzer, R. Lotz, T. Merz, P. Neumayer, E. Onkels, D. Reemts, M. Roth, G. Schaumann, F. Schrader, C. Spielmann, R. Stenner, A. Tauschwitz, R. Thiel, U. Thiemer, D. Ursescu, P. Wiewior, U. Wittrock, B. Zielbauer Gesellschaft für Schwerionenforschung mbH; TU Darmstadt; Lawrence Livermore National Laboratory, USA; Fachhochschule Münster; Julius-Maximilians Universität Würzburg; Max-Born-Institut Berlin

S. Borneis, H. Balonier, R. Bock, E. Brambrink , H. Brand, C. Bruske, J. Caird, R. Fuchs, E. W. Gaul, W. Geithner, S. Götte, C. Häfner, T. Hahn, W. Heddrich, H. M. Heuck, D.H.H. Hoffmann, D. Javorkova, H. J. Kluge, Th. Kühl, S. Kunzer, R. Lotz, T. Merz, P. Neumayer, D. Reemts, M. Roth, S. Samek, G. Schaumann, F. Schrader, W. Seelig, C. Spielmann, R. Stenner A. Tauschwitz, R. Thiel, D. Ursescu, P. Wiewior, U. Wittrock GSI Darmstadt, Germany; Technische Universität Darmstadt, Germany; Lawrence Livermore National Laboratory, USA; Fachhochschule Darmstadt, Germany; Fachhochschule Münster, Germany; Jagiellonian University, Krakow, Poland; Julius Maximilian Universität Würzburg, Germany One of the most important milestones of the PHELIX laser program was reached in January 2003, when the required Nova laser components from Lawrence Livermore National Laboratory (LLNL) arrived at GSI. The basis for the transfer was the agreement between the Department of Energy of the United States of America (DOE) and the Federal Ministry of Education and Research of the Federal Republic of Germany (BMBF) to cooperate in energy research, science and technology and development. Within the agreement which was signed on February 20, 1998 the basic science of dense plasma physics using intense ion and laser beams will be explored.