1. J. Fils for the PHELIX team GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany Sept. 27 2010 Speyer EMMI Workshop The PHELIX High Energy Laser Facility

2. Overview

3. Switch Yard 70 m Double-pass 31.5 cm amplifier Schematic view of the PHELIX facility Injection box Main Amplifier Sensor Faraday Isolator fs Front End Fiber ns Front End Pre-amplifier 2 x 19 mm heads 1 x 45 mm head X-ray Lab (low energy) TW compressor Target chamber Z6 experimental area Heavy ions Laser Bay Compressor Target Chamber sensor Areas recently improved

4. Performance of PHELIX in 2010 Long pulseShort pulse Pulse duration 0.7 – 20 ns0.5 – 20 ps On-target energy0.3 – 1 kJ120 J Maximum intensity10 16 Wcm -2 10 20 Wcm -2 Repetition rate at Joule level 1 shot every 3 min Repetition rate at maximum power 1 shot every 1h* Temporal contrast50 dB 60 to 80 dB depending on settings * with use of the adaptive optics

5. A selection of representative experimental results Progress in ion stopping (Courtesy of A. Frank) –PHELIX together with nhelix yields significant improvement in quality of experimental data. Progress in particle acceleration (Courtesy of K. Harres) –Up to 14 MeV protons were collimated using a coil Progress in X-ray laser development (Courtesy of D. Zimmer) –The DGRIP scheme achieves lasing at 7.26 nm with as little as 30 J of pump laser energy. reference 6. 8 MeV9.0 MeV Converging proton beams Stack located 405 mm from the target

6. Status & Recent Improvements of the Facility

7. Adjustable pulse length and improved intensity contrast 105010551060 0 0.5 1 Shot 525 Wavelength (nm) Intensity (normalized) 5.9 nm Modified pulse stretcher for adjustable pulse duration control A series of 4 Pockels cells distributed in the font end avoids pre-pulses -5-4-3-201 10 -10 10 -8 10 -6 10 -4 10 -2 10 0 intensity (normalized) ASE level Time (ns) Spectral width enhanced by use of a birefringent filter

8. Main amplifier with energies in the kilojoule range With a gain of up to 100 (17.5 kV), the main amplifier works as expected, only limited by the damage threshold of the Faraday rotator 0 100 200 300 400 500 600 700 800 900 1000 567891011 17.5 kV Output energy (J) Pre/amplifier energy (J) 17 kV 16 kV 16.5 kV

9. Direct on-shot measurement of the pulse duration A single-shot autocorrelator is used for alignment and on-shot measurements Together with a twofold increase in energy, we plan to upgrade the peak power to more than 750 TW in 2010 Shot 1071

10. Active wavefront correction Incoming pulse (distorted wavefront) Deformable mirror Wavefront sensor Outgoing pulse (corrected wavefront)

11. Active wavefront correction Three types of aberrations are being found in a complex laser system

12. Active wavefront correction On-shot aberrations at pre-amplifier level reduced by 60% Waiting time between pre-amplifier shots reduced from 10 down to 3 minutes Increase of main-amplifier repetition rate to 1 shot/hour. without correction with correction

13. We plan to improve the contrast by use of an ultrafast OPA 2 nJ 1 ps Mira Freq.shifter Stretch. Ampli.Yb:KYW Comp. Stretch. × 10 1054 nm 100 fs OPA 1040 nm, 100 ps Signal 300 µJ ASE is mostly created in the front-end because of low power available from the oscillator Boost this power using an ultrafast optical parametric amplifier –A gain in contrast of 10 5 expected –Low pre-pulse level –Higher energy stability because of diode-pumped amplifier This development is done within the frame of the Helmholtz Institut Jena (HIJ) SHG

14. Extension of the experimental capabilities at Z6 Ion beam 2ω beam line (in preparation) 10° beam line (in operation) 100 TW beam line (in preparation) target chamber PHELIX beam

15. PHELIX celebrates 2 years of operation PHELIX delivered more than 100 shifts in 2009, in line with the prediction –The facility delivered its 2000 th documented shot. –An internal beamtime allowed to test the amplifier up to 920 J. PHELIX has a strong impact on the scientific program of GSI. –Significant results were obtained in ion stopping experiments, manipulation of laser-accelerated particles and coherent X-ray generation We operate a recent facility which is being constantly improved –PHELIX operates in the ns to sub-ps regime at three different experimental places –Innovative solutions in many locations implemented –Future upgrades are being actively pursued in contrast improvement (uOPA project) frequency conversion (2  project) experimental capability (100 TW project) Summary

16. Thank you for your attention Picture: G. Otto, GSI

17. The nanosecond front end is based on fiber technology with programmable pulse shaping capability time (ns) 051015 20 0 0.5 1 intensity (normalized) Optical pulse

18. IN OUT Entrance window T > 90% We use a single-pass two-grating compressor with elliptical beams. Single-pass setup 2 MLD gratings 1740 lines/mm Size 480 x 350 mm² from MainAmp to Experiment

19. A 90-degree low-cost off-axis metallic parabola achieves good focusing capability. 510152025 0 1 2 3 4 5 surface roughness (nm) scattered energy (%) The 90-degree massive metallic mirror is machined to ~1 micron accuracy (PV), The surface roughness and machining precision have to the balanced to get the best trade-off between scattering losses and wavefront error. Mirror in its Holder Back View Estimation of scattered energy based on simulated surface roughness

20. Experimental evidence indicates an on- target intensity > 10 19 W.cm -2 A calculation based on the far-field intensity distribution yields 3.5 10 19 W.cm 2 According the accelerated proton spectra obtained by the Technical University Darmstadt (TUD), the intensity is rather ~10 20 W.cm 2 Proton density (MeV -1 ) Proton energy spectrum X,  m Y  m, focus intensity, 100 J, 0.7 ps pulse -100-50050100 -100 -50 0 50 100 0 0.5 1 1.5 2 2.5 3 3.5 x 10 19 75% in 50  m Strehl ratio: 0.3