8/3/2019 B. Aurand et al- X-ray laser developments at PHELIX

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X-ray laser developments at PHELIX

B. Aurand1,3,4,*, T. Kuehl1,3, V. Bagnoud1, B. Ecker1,2,3, U. Eisenbarth1,

D. C. Hochhaus1,4,6, P. Neumayer1,4, B. Zielbauer1,2*, D. Zimmer1,3,5,

K. Cassou5, S. Daboussi

5, O. Guilbaud

5, J. Habib

5, S. Kazamias

5, D. Ros

5,

J. Seres7, C. Spielmann7

1 GSI Helmholtzzentrum fr Schwerionenforschung GmbH Darmstadt, Ger.; 2 Helmholtz Institute Jena, Ger.; 3 Johannes Gutenberg University

Mainz, Ger.; 4 EMMI, GSI Darmstadt, Ger.; 5Universit Paris Sud 11, Fr.; 6Johann-Wolfgang-Goethe University Frankfurt, Ger.;7

Friedrich

Schiller University Jena, Ger.

*Email address: b.aurand@gsi.de

Development of x-ray lasers using the PHELIX laser at the GSI Helmholtz center for heavy-ion

research [1] is targeting a number of applications of novel x-ray sources in combination withenergetic heavy-ion beams. This includes Thomson scattering diagnostics of heavy-ion driven

plasmas, x-ray opacity measurements, and x-ray laser spectroscopy of highly-charged ions.

At PHELIX, the chirped pulse amplification scheme is employed, with the goal to achieve pulse

powers in the petawatt range. Total pulse energies above 100 J can be delivered onto the target.

Double pulses with individually adjustable pulse duration, energy ratio and variable delay can be

prepared in the front-end of the laser. This way PHELIX is an attractive pumping source also for

plasma x-ray lasers. Producing the double pulse in the front-end of the PHELIX laser considerably

simplifies the setup, especially for the larger beam diameters required at elevated energies. A

further improvement specifically useful for the application to x-ray lasers is the use of a 90 degree

off-axis parabola for focusing. At a slight deviation from the standard geometry, a very sharp line

focus can be produced. Fine tuning of the traveling wave characteristics required by the short

inversion life-time of the laser plasma is performed by slight changes of the compressor geometry,

controlled by an auto-correlation scheme utilizing the double pulses for time resolution.

Experimental results achieved using these developments will be presented. Developments centered

on the application of a novel double-pulse GRIP-like pumping scheme, DGRIP, where non-normal

incidence geometry is used for both the pre- and the main pulse for transient pumped Ni-like x-ray

lasers [2,3]. This scheme was used at lower energy levels to pump soft x-ray lasers in the 50 100

eV regime as well as for pulse energies above 100 J for the pumping of shorter wavelength soft x-

ray lasers [4].Searching for an efficient seeding source for plasma x-ray lasers a new x-ray parametric

amplification (XPA) process in neutral gases was identified [5]. High-order harmonic radiation

created in a gas cell was amplified in the same medium. A gain of up to 8x10 was obtained for

40eV photons created by a 350fs ~10 mJ pulse in argon and 260eV photons created by a 6fs ~1.5

mJ pulse in helium. This new scheme reduces the pumping threshold for intense soft x-ray sources

with comparable conversion efficiencies to plasma XRLs into the millijoule level.

References

[1] V. Bagnoud et al., Appl. Phys. B,DOI 10.1007/s00340-009-3855-7

[2] D. Zimmer et al., Optics Express 16, 10398 (2008),[3] D. Zimmer et al., Opt. Lett. 35, 450 (2010)

[4] D. Zimmer et al., submitted to Phys. Rev. A in 2010

[5] J.Seres et al. ; Nature Physics 10.1038/nphys1638