1. Rainer Hörlein 9/12/2015 1 ICUIL 2010 Watkins Glen Femtosecond Probing of Solid Density Plasmas with Coherent High Harmonic Radiation Rainer Hörlein

2. Contributors Rainer Hörlein 9/12/2015 ICUIL 2010 Watkins Glen 2 LMU / MPQ: Theory and Simulations: R. Hörlein D. Kiefer G. D. Tsakiris F. Krausz S. Rykovanov G. D. Tsakiris Queens University Belfast, UK: B. Dromey M. Zepf A. Henig D. Jung P. Heissler D. Habs Max-Born-Institute, Berlin, D: S.Steinke T. Sokollik M. Schnürer P. Nickles W. Sandner Los Alamos Nat. Lab, USA: M. Hegelich C. Gautier R. Shah S. Palaniyappan S. Letzring J. Fernandez and the entire TRIDENT Team

3. Overview Rainer Hörlein 9/12/2015 ICUIL 2010 Watkins Glen 3 1.Introduction 2.Dynamics of nm-Scale Foils 3.Plasma Probing using SHHG 4. Conclusions and Outlook

4. 1.1 Coherent Wake Emission Rainer Hörlein 9/12/2015 ICUIL 2010 Watkins Glen 4 Plexiglass Target (Density ≈ 1.3 g/cm^3): Glass Target (Density ≈2.6 g/cm^3) : 111312 14 17 15 16 111312 14 15

5. 1.2 Relativistic Harmonics Rainer Hörlein 9/12/2015 ICUIL 2010 Watkins Glen 5 Harmonic Spectra:Mirror Motion:

6. Rainer Hörlein 9/12/2015 ICUIL 2010 Watkins Glen 6 1.3 Thin Foils H. George, et al., NJP, 11, 113028 (2009) U. Teubner, et al., PRL, 92, 185001, (2004). K. Krushelnick, et al., PRL, 100, 125005, (2008). Experiments: CWE in transmission:ROM in transmission:

7. 2. Dynamics of nm-Scale Foils Rainer Hörlein 9/12/2015 ICUIL 2010 Watkins Glen 7 nm-scale diamond-like carbon foils promise access to new regimes for efficient ion acceleration S.G. Rykovanov et al., NJP. 10, 113005 (2008). O. Klimo et al., PR ST AB 11, 031301 (2008). A.Henig et al., PRL 103, 245003 (2009) and many others X Density

8. 2.1 The Berlin Laser System Rainer Hörlein 9/12/2015 ICUIL 2010 Watkins Glen 8 5 µm FWHM Pulse energy 1.2 J (0.7 J with PM) Pulse duration 40 fs Rep. rate10 Hz F/2.5 focusing Adaptive mirror Focused intensity 5x10 19 Wcm -2 Laser focus Berlin 30 TW CPA Ti:Sa system Double Plasma – Mirror (DPM) energy throughput ~65% contrast enhancement 10 3 to 10 4 no decrease in focusability

9. Rainer Hörlein 9/12/2015 ICUIL 2010 Watkins Glen 9 2.2 Probing nm-Foil Targets Harmonic Order 7891011 12 13 14 15 17 nm DLC Harmonic Order 7891011 12 13 14 15 5 nm DLC Harmonic Order 7891011 12 13 14 15 32 nm DLC

10. 2.2 Probing nm-Foil Targets Rainer Hörlein 9/12/2015 ICUIL 2010 Watkins Glen 10 2D-PIC Simulation a 0 =3.6, n max =100n c, 25nm ramp, τ=10 cycles Measured Density Density during relativistic interaction Consistent with 1D expansion of the foil target ionized on the leading edge of the 45fs laser pulse C s,av ≈2.2x10 7 cm/s T Exp ≈70fs R. Hörlein et al., arXiv:1009.1582 (2010)

11. 10 th harmonic x-position (microns) y-position (microns) 50 th harmonic x-position (microns) y-position (microns) Position on detector (cm) Harmonic order 3. Plasma Probing using SHHG Rainer Hörlein 9/12/2015 ICUIL 2010 Watkins Glen 11 harmonic target test plasma incident laser harmonic radiation (very) preliminary Simulations W. Theobald et al., PRL 77, 298 (1996). S. Dobosz et al., PRL 95, 025001 (2005). previous work using gas harmonics for example: hollow target 100s of micron harmonic source radius (microns) e - density (n c of w 0 )

12. 3.1 The TRIDENT Laser Rainer Hörlein 9/12/2015 ICUIL 2010 Watkins Glen 12 Pulse energy 80 J 1 shot/45 min. F/3 focusing TRIDENT short pulse beam: Pulse duration 500 fs Wavelength 1054 nm Adaptive mirror Focused intensity 5x10 20 Wcm -2 TRIDENT has ~10x longer pulse than MBI but ~100x more pulse energy i.e. 10x higher intensity on target

13. 3.2 Relativistic Forward Harmonics Rainer Hörlein 9/12/2015 ICUIL 2010 Watkins Glen 13 Harmonic radiation from 200 nm DLC Targets Harmonic Order 9101113 15 16 12 141820 17 1921 Normal incidence spectrometer Grazing incidence spectrometer Harmonic Order 60 40 20 Relative Intensity 10 1 0.1 n -3.5 scaling n -2.0 scaling n -2.75 scaling

14. 3.3 Plasma Probing: First Results Rainer Hörlein 9/12/2015 ICUIL 2010 Watkins Glen 14 harmonic target probed foil incident laser residual laser and harmonics Harmonic Order 60 40 20 Relative Intensity 10 1 0.1 Density Information 200nm DLC 200+80nm DLC

15. Conclusions and Outlook Rainer Hörlein 9/12/2015 ICUIL 2010 Watkins Glen 15 High harmonics generated on solid surfaces are a very versatile source of intense coherent XUV radiation High harmonics can be used to probe and monitor the interaction of intense femtosecond laser pulses with nm-scale foil targets Direct measurement of target density during relativistic interaction First clear observation of only odd-numbered relativistic harmonics in normal incidence geometry High harmonics generated with PW-scale short-pulse lasers could serve as unique backlighting sources for a wide range experiments