sflash First Seeding at FLASH 15.05.2012 On behalf of the sflash team Jörn Bödewadt Hamburg University Supported by BMBF under contract 05 ES7GU1 DFG GrK 1355 Joachim Herz Stiftung
NEW WORLD RECORD at FLASH For the first time direct FEL seeding at 38.5 nm was achieved on April 29 th 2012 with sflash 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 2
Outline Motivation / seeding schemes sflash setup Results till spring 2011 Upgrade program 2011 Results of beam time in 2012 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 3
Motivation (Spectrum) Use external laser seeding to stabilize the spectral distribution of the FEL SASE spectra measured at sflash@38.4 nm HGHG seeded spectra measured at FERMI@52.5 nm Courtesy E. Allaria, High Gain Harmonic Generation operation of a Free Electron Laser, Seeding Workshop 2011 Berkeley 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 4
Motivation (Timing) With existing FELs the temporal resolution for IR-XUV pump-probe experiments is limited due to the relative arrival time jitter of both pulses Ideally the jitter should be smaller than the individual pulse lengths Not all experiments are capable to use other arrival time measurements to sort the data With external laser seeding the drive laser for the seed and the FEL output pulse are intrinsically synchronized Still needs sophisticated synchronization of the seed laser and the machine 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 5
Seeding schemes Other FEL seeding schemes (XUV and soft X-ray) Hard X-rays Demonstrated at LCLS in January this year (hard X-rays) 38 nm HHG seeded FEL Proof of principle SCSS@160nm sflash first seeding at 38nm 266 or 200 nm Fermi@Elettra in operation (20-40 nm) 266 nm Proof of principle @ SLAC >300 nm Other facilities SDUVFEL (SINAP) FLASH 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 6
sflash Installation hutch for first experiments with sflash pulses Ti:sapphire laser system and HHG source HHG source * Optical Replica Synthesizer 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 7
sflash setup fully commissioned Results in 2011 overlap diagnostics (transversal, longitudinal, spectral) SASE gain of 10 5 10 6 achieved tools for on-line data analysis tested but NO signal for seeding detected lack of HHG diagnostics and laser power HHG energy @ 38nm at the source 2 nj Full absolute HHG energy energy at measurement the undulator 0.1 in the nj (measured undulatortransmisson of 5%) HHG problems energy with coupled HHG to diagnostics electron beam in the 0.004 lab nj (mirror (due to distortions) σ HHG >>σ - e beam ) bad HHG beam quality (M² or emittance) -> no optimum focusing possible Effective seed power 200 W. Shot noise power ~ 100 W Energy contrast ~0.3 very difficult to demonstrate the effect of the seeding -> upgrade of sflash components was needed Seed laser system Tunnel diagnostics XUV photo diode, Streak Camera, spectrometers 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 8
HHG laser system before upgrade 81 MHz Ti:sapphire oscillator CPA reg. amplifier with 4x multi pass booster section pump 81 MHz oscillator final compressor HHG target vacuum window 10 Hz reg. amplifier pump precompressor NIR focusing mirror 10 Hz booster amp. 1.5 nj 1.5 nj 4 mj stretcher 81 MHz 6 fs 64 ps 10 Hz 64 ps 10 Hz ~20 mj 14 fs ~35 mj ~170 fs f = 1.5m ; 3m ; 5m ; 7m 64 ps 90% ~60 mj 10% NIR pump beam to experiment HHG and NIR beam to accelerator (pulse lengths are rms values) 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 9
HHG laser system new 108 MHz Ti:sapphire oscillator (better suited for synchronization) Amplifier system maintained and new crystals installed changed compression scheme to a single compressor setup 10 Hz 10 Hz pump pump 81 MHz oscillator final compressor HHG target reg. amplifier precompressor NIR focusing mirror booster amp. 1.5 nj 1.5 nj 4 mj stretcher 81 MHz 6 fs 64 ps 10 Hz 64 ps 10 Hz ~20 mj 14 fs vacuum window ~35 mj ~170 fs f = 1.5m ; 3m ; 5m ; 7m 64 ps 90% ~60 mj 10% NIR pump beam to experiment HHG and NIR beam to accelerator (pulse lengths are rms values) 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 10
HHG laser system 2012 new 108 MHz Ti:sapphire oscillator (better suited for synchronization) Amplifier system maintained and new crystals installed changed compression scheme to a single compressor setup Increase of NIR pulse energy by a factor of 2 Better control of NIR pulse and beam shape (pulse lengths are rms values) 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 11
HHG source and diagnostic sflash Spectrometer Al filter Diode Al filter H21 ML, f=1.5 m Spectrometer H21 ML H21 test focus CCD HH-meter (R-GMD) HHG HHG Oscillator, stretcher, amplifier Compressor 800 nm, 400 ps, 80 mj Vacuum window 800 nm focus (f=1.5 m) W 0,x,800nm = 120 µm W 0,y,800nm = 109 µm 35 fs, 40 mj 800 nm ML, f=1.5 m M 2 x,800nm = 1.49 M 2 y,800nm = 1 3x10 15 W/cm 2 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 12
Seed laser performance 28g Test focus scan in diagnostic branch H21 w (µm) 650 600 550 500 450 400 350 300 250 200 150 100 50 0 in x in y 0 100 200 300 400 z (mm) w 0,x,H21 = 71 µm w 0,y,H21 = 30 µm z R,x,H21 = 44 mm z R,y,H21 = 17 mm M 2 x,h21 = 9.5 M 2 y,h21 = 4.4 H21 (38 nm) pulse energy at source: 10-20 nj with 5-15% rms 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 13
Injection beamline 2012 New mirrors MCP for HH meter EEHG injection chamber e-beam Al-Filter XUV diode New spectrometer 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 14
HHGBL spectrometer 120 zero order 100 Int. (arb. units) 80 60 40 27 25 29 31 23 21 19 20 0 0 10 20 30 40 λ (nm) 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 15
Mirror chamber 2, HH-meter 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 16
XUV photo diode at 10ORS sflash undulator Q12ORS ORS section screen 10ORS beam direction 200nm Al-Filter 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 17
April 29th 2012: HHG pulse energy at undulator 1 Measured charge Q meas = 49 pc Assuming only 21st harmonic -> E 21st = Q* Ep / QE QE = 6.76 (for 38nm); Ep = 32.55 ev -> E 21st = 235 pj (value from February: 250 pj) Assuming 4 harmonic orders (seen on spectrometer): 19th, 21th, 23th, 25th - > Q 21st = ½ * Q meas E 21st = Q 21st * Ep / QE -> E 21st = ½*235 pj = 117 pj For the measurements a 200nm Al-filter has to be inserted into the beamline to block the NIR laser. At 38 nm the transmission is about 0.35. For seeding this filter is always removed. So the seed pulse energy is a factor 3 larger: E 21st = 330 670 pj 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 18
New Streak Camera The Hamamatsu FESCA 200 was removed and returned to photo injector laser (Siggi) A new Streak Camera type Hamamatsu C5680 (Synchroscan) was installed Has a slightly lower resolution than the FESCA but can be synchronized to the RF-signal 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 19
Spectrometer in 28h Due to technical problems with the sflash tunnel spectrometer (broken image intensifier) we had to install a backup solution in 28h Using an existing XUV spectrometer from Lasse Schroedter Nominal wavelength range 10 75nm FEL beam in 28h HHG spectrum 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 20
Beam energy: 695 MeV Charge: 0.5 nc Machine preparation Compression: 500 fs (FWHM) Gaussian current distribution (CRISP4) Orbit: using wire scanners for reference positions in first undulator module No beam losses, SDUMP mode, Pyro and energy feedbacks on 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 21
sflash SASE Gain curve 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 22
Transverse overlap Superimposed beam profiles measured on Ce:YAG screen upstream Undulator 1 downstream Undulator 1 XUV beam Electron beam XUV beam [mm] [mm] [mm] [mm] 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 23
Transverse overlap 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 24
Longitudinal overlap ( coarse ) using synchrotron radiation from a short (N=5) electro-magnetic undulator together with 800nm laser pulses on a streak camera to find the temporal overlap 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 25
Spectral overlap HHG spectrum SASE spectrum 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 26
How to detect seeding If you don t expect a dramatic enhancement of your signal Typical numbers: 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 27
Spectral data With all undulators closed the CCD of the spectrometer was saturated @ 38.5nm 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 28
On behalf of the sflash team Thank you for your attention Sven Ackermann, Armin Azima, Jörn Bödewadt, Francesca Curbis, Hossein Delsim-Hashemi, Markus Drescher, Stefan Düsterer, Josef Gonschior, Eugen Hass, Ulrich Hipp, Katja Honkavaara, Rasmus Ischebeck, Shaukat Khan, Tim Laarmann, Christoph Lechner, Theophilos Maltezopoulos, Atoosa Meseck, Nils Mildner, Velizar Miltchev, Manuel Mittenzwey, Heinrich Münch, Otto Peters, Benjamin Polzin, Marie Rehders, Jörg Rossbach, Ernst-Otto Saemann, Holger Schlarb, Sebastian Schultz, Michael Schulz, Angad Swiderski, Roxana Tarkeshian, Markus Tischer, Antonio de Zubiaurre Wagner, Marek Wieland, Torsten Wohlenberg, and others 23.05.2012 J. Bödewadt - HASYLAB Wednesday Meeting 29