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Injection system of the 4GLS light source

Injection system of the 4GLS light source. B.L. Militsyn on behalf of 4GLS team ASTeC STFC Daresbury Laboratory. ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007. Outline. Introduction 4GLS light source Injection system of 4GLS XUV-FEL normal conductive RF photoinjector

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Injection system of the 4GLS light source

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  1. Injection system of the 4GLS light source B.L. Militsyn on behalf of 4GLS team ASTeC STFC Daresbury Laboratory ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  2. Outline • Introduction • 4GLS light source • Injection system of 4GLS • XUV-FEL normal conductive RF photoinjector • VUV-FEL High Average Current DC NEA photocathodes based injector • 4GLS laser system • IR-FEL thermionic injector • Status and perspectives • Conclusion B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  3. 4GLS Layout B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  4. XUV-FEL branch of 4GLS Beam energy 750 MeV Photon energy range, eV 8-40 35-100 Peak power, GW 3-5 1-3 Photon pulse length, fs 22 Repetition rate, kHz 1 B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  5. XUV-FEL injector Beam parameters at the entrance of main linac Bunch charge, nC 1.0 Bunch repetition rate, kHz 1.0 Beam energy, MeV 210 Normalised emittance, π·mm·mrad <2 Uncorrelated energy spread, % <0.05 RMS bunch length (σ ), ps ~2 B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  6. Normal conductive 1.5-cell RF photocathode gun Distribution of accelerating RF and focusing magnetic field in the gun B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  7. ASTRA simulation of the RF gun Simulation parameters Laser spot diameter, mm 4 Spatial laser spot distribution Uniform Temporal laser pulse shape Flat-top Laser pulse length, ps 20 Rise time, ps 2 Initial rms beam energy spread, V 0.4 Maximum RF accelerating field, MV/m 40 B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  8. ASTRA simulation of the XUV-FEL injector B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  9. ASTRA simulation of the XUV-FEL injector B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  10. Laser for the XUV-FEL injector Required energy of laser pulse is given by: For an CsTe2 photocathode Qe=1% at l=262 nm : Wavelength, nm 262 Repetition rate, kHz 1.0 Pulse shape Flat top Maximum rise time, ps 2 Pulse length, ps 10 Laser pulse energy, µJ 1 B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  11. VUV-FEL branch of 4GLS Beam energy 550 MeV Photon energy range, eV 3-10 Peak power, MW 350 Photon pulse length, fs 64 Repetition rate, MHz n*4.33 Maximum photon energy, eV 80 Average flux, 1/s/0.1% bp 1.0*1015 Repetition rate, GHz 1.3 B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  12. VUV-FEL injector Beam parameters at the entrance of main linac Bunch charge, pC 77 Bunch repetition rate, GHz 1.3 Operation mode CW Beam energy, MeV 10 Normalised beam emittance, π·mm·mrad < 2 Uncorrelated energy spread, % < 0.1 Bunch length, ps 5 B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  13. High voltage DC photocathode gun Parameter of the photocathode gun Gun voltage, kV 500 Average beam current, mA 100 Bunch repetition rate, GHz 1.3 RMS laser pulse length, ps 20 Laser pulse shape Gaussian Estimated operational life time, hours 27 Estimated rms transverse emittance, π·mm·mrad 2.8 Estimated rms bunch Length, ps 30 B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  14. Photocathode preparation set-up • Required photocathodes: • NEA III/V semiconductor • Transmission mode • High quantum efficiency • Fast response • High emission current density B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  15. Photoemission from “thick” NEA photocathodes Photoemission from “thick” NEA photocathodes illuminated by green light Energy distribution of electrons emitted from bulk GaAs photocathodes according to measurements made at Max Planck Institut für Kernphysik (MPI-K), Heidelberg, Germany. by the courtesy of A.S. Terekhov B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  16. 100 nm 1000 nm 2.3 ps 30 ps Photoemission from “thin” NEA photocathodes Data from Mainz: experiment, diffusion model if d≤L - thermalization length “hot” photo-electrons increase transverse energy spread B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  17. Beam dynamics in the VUV-FEL injector B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  18. Laser for VUV-FEL injector For GaAs photocathodes l<850 nm, forl=520 nm Wavelength, nm 520 Repetition rate, GHz 1.3 RMS pulse with, ps 10 Average laser power for Qe=10%, W 2.3 Average laser power for Qe=1%, W 23 Average laser power for Qe=1%,=0.7, W 33 Timing jitter, fs 100 B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  19. Time structure of the beam in the main linac B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  20. 4GLS laser system by the courtesy of G. Hirst B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  21. IR-FEL branch of 4GLS Beam energy 25-60 MeV Wavelength, mm 2.5-25 20-200 Repetition rate, MHz 13 Peak power, MW 3-20 Photon pulse length, ps 0.8-2.4 Switch yard frequency, Hz 100 B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  22. IR-FEL injector Bunch charge, pC 200 Bunch repetition rate, MHz 13 Peak current, A 8 to 80 Energy, MeV 25 to 60 Normalised emittance, π·mm·mrad < 10 RMS energy spread, % < 0.1 RMS bunch length, ps 1 - 10 B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  23. Thermionic emitter Formation of the grid voltage Grid modulated 6 mm LaB6 emitter B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  24. ASTRA simulation of a 400 kV thermionic gun B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  25. Beam in the transverse and longitudinal phase spaces B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  26. Status and perspectives • XUV-FEL injector R&D • VUV-FEL injector • Photocathode gun Drawing room • Preparation facility Drawing room • Photocathodes R&D • Laser system R&D • High voltage power supply R&D • Test beam line ERLP test beam line • IR-FEL injector R&D B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

  27. Conclusion • Injection system of 4GLS requires state of the art and beyond electron sources, laser and synchronisation devices • Though requirements for injector for XUV-FEL very close to the parameters of BESSY-PITZ project some research are required in thew derection of • High power gun cavity • High repetition rate low jitter laser system • Injector for VUV-FEL requires additional research in the direction of • Photocathode development • Photocathode preparation and manipulation technique • Very high voltage photocathode gun design • High frequency high power laser system • IR-FEL injector may be build on the bases of well known grid modulated thermionic gun B.L. Militsyn, ERL’07 Workshop, Daresbury, 21.05.2007-25.05.2007

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