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Few Slides from RF Deflector Developments and Applications at SLAC Juwen Wang

Few Slides from RF Deflector Developments and Applications at SLAC Juwen Wang SLAC Accelerator Seminar April 12 2011. Outline. Introduction to RF Deflectors Basic Theory and Design of RF Deflectors Deflector Applications (3 Types and 7 Examples) Manufacture and Characterization

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Few Slides from RF Deflector Developments and Applications at SLAC Juwen Wang

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  1. Few Slides from RF Deflector Developments and Applications at SLAC Juwen Wang SLAC Accelerator Seminar April 12 2011

  2. Outline Introduction to RF Deflectors Basic Theory and Design of RF Deflectors Deflector Applications (3 Types and 7 Examples) Manufacture and Characterization Future Work

  3. RF Deflector Applications Three Types and 7 Examples • - Time-resolved electron bunch diagnostics for the LCLS • - Measurement of bunch time jitter at LCLS • - Bunch longitudinal profile diagnostics at DESY • - Ultra short e- and x-ray beams temporal diagnostics for LCLS • - Drive/witness bunch longitudinal profile diagnostics for PWFA at FACET - Increase slice energy spread σE as well as measure of slice parameters for Upgrade ECHO-7 - Separator for High Energy Physics Experiments

  4. What the RF Deflectors Look Like? A LOLA-IV Ready for DESY Final Assembly of a 1m X-Band Deflector for LCLS Two Short X-Band Deflectors for ECHO-7 A Short 13-Cell S-Band LOLA Structure Under Measurement for LCLS Injector

  5. Two transverse RF deflectors at LCLS Paul Emma

  6. Bunch Measurement at LCLS Paul Emma

  7. Upgrade ECHO-7 Experiment at NLCTA Increase Slice Energy Spread and Measurement of Longitudinal Profile TCAV1 to increase σE TCAV2 to measure slice parameters Layout and upgrade of the ECHO-7 experiment • WHY increasing beam slice energy spread? • Echo-7 experiment demonstrated the ability to control the phase space correlations (D. Xiang, et al, PRL, 105, 114801 (2010)) • The advantage of EEHG over HGHG has not been fully demonstrated because the beam has very small slice energy spread • Scaling to x-ray FEL requires confidence in harmonic generation with the relative beam energy spread on the 10-4 level but NLCTA has σE /E~10-5 HOW: Using a rf deflecting cavity to increase beam slice energy spread to ~10 keV Dao Xiang

  8. Bunch Time Jitter Measurement at LCLS Paul Emma

  9. Regular X-Band Deflector Cups

  10. Coupler Design Simulation Maximum surface magnetic fields ~400 kA/m, Pulse heating 22 deg. C for 100 ns pulse. Maximum surface electric fields ~100 MV/m. Fields Normalized 20 MW of transmitted power, or 21.3 MeV kick for 89 cm structure V.A. Dolgashev, “Waveguide Coupler for X-band Defectors,” AAC 2008, SALC-WP-084

  11. Input/Output Coupler Assemblies Completed Coupler Assembly Mechanical Design Model

  12. Assembly of the Deflector

  13. Design Example – III Maximum Kick 6 and 0.2 MV for ECHO-7 Experiment

  14. A Typical Microwave Measurement Results for 9-Period CellStack Working 2pi/3 Mode Desired Horizontal Kick Dipole Modes Unwanted polarized Mode 80 MHz lower Vertical Kick Dipole Modes

  15. S11 Resonant Modes and Dispersion Curve for Horizontal Deflecting Modes Backward Wave 2π/3 horizontal deflecting Mode

  16. D27 Amplitude and Cumulated Phase Shift

  17. Beam at Maximum Kick Phase In Deflecting Plane of a Short TW RF Deflector • Top: distribution of deflection (V/m/4W) • Bottom: Integrated deflection (V/4W) There are high electric and magnetic fields in the coupler regions. Due to their standing wave characteristic, the total contribution to the kick is equivalent to 1/2+1/2 cell. Zhenghai Li

  18. Future Application – I Ultra short electron and x-ray beams temporal diagnostics with X-band deflector V(t) 2×1 m RF ‘streak’ Dipole e- Dy sz X-band TCAV energy D 90° time bs bd • High resolution, ~ few fs; • Applicable for all radiation wavelength; • Wide diagnostic range, few fs to few hundred fs; • Profiles, single shot; • No interruption with LCLS operation; • Both e-beam and x-ray.

  19. Future Application – II Plasma Wakefield Acceleration (PWFA) experiments at FACET Measurement of longitudinal profile for both Drive Beam and Witness Beam Plasma Wakefield Acceleration (PWFA) experiments at FACET will use unique two-bunch beam. Acceleration of witness bunch depends strongly on longitudinal profile of the two bunches as well as the inter-bunch spacing. Will also try non-Gaussian “ramped” driver bunch, which could provide especially high transformer ratio. Good single-shot measurement of longitudinal profile is essential for interpreting experimental results. (not real data) witness Ramped Driver Concept Ez ramped driver Mike Litos [1] M.J. Hogan, et al., New J. Phys. 12 055030 (2010) [2] R.J. England, et al., Phys. Rev. Lett. 100 214802 (2008) PWFA

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