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Few slides from J. Fox’ talk in last November’s LARP meeting

Few slides from J. Fox’ talk in last November’s LARP meeting. Constraints for design of new pick-ups and kickers for the wide band ecloud feedback. W. Hofle , CERN. c urrent tapered stripline pick-up has limitation in frequency due

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Few slides from J. Fox’ talk in last November’s LARP meeting

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  1. Few slides from J. Fox’ talk in last November’s LARP meeting LARP CM15 02.11.2010

  2. LARP CM15 02.11.2010

  3. LARP CM15 02.11.2010

  4. LARP CM15 02.11.2010

  5. LARP CM15 02.11.2010

  6. Constraints for design of new pick-ups and kickers for the wide band ecloud feedback W. Hofle, CERN current tapered stripline pick-up has limitation in frequency due to TE11 cut-off around 1.6 GHz  goal: extend bandwidth with future new pick-up LARP CM15 02.11.2010

  7. Example of “TMC” instability signals from pick-up not corrected for transfer functions  milder losses (10 to 20 % of the bunch is lost before the first BCT measurement point)  losses also correlated to max of vertical signal  oscillation profile is rather similar before losses  oscillations are quickly decaying after the intensity decrease B. Salvant et al.

  8. Motivation for new pick-up TMCI: extends beyond 1.6 GHz ecloud: spurious signals at 1.6 GHz extend transverse diagnostics to beyond 1.6 GHz non-linear phase response of existing wide band pick-ups (BPWs) not optimal for feedback with time domain sampling LARP CM15 02.11.2010

  9. Proposed long strip line as new pick-up gating on 1st pulse Frequency Domain |ZT (w)| t ^ ZT … load or short Beam L w f=1/(2t) ^ ZT (w) = ZT j sin(wt/2) e -jwt/2 t = 2 L/c sampling only the first pulse results in flat frequency response maximum bunch length 5 ns  L > 0.75 m for separation of pulses several striplines can be arranged in vacuum chamber (circumference) LARP CM15 02.11.2010

  10. SPS aperture LARP CM15 02.11.2010

  11. Pick-up close to QD installing pick-up at QD with circular aperture high vertical beta function (~100 m) frequency reach: 83 mm diameter: cut-off: 2.1 GHz can make aperture smaller than current BPW pick-ups Pick-up close to bends MBB: flat more rectangular chamber: cut-off frequency of relevant TE mode (132 mm width): 1.2 GHz not good for pick-up, but possibly for kicker if bandwidth < 1 GHz • Scenario under discussion: • new pick-up as CERN project, use high power feed throughs • in order to also be able to use it as a kicker for prototype tests • design study / construction of a kicker as a joint LARP/CERN effort • pick-up for installation in shutdown 2012-2013 ready for • feed back demonstrator in 2013 • Included in LIU project proposal at CERN LARP CM15 02.11.2010

  12. slow extraction radiation high current transverse FB RF, low radiation injection extraction CNGS/LHC special instrumentation no RF infrastructure extraction LHC

  13. space available for transverse feedbacks current layout SPS LSS3

  14. space available for transverse feedbacks 2 3 PU BPW 800 MHz 4 2 3 PU BPW QD 800 MHz 4 PU BPW PU BPW QD future layout (option 1) SPS LSS3

  15. Travelling wave cavity in SPS LSS3 LARP CM15 02.11.2010

  16. Current location of device used as kicker LARP CM15 02.11.2010

  17. Current location of device used as kicker LARP CM15 02.11.2010

  18. Short straight section at QF’s: flat chamber LARP CM15 02.11.2010

  19. Free space in dispersion suppressor LARP CM15 02.11.2010

  20. Issues: Layout in SPS LSS3 Current: 200 MHz TWC: 2x4, 2x5 space in LSS3 (straight section) used for pick-ups space in dispersion suppressor for kickers Option 1: 200 MHz TWC: 2x2, 2x3, 2x4 space for pick-ups close to QD’s preserved Option 2: TWC’s have more sections, no space left for pick-ups  study needed if all pick-ups & kickers for the future system can be put into dispersion suppressor; combine with study for movement of current damper from LSS2 to LSS3 and TWC upgrade location fixes aperture ! LARP CM15 02.11.2010

  21. Study items for new pick-up and kicker kick strength / bandwidth must come from simulations aperture, where are we going to install it equipment we want to put in the tunnel for final system is physical centering of the beam in the pick-up required ? is “electronic” centering possible ? kicker: what are we going to use, set of short strip lines ? LARP CM15 02.11.2010

  22. LARP CM15 02.11.2010

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