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PS TFB

Project triggered by: K. Schindl and R. Cappi Hardware: J. Belleman, A. Blas, T. Bohl, F. Caspers, J.L. Gonzalez, W. Hofle, J. M. Lacroix, S. Livesley, R. Louwerse, M. Paoluzzi, F. Pedersen, V. Rossi, J. Sladen

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PS TFB

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  1. Project triggered by: K. Schindl and R. Cappi Hardware: J. Belleman, A. Blas, T. Bohl, F. Caspers, J.L. Gonzalez, W. Hofle, J. M. Lacroix, S. Livesley, R. Louwerse, M. Paoluzzi, F. Pedersen, V. Rossi, J. Sladen Hardware simulations: V. Vendramini, E. Vogel Beam decoherence study:E. Benedetto, M. Chanel, M. Martini, E. Metral, F. Zimmermann PS TFB Where do we come from? Where are we? Where do we go? AB-RF-FB section meeting

  2. PS TFB History 05/98 First meeting, start of the PS TFB project 10/98 Start study of a kicker prototype (J-L Gonzalez) 06/99 H Kicker mechanical design started (J-M Roux) 11/99 Mechanical drawings in the final version. 01/00 Price Enquiry for a single bloc vacuum chamber (3 pieces; H + V + spare) 04/00 Second price enquiry sent for vacuum pipes in two pieces (no response for single bloc) 10/00 Order placed to Metaceram (Hiperceramics was second) 05/02 Order cancelled 08/02 New price inquiry 10/02 Order placed to Hiperceramics; delivery planned for April 2003 01/03 Project taken over by rf 10/03 Successful test of electronic prototype on old kicker an amplifier 11/03 Delivery of ceramic pipes 01/04 H kicker Delivered, Ceramic pipe not vacuum tight after brazing (weak metallization) 08/04 Re-design of transition pieces 10/04 Order placed for re-metallization (SCT) and new ceramic rings (Hiperceramics) AB-RF-FB section meeting

  3. PS TFB 1 2 3 AB-RF-FB section meeting

  4. PS TFB Kickers • Initial requirements: R. Cappi 1999 • Damping of a +/-1.5 mm oscillation within 100 turns (chromaticity) • Bandwidth: [10kHz - 20 MHz] (q = 0.1, 20 MHz kicker ripple) • Decision taken • 2 x 3 kW, magnetic kicker • Final result (F. Caspers 12/04) • Usable bandwidth = 10 MHz (limited by non linear phase and transit time factor (68 ns) • Field above Roberto’s specs (factor 7) AB-RF-FB section meeting

  5. PS TFB Kickers • Workload for modifying the magnetic kicker? • make it shorter (1/3) for transit time factor • Change the shape of capacitive plate to increase ZC • This means a complete re-design Could we use the old strip line kicker? yes!! (see next slide) AB-RF-FB section meeting

  6. PS TFB Kickers • Why is the strip line kicker ok for the job? • with 2 x 3 kW, it give almost exactly what is required in term of kick • Its bandwidth is only limited by the transit time factor of 3 ns (166 MHz) • What ‘s wrong with it? • Impedance matching to be improved • Impedance transformer required with present amplifiers From Reinier Input impedance: 12.5 Ω Output impedance: 112.5 Ω (x9) Each coax: 37.5 Ω = two 75 Ω in // Voltage gain = 3 AB-RF-FB section meeting

  7. PS TFB Kickers • Is there a security margin with the strip line kicker? • The LHC beams have been obtained without dampers  • Factor 6.25 in kick strength with nominal LHC beam (to be checked with totem beam) • (decoherence in 2ms, 0.32 ms calculated by Roberto) • Chromaticity could be lowered by a factor 2 in 2007 (new PFW power supplies) • What ‘s unknown (yet)? • Impedance transformer characteristics AB-RF-FB section meeting

  8. PS TFB Amplifiers • Initial requirements • Bandwidth: [10kHz - 20 MHz] • 3 kW on 12.5 Ω • Actual performances • Bandwidth: [100kHz - 35MHz] • 3 kW – 2 ms, 100 W CW • What ‘s unknown? • Precise phase response AB-RF-FB section meeting

  9. PS TFB Amplifiers • What’s wrong? • The first Betatron line (q. FREV) is not covered • Does it matter? • There are two answers to this question, one valid for injection damping, the other for h-t instabilities • ( Injection damping is faster than the growth rate of h-t instabilities -1ms vs 10 to 100 ms) • During injection, what matters is the spectrum of the beam. Less than 8 % of the energy is in the first Betatron line. If it isn’t driven instable, there should be only 8% less damping efficiency in linear regime and almost no difference in saturation mode. • For h-t modes, only the negative (n+Q).FREV lines are instable, but somehow “compensated” by the positive spectral lines… except (when ξ≠0) for the first negative line n = -7 or (1-q).FREV . • As q Є [0.2 0.4], n = -7 mode Є [348 kHz, 261 kHz]. This instable line is covered by the amplifier. Of course the q.FREV line should be “electronically” stable. Is there a proof? see next slide ! AB-RF-FB section meeting

  10. PS TFB Amplifiers Is there a proof that the system would work with 100 kHz HP cutoff? Injection error damping with wideband feedback With H.P. Simulations from Elmar 50 turns/div AB-RF-FB section meeting

  11. PS TFB Amplifiers details of the simulation • Is there a proof concerning h-t instabilities? • It is a well established theory ! AB-RF-FB section meeting

  12. PS TFB Amplifiers • Has everything been taken into account? • e-p instabilities: not observed in the PS ! • h-t modes: have a damping effect with positive ηξ (both negative at PS injection) => positive chromatic frequency. It damps the injection errors with a time constant of 5 ms (20 ms total damping) without emittance blow-up (simulation by Elias) • Chromaticity and Chromatic frequency: it changes the instable m-mode but not the • frequency at which it should be corrected. In 2007 we might have a lower ξ => less kick requirements • Broadband impedance: should damp the lower modes without blow-up. • Under simulation (E. B. + F. Z.) • Space charge: it is beneficial as it increases the filamentation time. • Under simulation (E. B. + F. Z.) • Octupolar tune: speeds-up filamentation but not foreseen in normal operation • Real kicker ripple (30 MHz): ok with the amplifier (35 MHz) AB-RF-FB section meeting

  13. PS TFB Electronic core • How do we do? • Use of LHC 1TFB and TFB hardware made compatible with minor add-ons • Specific FPGA programming software AB-RF-FB section meeting

  14. PS TFB Budget No budget allocation for 2005. 133 kCHF need to be found!! - 3kW power loads: 10k - Impedance matching transformers: 8k (6k FSU + 2k material) - Kicker modification (mechanical setup for fixing Xformers and loads + install new feedthroughs): 8k (7k FSU + 1k material) - Interlock circuit design and construction: 16k (6k study + 10k construction) - Construction of circuits developed for LHC: 12k - VME crate to plug new PCBs : 10k - Strip-line Kicker modification: 15k (5k mech. Study, 10k construction and material) - Power amplifiers modification: 35k (in case we do not change the PCB's) - Cabling in racks: 4k - Ceramic pipes end work: 10k - Unexpected: 5k Total: 133 kCHF What has been spent: H/V kicker study: 100k H kick construction: 100k Ceramic pipes: 100k Electronics, cabling: 50k Total: 350k Originally planned: 360k AB-RF-FB section meeting

  15. PS TFB Workload • - 3kW power loads: 1 W • - Impedance matching transformers: 4 W • Kicker modification : 4 W • Interlock circuit design and construction: 7 W • - Construction and test of circuits developed for LHC: 3 W • - VME crate: 1 W • - Strip-line Kicker modification: 4 W • - Power amplifiers modification: 12 W • - Cabling in racks: 1 W • Ceramic pipes end work: 1 W • FPGA programming: 8 W • Supervision: 3 W • Unexpected: 3 W • Commissioning (hard + beam): 3 + 3 W • Total: 58 W AB-RF-FB section meeting

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