1. KEK R&D for LHC Plan of 800MHz Cavity Calculation of 400MHz Cavity 16 th September 2009, LHC-CC09 at CERN K.Nakanishi

2. KEK activities (800MHz) Oide-san continuously supports our activities. New EP system – Construction will be completed in January 2010. – We will test this EP system for 509 MHz cavities. – We can modify this system for LHC CC. – HPR system will be also available. Vertical cold test for LHC CC – Our cryostat is applicable for LHC CC cold test. – We are planning to make a new RF system for 800 MHz (next slide). Many 509 MHz components are convertible. Aluminum model cavity – We will make a aluminum model cavity. To check fittings for new EP system and vertical cold tests.

3. RF system for vertical cold test Atsushi Kabe, KEK Narrow band device Designed for this system Common device

4. Multipacting simulations Multipacting simulation was done for 2-cell S-KEKB type cavity by Solyak-san. We thank LARP people. Multipactings at the opening of the coaxial coupler were found. This type of multipacting shoud be two-side, 1/2th-order multipacting. We have to increase coaxial gap to avoid the lowest order (n=1/2) multipacting. – Increase of gap length gives enough energy to emitted electrons to avoid secondary emission. We observed the same type of multipacting in our 509 MHz KEKB crab cavity at the coaxial coupler at low fields. – Gap length was large enough to avoid the lowest order. – We could process in one hour.

5. Multipacting on an iris Liling-san simulated multipacting for the baseline cavity. He found several multipacting levels. It is understood that a type of multipacting is a two-side, n-th order one. (n=1/2,3/2,5/2, etc.) We observed this type of multipacting in our KEKB crab cavity. Multipacting level exists where This type of multipacting was not severe in our KEKB crab cavity.

6. Concept of KEK compact crab cavity (e-crab) Use lowest mode. Techniques for single mode cavities are well developed. Use the electric field. In pillbox cavity, both of electric and magnetic field can kick the beam. The directions are opposite. Simple shape Simple shape is helpful to make clean surface.

7. Field distribution Electric and magnetic field kick the beam opposite directory. Gap length have to be adjusted to make effective kick voltage.

8. Gap length Gap length was chosen to make maximum kick voltage. Crab mode (TM010) should be lowest mode. Gap length -> 300mm Gap length [mm] Frequency of TE111 [MHz] Gap length [mm] Vkick/Esp [MV/(MV/m)] Vkick/Hsp [MV/(A/m)] Gap Diameter

9. HOM distribution mode Frequency [MHz] V_kick [V/J^1/2] Vz [V/J^1/2] R_z/Q [Ohm] E_sp [MV/m/J^1/2] H_sp [Oe/J^1/2] TM010 * 400.3892381920.29083804.08156 TE111440.8130.296713464509789.27107 TM011471.0370.089472453144697.74127 TM110574.36840614.40.29021608.44152 TE211576.6270.6330240.123273010.1484 TM110587.3570.1316590.00584103.26175 TE211600.5560.5932950.344733010.4589 TM111678.9810.43519313611237.03135 TE111681.7780.0585240.0500503.75130 (TM310) ** 700.3392536460.46629209.28229 *:Crab mode **:mode identification by cartesian coordinates.

10. HOM dumping (fluted pipe) ModeFrequency [MHz] QLQL TM0104031.7e10 TE1114361260 TM0114731.3e10 TM110568430 TM110572150 TE2115751.4e6 TE1115984240 TM111647650 TM2106991500

11. HOM dumping (coaxial antenna) ModeFrequency [MHz] QLQL TM0104002e10 TE1114404700 TM0114716700 TM1105742e12 TE2115772100 TE1115871e12 -6012800 -6791480 -6991.23e9 -7416410 -7932.52e8 -8012590

12. HOM dumping (fulute pipe & coax) ModeFrequency [MHz] RshQLQL TM0104031.1e52.4e5 Fulute4219.2e-317 Fulute421717 TE1114353.6e4415 TM0114714.8e4731 Fulute4944.4e-418 Fulute4947.6e-218 ModeFrequency [MHz] RshQLQL

13. Loss factor SigmaQ 75.5mm2.72x10 -8 C Loss factor [x10 -2 V/pC] Cavity8.00 With fluted pipe8.53 With coaxial antenna8.11 With fluted pipe and coax8.58 ~2.2kV

14. Longitudinal impedance Required impedance < 2kΩ

15. Transverse impedance (Horizontal) |Z/n| [Ohm]

16. Transverse impedance (vertical) |Z/n| [Ohm]

17. Heat load (just for crab mode) In KEKB, Rs of crab cavity was 140nΩ. Maximum Esp is 25MV/m. assumed

18. Input coupler Antenna position [mm] QextRF power* [kW] 1009.8e4144 1255.1e528 1503.4e64.2 Distance between the input coupler port and beam is assumed as 250mm. 77D standard coaxial component is applied as an input coupler. It is required RF power to make 25MV/m Esp.