HOM filter design for double quarter wave crab

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HOM filter design for double quarter wave crab cavity Binping Xiao, BNL

HOM filter design for double quarter wave crab cavity Binping Xiao, BNL

Outline • • • SPS double quarter wave crab cavity Constraint in the HOM

Outline • • • SPS double quarter wave crab cavity Constraint in the HOM filter design Design of HOM filter Fundamental mode in HOM filter Shunt impedance HOM power estimation 2

SPS double quarter wave Cryo jumper HOM FPC beam HOM x 2 © Capatina

SPS double quarter wave Cryo jumper HOM FPC beam HOM x 2 © Capatina et, al @CERN Adjacent beam pipe through the vessel 3

Constraint in the HOM filter design © Capatina et, al @CERN A liquid helium

Constraint in the HOM filter design © Capatina et, al @CERN A liquid helium vessel for the HOM filter was not shown here 348 mm 255 mm 139 mm Magnetic & thermal shielding reference 4

S 21 [d. B] L-shape filter - SPS Cu pin for RF feedthrough to

S 21 [d. B] L-shape filter - SPS Cu pin for RF feedthrough to outside load Flanges to separate HOM filter from cavity, 3 mm RF-seal Cu gasket. Band stop structure to reduce loss on Cu gasket Bend to lower peak magnetic field 570 MHz (-2 d. B) 0 -20 -40 -60 -80 -100 -120 -140 -160 -180 685 MHz (-20 d. B) 400± 17 MHz (128 d. B) 0 • • • 0. 5 Freq [GHz] 1 1. 5 2 L shape to meet the space constraint. Band stop structure to reduce loss on Cu gasket. 34 MHz rejection band at 400 MHz. Hook length tuned to minimize Hpk on hook surface. 5

L-shape filter - Modification 69 6

L-shape filter - Modification 69 6

L-shape filter - Modified Better coupling for 0. 6~2 GHz modes. 400 MHz rejection

L-shape filter - Modified Better coupling for 0. 6~2 GHz modes. 400 MHz rejection is optimized together with the cavity. 7

Filter integration • 3 HOM filters per cavity, with two 60 -degree away from

Filter integration • 3 HOM filters per cavity, with two 60 -degree away from the center to give clearance to the other beam pipe in horizontal kick scheme • Symmetrical design to minimize multipolar components. • 60 degree is chosen to provide more coupling to HOMs. • Compact to fit into cryomodule. • Longer RF cables can be easily attached to the L shape filter to reduce static heating.

Filter at 400 MHz - SPS E field H field For 400 MHz crabbing

Filter at 400 MHz - SPS E field H field For 400 MHz crabbing mode with Vt = 3. 34 MV: • Peak E field on the hook: 19. 3 MV/m, on the cavity: 36. 7 MV/m. • Peak H field on the hook: 61. 3 m. T, on the cavity: 71. 3 m. T. • Coupling to 400 MHz: 7. 9 x 109, 1. 1 W at each port to outside load. • 30 m. W dynamic loss per filter for 20 nΩ resistance. • 7. 8 m. W range RF loss on Cu gasket. • 10. 8 µW range RF loss on Cu pin. 9

Filter at 400 MHz - modified E field H field For 400 MHz crabbing

Filter at 400 MHz - modified E field H field For 400 MHz crabbing mode with Vt = 3. 34 MV: • Peak E field on the hook: 25. 7 MV/m, on the cavity: 37. 1 MV/m. • Peak H field on the hook: 47. 8 m. T, on the cavity: 70. 4 m. T. • Coupling to 400 MHz: 2. 2 x 1010, 0. 4 W at each port to outside load. • 30 m. W dynamic loss per filter for 20 nΩ resistance. • Sub µW range RF loss on Cu gasket. • Sub µW range RF loss on Cu pin. 10

Shunt impedance - SPS 1 E+07 Impedance R(ohm/cavity), RT (ohm/m/cavity) 1 E+06 1 E+05

Shunt impedance - SPS 1 E+07 Impedance R(ohm/cavity), RT (ohm/m/cavity) 1 E+06 1 E+05 1 E+04 1 E+03 1 E+02 1 E+01 1 E+00 1 E-01 1 E-02 1 E-03 1 E-04 5. 00 E-01 Vert 7. 50 E-01 1. 00 E+00 1. 25 E+00 1. 50 E+00 Frequency [GHz] Hori Longi 1. 75 E+00 2. 00 E+00 need the help from pickup port (for 1. 75 GHz) 11

Shunt impedance - Modified Vert Hori Longi Impedance R(ohm/cavity), RT (ohm/m/cavity) 1 E+07 1

Shunt impedance - Modified Vert Hori Longi Impedance R(ohm/cavity), RT (ohm/m/cavity) 1 E+07 1 E+06 1 E+05 1 E+04 1 E+03 1 E+02 1 E+01 1 E+00 0. 5 1. 0 Frequency [GHz] 1. 5 2. 0 We still need the help from pickup port (for 1. 5 GHz), I suggest we put two ports, one dedicate to PU and the other one dedicate to HOM. 12

HOM power estimation modified F (MHz) Mode Type Qext Longitudinal [Ω/cavity] Impedance Horizontal [Ω/m/cavity]

HOM power estimation modified F (MHz) Mode Type Qext Longitudinal [Ω/cavity] Impedance Horizontal [Ω/m/cavity] Vertical [Ω/m/cavity] HOM Power [Watt] Close to harmonic of 40. 08 MHz • Based on 25 n. S beam spectrum 564. 1 L 1600 586. 4 L 2630 681. 4 H 6710 21300 115000 701. 6 L 5 960. 1 L 1170 32 11400 45. 0 7. 6 339 36. 8 14 th 12. 4 25. 4 17 th 24 th © Calaga & Salvant @CERN • Power of transverse modes estimated based on 5 mm offsets. • HOM power is about 132 Watts per cavity 13

Thank you! 14

Thank you! 14