L. Xiao, LHC-crab-cavity WebEx meeting, Dec.09, 2008

Baseline Design: Significant coupling of input power to LOM/SOM couplers

FPCHOM

Update on LHC Crab Cavity Conceptual Design

LOM/SOM

L. Xiao, LHC-crab-cavity WebEx meeting, Dec.09, 2008

Alternative Design 1:Power coupler, HOM couplers in between of the two cells• Maintain field symmetry in LOM/SOM coupler regions• Avoid cross coupling between FPC and LOM/SOM couplers• Coax TM110-pi coupler rejects operating mode using field symmetry.

FPC Waveguide: TM110-0 mode

Coax: TM110-pi mode

Coax-to-coax:

LOM/SOM modes

Coax-to-coax:

LOM/SOM modes

HOM

L. Xiao, LHC-crab-cavity WebEx meeting, Dec.09, 2008

Alternative Design 2:Only TM110-0/π mode couplers in between of the two cells

LOM/SOM

HOM

Operating mode in coaxial beampipeOperating mode's coupling at LOM/SOM coupler

1.E+05

1.E+06

1.E+07

1.E+08

1.E+09

1.E+10

1.E+11

0 1 2 3 4 5 6 7 8

center conductor shift (mm)

Qext

at

LO

M/S

OM

co

up

ler

Qext for TM110-0 mode The center conductor will be slightly bent so that the rotating flange can adjust the tip of the center conductor to lie exactly along the E-field node of the operating mode field.