Alternative Design: Coax TM110-pi coupler rejects operating mode using field symmetry.
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L. Xiao, LHC-CC alternati ve design results, Feb.28 , 2009 1 O perating m ode's coupling atLO M /SO M coupler 1.E +07 1.E +08 1.E +09 1.E +10 3 3.5 4 4.5 5 5.5 6 6.5 7 LO M /SO M center conductor shift(m m ) Q extatLO M /SO M coupler Alternative Design: • Coax TM110-pi coupler rejects operating mode using field symmetry. • LOM/SOM coupler rejects operating mode using electric field node. • HOM coupler rejects operating mode using filter. LOM/SOM WG: TM110-0 Coax: TM110- pi LOM/SOM HOM HOM 800MHz LHC Crab Cavity Alternative Design 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.
description
LOM/SOM. LOM/SOM. WG: TM110-0. HOM. Coax: TM110-pi. HOM. 800MHz LHC Crab Cavity Alternative Design. Alternative Design: Coax TM110-pi coupler rejects operating mode using field symmetry. LOM/SOM coupler rejects operating mode using electric field node. - PowerPoint PPT Presentation
Transcript of Alternative Design: Coax TM110-pi coupler rejects operating mode using field symmetry.
L. Xiao, LHC-CC alternative design results, Feb.28, 2009
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Operating mode's coupling at LOM/SOM coupler
1.E+07
1.E+08
1.E+09
1.E+10
3 3.5 4 4.5 5 5.5 6 6.5 7
LOM/SOM center conductor shift (mm)
Qex
t at
LO
M/S
OM
co
up
ler
Alternative Design: • Coax TM110-pi coupler rejects operating mode using field symmetry.• LOM/SOM coupler rejects operating mode using electric field node.• HOM coupler rejects operating mode using filter.
LOM/SOM
WG: TM110-0
Coax: TM110-pi
LOM/SOM
HOM
HOM
800MHz LHC Crab Cavity Alternative Design
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.
L. Xiao, LHC-CC alternative design results, Feb.28, 2009
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Operating Mode
E-field B-field
E-BC
Frequency 800MHz
(R/Q) 99ohm/cavity
Deflecting Voltage VT for two-cell cavity 2.5MV
Epeak 29MV/m
Bpeak 69mT
Mode separation (Opt.-SOM) 89MHz
L. Xiao, LHC-CC alternative design results, Feb.28, 2009
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Monopole and Vertical Dipole Modes
Vertical Dipole modes
F (MHz) 888.130 889.123 899.865 906.237 985.622 996.683
R/Q(Ώ/cavity) 35.3 1.2 0.9 30.9 16.4 2.3
Qext 41 46 44 44 59 67
LOM modes
F (MHz) 587.056 587.218 608.210 608.288
R/Q(Ώ/cavity) 54.1 41.8 64.5 71.4
Qext 49 50 129 129
L. Xiao, LHC-CC alternative design results, Feb.28, 2009
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Horizontal Dipole Mode
Horizontal Dipole modes: TM110-o mode is the operating mode
F (MHz) 799.682 (pi mode)
799.985
(0-mode)
897.095 898.974 982.510 996.130
R/Q(Ώ/cavity) 1.1 99.5 0.08 1.0 11.2 4.1
Qext 3.6e4 >e9 1430 1395 932 1359
L. Xiao, LHC-CC alternative design results, Feb.28, 2009
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TM110-zero mode at horizontal plane: F=800.18MHz,
Multipacting in the Cell
E-field
B-field)/(1.25.0/05.1/)50(
)(05.1625.1*2*05.0)50(
25.12/5.2
mMVLVzmmrEz
MVec
fVcrmmrVz
MVVcellone
T
T
E-BC
Assuming two-cell crab cavity provides VT=2.5MV,
L=0.5m
L. Xiao, LHC-CC alternative design results, Feb.28, 2009
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Ez=0~5.6MV,
MP happened on disk areas
Resonant Electrons in 800 MHz Cell
2-points MP, 0.5,1, 1.5 order
L. Xiao, LHC-CC alternative design results, Feb.28, 2009
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Nb SEY Curve
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 500 1000 1500 2000impact energy (eV)
delta
dEz=0.1MV/m
Resonant Trajectories in 800 MHz Cell
Different Ez range
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