clic_dds_hpa study
DESCRIPTION
CLIC_DDS_HPA study. 30.11.2010. CLIC_DDS Study Collaboration. Vasim Khan Alessandro D’Elia Roger Jones. University of Manchester and Cockcroft institute, U.K. CERN, Switzerland. Alexej Grudiev Germana Riddone Vadim Soldatov Walter Wuensch Riccardo Zennaro. Outlook. - PowerPoint PPT PresentationTRANSCRIPT
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 1/21
CLIC_DDS_HPA study 30.11.2010
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 2/21
CLIC_DDS Study Collaboration
• Vasim Khan
• Alessandro D’Elia
• Roger Jones
• Alexej Grudiev
• Germana Riddone
• Vadim Soldatov
• Walter Wuensch
• Riccardo Zennaro
University of Manchester and Cockcroft institute, U.K.
CERN, Switzerland
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 3/21
Outlook
• High Phase Advance (HPA) Structures: Merits and Demerits
• CLIC_DDS_HPA
• Future of CLIC_DDS_HPA
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 4/21
High Phase Advance Structures
cosψ 2sinψ ψ
E sinψ 4
ω/cR/Q
RP
2acc
2
2A
absg
g
v
v
1) Low group velocity → Less power absorbed during breakdown
Ref: R.M. Jones, et. al., SLAC-PUB 8887
CLIC
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 5/21
NLC: Band partitioning
NLC: DS1 a = 4.23 mm
ψacc : 120°→ 150°:Lowest dipole kick factor reduces by ~ 20%
Ref: R.M. Jones, et. al., SLAC-PUB 9467
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 6/21
Fundamental mode Optimisation CLIC_DDS_HPA
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 7/21
Band partitioning: CLICDDS_A and DDS_HPA
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 8/21
120deg.Γx = 0.0126
Cell # 1a=4.0 mm, t=4.0 mm
150deg.Γx = 0.021
Cell # 1a=4.0 mm, t=3.2 mm6.1~
150
120Q
QΓ
1α Q
Dipole mode properties
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 9/21
DDS_HPA
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 10/21
RF parameters Unit DDS_A DDS_HPA42 DDS_HPA32
Phase advance / cell Deg. 120 150 150
Iris thickness mm 4/1.47 3.2/2.8 3.2/2.8
Bunch population 109 4.2 4.2 3.2
Q (In / Out) - 5020 / 6534 6931/7045 6931/7045
R’ (In / Out) MΩ/m 51 / 118 72.4/102.4 72.4/102.4
vg/c (In / Out) % 2.07 / 1.0 2.1 / 0.45 2.1 / 0.45
Eaccmax (L./UnL.) MV/m 105 / 132 93 .3/ 143 90/ 138
Pin MW 71 68.2 63.6
∆Tmaxsur
oK 51 51 48
Emaxsur MV/m 220 234 225
Scmax W/μm2 6.75 5.9 5.5
RF-beam efficiency % 23.5 29 23.3
Comparison: 120 vs 150
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 11/21
DDS_HPA: Merits and Demerits
Reduction in dipole bandwidth from 2.1 GHz to 1.8 GHz
1. Necessary to reduce bunch population to satisfy wakefield constrains
2. Luminosity reduction
Reduced input power Less power absorbed
during breakdown Kick factors reduced Better dipole coupling
Cost efficient ?
Merits Demerits
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 12/21
Enhanced damping: Eight manifoldsFour regular and four additional manifolds
Significant coupling
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 13/21
Cell parametersa = 4.3 mmt = 2.6 mmRc = 9.0 mmMr = 2.0 mmMc = 15.1 mm
Fundamental mode propertiesQ=7080R’/Q=10.356 (kΩ/m)vg=2.44 (%c)Es/Eacc=2.22Hs/Eacc=4.3 (mA/m)Sc/Eacc=5.45 x 10-4 (W/μm2/Eacc2)
Dipole mode properties
fsyn=16.1 GHz
Cell # 1
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 14/21
Cell parametersa = 2.5 mmt = 2.8 mmRc = 8.8 mmMr = 2.0 mmMc = 15.1 mmvg=0.32 (%c)
Cell # 24
fsyn=17.89 GHz
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 15/21
Lowest dipole mode propertiesΔf=2.25 σ=1.78 GHzΔf/fc= 10.5 (%c)
Two Cell result Need improvement
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 16/21
Regular manifold
Additional manifold
Damping material
εr=13tanδ=0.02NMr=2.8Damp_r=1
Eight manifolds and SicAs the coupling in the last cell is poor it is important to enhance coupling by optimising the last cell
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 17/21
Cell # 24 :NMr=2 .8 Damp_r=1.0
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 18/21
Accelerating modeNMr=2 .8 Damp_r=1εr=14 tanδ=0.04
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 19/21
DDS_HPA_SiC• SiC insertion in an 8-manifold cell improves damping
• The SiC properites and dimensions are optimised for Cell # 24
• This optimisation does not improve damping of Cell # 1
• Due to SiC losses, multiple avoided crossings are observed
• Need some modification in circuit model to incorporate additional losses (SiC) (future work ?)
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 20/21
Closing remarks
• CLIC_DDS_HPA: 1) Coupling looks promising
2) Need to improve bandwidth
• To be investigated in detail:
1) Eight manifolds
2) DDS_SiC damping
3) Circuit model modification to incorporate SiC losses
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 21/21
Acknowledgments
• We have benefited from discussions with Juwen Wang, Zhengai Li and Toshiyasu Higo on X-band structures
• Thanks to Igor Syratchev for suggesting to investigate CLIC_DDS_SiC.
Thank you
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 22/21
Additional slides
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 23/21
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 24/21
Cell # 1
Cell # 24
Cell # 1
Cell parametersa = 4.6 mmt = 2 mmRc = 9.0 mmMr = 2.0 mmMc = 15.1 mmvg = 3.6 (%c)
Fsyn~15.76 GHz
Cell # 24
Cell parametersa = 3.3 mmt = 3 mmRc = 9.0 mmMr = 2.0 mmMc = 15.1 mmvg = 0.95 (%c)
Fsyn~17 GHz
Four manifolds
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 25/21
Cell # 1Cell parametersa = 4.6 mmt = 2 mmRc = 9.0 mmMr = 2.0 mmMc = 15.1 mm
vg = 3.6 (%c)Fsyn~15.77 GHz
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 26/21
Cell # 24
Cell parametersa = 3.3 mmt = 3 mmRc = 9.0 mmMr = 2.0 mmMc = 15.1 mm
vg = 0.95 (%c)
Fsyn~17 GHz
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 27/21
Cell # 1Cell parametersa = 4.6 mmt = 2 mmRc = 9.0 mmMr = 2.0 mmMc = 15.1 mm
vg = 3.6 (%c)Fsyn~15.77 GHz
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 28/21
Cell # 24
Cell parametersa = 3.3 mmt = 3 mmRc = 9.0 mmMr = 2.0 mmMc = 15.1 mm
vg = 0.95 (%c)
Fsyn~17 GHz
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 29/21
Cell # 1 :NMr=2 .8 Damp_r=1.0
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Vasim Khan X-Band RF Structures, Beam Dynamics and Sources Workshop, Cockcroft Institute 30.11.10 30/21
Cell # 1Cell parametersa = 4.6 mmt = 1 mmRc = 9.0 mmMr = 2.0 mmMc = 15.1 mm
vg = 4.84 (%c)Fsyn~15.65 GHz