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CLIC_Main Linacs Multi-bunch wake effect in various damping schemes. Vasim Khan 07.03.2012. D. Schulte, PAC09, FR5RFP055. Assumption: Kick on only following trailing bunch. Kick on only following trailing bunch. Direct effect. Direct and indirect effect. a=. A=Exp[a]. A=. a=.
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CLIC_MainLinacsMulti-bunch wake effect in various damping schemes Vasim Khan 07.03.2012
D. Schulte, PAC09, FR5RFP055 Assumption: Kick on only following trailing bunch
Kick on only following trailing bunch Direct effect Direct and indirect effect a= A=Exp[a] A= a= Kick on multiple bunches A=
TD26_vg1.8_discR05_CC: GdfidL simulations with PML Wake @ bunch positions Envelope wake Courtesy of AlexejGrudiev
Amplification factors Envelope wake Wake Kick on only first trailing bunch Envelope wake Envelope wake Wake Wake
Systematic errors in bunch spacing Envelope wake Wake Envelope wake Envelope wake Wake Wake
Choke mode design Choke Mode Courtesy of Jiaru Shi Choke Mode TD26_discR05_CC
Wake (with phase information) nb311={Fc,Frms,Fworst}={357.924, 31.6057, 1094.08} Envelope Wake nb311={Fc,Frms,Fworst}={1515.58, 151.144, 6480.98}
DDS 8 x DDS_Circular DDS_A (Elliptical) CERN and Uni. Manchester + C.I. collaboration
DDS _Hybrid : CLIC_G + Manifolds WW WW=7.5 WH =6.5 Wpos=14.5 WH Wpos No interleaving Linear tapering
E-H Boundary condition H-H Boundary condition DDS_Hybrid DDS_Hybrid
Comparison * Only lowest dipole wake with 311 bunches is considered
Remarks • TD26 wake looks acceptable • Choke mode wake needs improvement. The 60 GHz (5th harmonic) mode detuning will certainly improve the wake • For conventional DDS the wake is unacceptably high • For hybrid DDS with possible interleaving wake might improve. However, fundamental mode rf parameters will get exacerbated Acknowledgments • Thank you A. Grudiev, J. Shi and A. D’Elia for providing the wake data and • D.Schulte and A. Latina for helping me understand the matrix calculations Thank you
Wake Envelope wake
Random bunch shift: -1% to 1% RMS = 0.5% Wake For nb=312 Wake on 120 bunches Fc=1.0087 Frms= 3.0016 Fworst= 15.61 Envelope wake For nb=312 Wake on 120 bunches Fc=1.058 Frms= 6.35 Fworst= 28.51