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Accelerating structures: 3 TeV and 500 GeV CLIC designs, HOM damping and technology alternatives. 26.05.2009 Alexej Grudiev. 3 TeV CLIC accelerating structure design 500 GeV CLIC accelerating structure design Alternative HOM damping Choke mode damping Damped Detuned Structure - PowerPoint PPT Presentation

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CLIC main linac acc. structure

Accelerating structures: 3 TeV and 500 GeV CLIC designs, HOM damping and technology alternatives 26.05.2009Alexej Grudiev CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.1CERN5/25/2009#Outline3 TeV CLIC accelerating structure design500 GeV CLIC accelerating structure designAlternative HOM dampingChoke mode dampingDamped Detuned StructureTechnology alternativesQuadrant Brazed DiskSingle rounded cellDouble rounded cell

Coupler alternativesMode launcher couplerElectric couplerMagnetic coupler with dampingRidged waveguide damping for lower pulse surface heating temperature rise

30 CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.3 TeV CLIC accelerating structure design CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.

WDS cell geometryWaveguide Damped Structure (WDS) 2 cellsMinimize E-fieldMinimize H-fieldProvide good HOM dampingProvide good vacuum pumping CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Optimization constraintsBeam dynamics (BD) constraints based on the simulation of the main linac, BDS and beam-beam collision at the IP:N bunch population depends on /, a/, f and because of short-range wakesNs bunch separation depends on the long-range dipole wake and is determined by the condition: Wt,2 N / Ea= 10 V/pC/mm/m 4x109 / 150 MV/mRF breakdown and pulsed surface heating (rf) constraints:Tmax(Hsurfmax, tp) < 56 K Esurfmax < 260 MV/mPin/Cin(tpP)1/3 = 18 MWns1/3/mm CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Optimizing Figure of MeritLuminosity per linac input power:

Collision energy is constantFigure of Merit (FoM = Lbx/N) in [a.u.] = [1e34/bx/m2%/1e9] CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Total cost modelTotal cost = Investment cost + Electricity cost for 10 years Ct = Ci + CeCi = Excel{fr; Ep; tp; Ea ; Ls ; f ; } Repetition frequency; Pulse energy; Pulse length; Accelerating gradient; Structure length (couplers included); Operating frequency; rf phase advance per cellCe = (0.032 + 2.4/FoM) CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Parameters of 3TeV structure CLIC_GStructure CLIC_GFrequency: f [GHz]12Average iris radius/wavelength: / 0.11Input/Output iris radii: a1,2 [mm]3.15, 2.35Input/Output iris thickness: d1,2 [mm]1.67, 1.00Group velocity: vg(1,2)/c [%]1.66, 0.83N. of reg. cells, str. length: Nc, l [mm]24, 229Bunch separation: Ns [rf cycles]6Luminosity per bunch X-ing: Lb [m-2]1.221034Bunch population: N3.72109Number of bunches in a train: Nb312Filling time, rise time: f , r [ns]62.9, 22.4Pulse length: p [ns]240.8Input power: Pin [MW]63.8Pin/CtPp1/3[MW/mm ns1/3]18Max. surface field: Esurfmax [MV/m]245Max. temperature rise: Tmax [K]53Efficiency: [%]27.7Figure of merit: Lb /N [a.u.]9.1

Parameters assuming coupler overhead CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.CLIC_G versus X-band measurement dataConstraints @ {200ns, BDR=10-6 bpp/m} ~ {180ns, BDR=3x10-7 bpp/m} CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.500 GeV CLIC accelerating structure design CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.

Beam dynamics constraints at 500GeV and conservative emittanceShort range wake limits bunch chargeLong range wake amplitude on the second bunch limits the bunch spacing:Wt(2) * N / < 20 V/pC/m/mm * 4x109 / 150 MV/m10 V/pC/m/mm has been used for 3TeVNominal parametersx,y = 660nm, 20nmx,y = 4mm, 0.09mmConservative parametersx,y = 3m, 40nmx,y = 8mm, 0.1mm CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Other constraintsRF constraints remains the same as for 3TeV:P/C*tp1/3 < 18 Wu(MW/mm*ns1/3)Esmax < 260 MV/mTmax < 56 KRF phase advance per cell: 120 or 150 degreeNo 3TeV constraints:Structure length Ls more than 200 mm; Pulse length tp is freeBunch spacing Ns is free3TeV constraints Ns = 6:Ls = 230 mm; tp = 242 nsLs = 480 mm; tp = 242 nsLs = 480 mm; tp = 483 ns

CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Figure of Merit

CLIC_G@3TeV: 9.1

CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.

If repetition rate is limited to 50 Hz213Case 2 has been chosen:As close as possible to 100 MV/mCost considerations which were not included in the optimizationBeam current in injectors is only ~2 times higher than for 3 TeVRF constraints for PETS are the lowest CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Parameters of the structuresCase3TeV nominal500GeV conservativeStructure CLIC_GCLIC_502Average accelerating gradient: [MV/m]10080rf phase advance: [o]120150Average iris radius/wavelength: / 0.110.145Input/Output iris radii: a1,2 [mm]3.15, 2.353.97, 3.28Input/Output iris thickness: d1,2 [mm]1.67, 1.002.08, 1.67Group velocity: vg(1,2)/c [%]1.66, 0.831.88, 1.13N. of reg. cells, str. length: Nc, l [mm]24, 22919, 229Bunch separation: Ns [rf cycles]66Luminosity per bunch X-ing: Lb [m-2]1.2210340.571034Bunch population: N3.721096.8109Number of bunches in a train: Nb312354Filling time, rise time: f , r [ns]62.9, 22.450.3, 15.3Pulse length: p [ns]240.8242.1Input power: Pin [MW]63.874.2Pin/CtPp1/3[MW/mm ns1/3]1817Max. surface field: Esurfmax [MV/m]245250Max. temperature rise: Tmax [K]5356Efficiency: [%]27.739.6Figure of merit: Lb /N [a.u.]9.13.3 CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Alternative HOM damping Choke mode cavity Damped Detuned Structure CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Magnetic field enhancement in WDS

NDSWDS CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.

The Choke mode cavityShintake, 1992 CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Radial choke for 2/3 cells

Electric fieldMagnetic fieldCoax. chokeCoax. chokeRadial chokeRadial chokeheatheat CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.20Alternative Wakefield SuppressionAlternate method entails heavy detuning and moderate damping of a series of interleaved structures (known as CLIC_DDS). This is a similar technique to that experimentally verified and successful employed for the NLC/GLC program.

Integration of Task 9.2 within NC WP 9 -anticipate test of CLIC_DDS on modules

Potential benefits include, reduced pulse temperature heating, ability to optimally locate loads, built-in beam and structure diagnostic (provides cell to cell alignment) via HOM radiation. Provides a fall-back solution too!

Initial studies encouraging. However, the challenge remains to achieve adequate damping at 0.5 ns intra-bunch spacing

Roger M. Jones, Vasim F. Khan4th CLIC Advisory Committee (CLIC-ACE), 26th - 28th May 2009Technology alternativesQuadrant set a side for the momentBrazed DisksSingle rounded cellDouble rounded cell CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.

WDS cell geometryWaveguide Damped Structure (WDS) 2 cellsMinimize E-fieldMinimize H-fieldProvide good HOM dampingProvide good vacuum pumping CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.TD24_vg1.8_disk as CLIC_G proto

Currently available technology is Single rounded brazed disks CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.TD24_vg1.8_disk transverse wake

CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Parameters of TD24_vg1.8_disk

Structure CLIC_GTD24Frequency: f [GHz]1212Av. iris radius/wavelength: / 0.110.11In/Output iris radii: a1,2 [mm]3.15, 2.353.15, 2.35In/Output iris thickness: d1,2 [mm]1.67, 1.001.67, 1.00Group velocity: vg(1,2)/c [%]1.66, 0.831.62, 0.81N. of reg. cells, str. length: Nc, l [mm]24, 22924, 229Bunch separation: Ns [rf cycles]66Lumi. per bunch X-ing: Lb [m-2]1.2210341.221034Bunch population: N3.721093.72109Number of bunches in a train: Nb312312Filling time, rise time: f , r [ns]62.9, 22.464.2, 23.1Pulse length: p [ns]240.8242.7Input power: Pin [MW]63.866.0Pin/CtPp1/3[MW/mm ns1/3]1818.6Scmax [MW/mm2]5.45.6Max. surface field: Esurfmax [MV/m]245240Max. temperature rise: Tmax [K]5362Efficiency: [%]27.726.5Figure of merit: Lb /N [a.u.]9.18.7Parameters assuming coupler overhead CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Double rounded disk design

Double rounded disk design is under way CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.30+ slides CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Coupler alternativesMode launcher couplerElectric couplerMagnetic coupler with damping CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Coupler design

Mode launcherElectric field couplerMagnetic field couplerCompact coupler CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.CLIC_G + compact coupler

CLIC_G (electric coupler)

CLIC_GCC (magnetic coupler) Prototype is under design CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Ridged waveguide damping for lower pulse surface heating temperature rise CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.

Ridged waveguide for HOM damping

Rectangular waveguideDouble-ridged waveguideRidged waveguideCLIC_GLDT (low T)idw = 7.5 mmadw = 9.25 mmidwadw CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.EM field configuration in RWDS Electromagnetic field configuration on the surface of a Ridged waveguide damped structure (RWDS) cell

Electric field

Magnetic field

Sc CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Structures with ridged waveguide damping

CLIC_GLDT : a = 3.15 2.35 mmCLIC_K : a = 3.3 2.35 mm

CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Wake field of proposed structures

CLIC-ACE, 26 May 2009Alexej Grudiev, Accelerating structures.Transve

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