Ian Bailey University of Liverpool / Cockcroft Institute Target Design and Photon Collimator...
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![Page 1: Ian Bailey University of Liverpool / Cockcroft Institute Target Design and Photon Collimator Overview EUROTeV: WP4 (polarised positron source) PTCD task.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649c9b5503460f9495948a/html5/thumbnails/1.jpg)
Ian Bailey
University of Liverpool / Cockcroft Institute
Target Design and Photon Collimator Overview
EUROTeV: WP4 (polarised positron source) PTCD task
I. Bailey, J. Dainton, L. Zang (Cockcroft Institute / University of Liverpool)
D. Clarke, K. Davies, N. Krumpa, J. Strachan (CCLRC Daresbury Laboratory)
C. Densham, M. Woodward, B. Smith, (CCLRC Rutherford Appleton Laboratory)
J.L. Fernandez-Hernando, D.J. Scott (CCLRC ASTeC Daresbury Laboratory / Cockcroft Institute)
P. Cooke, P. Sutcliffe (University of Liverpool)
In collaboration with
Jeff Gronberg, David Mayhall, Tom Piggott, Werner Stein (LLNL)
Vinod Bharadwaj, John Sheppard (SLAC)
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PPS Schematic - Single Target Station
Target and collimator
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Capture Optics
Positron beam pipe/NC rf cavity
Target wheel
Vacuum feedthrough
MotorPhotonbeam pipe
Working in collaboration with SLAC and LLNL.
Developing water-cooled rotating wheel design.
0.4 radiation length titanium alloy rim.
Radius approximately 0.5 m.
Rotates at approximately 2000 rpm.
PTCD is the EUROTeV-funded task to carry out design studies of the conversion target and photon collimator for the polarised positron source.
Target Systems
LLNL - draft design
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Target Station - Remote Handling
Vertical remote-handling design to mimimise footprint of target hall and therefore minimise civil engineering costs.
Change over times dominated by cooling / heating of OMD magnets?
RAL - draft design
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Target Wheel Design
LLNL - draft design
Iterative design evolution between LLNL and DL
Constraints:
• Wheel rim speed fixed by thermal load (~30kW) and cooling rate
•Wheel diameter (~1m) fixed by radiation damage and capture optics
•Materials fixed by thermal and mechanical properties and pair-production cross-section (Ti6%Al4%V)
•Wheel geometry (~30mm radial width) constrained by eddy currents.
DL - draft design
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DL Prototype Target Wheel
No internal water cooling channel in first prototype, but design fully compatible with channel.
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DL Prototype Target Wheel (2)
•Detail showing drive shaft and wheel hub.
•Option of cantilevered or pass-through drive shaft.
•Reducing drive shaft to 2” diameter allows use of standard feedthrough and water coupling.
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Eddy Current Simulations
LLNL - preliminary
LLNL - preliminary
Initial “Maxwell 3D” simulations by W. Stein and D. Mayhall at LLNL indicated:
•~2MW eddy current power loss for 1m radius solid Ti disc in 6T field of AMD.
•<20kW power loss for current 1m radius Ti rim design.
•However - LLNL simulations do not yet agree with SLAC rotating disc experiment.
•8” diameter Cu disc rotating in field of permanent magnet.
•OPERA-3D simulations are starting at RAL + FEMLAB at ANL.
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Photon Collimator N
. Golu
beva and V. B
alandin, D
ES
YA
. M
ikha
ilich
enko
, C
orne
ll
Copper
Niobium
EGS4 simulation - collimator sideview
Purpose of collimator
• Scrape beam
• Adjust beam polarisation
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Photon Beam Polarisation
Niobium
Purpose of collimator
• Scrape beam
• Adjust beam polarisation
10 MeV Photons - no electron beam jitter
SP
EC
TR
A sim
ulation
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FLUKA Photon Collimator Simulations (1)
Assume a 300kW 10 MeV photon beam with Gaussian transverse beam profile (1mm rms):
Power deposited in spoiler: ~2.5 kW
Power deposited in absorber: ~3 kW
(1.8% of total beam power)
Starting collimator geometry:
Inner radius of spoiler 1.2mm
Thickness of spoiler 2.3mm
Inner radius of absorber 53.5mm
Thickness of absorber 160mm
Collimator length 1500mm
Lei Zang, University of Liverpool
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FLUKA Photon Collimator Simulations
Electron fluence
(per primary photon)
Positron fluence
(per primary photon)
105 Events
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FLUKA Photon Collimator Simulations
Photon fluence
(per primary photon)
Energy deposition
(GeV per primary photon)
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Future PTCD ActivitiesTarget Prototyping
• Proposing 3 staged prototypes over 3 years (LC-ABD funding bid)
• Measure eddy current effects• top priority• major impact on design
• Test reliability of drive mechanism and vacuum seals.
• Test reliability of water-cooling system for required thermal load
• Develop engineering techniques for manufacture of water-cooling channels.
• Develop techniques for balancing wheel.
• First prototype mechanical deisgn progressing well.
• First prototype instrumentation and electronics design starting.
Remote-handling design • Essential that remote-handling
design evolves in parallel with target design.
• Determines target hall layout and cost.
• Evaluaitng change-over times.
Photon Collimator design• Use realistic photon beam.• Activation simulations (in
collaboration with DESY).• Thermal studies and cooling
design.• Variable aperture (optimise in
association with beam jitter simulations)?