Re-configuration of the Linac reference system at SLAC IWAA2016 – Grenoble, October 2016
Georg Gassner Michael Gaydosh
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A Changing SLAC Linac
IWAA2016 - Re-configuration of the Linac reference system at SLAC Grenoble, October 2016
Sector 0 Sector 10 Sector 20 Sector 30
0 500 1000 1500 2000 2500 3000 3500
Extension line Bypass line
LCLS-I
Bypass BSY LTU EBD
Undulators
SXU
HXUL1 L2 L3
SRF Cryomodules (L0, L1, L2, L3)
joined by warm beamline sections
Z (m)
crossover
Beam SpreaderDogleg
µ wall
Cryoplant & cryo distribution
Injector & L0
Dumps
Proposed FACET II
FEE
End Stations
- 1966 – 2008 (SLC, PEP, PEPII)
- 2009 – 2012
- 2012 – 2016
- 2016 –
LCLS-I LCLS-I
LCLS-I
FACET
LCLS-II (construction)
FACET II (proposed)
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Linac Laser Alignment System (LLAS)
IWAA2016 - Re-configuration of the Linac reference system at SLAC Grenoble, October 2016
270 girders of 12m and 3m length. Every girder has one Fresnel zone plate target.
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Linac Alignment System - Girder
IWAA2016 - Re-configuration of the Linac reference system at SLAC Grenoble, October 2016
All components on top are aligned to the girder. Upstream end has Fresnel zone plate target. Downstream end coupled with next girder.
Target
Quadrupole
Accelerator Structure
Waveguides
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Linac Alignment System - Girder
IWAA2016 - Re-configuration of the Linac reference system at SLAC Grenoble, October 2016
Height / Roll Adjustment jacks
Horizontal Adjustment Jack
Telescope mount
Fiducials
Fresnel Lens Target
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Removal of Light Pipe from Sector 0 – Sector 10
IWAA2016 - Re-configuration of the Linac reference system at SLAC Grenoble, October 2016
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Reconfigure Linac Laser Alignment System (1)
IWAA2016 - Re-configuration of the Linac reference system at SLAC Grenoble, October 2016
Every Lens has different focal length to focus dot in S0 • Option A) New Fresnel lens at every location (too expensive). • Option B) One glass lens 100m upstream of S10 (radiation
damage, glass would turn black). • Option C) Telescopic mirror system (Alan Fisher).
Spherical Lenses
Sector 10-9
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Reconfigure Linac Laser Alignment System (2)
d1 d2
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Reconfigure Linac Laser Alignment System (3)
IWAA2016 - Re-configuration of the Linac reference system at SLAC Grenoble, October 2016
Current Image at S0 Simulated Image at S10 after re-configuration (VirtualLab)
5mm
Distortions are caused by the hole in the large mirror and the supports for the small mirror.
(Alan Fisher)
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Alignment Network S0-S30 – Layout
IWAA2016 - Re-configuration of the Linac reference system at SLAC Grenoble, October 2016
S0-S10 no longer has a light pipe and the bypass lines are not connected to the girders -> Monument based network. Opposing wall monuments to mitigate effect of refraction.
3km
12m
3.3m
Cryomodule Wall Monument Floor Monument
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Alignment Network S0-S30 - Measurements
IWAA2016 - Re-configuration of the Linac reference system at SLAC Grenoble, October 2016
311 Laser Tracker (Leica AT401/402) setups with 5082 measurements 577 Height differences (Leica DNA03) 200 Linac Light Pipe readings Least Squares Adjustment with LEGO software which allows the Linac Light Pipe readings (jackpoint to target σ=±0.5mm ) to be included as deviations from a straight line.
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Alignment Network S0-S30 – Results (1)
IWAA2016 - Re-configuration of the Linac reference system at SLAC Grenoble, October 2016
13 µrad
Comparison of coordinate results between adjustment with LLAS and without LLAS. Location of
radiation chicane no direct line of sight
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Alignment Network S0-S30 – Results (2)
IWAA2016 - Re-configuration of the Linac reference system at SLAC Grenoble, October 2016
Comparison of nominal location of Linac quadrupoles with their actual location along the beamline: The length of the Linac is 75 mm longer than designed. The pitch is 3 µrad steeper than designed in 1964.
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Summary
IWAA2016 - Re-configuration of the Linac reference system at SLAC Grenoble, October 2016
The Linac Laser Alignment System has been re-configured for fast recovery after earthquake (S10-S30) (1-2days for 2km beamline) Installed a machine independent monument network throughout the 3km long Linac in preparation for LCLS - II