re-configuration of the linac reference system at slaciwaa2016 - re-configuration of the linac...

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