Undulator Alignment Strategy Heinz-Dieter Nuhn, SLAC / LCLS April 20, 2006

1. Undulator Alignment StrategyHeinz-Dieter Nuhn, SLAC / LCLSApril 20, 2006 • Alignment Overview • Alignment Tolerances • Alignment Monitoring • Correction Zones 1

2. Undulator Alignment Overview • The focus of the undulator alignment is on • Quadrupoles and Beam Position Monitors (BPMs) • Beam Finder Wires (BFW) • Undulator Strongbacks (Segments) • The alignment procedures include • Girder Component Alignment [checked on CMM] • Conventional Tunnel Alignment • Beam Based Alignment (BBA) [Energy Scan followed by BFW] • Continuous Monitoring and Correcting of Component Positions • Auxiliary alignment procedures include • Segment Fiducialization [SUSA wrt. Segment fiducials] • Quadrupole Fiducialization [Magnetic center wrt. Quad fiducials] • BFW Fiducialization [Wire location wrt. BFW fiducials] 2

3. Main Alignment Concepts • Pre-alignment (baselining) uses the manual adjustments on top of the support structures. • Relative alignment of Girder components is achieved and maintained through common-girder mounting checked by CMM • Girder-to-Girder alignment is (remotely) controlled based on cam-shaft technology • During initial alignment [with focus on quadrupole and BFW positions] • For quadrupole position control, i.e. beam steering during BBA • For compensation of ground motion effects etc. • Beam-Based-Alignment uses quadrupole magnets in two ways: • via off-center dipole fields. [Change is done through cam-based girder motion, which will align all girder components to the beam. Minimum motion range covers area of circle with 700 µm radius ] • via dipole trim-windings on Quadrupole Magnets (used for fine adjustments.) [Range equivalent to ±100 µm of Quad motion] 3

4. Girder Components Summary • Main girder components include • Beam Finder Wire (BFW) • Undulator strongback arrangement mounted on horizontal slides • Vacuum chamber support • BPM • Quadrupole • Mounts for the Wire Position Monitor (WPM) system • Sensors of the Hydrostatic Leveling System (HLS) • Diagnostics components • The undulator strongback arrangement (Segment) is mountable on and removable from the girder with the vacuum chamber in place and without compromising the alignment of the vacuum chamber • Segments will be taken off the girder for magnetic measurements • Segments will be interchangeable without the need for the CMM • The complete girder assembly will be aligned on the Coordinate Measurement Machine (CMM). 4

5. BFW Vacuum Chamber Wake Mitigation Wires Beam Finder Wire (BFW) A misaligned undulator will not steer the beam. It will just radiate at the wrong wavelength.The BFW allows the misalignment to be detected. (also allows beam size measurements) BFW Undulator Quad Beam Direction 5

6. Undulator–to–Quad FiducializationTolerance Budget Individual contributions are added in quadrature 6

7. Undulator–to–BFW FiducializationTolerance Budget Individual contributions are added in quadrature 7

8. Alignment Tolerance Summary 8

9. 1‘ stay-clear wall monuments (with removable spherical target) 6’ floor monument (with removable spherical target) Survey Monuments Extract from ESD 1.4-113 Undulator Tunnel Survey Monument Positions B. Fuss 9

10. UH Tunnel West Side Thermal Barrier STA 2237.33 ft 681.939 m UH Tunnel Start STA 1672.09 ft 509.653 m BTH 2250 1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200 1600 1650 Beam Dump Undulator Hall Tunnel SLOPE SLOPE 24” Vertical Penetration (approx. position) Undulator Hall Network Monuments Tracker Positions Quadruples Level Tracker Inputs: sD = 30 μm sh = 30 μm / D sv =50 μm /D sdh = 50 μm Results: sz = 22 μm sx = 47 μm sy =46 μm 10

11. Undulator Alignment Controls • Manual Adjustability: • Rough CAM position adjustability relative to fixed support.ranges: x (12 mm); y (25 mm); z (12 mm) • Quadrupole, BFW, BPM, Vacuum Chamber, and Segment adjustability to Girder. ranges: x (>1 mm); y (>1 mm); z (>1 mm) • Remote Adjustability: • Girder: x, y, pitch, yaw, roll [1.5 mm x and y] • Enables alignment of all beamline components to the beam axis. • Roll motion capability is to be used to keep roll constant • Undulator: x [ 80 mm range] • Provides control of undulator field on beam axis. • Horizontal slide stages move undulator strongback independent of Girder and vacuum chamber. 11

12. Undulator Segment Supports Manual Adjustments Horizontal Slides Segment Vacuum Chamber Support Girder Cam Movers ManualAdjustments Fixed Supports 12

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14. Undulator Alignment Monitoring Elements • Hydrostatic Leveling System (HLS) • Monitored Degrees of Freedom are: y, pitch, and roll • Wire Position Monitoring System (WPM) • Monitored Degrees of Freedom are: x, (y), (pitch), yaw, and roll • Temperature Sensors • In support of HLS/WPM readout corrections, undulator K corrections, and component motion interpretation. • Beam Position Monitors* • Monitored quantities are: x and y position of electron beam • Quadrupoles* • Monitored quantities are: electron beam x and y offset from quad center *Transverse Locations Tracked by HLS and WPM 14

15. Component Position Monitoring Systems(Alignment Diagnostics System – ADS) Wire Position Monitor system (WPM) Resolution < 100 nm in X & Y direction Instrument Drift< 100 nm per day Moving Range±1.5 mm in X & Y direction Accuracy0.1 % of full Scale AvailabilityPermanent, no interrupts X and Y, can be measuredRoll, Jaw & Pitch can be calculated. Hydrostatic Leveling System (HLS) Capacitive Sensor Precision < 1 mm Instrument Drift ~1-2 mm / month Accuracy< 0.1 % of full Scale Roll Y Ultrasound Sensor Precision < 0.1 mm Instrument Drift potentially no drift Accuracy< 0.1 % of full Scale Pitch Y, can be measuredRoll & Pitch can be calculated. 15

16. ADS…Common Sensor Support Quadrupole X & Y- Position will be measured relative to the references. Roll, Pitch, Yaw and Torsion of the Girder can be calculated. 16

17. Strategies for Controlling Component Motion • Girder motion will be caused by • Ground Motion • Temperature Changes • CAM Rotation • Girder motion will be monitored in 2 ways. • Directly, through the Alignment Diagnostics System • Indirectly, through impact on electron beam trajectory (as detected by BPMs) • Girder Positions will be frequently corrected using the CAM movers. 17

18. Correction Zones Zone 1 (non-invasive correction) • 120-Hz traj-feedback (LTU BPM’s) • 0.1-Hz traj-feedback (und. BPM’s) Zone 2 (Dt> 1 hr, P/P0 > 90%, non-invasive) • Maintain component alignment based on ADS mo Zone 3 (Dt> 24 hr, P/P0 > 90%, non-invasive) • Maintain component alignment based on ADS • Possible x-ray pointing correction Zone 4 (Dt> 1 mo, P/P0 > 75%, machine time) • One iteration of BBA (<1 hr) Zone 5 (Dt> 6 mo, shut-down) • Reset movers set to zero and manual realignment (1 wk) • Full 3 iterations of BBA (~3 hrs) 18

19. Alignment Function Diagram MMF Undulator Hall USE OF DIAGNOSTICS COMPONENTS Segment Tuning and Fiducialization Supports Alignment Quadrupole Fiducialization Environmental Field Measurement BFW Fiducialization Girder Pre- Alignment Component Alignment on Girder ADS Installation ADS(HLS/WPM) Undulator Segment Installation Girder Alignment using ADS BPMs Quads Electron Beam-Based Alignment Segment Tuning Loose End-Alignment BFWs Continuous Position Correction Every 2 – 4 weeks: Invasive Correction Once per month: Swap 3 Segments Once every 6 month: Re-baselining 19

20. Conclusions • The X-ray-FEL puts very tight tolerances on magnetic field quality, electron beam straightness, and Segment alignment. • These tolerances can be achieved through Beam Based Alignment (BBA) procedures based on BPMs and Quadrupoles (with energy scan) as well as BFWs. • Relative component alignment to required tolerances will be achieved through common girder mounting. • Main tasks of the conventional alignment and motion systems are • Component fiducialization and alignment on girder • Conventional alignment of girders in Undulator Hall as prerequisite for BBA • The Alignment Diagnostic System measures and enables the correction of girder movement due to ground motion, temperature changes, and CAM mover changes. • A strategy is in place for using the monitor systems and controls to establish and maintain a straight trajectory. 20

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