Undulator Alignment Strategy for Beam Position Monitoring and Correction Zones

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 [add] • 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 (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 quadrupoles 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. • via dipole trim-windings on Quadrupole Magnets (used for fine adjustments.) [Add ranges in terms of quad motion and angles] 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 Observation Points Quadruples Leveler 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 [ 8 cm range] • Provides control of undulator field on beam axis. • Horizontal slide stages move undulator strongback independent of Girder and vacuum chamber. 11

12. Fixed Support / Girder Assembly Cam Movers Undulator Girder Connecting Plate Interface Plate Fixed Supports Design of the Fixed Support, Interface Plate and Connecting Plate for SUT 12

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14. Main 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* • Measurement of electron beam offset from quad center in x and y *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 Component Monitoring Systems • Indirectly, through impact on electron beam trajectory (as detected by BPMs) • Girder Positions will be frequently corrected using the CAM movers. • Both monitoring venues complement each other but each will be sufficient for maintaining trajectory straightness. 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 WPM/HLS mo Zone 3 (Dt> 24 hr, P/P0 > 90%, non-invasive) • Maintain component alignment based on WPM/HLS • Possible x-ray pointing (few min.) 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. Main Alignment Procedures Summary • At Magnetic Measurement Facility (MMF) • Undulator Segment Tuning and Fiducialization (Establishes SUSA) • Quadrupole Fiducialization • BFW Fiducialization • Complete Component Installation and Alignment on Girder • In Undulator Hall (UH) • Installation and Alignment of Girder Support Structures in Tunnel • Earth Field Compensation Measurement in Tunnel • Girder Installation and Pre-Alignment in Tunnel • Complete Installation and Checkouts of WPM and HLS • Continuous Component Position Monitoring through WPM and HLS • Undulator Segment Installation on Girder • Girder Alignment using WPM / HLS • Electron Beam-Based Alignment with BPMs and Quadrupoles • Loose-End Alignment via BFW based on Interaction with Electron Beam • Continuous Component Position and BPM Offset Correction through WPM and HLS • Periodic Re-Baselining of CAM Movers to Correct for Ground Motion etc. 19

20. Alignment Function Diagram MMF Undulator Hall USE OF MAIN DIAGNOSTICS COMPONENTS Supports Alignment Segment Tuning and Fiducialization Environmental Field Measurement Quadrupole Fiducialization Girder Pre- Alignment WPM and HLS Installation WPM/HLS BFWFiducialization Undulator Segment Installation Girder Alignment using WPM and HLS Component Alignment on Girder Electron Beam-Based Alignment BPMs Quads BFWs Loose End-Alignment Continuous Position Correction Every 2 – 4 weeks: Invasive Correction Once per month: Swap 3 Segments Once every six month: Re-baselining 20

21. 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 task of conventional alignment and motion systems are • Girder component alignment and fiducialization • Conventional alignment as prerequisite for BBA • A Component Monitoring System based on HLS and WPM will be used to measure and correct the effect of ground motion, temperature changes, and movers. • The strategy for using the set of monitor system and controls to establish and maintain a straight trajectory is in place. 21

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