Magnetic Measurements and Alignment at SLAC Robert Ruland & Zack Wolf Implementation of Magnetic Measurement Facility (MMF) Undulator Tuning Fiducialization Alignment Overview of Alignment Strategy Monitoring Systems Summary I would like to acknowledge Isaac Vasserman’s and Joachim Pflüger’s indispensable help and expert advice.

Design Driving Requirements Magnetic Measurements The measured values for Keff shall be within ± 0.0005 (i.e., ± 0.015%) of the design values (LCLS Undulator Requirements PRD 1.4 – 001) Alignment -Quadrupoles- Beam-based-alignment is used to keep the straightness of the electron beam trajectory to 3 µm Conventional alignment needs to provide ab-initio condition for BBA to converge, min. req. 100µm, desired 80µm (BBA System Requirements PRD 1.4 – 003) Alignment -Undulators- Mechanically coupled to BBAligned Quads Relative alignment quad-to-und driven by sensitivity of K to position, 1.5*10-4 is correlated to 70µm in Y, 180µm in X (total error budget)

Fiducialization Accuracy Requirement Required fiducialization accuracy is driven by error budget for aligning undulator wrt to beam-based-aligned quad, i.e. in order to stay within the total error budget of 70µm vertically, quadrupole fiducialization needs to done to 25µm and undulator segments need to be done to 40µm

SLAC LCLS Magnet Measurements Facility SLAC presently does not have a facility to perform the magnetic measurements tasks necessary for LCLS with the required accuracy: Need to build new facility. Proposed Location: Bldg 81, about 0.8 km away from tunnel Sufficient power for HVAC & test equipment No heavy machinery nearby Manageable space constraints

Facility Construction & Design Goals Funding LLP Funds Building & Climate Control K$1200 + K$300 Contingency Measurement Equipment K$784 +K$336 Contingency Construction Schedule T1 Aug 04 (Engineering) T2 Oct 04 (Final Construction Drawings) T3 Jan 05 (Construction Start) Beneficial Occupancy July / August 05 Design Specifications Full set of specs: LCLS-TN-04-1 Z. Wolf, R. Ruland, "Requirements for the Construction of the LCLS Magnetic Measurements Laboratory“. Magnetic Measurements Lab: Temperature stability of ± 0.1º C, short term temperature swings of up to 0.3 ºC with less than 1 hour duration are acceptable Fiducialization Lab and Assembly Area: Temperature stability of ± 1º C Storage Area: Temperature Stability of ± 2.5º C The specs were reviewed and approved by our advising experts I. Vasserman, APS and Dr. J. Pflüger, DESY

MMF Capabilities / Functions Assembly Cradle Assembly Bench Vacuum Chamber Alignment Bench Granite table with Height Gauge Undulator Segment / Cradle Storage At least 2 Und. Segments in MM lab (0.1º C) At least 2 Und. Segments in F&A lab (1º C) 8 Cradles, quads, BPMs, Vacuum chamber and misc. supports in F&A lab (1º C) About 20 undulator segments / cradles in storage area (2.5º C) Magnetic Measurements Undulator Test Bench #1 (8 m) final gap setting, final tuning Undulator Test Bench #2 (4 m) – existing prototyping procedures, software development, initial gap setting Hall Probe Calibration System Test magnet and NMR system Quad Integrated Field Strength Bench Stretched Wire Quadrupole Fiducialization Platform Vibrating Wire Pointed-Magnet Fixture Calibration Bench Fiducialization & Assembly Fiducialization CMM 4.2 m Quadrupole Fiducialization Platform Vibrating Wire mounted on CMM BPM, Diagnostics Fiducialization Magnetic Measurements Facility Requirements, PRD 1.4 - 002

MMF Lay-out Test stand lay-out is driven by requirement to match the Earth Magnetic Field conditions in lab to Undulator Hall, i.e. azimuth and gap orientation need to be identical

MMF Work Flow Moving and Rigging Cradle Assembly Workflow Forklift is used to move undulator segment in and out storage racks as well as on and off dollies Dollies are used to move segments between rooms Cranes are used to load segments on and off benches Cradle Assembly Workflow Move cradle onto assembly bench Install quad, vacuum chamber, and BPM Move cradle onto alignment bench Align and straighten vacuum chamber Tuning / Fiducialization Workflow In storage area, load dolly with undulator segment Roll dolly into F&A lab, adjust to temperature for 3 days Roll dolly into MM lab, adjust to temperature for 7 days Set-up undulator on bench #2, pre-adjust gap, 2 days Move onto bench #1, fine-adjust gap, tune, measure pointed magnet fixture offset, 3 days Move onto CMM, finish fiducialization, 1 day Move undulator to assembly bench, mount to pre-assembled cradle, 1 day Move onto CMM, align quad + BPM wrt undulator, set undulator offset for location specific K, 2 days

New 8 m Undulator Test Bench Design parameters are driven by measurement accuracy requirement of 1.5*10-4 and by fiducialization error budget which allows only 20 µm for dX and dY of Hall probe position Minimum of 7.5m Total Travel Length Undulator 3.4m + carriage 1m + zero gauss chamber 0.5m + fiducialization needle fixtures 1m + stretched wire set-up 1m + 2*over travel 0.6m Bench design is modeled after DESY 12 m bench. The proposed design parameters were reviewed by Isaac Vasserman, APS, and Joachim Pflüger, DESY. Undulator Measurements Specifications have been written up in: Z. Wolf, Requirements for the LCLS Undulator Magnetic Measurement Bench, LCLS-TN-04-8

Undulator Fiducialization Proposed Method: Pointed Magnet Fixture Step 1: measure offset between undulator axis and pointed-magnet reference fixture on MM Bench Step 2: Measure pointed-magnet reference fixture wrt undulator fiducials on CMM

Pointed Magnets Centering Sensitivity Centering Test 5 µm in Y 20 µm in X

Quadrupole Fiducialization Finding the axis Based on Vibrating Wire or Pulsed Wire Have Pulsed Wire prototype setup. Routinely achieve repeatabilities even in environment with wide temperature swings of better than 5 µm Also have Vibrating Wire prototype set-up. It promises better yaw and pitch resolution. Implementation based on setup by Dr. Temnykh from Cornell Transfer onto quadrupole fiducials Use Wire Finders (developed for VISA) to locate wire and reference to its tooling balls Use Coordinate Measurement Machine (CMM) to transfer information from WF to Quad fiducials. Vibrating Wire system will be mounted onto optical table which can be set-up on undulator fiducialization CMM

Cradle Assembly After fiducialization, undulators, quadrupoles, and BPMs as well as the vacuum chamber with its strong back will be assembled into one unit and aligned with respect to each other. Undulator Roll-away feature puts more emphasis on vacuum chamber alignment, needs to be straightened and aligned in Y to stay within a 100 µm envelope

Test Stand Implementation Schedule

Test Stand Implementation Schedule

Undulator Measurement Schedule Detail

Undulator Measurement Schedule

Alignment Cradle Approach Alignment Procedure Monitoring Systems Integration Hydrostatic Leveling System Wire Position Monitoring System

Cradle Approach and Tolerances Pre-Alignment Relative alignment requirements quad-to-undulator segment (40 µm for alignment step in total error budget) cannot be fulfilled by conventional alignment methods. Pre-assemble undulator segment, quadrupole, BPM, and vacuum chamber on “cradle” Relative alignment is carried out in MMF using CMM Tunnel Alignment Will use undulator fiducials for optical alignment Align cradles using optical alignment methods, supported by HLS and portable stretched wire measurements to strengthen global straightness Quadrupole ab-initio position tolerance driven by BBA requirements; BBA quality is correlated to quality of initial alignment. Alignment StD of 150 µm sufficient for BBA to converge, goal is alignment StD of < < 100 µm

Component Alignment Procedure Proposing to use same alignment sequence as successfully done with PEPII and SPEAR3: Install and measure network Mark Anchor positions on floor Drill, set Anchors and install mounting plates Pre-align mounting plates to 0.5 mm in X, Y and Z Install Granite tables which are referenced to mounting plates Align mounting tables in Y to 100 µm Align Cam Mover pairs in X to 200 µm Install Hydrostatic Level System Install Undulator Cradle Assembly Install Stretched Wire Monitoring System Fine align assemblies Y to 50 µm, X to 80 µm

Integrating Monitoring Systems into Cradle / Support System The horizontal and vertical position of each cradle assembly will be monitored by a hydrostatic level system (HLS) and a wire position monitoring system (WPMS)

Hydrostatic Level System Developed HLS for NLC ground motion studies Hydrostatic Leveling System Specification ESD 1.4 - 105

HLS Stability and Resolution

Wire Position Monitoring System System was originally developed for the FFTB experiment, Wire Position Monitoring System ESD 1.4 - 104

WPM Stability and Resolution

Documentation PRD 1.4 – 002 Magnetic Measurement Facility Requirements ESD 1.4 – 104 Wire Position Monitoring System Specifications ESD 1.4 – 105 Hydrostatic Leveling System Specifications LCLS-TN-04-08 Requirement for the LCLS Undulator Magnetic Measurement Bench (August  2004) LCLS-TN-04-07 Introduction to LCLS Undulator Tuning (June 2004) LCLS-TN-04-01 Requirements for the Construction of the LCLS Magnetic Measurements Laboratory (February 2003) LCLS-TN-03-07 ANL and DESY Undulator Tuning Procedures (July 2003) LCLS-TN-03-08 LCLS Undulator Coordinate System (April 2004) In preparation Triggering hardware for bench measurements, Sept. 2004 Algorithms for Computer Aided Tuning, Sept. 2004 Pointed Magnet Calibration, Oct. 2004 Undulator Segment Fiducialization, Oct. 2004 Quadrupole Fiducialization, Nov. 2004 Hall Probe Calibration, Dec. 2004 MMF Review Workshop, planned for Oct. 2004 LCLS Alignment Review Workshop, planned for Spring 2005

Summary and Conclusion Magnetic Measurements MMF design mature and on schedule Test stand design and development on schedule Preparing MMF review workshop in 9/04 Have ramped up staff, all senior personnel on board Alignment Using same approach as successfully done for SPEAR3, PEP2 Monitoring sensors designed and tested, prototype systems running Preparing Alignment review workshop in Spring 2005 Key personnel already on staff

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Undulator Test Bench Implementation Schedule Undulator delivery commences in July 2006 Expected delivery of bench and components in August 2005 Not enough time to complete integration, software development, testing and commissioning by 7/06  Upgrade 4m bench obtained from APS with equivalent hardware as 7m bench to serve as test bed for software development and procedure testing. New components: Etel Linear Motor with integrated Heidenhain encoder X and Y Cross-slides with Heidenhain encoders Servo Motors and controllers Hall Probes and Hall Probe Calibration System (will also be used with 7m bench)

Bench Specifications Total travel length in Z 7500 mm. Make carriage as long as cost wise reasonable to minimize yaw, at least 1000 mm Make bench cross-section as large as reasonable, min 800 mm wide, 500 mm high Travel length in X as much as bench width permits, min 100 mm Travel length in Y: 100 mm or more if w/o loss of accuracy Granite base straightness in Z and X: <20 µm Position accuracy at probe tip required Z, X, Y: 3 µm, 20 µm, 20 µm, desired: 3 µm, 10 µm, 10 µm. Z-axis drive linear motor with 1 µm positioning resolution X, Y axes drive lead-screw with 1 µm positioning resolution No stepping motor on any axis Z position measurement with incremental encoder type Heidenhain LIDA, a second encoder on opposite side of bench could be considered to monitor yaw rotation of carriage, Agilent interferometer could be integrated for encoder calibration) X, Y axes motion measured with Heidenhain glass scale encoders Perpendicularity of X and Y axes to be better than 0.1 mrad Probe axis be equipped with rotary stage with 0.01º resolution and 4-axes goniometer Support bench on foundation separate from laboratory floor Support undulator independent from bench on common foundation Support cable carrier independent from bench on common foundation Equip cable carrier with drive system synchronized as slave to Z-axis drive

Manpower Requirements We have ramped up the staffing in the Magnetic Measurements Group to cope with the MMF work and at the same time to allow our conventional work to continue. MMF Development 2 Senior Physicists 1.5 Engineering Physicists 1 Metrology Engineer 2 Technicians Conventional Work 1 Senior Physicist 0.5 Engineering Physicist 1 Technician 1 Research Assistant Will be able to handle Undulator Production Measurements with existing manpower, supplemented with help from the Alignment Engineering and Quality Inspection Groups. There is no other significant competing work scheduled.

Global Alignment BO of the undulator hall is earlier (01/07) than BO of LTU Ú cannot establish direct connection to LINAC coordinate system Establish global alignment reference by connecting undulator hall reference network through vertical survey shafts at both ends of hall to surface monuments Surface monument coordinates are determined using differential GPS and leveling Expected tolerance for global coordinates in undulator hall: dX, dY, dZ < 1 mm

Undulator Fiducialization Detail Align the poles of the undulator to the test stand using capacitive sensors. Move the Hall probe to the mid-plane of the undulator. This is done by performing scans at different heights, fitting the K value as a function of y, then finding the y value that minimizes K. Tune the undulator. Fine tuning of the gap is required in advance. Repeat step 2 to make sure the mid-plane hasn’t moved during tuning. Scan at different x positions. Move to the x value that gives the desired K. The Hall element is now moving on the ideal beam axis of the undulator. Move to pointed magnets attached to the undulator ends. Find the offset from the ideal undulator axis to the center of the pointed magnets. Move the undulator to a CMM. Locate the pointed magnets relative to tooling balls on the undulator. Apply the offset from the pointed magnets to the ideal beam axis.