1. 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.

2. Design Driving Requirements
Magnetic Measurements
The measured values for Keff shall be within ± (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)

3. 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

4. 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

5. Facility Construction & Design Goals
Funding
LLP Funds
Building & Climate Control K$ 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

6. 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

7. 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

8. 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

9. 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

10. 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

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

12. 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

13. 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

14. Test Stand Implementation Schedule

15. Test Stand Implementation Schedule

16. Undulator Measurement Schedule Detail

17. Undulator Measurement Schedule

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

19. 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

20. 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

21. 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)

22. Hydrostatic Level System
Developed HLS for NLC ground motion studies Hydrostatic Leveling System Specification ESD

23. HLS Stability and Resolution

24. Wire Position Monitoring System
System was originally developed for the FFTB experiment, Wire Position Monitoring System ESD

25. WPM Stability and Resolution

26. 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 Requirement for the LCLS Undulator Magnetic Measurement Bench (August  2004)
LCLS-TN Introduction to LCLS Undulator Tuning (June 2004)
LCLS-TN Requirements for the Construction of the LCLS Magnetic Measurements Laboratory (February 2003)
LCLS-TN ANL and DESY Undulator Tuning Procedures (July 2003)
LCLS-TN 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

27. 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

28. END Of
Presentation

29. 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)

30. 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

31. 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.

32. 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

33. 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.