Beam Finder Wire BFW Fiducialization

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Beam Finder Wire (BFW)Fiducialization
Zack Wolf, Dean Walters, James Bailey, Eric
Lundahl
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Need For A BFW
The undulator will not steer the beam. It will
just radiate at the wrong wavelength. The BFW
allows this to be detected.
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BFW Specifications
LCLS PRD 1.4-004
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BFW Operation
Out The beam goes through a small beampipe
making a smooth transition to external beampipes
In Wires are inserted into the beamline. The
whole girder is moved to scan the wires across
the beam.
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BFW Use
Either turn quad off, or use wire system to
re-center on beam
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Fiducialization Accuracy Requirements
Rough Error budget

• Locate wire relative to local fiducials
  (optically) 25 um
• 2) Locate local fiducials relative to outside
  tooling balls (CMM) 15 um
• 3) Repeatability of positioning wires 80 um in
  X, 30 um in Y

LCLS PRD 1.4-004
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Fiducializing theBeam Finder Wire
Dean Walters, James Bailey,
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Cases to Consider Fiducialization

• Case 1 - Initial installation of the BFW
• Below is the outline of the Initial Installation
  followed by the outline of the Replacement of the
  BFW
• Case 2 - Replacement of the BFW
• The replacement of the BFW is the more difficult
  case
• Since the case of replacement is constrained
  access-wise, careful placement of fiducials and
  the BFW/Vacuum Chamber is important.

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Case 1 - Initial Fiducializing of the BFW

• Step 1 - Wire to BFW Frame Fiducials

BFW Frame
External Stationary Fiducials (ESF)
BFW Alignment Stand
External Moving Fiducials (EMF)

• On the BFW Alignment Stand the position of each
  wire can be measured WRT the EMF
• Measure the Beam Guide WRT the EMF
• With the BFW actuated in each (up down)
  position, adjust the stops for each position from
  the EMF to ESF per nominal dimensions .

Beam Guide
Wire
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Case 1 - Initial Fiducializing of the BFW

• Step 2 - BFW Frame to vacuum Chamber Alignment

• Bolt BFW Frame to Vacuum Chamber and make vacuum
  seal.
• Adjust the lower stops to place the Beam Guide
  in the center of the Chamber ports.
• Then measure the EMF WRT to CSF
• Adjust the upper stops to correctly place the
  wires WRT the Girder Axis (GA)
• Then measure the EMF WRT to CSF

Chamber Stationary Fiducials (CSF)
BFW Chamber Alignment Stand
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Case 1 - Initial Fiducializing of the BFW

• Step 3 - Alignment of BFW/Vacuum Chamber to
  Undulator Vacuum Chamber

• The BFW Chamber along with the BFW is placed in
  the beam line.
• Adjust the Chamber supports to place the upstream
  port in line with the Undulator Vacuum chamber.
• The mating flanges will have the ability to self
  center to each other.
• Make up the vacuum flange seal.
• There will be the ability to make fine position
  adjustments after the seal is made.
• Re-measure the placement of the Chamber CSF and
  the EMF WRT to the GA

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Case 2 - Replacement of the BFW
Beam Finder Wire
BFW/Vacuum Pump Chamber

• Assumptions for replacement of the BFW.
• The existing BFW was aligned
• The BFW/Vacuum Pump chamber stays in place in the
  beam line
• The BFW/Vacuum Pump Chamber is supported so that
  when the BFW is removed that it remains
  accurately in place

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Case 2 - Replacement of the BFW

• Step 1 This is the same as Step 1 of the
  Initial Fiducialization
• Step 2 - In the case of replacement the data
  from Step 2 in the initial case will be used with
  the new BFW frame.
• Step 3 This is different than the other Step 3
  in that the stops will be adjusted in the field
  using the preexisting data.
• This will be more difficult since some
  lines-of-sight will be blocked due to existing
  installed equipment.
• Access to adjustments will also be more awkward
  in the field then in Case 1 where the adjustments
  will be made in the lab.
• The new installed assembly will be measured in
  both positions after all adjustments have been
  made to record the final placement.

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How Fiducialization Is Really Done
Eric Lundahl
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Optically Find Wires WRT Local Fiducials
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Locate ToolingBalls With CMM
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Previous SLAC Experience