Undulator Commissioning

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Undulator Commissioning

• Heinz-Dieter Nuhn LCLS Undulator Group Leader
• June 8, 2009

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29 Undulators Installed
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Segment Installation Schedule

• Undulator Segments are being installed in the
  tunnel as they finish tuning
• 1/25/2009 3/2/2009 (U25 (SN16) Test
  installation)
• 3/3-24/2009 U13 U33
• 4/22/2009 U09 U12
• 5/13/2009 U06 U08
• 6/3/2009 U04 and U05
• 6/3/2009 Removed U33 for damage check.
• 6/17/2009 U02, U03, and U33 installation
  planned.
• Three plus one more undulators are to be
  installed
• Regular Undulator Rotation Program will start
  after temperature calibration procedure

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Undulator Beam Operation Highlights

• December 13, 2008
• First electron beam through undulator vacuum
  chamber.
• No extra steering corrections necessary to get
  100 transmission to main dump.
• Pre-beam girder alignment was sufficient.
• April 10, 2009
• First electron beam through undulator segments.
• Detected FEL beam after 105 minutes, CCD
  saturation 20 minutes later.

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Preset Girder Positions for First Beam

• The girders were moved in x and y direction
  before the first beam was sent through the
  undulator, mostly to align the beam pipes and the
  quadrupoles as close to a straight line as
  possible but also to use the off-axis quadrupole
  fields to compensate for the earth magnetic
  field. Both corrections were based on
  measurements provided by the Metrology group.
• The first beam shot did not need any alignment
  correction to pass through the undulator beam
  pipe (remember a 130-m-long soda straw) to the
  main dump. The maximum orbit error was only about
  1 mm. The plot is from J. Welch's
  girderPositionPlotGui and shows schematically the
  position by which each of the girders was
  displaced.

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Checking Undulator K Using YAG Luminescence
Yttrium K Edge at 17.038 keVequals 3rd harmonic
of undulatorradiation at 11.286 GeV
Expected Kund 3.49260.0005
3rd hamrmonic ofSpontaneous Undulator Radiation
on YAG Crystal
Ee 11.1 GeV
Kmin 3.3532
Kavg 3.4616
Ee 11.3 GeV
Kmax 3.4256
Spontaneous Radiation fromDump Bend
Ee 11.5 GeV
Ee 11.7 GeV
Ee 11.9 GeV
More precise bracketing gave Kavg 3.49320.0045
(1.7 10-4 from expected value)
10 or 11 undulators IN, Ipk 500 A, LH 200
uJFirst and third harmonic of spontaneous
radiation as background
by J. Welch and J. Frisch
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YAG Screen Image of First Lasing
FIRST LCLS FEL LIGHT
10 or 11 undulators IN, Ipk 500 A, LH 200
uJFirst and third harmonic of spontaneous
radiation as background
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Undulator Characterization 1st Field Integral U09
Horizontal (I1X) and vertical (I1Y) first field
integrals measured by fitting a kick to the
difference trajectory as function of undulator
displacement
Reference Point
Beam Based Measurements
MMF Measurement
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Measurement of 1st Field Integral U11
Reference Point
Beam Based Measurements
MMF Measurement
The beam-based measurement relies on the RF
cavity BPMS to achieve a 20 nrad measurement
resolution of the kick angle inside the undulator
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Alignment Tolerance Verification
Random misalignment with flat distribution of
widh a gt rms distribution a/sqrt(3)
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Simulated Horizontal Module Offset
Simulation and fit results of Horizontal Module
Offset analysis. The larger amplitude data occur
at the 130-m-point, the smaller amplitude data at
the 90-m-point.
130 m
Horizontal Model Offset (Gauss Fit) Horizontal Model Offset (Gauss Fit) Horizontal Model Offset (Gauss Fit)
Location Fit rms Unit
090 m 0782 µm
130 m 1121 µm
Average 0952 µm
90 m
BudgetTolerance
Simulated Saturation occurred at 90 mActual
Simulation occurred at 68 mCorrection factor
sqrt (90/68) 1.15This brings average to 1.10
mm
S. Reiche Simulations 2006
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LCLS Tolerance Budget
Tolerance Budget Components
Error Source si fi si fi Units
_at_ 130 m (24.2 red.)
Hor/Ver Optics Mismatch (z-1)0.5 0.71 0.452 0.32
Hor/Ver Transverse Beam Offset 30 0.176 3.7 µm
Module Detuning DK/K 0.060 0.400 0.024
Module Offset in x 1121 0.125 140 µm
Module Offset in y 268 0.298 80 µm
Quadrupole Gradient Error 8.8 0.029 0.25
Transverse Quadrupole Offset 4.7 0.214 1.0 µm
Break Length Error 20.3 0.049 1.0 mm
z lt 1.10.64ltb/b0lt1.56
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Girder Stability Position / Temperature

• Temperature fluctuations, girder deformation, and
  ground motion cause changes in
• Undulator strength, which depends on
• Temperature
• Beam trajectory
• Quadrupole position instability, which causes
• Changes to the electron beam trajectory (phase
  errors)
• Good News Observed stability of girder positions
  and temperatures is better than expected.

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Girder Stability During 2008 Winter Break
Measurements show how much the girderposiiton
deviatation from a straight line changed over
the period of one week duringlab closure.
RMS Position Change lt 1 µm
Alignment Diagnostics System (ADS)
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Girder 13 Stability During 19h Operation
200 nm
Alignment Diagnostics System (ADS)
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Girder 15 Movement (18 h) During ROD (11 h)
Mechanical Hysteresis
gt1 µm
Alignment Diagnostics System (ADS)
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Temperature Recording of Girder 16
REPAIR OPPORTUNITY DAY (ROD)
SHUT DOWN (UND INSTALLATION)
HVAC SETPOINT ADJUSTMENT
50 mK
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Temperature at all Girders
Upstream U23
Center U23
Downstream U23
Mounted to Undulator
On Girder
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K is Adjusted for Temperature Deviations
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Use of (T-)Corrected K Values
TEMPERATURE CORRECTED K
K ADJUSTMENT RANGE
TAPER REQUIREMENT
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Radiation Control and Monitoring

• Undulator radiation damage is greatly reduced
  through Machine Protection System (MPS) hardware
  interlocks that inhibit beam to the undulator
  hall when
• PEP/ANL type BLM signals are above threshold
• Beam loss fiber signals are above threshold
• Horizontal and/or vertical trajectory is outside
  1mm
• Comparator toroids indicate beam loss.
• Any of the upstream profile monitors is inserted
• More than 1 BFW is inserted or a BFW is moving
• A regular TLD monitoring program is in place(s.
  below)
• A regular undulator circulation program will
  start soon (s. below)

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TLD Replacement Program

• Thermo Luminescent Dosimeters (TLDs) are mounted
  inside the Undulator Hall and are regularly
  replaced and evaluated
• Baseline 10/3/2008 12/9/2008 (10 TLDs)
• Startup 12/12/2008 12/17/2008 (12
  TLDs)
• 1st Undulator 1/28/2009 2/4/2009 (15 TLDs)
• 1st Undulator 2/4/2009 2/11/2009 (14
  TLDs)
• 1st Undulator 2/11/2009 2/18/2009 (18
  TLDs)
• 1st Undulator 2/18/2009 3/2/2009 (48 TLDs)
• FEL Operation 3/24/2009 4/22/2009 (68 TLDs)
• FEL Operation 4/22/2009 5/6/2009 (125 TLDs)
• FEL Operation 5/6/2009 5/27/2009 (128 TLDs)
• FEL Operation 5/27/2009 (128 TLDs)
• FEL Operation
• Latest TLD placements include detection of
  neutrons and high energy gamma through use of
  moderators and W and Pb absorbers.
• TLD volume is expected to taper down after
  initial observation period.

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TLD Readings at First Undulator
LOCATION WEEK 1 PHOTON rad WEEK 2 PHOTON rad WEEK 3 PHOTON rad
U25ANL-BLM 0.081 0.106 0.051
U25 PEP-BLM 0.042 0.048 0.030
U25 Back X 0.065 0.008 0.033
U25 Back Y 0.012 0.071 0.064
U25 Back -X 0.039 0.026 0.029
U25 Back Y 0.013 0.042 0.014
U25 Front X 0.112 0.093 0.072
U25 Front Y 0.217 0.105 0.110
U25 Front -X 0.046 0.055 0.025
U25 Front -Y 0.141 0.123 0.093
Recorder Photon Doses about 0.1 rad per week
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SN16 Radiation Damage Test
HAS BEEN INSTALLED ON GIRDER 25 DURING BEAM
OPERATION
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Dose During Initial X-Ray Operation
rad
e-folding length 8.7 m
Increased TLD Readings are expected to be
predominantly low energy synchrotron radiation,
not to cause significant magnet damage
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Dose During Recent X-Ray Operation
e-folding length 8.7 m
neutron dose at end of undulator line about 100
mrad/week or less
Increased TLD Readings are expected to be
predominantly low energy synchrotron radiation,
not to cause significant magnet damage
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TLD Readings at End of Undulator Line
LOCATION Photon Dose over 3 weeks rad
Downstream U32 without / with 1.6 mm Pb wrap 0.52 / 1.84
Downstream U33 without / with 1.6 mm Pb wrap 1.38 / 6.37
Downstream (about 2.5 m) U33 without / with W 0.62 / 0.05
Downstream (about 2.5 m) U33 without / with Al 0.59 / 0.31
U33 Cam Motors CM2 / CM5 0.00 / 0.02
U33 Horizontal Slide Motor SL1 0.08
On top of RFBPM Chassis U31 / U32 0.04 / 0.31
Girder Motion Electronics Racks U25 / U29 / U33 0.03 / 0.01 / 0.01
WPM Electronics Racks U25 / U31 2.08 / .08
North Side of Tunnel opposite of U33 0.08
Shielded
Electronics
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SN20 Radiation Damage Test
HAS BEEN INSTALLED ON GIRDER 33 DURING FEL
OPERATION
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Undulator Circulation Program

• Undulators will be periodically removed from the
  Undulator Hall to be re-measured at the MMF to
  check for radiation damage
• A test-undulator was re-measured after several
  weeks of beam operation. No damage was found.
• First undulator that participated in FEL run was
  removed on June 3 and MMF testing has found it to
  be undamaged
• Depending on MMF availability, up to 2 undulators
  per month will be removed from the Undulator Hall
  for checking
• After the undulators have been found undamaged
  they will be reinstalled onto the original girder

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Summary

• Undulator tuning and installation close to
  completion
• Initial beam operation went extremely smoothly
  no tweaking required
• Temperature and girder stability are well within
  tolerance
• Beam loss control and radiation monitoring is in
  place
• High radiation levels at initial FEL operation
  are expected to be predominantly low energy
  photons that should not generate demagnetization
• Very low dose levels measured at electronics
  components
• Undulator circulation program has started

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End of Presentation