Undulator Commissioning
Heinz-Dieter Nuhn – LCLS Undulator Group Leader
June 8, 2009
Undulator Plans
June 2009 FAC
1
1
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
29 Undulators Installed
Undulator Plans
June 2009 FAC
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2
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
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
Undulator Plans
June 2009 FAC
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3
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
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.
Undulator Plans
June 2009 FAC
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4
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
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-mlong 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.
Undulator Plans
June 2009 FAC
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5
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
Checking Undulator K Using YAG Luminescence*
3rd hamrmonic of
Spontaneous
Undulator
Radiation on YAG
Crystal
Expected Kund = 3.4926±0.0005
Ee = 11.1 GeV
Yttrium K Edge at 17.038 keV
equals 3rd harmonic of undulator
radiation at 11.286 GeV
Kmin =3.3532
Kavg =3.4616
Ee = 11.3 GeV
Spontaneous
Radiation from
Dump Bend
Kmax =3.4256
Ee = 11.5 GeV
Ee = 11.7 GeV
Ee = 11.9 GeV
More precise bracketing gave Kavg =3.4932±0.0045 (1.7 ×10-4 from expected value)
10 or 11 undulators IN, Ipk = 500 A, LH = 200 uJ
First and third harmonic of spontaneous radiation as background
Undulator Plans
June 2009 FAC
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*by J. Welch
and J. Frisch
Heinz-Dieter
Nuhn
nuhn@slac.stanford.edu
YAG Screen Image of First Lasing
FIRST
LCLS FEL
LIGHT
10 or 11 undulators IN, Ipk = 500 A, LH = 200 uJ
First and third harmonic of spontaneous radiation as background
Undulator Plans
June 2009 FAC
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7
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
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
Undulator Plans
June 2009 FAC
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8
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
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
Undulator Plans
June 2009 FAC
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9
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
Alignment Tolerance Verification
Random misalignment with flat distribution of widh ±a => rms distribution a/sqrt(3)
Undulator Plans
June 2009 FAC
10 10
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
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)
90 m
Location
Fit rms
Unit
090 m
0782
µm
130 m
1121
µm
Average
0952
µm
Budget
Tolerance
Undulator Plans
June 2009 FAC
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11
Heinz-Dieter Nuhn
S. Reiche Simulations
2006
nuhn@slac.stanford.edu
LCLS Tolerance Budget
1
  fi 2
P
e 2
P0
Tolerance Budget Components
si fi
Units
0.452
0.32
z < 1.1
0.64<b/b0<1.56
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
Error Source
Hor/Ver Optics Mismatch
(z-1)0.5
Hor/Ver Transverse Beam Offset
Undulator Plans
June 2009 FAC
si
fi
@ 130 m
(24.2% red.)
0.71
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Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
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.
Undulator Plans
June 2009 FAC
13 13
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
Girder Stability During 2008 Winter Break
Measurements show how much the girder
posiiton deviatation from a straight line
changed over the period of one week during
lab closure.
RMS Position Change < 1 µm
Alignment Diagnostics System (ADS)
Undulator Plans
June 2009 FAC
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Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
Girder 13 Stability During 19h Operation
200 nm
Alignment Diagnostics System (ADS)
Undulator Plans
June 2009 FAC
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Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
Girder 15 Movement (18 h) During ROD (11 h)
Mechanical Hysteresis
>1 µm
Alignment Diagnostics System (ADS)
Undulator Plans
June 2009 FAC
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Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
Temperature Recording of Girder 16
SHUT DOWN (UND INSTALLATION)
REPAIR OPPORTUNITY DAY (ROD)
HVAC SETPOINT ADJUSTMENT
50 mK
Undulator Plans
June 2009 FAC
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Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
Temperature at all Girders
Upstream U23
Center U23
Downstream U23
On Girder
Undulator Plans
June 2009 FAC
Mounted to Undulator
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Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
K is Adjusted for Temperature Deviations
Undulator Plans
June 2009 FAC
19 19
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
Use of (T-)Corrected K Values
TEMPERATURE CORRECTED K
K ADJUSTMENT RANGE
TAPER REQUIREMENT
Undulator Plans
June 2009 FAC
20 20
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
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)
Undulator Plans
June 2009 FAC
21 21
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
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.
Undulator Plans
June 2009 FAC
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Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
TLD Readings at First Undulator
LOCATION
WEEK 1 PHOTON [rad]
WEEK 2
PHOTON [rad]
WEEK 3
PHOTON [rad]
U25:ANL-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
Undulator Plans
June 2009 FAC
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Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
SN16 Radiation Damage Test
HAS BEEN INSTALLED ON GIRDER 25 DURING BEAM OPERATION
Undulator Plans
June 2009 FAC
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Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
[rad]
Dose During Initial X-Ray Operation
e-folding length 8.7 m
Increased TLD Readings are expected to be predominantly low energy synchrotron radiation, not to cause significant magnet damage
Undulator Plans
June 2009 FAC
25 25
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
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
Undulator Plans
June 2009 FAC
26 26
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
Electronics
Shielded
TLD Readings at End of Undulator Line
Undulator Plans
June 2009 FAC
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
27 27
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
SN20 Radiation Damage Test
HAS BEEN INSTALLED ON GIRDER 33 DURING FEL OPERATION
Undulator Plans
June 2009 FAC
28 28
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
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
Undulator Plans
June 2009 FAC
29 29
Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
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
Undulator Plans
June 2009 FAC
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Heinz-Dieter Nuhn
nuhn@slac.stanford.edu
End of Presentation
Undulator Plans
June 2009 FAC
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Heinz-Dieter Nuhn
nuhn@slac.stanford.edu