Transcript Undulator Tuning and Fiducialization Schedule

LCLS Undulator Tuning
And Fiducialization
Zack Wolf, Yurii Levashov,
Achim Weidemann, Seva Kaplounenko,
Scott Jansson, Ralph Colon,
Dave Jensen, Scott Anderson
October 30, 2007
LCLS Undulator Tuning
1
Zachary Wolf
[email protected]
Progress Since Last FAC
Progress
We have 15 undulators tuned and fiducialized.
The MMF temperature control is working well.
The reference undulator measurements repeat within spec.
The Hall probe calibrations are stable.
The Hall probe reference magnet measurements are stable.
A study of the stainless steel beam pipe and steel support was made.
A study of undulator mounting effects is under way.
The undulator quadrupole fiducialization system was commissioned.
Challenges
Now we need to set K to a specified value. Can’t re-assign slot number.
Bad bolts.
Machining accuracy of tapered shims.
The rough tuning is taking longer than expected.
New air compressor still not installed.
October 30, 2007
LCLS Undulator Tuning
2
Zachary Wolf
[email protected]
Hall Probe Calibrations In Fixed Mount
The Hall probe is
calibrated in the
same mount it is
used in.
Measurements are made in a reference magnet before
the final data set is taken.
October 30, 2007
LCLS Undulator Tuning
3
Zachary Wolf
[email protected]
Reference Undulator, Reference Magnet
within spec
change probe
mount
(4 undulators tuned,
will re-measure)
temperature?
need more studies
taken during reference
undulator measurements
Y. Levashov
October 30, 2007
LCLS Undulator Tuning
4
Zachary Wolf
[email protected]
Schedule
Present Status:
15 undulators tuned and fiducialized
2 in fine tuning
1 in rough tuning
2 deferred for major re-work (bad end magnets, large sag might hit beam pipe)
(minor problems like bad bolts or requiring gap shim replacement
are fixed as we go)
Present Schedule:
17 tuned and fiducialized
1 tuned
We are 2 to 4 weeks behind schedule (which is 6 months ahead
of installation).
October 30, 2007
LCLS Undulator Tuning
5
Zachary Wolf
[email protected]
Actions To Help The Schedule
Problems
Rough tuning is taking a long time
Difficult to set K to a specified value (can no longer just re-assign slots)
Need to replace bad bolts
Need to replace many gap shims
(±50 micron strongback tolerance, ±20 micron shim range)
Problems with large tapered shim dimension deviations
(need to measure shim removed and measure shim replaced)
Need to set gap to 4 microns (!) for beam axis to be within ±1 mm of
magnetic center (±2 mm good field region)
Solutions
New gap shimming stand
Measure size of removed shim and size of replacement shim
Use capacitive sensors for rapid feedback
Kugler bench assists with rough tuning when required
Coordinate technicians time better (start shimming at 7am)
Set K and do phase shimming in one step
October 30, 2007
LCLS Undulator Tuning
6
Zachary Wolf
[email protected]
Phase Relative To A Reference Wave
Is Used To Set Gap And Do Phase Shimming
after an iteration
measurement
requires
alignment of
undulator and
probe
problem
problem
need phase
matching shim,
not a problem
October 30, 2007
LCLS Undulator Tuning
problem
7
Zachary Wolf
[email protected]
Gap Shim, Capacitive Sensor Feedback
check gap
shimming with
capacitive
sensors
shims were
replaced at
the error
locations
error
fast,
doesn’t
require much
alignment
the removed
shims were
undersize,
the replaced
shims were
oversize
error
error
can catch these problems much quicker now
October 30, 2007
LCLS Undulator Tuning
8
Zachary Wolf
[email protected]
Installed New Gap Adjustment Stand
tuning can
continue
while the
technicians
adjust the gap
the Kugler
bench was used
for rough tuning
when required
can use CMM
for feedback
on gap
adjustment
October 30, 2007
LCLS Undulator Tuning
9
Zachary Wolf
[email protected]
Beampipe Magnetic Effect Study
October 30, 2007
LCLS Undulator Tuning
10
Zachary Wolf
[email protected]
Undulator Mounting Tests
MMF
Tunnel
flat on flat:
over-constrained, however, there
is compliance in aluminum feet
and in the stages, and undulator (?)
kinematic mount:
well defined,
repeatable
October 30, 2007
LCLS Undulator Tuning
11
Zachary Wolf
[email protected]
Undulator Foot
Used For Mounting And Positioning
October 30, 2007
LCLS Undulator Tuning
12
Zachary Wolf
[email protected]
Issue Under Test
Ideal
Entrance end
October 30, 2007
LCLS Undulator Tuning
1 mrad
roll tolerance,
twist is smaller
Error in
Correction
slot for foot
Move axis
Twists undulator?,
to correct
distorts foot?
height by
Axis at wrong
adjusting foot
height
twist is not the issue
Exit end
Tooling ball gives axis y position
13
Zachary Wolf
[email protected]
Tests Of Mounting Method Differences
The undulator
appears to
sit the same
way on flat
feet as on the
kinematic
mount.
0.03 mrad,
negligible
negligible difference in twist of two undulators tested so far
will check on all undulators
October 30, 2007
LCLS Undulator Tuning
14
Zachary Wolf
[email protected]
To-Do List
When we are done with production
• fix undulators with severe problems
(we need to buy more tapered shims)
• study temperature dependence of K
• re-measure first five undulators
• study further undulator handling requirements
Other Projects
• girder alignment plan
• build quadrupole coils for gun solenoids
October 30, 2007
LCLS Undulator Tuning
15
Zachary Wolf
[email protected]
Undulator Quadrupole Fiducialization Plan
October 30, 2007
LCLS Undulator Tuning
16
Zachary Wolf
[email protected]
Undulator Quadrupole Fiducialization
System Commissioning
Repeatable
flip magnet,
center position doesn’t change
no bias from Earth’s field
October 30, 2007
LCLS Undulator Tuning
17
Zachary Wolf
[email protected]
Undulator Quadrupole Measurements
Scott Anderson
will do the fiducialization
October 30, 2007
LCLS Undulator Tuning
Andrew Fisher
will do the strength
and harmonics
measurements
18
Zachary Wolf
[email protected]
Leftovers From Last FAC
Hall Probe Position Problem
Problem:
The vertical trajectories on the
Dover bench and Kugler bench
did not agree.
The horizontal field integrals from
the Hall probe had a large y
dependence. Coil measurements
showed no such dependence.
October 30, 2007
LCLS Undulator Tuning
We stumbled onto a paper Isaac
wrote in 1997!
The Sentron probes are sensitive
to planar Hall effects after all!
19
Zachary Wolf
[email protected]
Solution To The Hall Probe Problem
Isaac’s hypothesis:
planar Hall effect
(30 microns Dover bench,
10 microns Kugler bench)
Solution:
Measure the positions of the Hall elements.
Tune the horizontal trajectory with the By probe on the midplane.
Tune the vertical trajectory with the Bx probe on the midplane.
Use only the long coil for final field integral measurements.
October 30, 2007
LCLS Undulator Tuning
20
Zachary Wolf
[email protected]
Undulator Sag Changes Hall Probe Y Position
Relative To The Midplane
October 30, 2007
LCLS Undulator Tuning
21
Zachary Wolf
[email protected]
Effect Of Hall Probe Error On Trajectories
μm
X Trajectory
μm
2
12
-2
-2
Y Trajectory
y=+200 μm
6
y=+100 μm
-1
2
y=0 μm
-2
1
y=-100 μm
-6
2
y=-200 μm
-14
October 30, 2007
LCLS Undulator Tuning
22
Zachary Wolf
[email protected]
μm
Constant Bx0 Corrects Bx To Long Coil Field Integral
Y Trajectory
12
-2
μm
Corrected Y Trajectory
2
y=+200 μm
Bx0=+0.52 G
-2
6
y=+100 μm
Bx0=+0.29 G
-1
2
y=0 μm
Bx0=0.00 G
-2
1
y=-100 μm
Bx0=-0.29 G
-6
2
y=-200 μm
Bx0=-0.63 G
-14
October 30, 2007
LCLS Undulator Tuning
23
Zachary Wolf
[email protected]
Effect Of Undulator Sag And Hall Probe Error On K
Y (μm)
K, No Bx0 Correction
K, After Correction
ΔK (%), From
Correction
+200
3.491564
3.490271
-0.037
+100
3.488016
3.487728
-0.0083
0
3.486728
3.486728
0.0000
-100
3.487804
3.487244
-0.016
-200
3.491692
3.489325
-0.068
Conclusion:
The trajectory curvature caused by the Hall probe error when the undulator
sags by 100 microns will change K by less than 0.016% if no correction is
applied. We do apply a correction, making the effect much smaller.
October 30, 2007
LCLS Undulator Tuning
24
Zachary Wolf
[email protected]
Conclusion
Production undulator tuning is underway.
The lab and equipment are performing well.
(But we still need the new air compressor installed.)
15 undulators are tuned and fiducialized.
Hall probe calibrations are now stable.
Reference undulator measurements are within spec.
Reference magnet measurements are stable.
The magnetic effect of a stainless steel beam pipe was studied.
We are checking that the way the undulator is mounted
will not change the fiducialization, and twist can be
compensated by a pitch adjustment.
We have a quadrupole fiducialization plan.
The quadrupole fiducialization system was commissioned.
After production, we will fix undulators and continue studies.
October 30, 2007
LCLS Undulator Tuning
25
Zachary Wolf
[email protected]