Alignment and Stability of NSLS-II Magnet System* · PDF file ·...

Alignment and Stabilityof NSLS-II Magnet System*

Animesh JainSuperconducting Magnet Division

Brookhaven National Laboratory, Upton, NY 11973for the NSLS-II Magnet Team

48th ICFA Advanced Beam Dynamics Workshop on Future Light Sources (FLS2010)

SLAC National Accelerator Laboratory, Menlo Park, California, 1-5 March, 2010

* Work supported by the U.S. Department of Energyunder contract DE-AC02-98CH10886

Alignment & Stability of NSLS-II Magnet System: Animesh Jain, BNLFLS2010: March 1-5, 2010

1

AcknowledgementsM. Anerella, R. Ceruti, J. Cintorino, T. Dilgen, S. Dimaiuta, L. Doom, G. Ganetis, P. He, R. Hubbard, P. Joshi, F. Karl, P. Kovach, F. Lincoln, W. Louie, A. Marone, J. Mc Caffrey,

D. Oldham, S. Ozaki, V. Ravindranath, P. Ribaudo,A. Sauerwald, S. Sharma, J. Skaritka, C. Spataro,

D. Sullivan, P. Wanderer, F. Willeke

D. Harder, G. Rakowsky, NSLSAlexander Temnykh, Cornell University

L. Rivkin, D. George, Swiss Light SourceDieter Einfeld, Montse Pont, ALBA


2

NSLS-II Lattice and Magnets

•Standard Quadrupole (66 mm):•Type A: Single coil, short,11 T/m•Type B: single coil, wide, 11 T/m•Type C: Double Coil, long, 22 T/m•Type D: Doulbe Coil, short, 22 T/m•Type E: Double Coil, Wide, 22 T/m•Large Aperture: 90 mm, 15 T/m

•Standard Sextupole: 68 mm•Type A: Symmetric•Type B: Wide•Large Aperture: 76 mm•All sextupoles have maximum strength of 400 T/m2

Field Stability requirements:Dipole: 25 ppm rms Δp/p<5x10-5

Quadrupole: 50 ppmPeak to peak beta beat <0.5%and peak to peak tune jitter <1x10-3

Sextupole: 100ppm

Alignment Specifications:100 μm girder to girder; 30 μm magnet to girder; ±0.2 mrad magnet roll

Courtesy: Weiming Guo, NSLS-II


3

Steps Involved in Alignment• Determine magnetic axis of all elements on a girder using

Vibrating Wire Technique, first developed at Cornell.• Move magnets on a girder to a common axis.• Secure magnets to the girder without disturbing the

alignment.• Verify alignment after securing the magnets.• Fully characterize the magnet and girder positions in

space.• Reproduce the magnet and girder positions during the

final installation in the machine.


4

Magnet Alignment R&D• Although the vibrating wire technique had been used in the

past for quadrupole measurements, very little work had been done in sextupoles.

• An R&D program was initiated to further develop the technique at BNL and demonstrate the required accuracy for both quadrupoles and sextupoles.

• Good measurement reproducibility has been achieved as a result of several improvements made over the course of this R&D program, which started in January, 2007.

• Work is still underway to study alignment stability and to adapt the measurements for a production environment.


5

The Vibrating Wire Technique: Basics

• An AC current is passed through a wire stretched axially in the magnet.• Any transverse field at the wire location exerts a periodic force on the

wire, thus exciting vibrations.• The vibrations are enhanced if the driving frequency is close to one of the

resonant frequencies, giving high sensitivity. • The vibration amplitudes are studied as a function of wire offset to

determine the transverse field profile, from which the magnetic axis can be derived.

X-YStage

X-YStage

X Y

Weight

Wire carryingsinusoidal current

MagnetMover

Magnet

WireVibrationSensors


6

Wire End Support (V-notch)

Fiducials relate the wire ends to the overall girder coordinate system.

Stainless V-notch

Fiducialnests (7)

Holes to help locate the notch relative to fiducials

A V-notch with radius much smaller than the wire was chosen. The wire position is thus insensitive to the actual radius of the V-notch.

Notch with radius< Wire radius

φ

h


7

Wire Vibration Sensors

As the wire is moved horizontally or vertically, the position of the wire relative to the sensor changes slightly (~ a few microns) due to imperfections in the stage motion. This causes a change in the operating point of the sensor.An automated piezo stage was added to keep the wire “centered” in the sensors during a scan.

Coarse manual adjustment in orthogonal axis

X-Sensor

Fine, automated adjustment along measurement axis using piezo stages

Y-Sensor

The wire motion sensors are inexpensive photointerrupters(Model GP1S094HCZ0F)

A pair of sensors is located on both ends of the wire, thus allowing two simultaneous measurements.

Courtesy: Paul Kovach, SMD, BNL.


8

Complete Wire Mover AssemblyCamera to ensure wire is correctly seated in the notch

Light Shades to reduce noise from stray light

V-notch holder with fiducials

A similar assembly is present at the other end of the wire, except that the pulley and weight are replaced by a fixed wire end.

Courtesy: Paul Kovach, SMD, BNL.


9

Alignment Issues Studied• Wire sag correction• Detector sensitivity to orthogonal motion• Sensitivity to Yaw/Pitch of magnets• Accuracy of quadrupole center measurement• Accuracy of sextupole center measurement• Background field correction• Ability to precisely move magnets (manually) and

secure to the girder.• Reproducibility of the girder vertical profile.• Stability of magnet alignment after transporting a

girder.


10

Reproducibility of Horizontal Center in QuadReproducibility of Horiz. Center in ALBA Q500

-0.021

-0.020

-0.019

-0.018

-0.017

-0.016

-0.015

0 2 4 6 8 10 12 14Measurement Sequence Number

Hor

izon

tal C

ente

r (m

m)

Sensor #1Sensor #3

Std.Dev. = 0.003 mm22-Oct-2008

Total variation over 3.5 hrs ~ 2 microns

Agreement between two sensors ~ 0.2 micron


11

Reproducibility of Vertical Center in QuadReproducibility of Vertical Center in ALBA Q500

-0.010

-0.009

-0.008

-0.007

-0.006

-0.005

-0.004

-0.003

-0.002

-0.001

0.000


Ver

tical

Cen

ter

(mm

)

Sensor #2Sensor #4 Std.Dev. = 0.003 mm

22-Oct-2008

Total variation over3.5 hrs ~ 8 microns

This could be temperature related

Agreement between two sensors ~ 0.1 micron(improved from ~ 5 microns in earlier data).

Temperature stabilized environment is required !


12

Sextupole Measurements Using By and Bx

• Obtaining centers from By vs. x and By vs. y plots uses only one set of sensors, and requires quadratic fits.

• One could also use scans of Bx vs. x (or y) for various values of y(or x). These plots are expected to be linear with slopes proportional to offsets in y (or x) direction.

• Doing three such scans allows to obtain centers from both Bx and By data. With 2 sets of sensors, one gets four values of magnetic center.

• Yet another way is to use circular scans instead of linear scans.• 4 Methods × 2 Sensor sets = 8 independent measurements.

⎥⎥⎦

⎤

⎢⎢⎣

⎡ −−−= 2

20

20

3)()(

refy

RyyxxBB

⎥⎥⎦

⎤

⎢⎢⎣

⎡ −−= 2

003

))((2ref

xR

yyxxBB


13

-40

-20

0

20

40

60

80

100

120

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0Wire Horizontal Position (mm)

By (a

rbitr

ary

units

)

X1 Sensor X2 Sensor

Horizontal center is defined as the point where B y vs. x has zero slope

XCenter(1) = -0.0057 mm

XCenter(2) = -0.0061 mm

Sextupole Measurements: By Scans

Parabolic fits

-180

-160

-140

-120

-100

-80

-60

-40

-20

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0Wire Vertical Position (mm)

By (a

rbitr

ary

units

)

X1 Sensor X2 Sensor

Vertical center is defined as the point where B y vs. y has zero slope

YCenter(1) = 0.0039 mm

YCenter(2) = 0.0037 mm

19-Dec-2008

19-Dec-2008


14

Sextupole Measurements: Bx ScansSLS Sextupole SR110 at 100 A; Quad @0A; 19-Mar-08

-40

-30

-20

-10

0

10

20

30

40

-1.2 -0.8 -0.4 0.0 0.4 0.8 1.2Wire Horizontal Position (mm)

Bx

(arb

itrar

y un

its)

Y1 (Y = –0.6 mm) Y1 (Y = 0.0 mm) Y1 (Y = +0.6 mm)Y2 (Y = –0.6 mm) Y2 (Y = 0.0 mm) Y2 (Y = +0.6 mm)

Vertical center is defined as the point where B x vs. x has zero slope


15

Sextupoles Measurements: Circular Scans

Fit measured data to a truncated Fourier Series, giving quadrupoleand sextupoleterms.Both X and Y Centers can be obtained using any of the 4 detectors in a single scan.

Circular Scan (R = 1 mm) in SLS Sextupole at 100A

-60

-40

-20

0

20

40

60

0 45 90 135 180 225 270 315 360Angle (deg.)

Sign

al (a

rbitr

ary

units

)

X1 X1Fit Y1 Y1FitX2 X2Fit Y2 Y2Fit

19-Mar-2008Uncorrected


16

Summary of Sextupole Center Measurements in SR110 at 100A19-Mar-2008: Comparison of Circular and Linear Scan Results

X_Center(μm)

Y_Center(μm)

X_Center(μm)

Y_Center(μm)

X_Center(μm)

Y_Center(μm)

1 X1 (B_y) 13.7 -30.8 -155.1 -31.3 -168.8 -0.52 Y1 (B_x) 8.3 -31.8 -160.8 -32.5 -169.1 -0.73 X2 (B_y) 13.7 -34.1 -154.5 -33.1 -168.3 1.04 Y2 (B_x) 8.7 -31.1 -160.1 -31.5 -168.8 -0.45 X1 (B_y) 10.0 -31.5 -160.9 -32.5 -170.9 -1.06 Y1 (B_x) 10.8 -32.9 -160.0 -35.0 -170.8 -2.17 X2 (B_y) 9.4 -31.6 -161.5 -32.9 -170.9 -1.38 Y2 (B_x) 10.1 -32.1 -160.6 -30.5 -170.7 1.6

10.6 -32.0 -159.2 -32.4 -169.8 -0.42.1 1.1 2.8 1.4 1.1 1.211.1 -31.9 -157.6 -32.1 -168.7 -0.23.0 1.5 3.3 0.8 0.3 0.810.1 -32.0 -160.7 -32.7 -170.8 -0.70.6 0.7 0.6 1.9 0.1 1.61.0 0.1 3.1 0.6 2.1 0.5

Uncorrected Background Corrected Correction Needed inMethodNumber Scan Type Sensor

Used

CIRCULAR(single scan;

25 points)

LINEAR(6 scans;7 points

each)

Mean of all 8 methods:

Std. Deviation of all 8 methods:

Circular to Linear Scan Diff.:

Mean of Circular Scan Data:

Std. Deviation of Circular Scan:

Mean of Linear Scans:

Std. Deviation of Linear Scans:

Comparison of Sextupole Data Using Bx and By


17

Issue of Background Fields in Sextupole Meas.• There is a significant quadrupole background field from

quadrupole magnet(s) even when these are unpowered.

• Based on rotating coil data, the remnant integrated quadrupole field is ~0.02 T. This could amount to a change in horizontal center by hundreds of microns, depending on quad position and the mode used for sextupole measurements.

• The vertical center measurement is not affected because By(or Bx) is independent of y (or x) in a quadrupole field.

• Effectiveness of background correction has been tested by measuring a sextupole in the presence of a quadrupole which was either unpowered, or was powered at 2 A (apparent center shift of ~600 microns). Corrected center = ±5 microns.


18

Reproducing Girder Vertical Profile• The girder, if supported at the four corners only, has a sag of

about 150 microns.

• Based on studies done in a prototype girder, the vertical profile of the girder could vary by as much as ~20 microns simply as a result of handling.

• It is, therefore, essential to not only measure the magnet centers precisely, but also to have a precise means of characterizing and then reproducing the girder vertical profile during installation.

• It was demonstrated that the girder vertical profile can be measured to better than ~10 microns using multiple laser trackersetups in a temperature controlled chamber (< ±0.1 C).


19

Feasibility of Profiling by Laser Tracker

A Laser Tracker target was placed on an adjustable mount and its vertical position was monitored with a digital dial gauge. The laser tracker was used to measure changes in the vertical position and the results were compared to the dial gauge readings. Typical agreements were within well below 10 microns.


20

NSLS-II Prototypes in Vibrating Wire Test Stand

Temperature stabilization < ±0.1°C


21

Alignment Stability During Girder Handling

Alignment Errors With Respect to a Best Fit Straight Line

-0.008

-0.006

-0.004

-0.002

0.000

0.002

0.004

0.006

0.008

1.0 2.0 3.0 4.0 5.0 6.0Axial Position (m)

Hor

izon

tal C

ente

r (m

m)

6/12/09 6/22/096/23/09(1) 6/23/09(2)7/7/09 7/9/097/10/09

North EndSouth End

After Truck Ride-0.008

-0.006

-0.004

-0.002

0.000

0.002

0.004

0.006

0.008

1.0 2.0 3.0 4.0 5.0 6.0

Axial Position (m)

Ver

tical

Cen

ter

(mm

) 6/12/09 6/22/09 6/23/09(1)6/23/09(2) 7/7/09 7/9/097/10/09

North EndSouth End

After Truck Ride

Before Truck Ride

Four NSLS-II Prototype Quadrupoles on a Prototype Girder

Watch a video of the truck ride: http://www.youtube.com/watch?v=M1nHF7KnsmU (7:21 min)


22

Vibrational & Thermal Stability• Beam size in the middle of straight sections:

σx ≈ 30 μm, σy≈ 3 μm• Beam must be stable to within < 10% of its size.• Tolerances, including closed orbit amplification factors:

• Typical ground motion near NSLS-II is ~400 nm in 0.5-4 Hz band, but can be handled by real time orbit feed back system.

• Ground motion at 4 Hz and above is ~ 15 nm.• Girder system should have high natural frequency (>30 Hz),

so as not to amplify the large motion at lower frequencies.

Tolerance Limits ΔX Quads RMS

ΔY Quads RMS

Random Magnet Motion < 150 nm < 25 nm Random Girder Motion < 600 nm < 70 nm


23

Girder Design

1.2 m

5 m

0.86 m

Sectional view showing 1 inch thick welded stiffener plates

Finite Element Analysis was calibrated against measurements of modes in a prototype girder

Expected for final girder-magnet system: 34 Hz (rocking mode) and 51 Hz (twisting mode)

Courtesy: V. Ravindranath, NSLS-II


24

Girder Resonant Frequency Vs. Torque

It is essential to tighten the eight girder mounting bolts to at least 1000 ft-lbs in order to achieve a lowest order resonant mode > 30 Hz (with the magnets mounted). This must be done while maintaining the overall girder alignment to better than 100 μm.

40

50

60

70

80

90

100

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Torque (ft-lbs)

1st M

odal

Fre

quen

cy (H

z)

Prototype girder with no magnets installed



25

Thermal Stability• Temperature changes in the cooling water (±0.05°C) and tunnel

temperature (±0.1°C) can induce motion of components.• Spatial temperature gradients can cause differential motion. • For sub-micron dynamic stability, temperature fluctuations in

the mechanical components should be within ±0.01°C.• The thermal inertia of the girder/magnets helps to limit the effect

of ambient temperature changes.• Measurements have been made of the girder temperature

changes in a controlled environment.• Work is in progress to design thermal deformation resistant

(visco-elastic) girder mounts, and to study effects of diurnal temperature cycles.


26

Girder Vs. Ambient Temperature Changes

25.75

26

26.25

26.5

26.75

27

27.25

27.5

27.75

8:00

:00

PM

8:50

:00

PM

9:40

:00

PM

10:3

0:00

PM

11:2

0:00

PM

12:1

0:00

AM

1:00

:00

AM

1:50

:00

AM

2:40

:00

AM

3:30

:00

AM

4:20

:00

AM

5:10

:00

AM

6:00

:00

AM

6:50

:00

AM

7:40

:00

AM

8:30

:00

AM

9:20

:00

AM

10:1

0:00

AM

11:0

0:00

AM

11:5

0:00

AM

12:4

0:00

PM

1:30

:00

PM

2:20

:00

PM

3:10

:00

PM

4:00

:00

PM

4:50

:00

PM

5:40

:00

PM

Time

Tem

pera

ture

(Deg

C)

∆Tambient = ± 0.75 °C

∆Tgirder = ± 0.08 °C Home-built chamber for girder studies

800 cfm air blower with heater to control temperature8 thermistor temperature sensors.

Temperature Stability = ±0.025°CUsed for cycling ambient by ±0.75°C

ΔTGirder ~ 10% of ΔTambient

In good agreement with finite element calculations.



27

Effect of Girder Temperature Changes

REF DVRT

Insulated grouted plate

0.75

1.25

1.75

2.25

2.75

3.25

3.75

4.25

4.75

9:28

:45

PM

1:38

:45

AM

5:48

:45

AM

9:58

:44

AM

2:08

:44

PM

6:18

:44

PM

10:2

8:44

PM

2:38

:44

AM

6:48

:44

AM

10:5

8:44

AM

3:08

:44

PM

7:18

:44

PM

11:2

8:44

PM

3:38

:44

AM

7:48

:44

AM

11:5

7:44

AM

4:07

:44

PM

8:17

:43

PM

12:2

7:43

AM

4:37

:43

AM

8:47

:43

AM

12:5

7:43

PM

5:07

:43

PM

Tem

pera

ture

(Deg

C)

24.5

24.625

24.75

24.875

25

25.125

25.25

25.375

25.5

Def

lect

ion

(mic

rons

)

Gir_center_deflection Spectator_DVRT Girder_Temperature

FRI SAT SU MON TUE

∆T = 0.25 °C

∆dref = 0.25 μm

∆dgir = 1.5 μm

∆dgir = 2.5 μm

∆T = 0.5 °C

∆dref = 0.5 μm

Girder displacement measured~ 50 nm for ΔTGirder = 0.01°CGirder deflection expected to be less than 20 nm

Work is in progress to design deformation resistant girder mounts using visco-elastic film.


FEA Model Results:Girder displacement:80 nmGirder deflection : 20 nm


28

Conclusions• An extensive R&D program has been carried out to build a state-of-

the-art vibrating wire system, and to study various error sources.• Measurement procedures are developed to minimize the errors.• Excellent consistency (at sub-micron level) is routinely achieved

between data from two sets of sensors.• Absolute accuracy of < 5 μm, as judged by correlation with

mechanical motion, and consistency between four independent methods of measuring a sextupole, has been demonstrated.

• It has been shown that magnets can be secured to the girder while maintaining alignment within ~ 5-10 μm.

• The alignment of the magnets was shown to survive careful handling.• Vibrational stability requires careful control of resonant modes.• Thermal deformations need to be minimized even with ±0.1°C control

of the ambient temperature.


29

Thank You !


30

Supplemental Material


31

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

134 135 136 137 138 139 140 141Frequency (Hz)

<A_x

*I>

or

<A_y

*I>

A_x1 A_x1Calc A_y1 A_y1CalcA_x2 A_x2Calc A_y2 A_y2Calc

f x1=22.902 Hzf y1=22.899 Hzf x2=22.903 Hzf y2=22.900 Hz

Resonant Frequency and Wire Sag

Correction for large wire sag (~550-600 microns for ~7.3 m length) is very important, which in turn requires a very precise knowlege of resonant frequency.±0.02 Hz ⇒± 1 micron

2032 f

gSag =

0220

0

)()( Y

ffffffAfY ++−

−=

γ

lmT

Lf

21

0 =

TgLmSag

8

2l=

~7.3 m long, 0.125 mm dia. Cu-Be wire; 1.05 Kg weight

T = TensionL = Length

= mass per unit length

lmMode = 6


32

Experimental Setup for Sag Measurements

A vertical wire sensor is mounted on a vertical stage and is placed at axial center of the wire. For a given weight, the sensor is adjusted until zero signal is obtained, and the resonance frequency is measured. A dial indicator is used to monitor change in detector position (or sag) with weight.

Dial indicatorSensorWire


33

Sag: Measured Vs. Calculated

-150

-100

-50

0

50

100

150

0.0017 0.0019 0.0021 0.0023 0.0025 0.0027

1/f 2 (s2)

Cha

nge

in W

ire

Hei

ght (

mic

ron) Horizontal Sensor

Vertical SensorCalculated

Wire position appears to have changed systematically by ~19 μm for data points #10-11.

#1,2

#10

#3

#4

#5

#6 #7

#8

#9

#11

Dial indicator accuracyis ±3 μm


34

Stability of Wire Sag Over Several Days

SLS Quadrupole SLS Sextupole

546

548

550

552

554

556

558

560


Com

pute

d Sa

g (m

icro

ns)

Using X Detector

Using Y Detector

October 26-29, 2007

Oct. 30-Nov.1, 2007

Resonant frequency, and hence sag, is continuously derived as part of the measurements. Thus stability is strictly needed only at time scale of~1 hour .


35

Detector Sensitivity to Orthogonal Motion

Measured signal is contaminated by sensitivity to motion along the orthogonal axis, thus causing errors in the measurement of magnetic center.

Response of X1 & Y1 Detectors to X1 Stage Motion

y = -0.00026x - 0.00070y = 0.0137x + 0.0089

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

-50 -40 -30 -20 -10 0 10 20 30 40 50Wire X1-Motion (microns)

X1

Sens

or O

utpu

t (V

)

-0.020

-0.015

-0.010

-0.005

0.000

0.005

0.010

0.015

0.020

Y1

Sens

or O

utpu

t (V

)

Sensor X1Sensor Y1

18-Dec-08

A rigorous analysis has shown that the error in horizontal/vertical center is minimized if wire is scanned at the vertical/horizontal center in both quadrupoles and sextupoles. This implies that a rough center must be found first before the final scan.


36

Resonant Mode to Use: Yaw/Pitch Sensitivity

• Should have a maxima near the axial center of the magnet being measured.

• Preferably even numbered modes should be used to avoid contribution from any axially uniform background fields (e.g. earth’s field).

• It may be impractical to find a mode with maxima exactly at the axial center for every magnet on the girder. This causes sensitivity to yaw and pitch.

• One should choose a mode that minimizes sensitivity to yaw and pitch without sacrificing signal strength.


37

Sensitivity to Yaw and Pitch( )∑

∞

=

=1

/sin)(n

yny LznBzB π Signal for mode = n is proportional to Byn(for a given detector position)

In a quadrupole magnet with offset x0 and yaw angle Θ, located at z = zmag:Θ−−= )()( 0 magy zzGGxzB

⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛⎟⎟⎠

⎞⎜⎜⎝

⎛−⎟⎟

⎠

⎞⎜⎜⎝

⎛⎟⎟⎠

⎞⎜⎜⎝

⎛⎟⎠

⎞⎜⎝

⎛Θ−

⎟⎟⎠

⎞⎜⎜⎝

⎛⎟⎟⎠

⎞⎜⎜⎝

⎛⎟⎠⎞

⎜⎝⎛=

LLn

LLn

LLn

Lzn

nGL

LLn

Lzn

nGxB

magmagmagmag

magmagyn

2cos

22sincos4

2sinsin4

22

0

ππππ

π

πππ

Error in center determination due to yaw:

Θ⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛⎟⎟⎠

⎞⎜⎜⎝

⎛−⎟⎟

⎠

⎞⎜⎜⎝

⎛⎟⎠⎞

⎜⎝⎛=Δ

LLn

LLn

Lzn

nLx magmagmag

2cot

21cot0

ππππ

A similar analysis for sextupoles is much more tedious, but the same expression for Δx0 is obtained in the end!

A similar expression applies to vertical offset and pitch angle.

zmag = magnet axial position; G = Gradient

Lmag = magnetic length

L = wire length


38

Yaw/Pitch Sensitivity for Various Modes

-40

-30

-20

-10

0

10

20

30

40

0 2 4 6 8 10 12 14 16Mode Number

Yaw

/Pitc

h Se

nsiti

vity

(m

icro

n/m

rad)

m 23.0m 98.3

m 27.7

==

=

mag

magLzL


39

Horizontal Scans (Bx): Slope Vs. Y OffsetSR110 at 100 A (UnCorrected) Quad at 0A; 19-Mar-08

-30

-20

-10

0

10

20

30

-0.6 -0.4 -0.2 0.0 0.2 0.4 0.6Wire Vertical Position (mm)

dBx

/dx

(arb

itrar

y un

its)

Y1 Sensor

Y2 Sensor

YCenter(1) = -0.0329 mm

YCenter(2) = -0.0321 mm

YCenter(1) = -0.0306 mm

YCenter(2) = -0.0304 mm

From dBx/dx Vs y Plots:


40

Vertical Scans (Bx): Slope Vs. X Offset

XCenter(1) = -0.0100 mm

XCenter(2) = -0.0094 mm

SR110 at 100 A (UnCorrected) Quad at 0A; 19-Mar-08

-30

-20

-10

0

10

20

30

-0.6 -0.4 -0.2 0.0 0.2 0.4 0.6Wire Horizontal Position (mm)

dBx

/dy

(arb

itrar

y un

its)

Y1 Sensor

Y2 Sensor

XCenter(1) = 0.0108 mm

XCenter(2) = 0.0101 mm

From dBx/dy Vs x Plots:


41

Horizontal Center Reproducibility in Sextupole

0

2

4

6

8

10

12

14

1 2 3 4 5Measurement Sequence Number

Hor

izon

tal C

ente

r (m

icro

ns)

Sensor #1 (B_y) Sensor #3 (B_y)

Sensor #2 (B_x) Sensor #4 (B_x)

12-Mar-2008Scans over ±1.2 mm

100 pts/cycle; 200 cycles; 24 freq. steps1.5 hr per measurement

Std.Dev.(B_y) = 0.004 mmStd.Dev.(B_x) = 0.001 mm


42

Procedure for Multipole Alignment on a Girder

• Install magnets on a girder, install vacuum chamber, and carry out a rough alignment using a laser system (horizontal and vertical offsets, pitch and yaw) and inclinometers (roll).

• Set up girder on a vibrating wire test stand in a temperature controlled environment (±0.1C), and wait for steady state.

• Tighten the 4 corner studs on the girder to several hundredft-lbs, secure center bolts and tighten to ~ 100 ft-lbs.

• Power one magnet at a time and measure the magnetic center using vibrating wire technique in the vibrating wire coordinate system, including appropriate correction for wire sag.

• Repeat for all magnets on the girder.


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Procedure for Alignment on a Girder (contd.)• Force all displacement gauges to display the corresponding

measured magnet offsets.

• Lock the magnets in place, while monitoring the magnet positions to bring the magnets on-axis by making all gauges to read zero again.

• If required, carry out vibrating wire measurements again to confirm alignment.

• Survey the wire ends, and all girder and magnet fiducialsusing laser trackers. In particular, measure the girder vertical profile precisely (better than ±10 microns).

• Disconnect and remove the girder from the test stand.


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ELEVATION DELTA [LASER TRACKER‐DIAL GAUGE] VS POSITION

‐20.0

‐15.0

‐10.0

‐5.0

0.0

5.0

10.0

0 2 4 6 8 10 12 14

POSITION #

ELEV

ATION DELTA

[MICRONS]

TRACKER 101 D1 4'

TRACKER 101 D1 4'

TRACKER 100 D4 4'

TRACKER 100 D4 4'

TRACKER 101 D4 15'

TRACKER 101 D4 15'

TRACKER 100 D1 15'

TRACKER 100 D1 15'


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Alignment Stability• Four NSLS-II prototype quadrupole magnets were mounted on a

prototype girder, and prealigned using a laser system.• The girder was installed in the temperature controlled room and the

magnets were hooked up to power and water supplies.• The magnetic centers of all the magnets were measured, and all the

remaining steps in the alignment process outlined earlier were carried out.

• The girder was then removed from the test bench, loaded on a truck, driven around the laboratory site, unloaded and reloaded on the truck, and then brought back to the test area.

• The girder was reinstalled, the girder vertical profile was reproduced using survey, and magnetic centers were measured again to see if the initial alignment of the magnets was maintained.

Alignment and Stability of NSLS-II Magnet System* · PDF file ·...

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Transcript of Alignment and Stability of NSLS-II Magnet System* · PDF file ·...