a mole for warm magnetic and optical measurements of lhc dipoles immw xi, brookhaven national...
TRANSCRIPT
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Eleventh International Magnet Measurement WorkshopEleventh International Magnet Measurement WorkshopSeptember 21 - 24, 1999September 21 - 24, 1999
Brookhaven National Laboratory, Upton, New York, USABrookhaven National Laboratory, Upton, New York, USA
A Mole for warm magnetic and optical A Mole for warm magnetic and optical measurements of LHC dipolesmeasurements of LHC dipoles11
Thursday, 23 Sept.1999Berkner B
10:50-11:20
L Bottura1, M Buzio1, G Deferne1, H Jansen2, C Glöckner2, A Köster2,
P Legrand1, A Rijllart1, P Sievers1 , F Villar1
1 CERN, European Organization for Nuclear Research - 1211 Geneva 23, Switzerland2
Frauenhofer Institut IPT, Aachen, Germany
1Also published in the proceedings of the 16th International Conference on Magnet Technology, Ponte Vedra Beach, IL, 26 Sept- 2 Oct 1999
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
IntroductionIntroduction Mechanical layoutMechanical layout VR DemoVR Demo11
Magnetic performance Magnetic performance Optical performanceOptical performance ConclusionsConclusions
A Mole for Warm Magnetic and Optical A Mole for Warm Magnetic and Optical Measurements of LHC DipolesMeasurements of LHC Dipoles
A Mole for Warm Magnetic and Optical A Mole for Warm Magnetic and Optical Measurements of LHC DipolesMeasurements of LHC Dipoles
1 http://home.cern.ch/m/mtauser/www/applications/mole/virtualmole.wrl
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
IntroductionIntroductionIntroductionIntroduction
Why use a mole ?Why use a mole ? Purpose: measure magnetic axis Cold measurements done for max. efficiency with 15 m long coil shaft, obstructing line-of-sight to the coil center travelling probe is needed Additional duties: warm field quality of all dipoles, cold field of samples
Requirements for series measurementsRequirements for series measurements Coil center position: precision better than 0.1 mm Warm measurements: 50 mm, B 25mT Rugged, quick and simple to setup and operate As many off-the-shelf components as possible
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Mole test bench overviewMole test bench overviewMole test bench overviewMole test bench overview
rear reference bench(transport motor, cable connections)
magnet
front reference bench(telescope)
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Front reference benchFront reference benchFront reference benchFront reference bench
CCD camera
Telescope
mole support shell (closed)
Sliding support
focusing system
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Rear reference benchRear reference benchRear reference benchRear reference bench
Transport motor
Cable receptacle
Axis transfer jigMole
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Front reference benchFront reference benchFront reference benchFront reference bench
Laser for alignment measurement
optical alignment targets (4)
axis transfer carbon fiber jig
Telescope/CCD/DSP unit
transport belt
granite table
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
StatusStatusStatusStatus Warm Mole Warm Mole
First unit accepted and under commissioning Two more units to come, will perform warm test of all LHC dipoles Can be readily adapted to warm quadrupole tests
Cold MoleCold Mole Order started, last design details now being finalized Will perform cold tests for a sample populations of LHC dipoles to get warm-cold axis correlation Further units may be slightly modified for cold quadrupole tests
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Mechanical layoutMechanical layoutMechanical layoutMechanical layout
Main featuresMain features three mmlong radial coils coil drive: Shinsei travelling-wave ultrasonic piezo motor 4096 CPR Heidenhein angular encoder On-board feedback auto-leveling system Spring-loaded roller system Motorized traction belt drive Two granite benches to establish reference positions LED+lens system to create virtual light-spot in the coil centre Telescope + CCD camera + DSP to measure light-spot position All functions remotely controlled via RS232 Auxiliary optical system to transfer axis to magnet fiducials
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Main components Main components Main components Main components
Coil
Elastic coupling(with helical groove for the cable)
Ball-bearing support flange
Piezo motorWyler encoder
Potentiometer
3:1 reductiongearbox
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Longitudinal transportLongitudinal transportLongitudinal transportLongitudinal transport
closed-loop pre-tensioned Inconel transport belt
feedback-controlled DC motor drive
referencing given by optical barriers at both ends of the magnet (self-calibration at the end of each trip)
max. velocity about 1 m/s
precision of positioning better than 0.5 mm
mole must be switched manually between apertures
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Longitudinal reference positionLongitudinal reference positionLongitudinal reference positionLongitudinal reference position
lower half-shellsupport
Optical barrier(receptor)
spring-loadedroller
LED viewingaperture
front transport belt attachment
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
SafetySafetySafetySafety
interlock system: mole will stop if covers are removed, transport cable gets tangled, transport motor drains overcurrent
reduced velocity close to the edges
longitudinal position cross-checked with two independent measurements (angular encoder + linear potentiometer)
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
AutolevelingAutolevelingAutolevelingAutoleveling
Why autoleveling ?Why autoleveling ? imperfections of beam pipe/rollers rotation of container during travel observed rotation up to 2~3°/m transport belt & cable may be twisted coil must be level prior to measurement
How does it work ?
DC motor engaged in container to rotate coil+encoder+piezo motor feedback system using wide-range level meter precision achieved better than 4 mrad time needed less than 5 s autoleveling done at the end of each longitudinal movement
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Auto-leveling mechanism Auto-leveling mechanism Auto-leveling mechanism Auto-leveling mechanism
Motor shaft gear
Wide-rangelevel meter Roller (fixed tangentially
by friction)
Inner gear (linked with container)
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Auto-leveling mechanism Auto-leveling mechanism Auto-leveling mechanism Auto-leveling mechanism
Final configurationStart End of travelling
travel autolevel
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Optical measurementOptical measurementOptical measurementOptical measurement
TelescopeTelescope accurately leveled and aligned wrt magnet mounted on rails to serve both apertures
CCD cameraCCD camera 752 pixel, 6.00 mm size self-aligned to telescope via reference marks
DSP image processorDSP image processor threshold filtering + center of gravity calculation measurements internally averaged over multiple takes software calibration map
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Virtual lightspotVirtual lightspotVirtual lightspotVirtual lightspot
Virtual lightspot
LED
the virtual image remains in the coil center even when the mole rotates
Magnifying lens
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Optical measurementOptical measurementOptical measurementOptical measurement
PerformancePerformance mm mm 20 m range total error 60 m measurement time 4 s at closest range
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Optical system calibrationOptical system calibrationOptical system calibrationOptical system calibration
Mole XY calibration check (z=20m)
-3.5
-2.5
-1.5
-0.5
0.5
1.5
2.5
3.5
-12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12
x [mm]
y [
mm
]
XYTable
Optical
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Optical system calibrationOptical system calibrationOptical system calibrationOptical system calibration
Measured X Error vs. y position (z=20 m) (zoomed)
-80
-60
-40
-20
0
20
40
60
80
100
120
140
-4 -2 0 2 4
y [mm]
dx
[
m]
x=-10
x=-8
x=-6
x=-4
x=-2
x=2
x=4
x=6
x=8
x=10
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Example: optical measurement Example: optical measurement Example: optical measurement Example: optical measurement
MBL1N1 beam pipe shapeLeft aperture, X (horizontal) coordinate
(avg. diff=74 m)
0100020003000400050006000700080009000
0 5 10 15 20
z [m]
x [
mic
ron
]
LHC/MTA Mole
EST/SU Mole
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Focusing systemFocusing systemFocusing systemFocusing system
How does it workHow does it work no autofocus needed longitudinal position sent to the camera at the end of each movement focusing motor follows a software calibration table total error if out-of-focus 1 m/mm
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Magnetic performanceMagnetic performanceMagnetic performanceMagnetic performance
Harmonic CoilsHarmonic Coils mm fiberglass/epoxy coil support 3 radial coils with 400 turns, 3.4 m2 area 1 coil for main dipole, 1 for dipole compensation + 1 spare
System precisionSystem precision Main dipole: better than 10-4
Dipole angle: better than 0.2 mrad Multipoles: generally better than 2·10-6 relative to B1 bucking factor 2000
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Example: multipoles Example: multipoles Example: multipoles Example: multipoles
F ie ld h a rm o n ic s in A p . 1 o f M B L 1 N 1 @ I = 3 0 Al ine a rly c o rre c te d fo r fe e d do wn - a ll units @ 1 7 m m
0 .0 0 0 1
0 .0 0 1
0 .0 1
0 .1
1
1 0
1 0 0
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Example: calibrated dipole angle Example: calibrated dipole angle Example: calibrated dipole angle Example: calibrated dipole angle
MBL1N1 Field Angle - Aperture 1
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
0 2000 4000 6000 8000 10000 12000 14000
z (mm)
an
gle
(m
rad
)
Mole (calibrated) 10/5/99, ±30A
Chaconsa scanning machine18/5/97, ±15A
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Axis TransferAxis TransferAxis TransferAxis Transfer
Why transfer the magnetic axis ? Why transfer the magnetic axis ?
harmonics, and hence magnetic axis, are measured in the coil reference frame the center of the coil is measured in the telescope reference frame the magnetic axis is needed in the reference frame of the magnet fiducials
How the transfer will be doneHow the transfer will be donethe granite tables establish two reference positions per aperture,
vertically and laterally reproducible within 20 m reference positions are measured by the telescope relative position of magnet fiducials and granite tables is measured by means of an auxiliary laser system relative position of coil center wrt magnet fiducials can thus be computed
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Axis TransferAxis TransferAxis TransferAxis Transfer
Telescope frame
Mole coil positionalong magnet
Granite table jig
Granite table reference line
Magnet
fiducial line
Granite jig reference line
Auxiliary alignment laser beam
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Axis TransferAxis TransferAxis TransferAxis Transfer
Telescope reference frame
Mole coil position
Magnetic center (z)
Marble table jigs line
Magnet fiducial line
Marble table reference line
Y
Z
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Problems encounteredProblems encounteredProblems encounteredProblems encountered
Unsteady velocity of piezo-motor, getting worse with motor heatingUnsteady velocity of piezo-motor, getting worse with motor heating Micro cables and connectors delicate and difficult to handleMicro cables and connectors delicate and difficult to handle Fine alignment of the lensFine alignment of the lens Image distortion due to thermal gradients in the magnetImage distortion due to thermal gradients in the magnet
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Piezo motor rotation speedPiezo motor rotation speedPiezo motor rotation speedPiezo motor rotation speed
Rotation speed quality Rotation speed quality
encoder detects low-frequency rotation speed oscillations up to 8% oscillation amplitude gets larger as motor heats up oscillations interfere with measured harmonics (errors in b2 up to 0.5 units
observed)
Improvements under wayImprovements under wayoptimization of stiffness and damping of the coil/motor link
to minimize response fine tuning of motor speed map (t) to minimize excitationenhanced motor cooling automatic off-line filtering of spurious harmonics
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Piezo motor rotation qualityPiezo motor rotation qualityPiezo motor rotation qualityPiezo motor rotation quality
Backward run
Forward run
average
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Piezo motor rotation qualityPiezo motor rotation qualityPiezo motor rotation qualityPiezo motor rotation quality
Mole Rotation & Magnetic Measurement Test
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
1 11 21 31 41 51 61 71 81 91 101 111 121 131 141
M e asure me nt n.
b2
Speed variation p.p. (FW D) (rad/s )
-b3
Speed variation p.p. (BW D) (rad/s )
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
Piezo motor rotation qualityPiezo motor rotation qualityPiezo motor rotation qualityPiezo motor rotation quality
Mole Rotation & Magnetic Measurement Test
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Amplitude of lowest frequency component in(t) (rad/s)
Dev
iatio
n fr
om
avg
. of h
arm
on
ic (u
nit)
b3-b3avg
b2-b2avg (f=4 Hz)
b2-b2avg (f=2 Hz)
A mole for warm magnetic and optical measurements of LHC dipoles
IMMW XI, Brookhaven National Laboratory, 21-24 Sept. [email protected]
ConclusionsConclusionsConclusionsConclusions
Magnetic and optical performance generally exceeding specificationsMagnetic and optical performance generally exceeding specifications Well suited for industrial-type test environment Well suited for industrial-type test environment Test bed for further technological improvements (piezo-motor, remote Test bed for further technological improvements (piezo-motor, remote
encoders, etc.)encoders, etc.) Software integration under waySoftware integration under way Minor improvements under way: smoother velocity control, better optics Minor improvements under way: smoother velocity control, better optics
alignmentalignment