1. NEW UPGRADE TO THE APS MAGNETIC FIELD INTEGRAL MEASUREMENT SYSTEM
Joseph Z. Xu and Isaac Vasserman
Advanced Photon Source, Argonne National Laboratory
12/26/2017
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2. Introduction
Initial set up of long stretched wire coil system: flipping mode of operation with 4 points of measurement during rotation over 360 ̊. 10-turn Litz wire was used.
Next steps involved rotation mode with continuous measurements each 0.1 ̊, fitting to sine wave. Single turn beryllium copper wire was used.
The latest upgrade is described below.
Joseph Xu and Isaac Vasserman, APS Integral System Upgrade, IMMW19
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3. APS magnetic field integral measurement system hardware
2 sets of 3-axis precision linear positioning stages, remotely controlled by servo motors. (LinTech linear stages; SmartMotor servo motors)
2 sets of precision rotary positioning stages, remotely controlled by servo motors. (Parker rotary stages; SmartMotor servo motors)
2 sets of coil mounting stages.
1 set of coils. (150 micron beryllium copper wire)
2 linear encoders. (Acu-rite linear encoders)
1 rotary encoder. (Heidenhain rotary encoder)
Servo motors
Y stage
Coil mounting stage
Rotary stage
Rotary encoder
Z stage
X stage
Linear encoder
Joseph Xu and Isaac Vasserman, APS Integral System Upgrade, IMMW19

4. Spring loaded Z stage for adjusting coil tension
Coil mounting stages
Rotary stages for
adjusting the
coil width
X/Y stages for
coil rotation center
Spring loaded Z stage for adjusting coil tension
Coil mounting stages have coil rotation enter and width adjustable stages, allowing the change of the coil width from 0 mm up to 20 mm.
Control software has delta, cross, and straight-shaped coil scanning configuration for second integral measurements.
The system allows direct measurement of the first and second integrals, as well as rotational scan shifted in X and Y directions for multipole component measurement.
Wires are outside of motors, encoders, and shields. This allows direct comparison with Hall probe integral measurement results (covers the same distance).
Joseph Xu and Isaac Vasserman, APS Integral System Upgrade, IMMW19

5. APS magnetic field integral measurement system controls
1 DC amplifier with low-pass signal filter. (Ectron 428-O DC signal conditioner)
1 FPGA reconfigurable data acquisition card. (National instruments PXI-7841R)
1 PXI control card. (National instruments)
1 PXI shelf. (National instruments)
LabView based control software.
True synchronization between position and signal.
TCP/IP based access protocol. (Can be accessed via the Internet from anywhere at any time, wired or wireless.)
Joseph Xu and Isaac Vasserman, APS Integral System Upgrade, IMMW19

6. APS magnetic field integral measurement system user interface and main features
Rotation coil
First field integral (horizontal and vertical) measurements.
Second field integral (horizontal and vertical) measurements.
Multipole rotation coil
Multipole components of first field integral measurements over X axis.
Multipole components of first field integral measurements over Y axis.
Translation coil
Multipole components of first field integral measurements over Y axis
Stretched wire
Joseph Xu and Isaac Vasserman, APS Integral System Upgrade, IMMW19

7. First integral measurement results
First field integral measurements with different coil width. Difference between data for d=0.5 mm and d=3.9 mm is ~6 %, which is close to accuracy of coil width set up. Calibration was done only for 3.9 mm width.
Joseph Xu and Isaac Vasserman, APS Integral System Upgrade, IMMW19

8. Second integral measurement results
One end coil width is set to 0 to measure second field integral.
Joseph Xu and Isaac Vasserman, APS Integral System Upgrade, IMMW19

9. Discussion
Measurements of the first field integral were done using permanent magnet dipole for different width of the coil: 0.5 mm; 1 mm; 2 mm; and 3.9 mm.
All results agree with accuracy of the coil width set up, which is done using optical level.
RMS error of measurements is larger with small gap width, so more statistics are required in these cases.
Measurements of second field integral was done using two options: figure 8 (cross), which involves contribution of first field integral to the flux and delta shape, which allows direct measurement of the second field integral.
Results of the measurements agree very well:
Option 1: J2=-984 kG-cm^2
Option 2: J2= kG-cm^2
Horizontal field device does not allow scanning in X direction. An option of vertical scanning was implemented. Main difference between horizontal and vertical scanning: scanning in X direction provides decoupled components (skew from horizontal field, normal from vertical field), scanning in Y direction provides coupled components from each field scan.
Joseph Xu and Isaac Vasserman, APS Integral System Upgrade, IMMW19

10. Conclusion
An upgrade to the APS stretched-coil magnetic field integral measurement system has been completed.
The new system is capable of coil width adjustment.
It can measure the first as well as the second integrals of magnetic field directly.
Measurement results are in agreement with that of the cross configuration as well as that of the Hall probe (covers the same distance).
Joseph Xu and Isaac Vasserman, APS Integral System Upgrade, IMMW19