A new 3-axes magnetic field measurement system based on the Hall - PowerPoint PPT Presentation

A new 3-axes magnetic field measurement system based on the Hall elements E. Hirose, K. H. Tanaka, T. Takahashi, Y.Satou, K. Agari, M. Ieiri, Y. Kato, M. Minakawa, H. Noumi, Y. Sato, Y. Suzuki, H. Takahashi, M. Takasaki, A. Toyoda, Y. Yamada and Y. Yamanoi KEK Beam Channel Group TOKIN Corporation

The typical magnet for 50GeV transfer line Bore:200mm 3 m 1.2m Weight : ～ 40ton

The new 3-axes magnetic field measurement system The mechanics The Auto-level unit for moving rod The Control unit The Magnet The rod 3-axes Hall probe The Base Plate

The Base Plate 7m long 2m wide iron base. The base level stability is within 0.1mm against the magnet weight 40 ton. 7m 2m The base plate supports Pivots fitting on the base prepared on the floor, which were fixed by anchor bolts.

The rod Material : carbon fiber composite 2200 Diameter : 20mm Thickness : 2mm The weight of Hall probe : < 50g 2200 10.1 Quantity of Measuring position from the part of deflection [mm] support [mm] 700 1200 1700 2200 The rod 1200 0.7 1.9 length 1700 1.0 2.4 3.8 [mm] 2200 1.8 4.4 7.2 10.1

The Hall Sensor unit 16-pin Heater Flexible connector polyimide Nichrome coil A PEEK block base film Vy Vx Cover with marked the positions The measured temperature coefficient of Hall elements : Vz -0.075%/degree 1-axis Hall elements : National OH008

The angler resolution of a 3-axes Hall probe 2 Θ y = 180.92 1 . 5 1 ] V 0 . 5 [ e g a t l 0 o v l 0 5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 3 5 0 l a - 0 . 5 H - 1 Θ x = 91.35 - 1 . 5 - 2 R o t a t i n g a n g l e [ d e g r e e ] V x V y V z Measured angle between X and Y Hall elements : 89’34’’

Operating the Hall • Current supply elements and data – Operating current : 6mA – Stability : +-0.02% taking • Temperature controller – 60 ℃ +-0.01 – The error by temperature : about 0.15mTesla for 2Tesla • Heater power supply • Switching digital voltmeter – Hall voltage of each axis – Current of Magnet power supply – Interfaced to the PC via GP-IB

The mechanics for moving rod The control unit Y : ± 500 X : ± 500 Z : 0 ～ +2000 •They moved by servo motors via PCI motor control board •The accuracy of the positions : within 0.1mm • The rod can be moved through the axis step by step •The motion speed is controlled to be slow start/slow stop manner •interval distance=5mm (movement time:2.3sec, waiting time for stopping the rod oscillation :1sec)

Adjusting the rod axis and magnet axis Another point Starting point Magnet axis The rod Remote control unit and Auto- level unit Given the starting point and another point on the magnet axis, the field measurement points on the magnet coordinate can automatically be calculated and positioned in software way.

The operating monitor Date Power supply Filename Define the Waiting time starting point Position Interval distance > 1mm Hall Voltage Define the final point

2 . 5 y = 4 . 8 5 2 4 1 E - 0 3 x 6 - 2 . 9 3 1 6 6 E - 0 2 x 5 + 6 . 8 6 4 9 2 E - 0 2 x 4 - 7 . 6 3 5 0 2 E - 0 2 x 3 + 3 . 7 9 6 4 1 E - 0 2 x 2 + 1 . 1 5 0 1 2 E + 0 0 x - 5 . 1 8 9 3 0 E - 0 3 Calibration ] a l s 2 e T [ y t i s 1 . 5 n e D 2 . 5 x u l y = 3 . 2 6 0 5 4 E - 0 3 x 6 - 1 . 7 7 5 4 4 E - 0 2 x 5 + 3 . 6 0 7 4 2 E - 0 2 x 4 - 3 . 2 8 0 3 9 E - 0 2 x 3 + 1 . 0 2 4 4 9 E - 0 2 x 2 + 1 . 1 7 7 0 7 E + 0 0 x - 7 . 9 6 5 2 9 E - 0 3 F 1 ] a c l i s 2 t e e T n [ g y t a 0 . 5 i s M 1 . 5 n e D x u 0 l F 1 c 0 0 . 5 1 1 . 5 2 i t e n H a l l V o l t a g e [ V ] g a 0 . 5 M • A dipole magnet (max flux 0 0 0 . 5 1 1 . 5 2 density = 2.2Tesla) was used X H a l l V o l t a g e [ V ] for calibration of Hall probe 2 . 5 6 5 4 3 2 y = 5 . 9 2 3 1 2 E - 0 3 x - 3 . 7 0 8 5 9 E - 0 2 x + 8 . 7 9 3 6 3 E - 0 2 x - 9 . 7 0 1 3 3 E - 0 2 x + 4 . 7 0 7 1 4 E - 0 2 x + 1 . 1 4 7 7 3 E + 0 0 x - 4 . 9 0 9 6 1 E - 0 3 • Absolute flux density was ] a l s 2 e T measured be NMR at the same [ y t i s 1 . 5 n e time D x u l F 1 c • The error of fitting is estimated i t e n g a 0 . 5 within 3 Gauss at whole M 0 measurement range. 0 0 . 5 1 1 . 5 2 Y H a l l V o l t a g e [ V ]

Conclusion • A new 3-axes magnetic field measurement system based on the Hall elements has been constructed at KEK • We can align the measuring machine and the magnet at the accuracy within 0.1 in total be simply putting the magnet on the base • The field measurement points on the magnet coordinates can automatically be calculated and positioned in software way • 3 Hall elements could be mounted in one sensor unit and the angle between X and Y Hall elements is 89’34’’ • The temperature of Hall elements can be controlled within 60 +-0.1 degree • The deflection of rod was less than 10mm for 2200 mm carbon rod length • We have successfully measured the field of the Q-magnet, whose bore diameter and length are 200mm and 3m