Current driven wire based magnetic measurement systems ZORIN, Artem - - PowerPoint PPT Presentation

Current driven wire based magnetic measurement systems

ZORIN, Artem

• Dr. MEZENTSEV, Nikolay

KANONIK, Pavel Budker Institute of Nuclear Physics, lab 8-2

SFR-2016 X-ray apparatus

Electron beam + magnetic field = synchrotron radiation. A wiggler/undulator = many magnets, but it is not a bending magnet. Electron beam trajectory shouldn’t change. J1 means angle, J2 means shift. Tasks: minimize and measure J1, J2 and some other parameters.

  

     

L s L

s d s B ds J ds s B J

2 1

) ( ) (

2

3 PSU = B, J1, J2

3

Hall probe sensor

• Much space
• Much time, no ramping
• Mechanics
• Calibration
• Liquid He

4

Moving wire based systems

• Faraday's law of induction: moving wire +

magnetic field = voltage

• Different configurations of wire are possible:

straight wire, coil, eight-form coil…

• Mechanics
• Much space

5

Current driven wire based systems

• Current moves through stretched wire and

interacts with magnetic field (Ampere force). The wire deflects, and its position is measured.

Wiggler Sensor Sensor m

6

Constant current method

p

Current wire I = 2A.

l1 l2 L1 L2 δX1 δX2

                2 2 1 1 * 2

1

L x L x I T I T L I I first   

• first field integral

) 1 2 ( 2

2 sec

x x I T I T x L I I

• nd

             

• - second field integral

7

Median plane

y = 0,0143x + 9,8244

• 150
• 100
• 50

50 100 150

• 2500
• 2000
• 1500
• 1000
• 500

500 1000 1500 2000 2500

Wiggler focuses

8

Sextupole measurement

• 50
• 40
• 30
• 20
• 10

10 20 30 40

• 15
• 10
• 5

5 10 15

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Ramping up and down

50 100 150 200 250 300 350 400

• 0.00010
• 0.00005

0.00000 0.00005 0.00010 0.00015

I1 I2 B meas B set

Time, s I1, T*m; I2, T*m*m

0.0 0.5 1.0 1.5 2.0 2.5

Field, T

50 100 150 200 250 300 350 400

• 0.0003
• 0.0002
• 0.0001

0.0000 0.0001

I1 I2 B meas B set

Time, s I1, T*m; I2, T*m*m

0.0 0.5 1.0 1.5 2.0 2.5

Field, T

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Vibrating wire technique (resonant method)

• Let 𝑔

0 is wire self-resonant frequency

• Let 𝐵 is amplitude of oscillation (measured

by a sensor) when the wire is driven by harmonic current frequency 𝑔

• It is possible to show that

𝐽

𝑔𝑗𝑠𝑡𝑢 ~ 𝐵(𝑔 = 𝑔 0), 𝐽𝑡𝑓𝑑𝑝𝑜𝑒 ~ 𝐵 𝑔 = 2𝑔 0 , and

so on

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• Sensor

position

• Phase

detection

• Coefficients,

supports, calibration

• Q-factor,

time

12

Software interface

13

Pulsed Wire Method

• J1
• J2
• Axis tilt
• Axis offset

14

15

Problems

• Sag, tension, sensitivity, I, diameter
• Noise: wind, acoustic waves, vibration
• Earth magnetic field
• Wire imperfectness (for pulsed method)

16

Conclusion

• Hall probe: liquid helium, constant field
• Constant current method: the best for
• wigglers. Accuracy is better 5*10^-5 T*m,

limited by PSUs

• Vibrating wire (resonant) method: good for

zeroing integrals, problems with calibration

• Vibrating, pulsed methods: perspective for

superconducting undulators

17

Thank you!

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