Magnetic survey of the cesr interaction region quadrupole magnets using vibrating wire technique
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Magnetic survey of the CESR interaction region quadrupole magnets using vibrating wire technique. Alexander Temnykh and Scott Chapman Cornell University, Ithaca, NY 14850, USA. BNL NSLS, 6/1/06. Content. Introduction Setup Magnetic survey and alignment Permanent quadrupole magnets

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Magnetic survey of the cesr interaction region quadrupole magnets using vibrating wire technique

Magnetic survey of the CESR interaction region quadrupole magnets using vibrating wire technique.

Alexander Temnykh and Scott Chapman

Cornell University, Ithaca, NY 14850, USA

BNL NSLS, 6/1/06


Content
Content

  • Introduction

  • Setup

  • Magnetic survey and alignment

    • Permanent quadrupole magnets

    • Super – conducting quadrupoles

  • Summary and Conclusion

A. Temnykh, BNL NSLS, 6/1/06


Introduction basic
Introduction (basic)

Vibrating wire setup is a stretched wire with AC current with natural wire vibrating frequencies. Standing wave amplitude and phase will depend on the location of the magnetic field.

AC current with

resonance frequency

Lorenz forces

No excitation if the field in the node of standing wave.

Maximum excitation if the field location at maximum standing wave amplitude

A. Temnykh, BNL NSLS, 6/1/06


Introduction advanced
Introduction (advanced)

  • Equation for the string motion driving by AC current:

  • Solution - sum of standing waves

A. Temnykh, Vibrating wire field-measuringtechnique, Nuc. Inst., A 399 (1997) 185-194

  • Measuring xn one can find Bn and reconstruct B(z) !!!

A. Temnykh, BNL NSLS, 6/1/06


Cesr final focusing quadrupole magnets survey alignment setup
CESR final focusing quadrupole magnets survey /alignment setup

Wire geometry:

SC

SC

PM

Q0E/W – permanent quadrupole magnets

Q1E/W and Q2E/W super-conducting quadrupole magnets in cryostats

(1) – 7.536m long 0.1mm copper-beryllium wire

(2) – precise moving stages with optical targets.

(3) – constant tension mechanism.

(4) – wire motion sensors

A. Temnykh, BNL NSLS, 6/1/06


Permanent magnets survey analysis example

Q0W setup

Q0E

Permanent magnets survey (analysis example)

Reconstructed horizontal

magnetic field, Bx(z)

Vertical standing wave amplitudes

Wire vertical position at Q0E,W

Y = 0.039mm

Y = -0.061mm

dy = - 0.1mm differential effect

Q0E

Q0W

A. Temnykh, BNL NSLS, 6/1/06


Permanent magnets survey all sc quads turned off

Q0E setup

Q0E

Q0E

Q0E

Q0W

Q0W

Q0W

Q0W

Permanent magnets survey(all SC quads turned off)

Vertical position survey

Horizontal position survey

ywire = -0.061mm

xw = 0.07mm

dywire = 0.1mm

effect

dxw = 0.1mm

effect

PM quads vertical position:

Q0E -0.20mm, Q0W 0.11mm

PM quads horizontal position:

Q0E -0.14mm, Q0W 0.11mm

A. Temnykh, BNL NSLS, 6/1/06


Super conducting magnets survey

Q1E, vertical setup

Q1E, horizontal

1) I(Q1W) = 243A

Y = -0.159 +- 0.013mm

2) I(Q1W) = 465A

Y = -0.169 +- 0.018mm

1) I(Q1E) = 231A

y = 0.142 +- 0.007mm

2) I(Q1E) = 466A

y = 0.141 +- 0.010mm

1) I(Q1W) = 233A

x = -0.019 +- 0.001mm

2) I(Q1W) = 466A

x = -0.022 +- 0.002mm

1) I(Q1E) = 231A

x = -0.010 +- 0.004mm

2) I(Q1E) = 466A

x = -0.002 +- 0.001mm

Super-conducting magnets survey

For Q1E & Q1W survey the 4th order standing wave has been used.

Surveyed magnets

Q1W, vertical survey

Q1W, horizontal

A. Temnykh, BNL NSLS, 6/1/06


Super conducting magnets survey1

Vertical setup

Horizontal

Horizontal

Vertical

1) I(Q2W) = 183A

x = -0.033 +- 0.001mm

2) I(Q2W) = 366A

x = -0.029 +- 0.001mm

1) I(Q2W) = 183A

Y = 0.006 +- 0.017mm

2) I(Q2W) = 366A

Y = -0.001 +- 0.021mm

1) I(Q2E) = 180A

x = -0.006 +- 0.002mm

2) I(Q2E) = 360A

x = -0.001 +- 0.001mm

1) I(Q2E) = 180A

y = 0.109 +- 0.007mm

2) I(Q2E) = 360A

y = 0.119 +- 0.003mm

Super-conducting magnets survey

For Q2E & Q2W survey the 6th order standing wave has been used.

Surveyed magnets

Standing wave amplitude with sign versus string position

Q2W magnetic survey

Q2E magnetic survey

A. Temnykh, BNL NSLS, 6/1/06


Magnetic survey summary
Magnetic Survey summary setup

Over all survey precision ~ 0.07mm

~0.050 mm from wire ends position optical survey

~0.010 mm from magnetic survey

A. Temnykh, BNL NSLS, 6/1/06


Magnetic survey of the cesr interaction region quadrupole magnets using vibrating wire technique

“Standard” setup

bar

Solenoid still yoke

wire

Optical wire position sensor mounted on platform

Transferring of the wire position to outside world

(resent development).

Precise moving

platform

  • Wire position sensor signal as function of platform position.

  • Wire is free

  • Wire is pressed against the “standard” bar

  • Touch point.

(2)

(1)

(3)

A. Temnykh, BNL NSLS, 6/1/06


Magnetic survey of the cesr interaction region quadrupole magnets using vibrating wire technique

Pulsed to VW setup conversion setup

(sensitivity study)

Sensitivity ~ 0.2Gcm !

A. Temnykh, BNL NSLS, 6/1/06


Magnetic survey of the cesr interaction region quadrupole magnets using vibrating wire technique

VW using for sextupole magnet alignment setup

Sextupole magnet example:

10cm long,

30mm bore radius

1.5T field on pole tip

Sextupole center from

quadratic fit:

X = 0.0018 +- 0.0013mm

A. Temnykh, BNL NSLS, 6/1/06


Conclusion
Conclusion setup

  • WV technique has been used for magnetic survey of permanent and super-conducting quadrupole magnets of IR of Cornell Electron Storage Ring (CESR). The survey has been done in situ with CLEO detector field turned ON.

  • The technique demonstrated ~0.010mm or better precision in the finding of the quadrupole magnet magnetic centers.

  • The factors limiting the overall survey precision are:

    • Optical survey of the wire ends ~ 0.050mm

    • Stages motion ~ 0.010mm

    • Both can be improved.

    • Note: fundamental mode frequency variation df/f ~ 5x10-4 produces the sag error ~0.002mm.

A. Temnykh, BNL NSLS, 6/1/06


Vibrating wire sensitivity test at nsls

Vibrating Wire Sensitivity Test setupat NSLS

Alexander Temnykh1

and

George Rakowsky, Dave Harder & Mike Lehecka

June 1, 2006

1Cornell University


Nsls pulsed wire bench converted to vibrating wire for sensitivity study
NSLS Pulsed Wire Bench Converted to Vibrating Wire setupfor Sensitivity Study

PHOTO-OPTICAL

WIRE POSITION

DETECTORS

(X & Y)

CALIBRATED

P-M DIPOLE

(100 G-cm)

E-M

DIPOLE

(VARIABLE)

X-Y-Z

STAGE

X-Y-Z

STAGES

125 µm

BeCu WIRE

AUDIO

OSCILLATOR

~56 Hz

2nd Harmonic

Vibration Mode

~1kg

SCOPE

PC

~1.5m

1.4m

5.1m

Method: • Vary EM current to cancel PM dipole kick.

• Measure wire vibration amplitude vs. current

A. Temnykh, BNL NSLS, 6/1/06


Magnetic survey of the cesr interaction region quadrupole magnets using vibrating wire technique

Vibrating Wire Sensitivity Study setup

Sensitivity ~ 0.2Gcm !

A. Temnykh, BNL NSLS, 6/1/06


Magnetic survey of the cesr interaction region quadrupole magnets using vibrating wire technique

Using VW for Sextupole Magnet Alignment setup

Sextupole magnet example:

10cm long,

30mm bore radius

1.5T field on pole tip

Sextupole center from

quadratic fit:

X = 0.0018 +- 0.0013mm

A. Temnykh, BNL NSLS, 6/1/06