superconducting magnets acoustic emission sensors in · • acoustic emission sensors sensors...

Marcos AraqueSIST/GEM Final Presentation6 August 2018

Acoustic Emission Sensors in Superconducting Magnets

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Acoustic Emission Quench Detection Sensors in Superconducting Magnets

Quenching in Superconducting Magnets

Data Acquisition and Results

Acoustic Emission (AE) Sensor

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Acoustic Emission Quench Detection Sensors in Superconducting Magnets

Quenching in Superconducting Magnets

Data Acquisition and Results

Acoustic Emission (AE) Sensor

Electromagnets made of superconducting wire

Zero Resistance More Current Stronger Magnetic Fields Higher Energy Beams

Superconducting Magnets

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Careful design and maintenance required

• Appropriate stress applied • Must remain superconducting• Quench - Sudden loss of superconductivity in part of a coil

Superconducting Magnets

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Factors that cause quenching include:

• Mechanical disturbances (microcracks)• Electrical disturbances/ faults• Magnetic field strength/ rate of change• Defects in magnet

Magnets “trained” to withstand higher quenching currents by gradually increasing operating current (ramp)

Quenching

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Quenching

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Quench detection and diagnostic techniques:

• Strain gauges• Quench antenas• Coil voltage taps• Acoustic Emission sensors

Sensors trigger heat sink to the magnet to more evenly distribute heat from a quench

Quenching

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Acoustic Emission Sensor

Quenching in Superconducting Magnets

Data Acquisition and Results

Acoustic Emission (AE) Sensor

Advantages of AE sensors:

• Comparable or faster signal detection (millisecond timescale)

• Isolated measurement system external to the magnet• Negligibly affected by magnetic fields• Inexpensive

How are they designed?

Acoustic Emission Sensor

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Engineering Design Process

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System Requirements

Design Schematic

Create Printed Circuit Board (PCB)

Design Electrical Casing

Hardware Testing

Functional Circuit

Piezoelectric Ceramic5 mm Inner Diameter10 mm Outer Diameter

Transducer: converts mechanical stress into an electrical signal (voltage) and vice versa

Entire circuit is designed to optimize this signal

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AE Sensor

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Schematic

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Amplifies signal using MOSFET amplifying circuit

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Schematic

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Decouples power signal from AE signal and strengthens output signal

Schematic

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Electrical Casing

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Electrical Casing (Junction Box)

• Maintains solid, reliable connections

• Protects circuit• Reduces defects over time

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Electrical Casing

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Acoustic Emission Quench Detection Sensors in Superconducting Magnets

Quenching in Superconducting Magnets

Data Acquisition and Results

Acoustic Emission (AE) Sensor

Data collection of sensors in 1 dimension:

• 33 x 2 x 1 inch aluminum bar• AE sensors mechanically screwed in on both ends• Bar tapped with a hammer at various points

Data Acquisition

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1-dimensional source localization:

Time differenceVelocity of sound in bar AE source location

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• Velocity of sound in bar determined to be 1.989 km/s• Standard deviation: 2.34 cm• Standard error: 0.33 cm

1. Conduct 2 dimensional localization2. Improve sensor/experiment accuracy (COMSOL

simulation, more sensors)3. Test on prototype magnets

Results

Next Steps

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Questions?

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Collaborations / Partnerships / Members

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Appendix

Circuit on Breadboard

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Cryo Amplifier PCB

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Coupling Box PCB

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Sample Data for 1-D AE localization

MOSFET animation: https://upload.wikimedia.org/wikipedia/commons/2/2f/FET-Ani.gif

Transducer animation: https://www.teachengineering.org/content/uoh_/lessons/uoh_piezo/uoh_piezo_lesson01_figure1.gif

Marchevsky, M., et al. “Acoustic Emission during Quench Training of Superconducting Accelerator Magnets.” Cryogenics, Science Direct, 31 Mar. 2015, www.sciencedirect.com/science/article/pii/S0011227515000399.

References

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