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Quench antenna and acoustic emission studies in HQ02a2

Quench antenna and acoustic emission studies in HQ02a2. M. Marchevsky , LBNL. Quench antenna in HQ02a2. 17. 16. 20. 15. “A”. Orientation for the C16 heater tests (ramps 33,34). 17. 16. 20. 15. “B”. Orientation for the remaining heater tests and spontaneous quenches (ramps 35-46).

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Quench antenna and acoustic emission studies in HQ02a2

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  1. Quench antenna and acoustic emission studies in HQ02a2 M. Marchevsky, LBNL

  2. Quench antenna in HQ02a2 17 16 20 15 “A” Orientation for the C16 heater tests (ramps 33,34) 17 16 20 15 “B” • Orientation for the remaining heater tests and spontaneous quenches (ramps 35-46)

  3. Quench antenna signals Heater test (Ramp 35): Imag=14605 A, 20B02 fired at 165 V Spontaneous quench (Ramp 46): Imag=15992 A, quench at -3.1 ms in 16a10_a9 (per VTaps) Quench starts in the middle of the coil and propagates toward the return end (QA3 -> QA2) at ~110 m/s By VTaps this quench is detected at -7.1 ms. Quench is detected ~ 0.5 ms earlier by the QA than by VTaps

  4. Acoustic sensor in HQ02a2 PZT sensor / cold preamp (Slowed down 4x times) Imag Acoustic sensor Installed at the bottom load plate Q trigger Yoko DAQ QA(1-7) AE MTF DAQ RT preamp

  5. Acoustic signature of the quench Heater test: Imag= 14605 A, 20A02 fired at 275 V, at -15.5 ms Quench was detected at – 4.6 msby Vtaps. Acoustic noise is seen ~ 0.2ms after heater firing; quench itself is masked by the heater noise. Spontaneous quenchat Imag= 15992 A. Quench detected with Vtaps at at -3.9 ms Acoustic noise is seen starting at -4.52 ms.

  6. Long-term acoustic precursor to quench Ramp 45 to a spontaneous quench at 16098 A. Increasing spike envelope in the “flux jump” region as well as towards the quench is observed. Large mechanical event is observed at -180 ms prior to the quench.

  7. Conclusions • Heater-induced and spontaneous quenches were successfully detected with the axial-field quench antenna installed in the warm bore. Heater-induced quenches originated near the magnet center and propagated towards the ends at ~100 m/s velocity. • Acoustic sensor installed at the bottom load plate has successfully detected quenches by acoustic emission. Timing of the acoustic signals was in good correlation with the voltage tap signals of the developing spontaneous quenches • Long-term acoustic precursor (expanding spike amplitude envelope) towards the quench is observed. This is consistent with the previously seen behavior of the HQ01 magnet.

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