Analysis of Training Quench Energy Releases in LHC Superconducting Dipole Magnets Part III Evan Sengbusch Supervisors: Marco Calvi and Mario Di Castro Accelerator Technology Department, CERN

Outline LHC dipole magnets and quench phenomena Introduction to wavelet analysis Data acquisition techniques and improvements Preliminary Results Outlook

Dipole Magnets NbTi Superconducting Cables (1.9 K) Strong Lorentz Forces Stainless Steel Collar P P

Quench Heating During current ramp, thermal energy releases cause NbTi cables to lose superconductivity Current is diverted through large diode Resistive quench heaters fire to quickly dissipate remaining stored energy in the magnet Process costs time and money Possible to predict quenches?

Quench Antenna Signal Quench Occurs Here and Quench Heaters Fire Voltage Fluctuations as Energy Stored in Magnet is Dissipated Spikes Before Quench

Continuous Wavelet Transform: Equivalent to expanding function into a linear combination of basis funtions: where these basis functions are obtained by scaling and translating a mother wavelet: Wavelet Analysis Fourier Transform: Equivalent to expanding function into linear combination of basis functions: Gives frequency domain information about signal that was originally sampled in the time domain

Wavelet Analysis Morlet Mother Wavelet Translation and Integration CompressionIntegration And so on…

Two dimensional matrix determined by coefficients: Major advantage: gives time domain and frequency domain information simultaneously Most important disadvantage: poor frequency resolution at high frequency with respect to Fourier transform Wavelet Analysis Results

Originally able to record 12 channels at 50 kHz each Goal: Record all 30 channels at 50 kHz for a full quench cycle Data Acquisition S01S02S03S04S05S06S07S08S09S10S11S12S13 S01S02S03S04S05S06S07S08S09S10S11S12S13 Aperture 1 Aperture 2

Data Acquisition Dipole Magnet Standard Acquisition System BNC-2090 PXI-8187 Embedded Controller LabVIEW RT Software ALL 30 CHANNELS ARE NOW OPERATIONAL

Preliminary Results Excited Frequencies in Center of Magnet: 4, 6.5, 10.5, 13.5 kHz Excited Frequencies in Magnet Extremities: 6.5 kHz Frequency (kHz) Family 1Family 2Family 3 SESESE 4XXXX 6.5XXXXX 10.5XX 13.5X 14.5XX

Outlook Take as much data as possible in the next 6 months Work on a much more complete analysis of the pre- quench spike behavior Design and test monitoring system which uses online wavelet analysis to predict quenches for future accelerators

Acknowledgments Accelerator Technology Department, CERN: Marco Calvi Mario Di Castro Andrzej Siemko University of Michigan: Jean Krisch Homer Neal Jeremy Herr National Science Foundation Ford Motor Company

In Memory of James Van Allen