Tatiana Kozlova, Novosibirsk State University Supervisor: Darryl Orris, TD/Test & Instrumentation Department AC loss measurements of superconducting quadrupole magnet Nb 3 Sn Summer student meeting, September 1, 2009

2 Applicability We have to know the value of energy losses in the magnet for understanding how much heat should we carry off; for magnet design; What do we have? “eieo” (energy input – energy output) program for AC energy loss measurements

3 Goal To improve the LabView program “eieo” for AC loss measurements Steps Applying “eieo” program to the system connection software with the experimental setup; determine transfer functions; Performing calibration of the energy loss measurement system noise addition; moving the end point; Measuring AC loss of SC magnet Analyzing data Optimization

4 Theory Superconductors the critical surface in HJT space where superconductivity prevails below this surface and normal resistivity above it Nb 3 Sn: T c ~18 K H c ~25 T J c ~6*10 6 A/sm 2 Energy losses Magnetization (hysteresis) losses depend on the max magnetic induction excursion Resistive (eddy current) losses depend on the rate of frequency

5 Experimental Setup High-Speed Analog Output (6733) W – energy loss I – current, U – voltage, t - time SC Magnet Energy Loss Measurement System Multifunctional Input/Output (6052E) Digit flex multimeter (4071)

6 Software (National Instruments LabView version 8.6) The front panel of the “eieo” program List of parameters: Ramp rate Cycle/Run Profile/Ramp I min, I max Time Dwell Noise level (T, A) Sampling rate Magnet inductance Result: Energy loss Mean root square deviation

7 Calibration of the energy loss measurement system Noise addition W1 – “eieo” t – time of signal, N – number of points, R=2mΩ – resistance of the load

8 Calibration of the energy loss measurement system Moving the end point Mean root square deviation

9 Mirror quadrupole magnet Coil cross-section with magnetic field vectors Magnet Nb 3 Sn parameters: 4,2 K1,9 K Quench current, (kA)1314 Peak field in the coil, (T)11,212

Energy losses in TQM Hysteresis loss = 403±5.3 J Eddy current loss = 637±24 mJ/A/s Ramp rate, A/sW, JW_move, Jsigma, JUint, mVUint_move, mV Ramp rate, A/sEnergy loss, J

11 Conclusions Calibration of energy loss system was performed; The function of moving the end point was added; The value of energy loss for TQM-03 was received: Hysteresis loss = 403±5.3 J Eddy current loss = 637±24 mJ/A/s Plans: Modify a program for a new digital multimeter (HP 3458A); Investigation the influence of Dwell Time ( decay of persistent current ) and Multifunctional I/O; Choose optimal regime. Thanks for your attention