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Spectrometer Solenoid Update

Spectrometer Solenoid Update. MICE VC 150 August 23, 2012. Steve Virostek - LBNL. Topics. Summary of initial magnet training Burned out HTS lead Second series of magnet training Schedule. Initial Magnet Training. First magnet cooldown completed on 5/25/12

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Spectrometer Solenoid Update

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  1. Spectrometer Solenoid Update MICE VC 150 August 23, 2012 Steve Virostek - LBNL

  2. Topics • Summary of initial magnet training • Burned out HTS lead • Second series of magnet training • Schedule

  3. Initial Magnet Training • First magnet cooldown completed on 5/25/12 • Excess cooling capacity found to be >3 W • Start of training delayed by helium shortage • LHe issue solved with help from Fermilab • Seven training runs were carried out between 6/13/12 and 7/3/12 • Quench currents ranged from 185 A in all coils to 185 A in M1 and 245 A in M2 and E1/C/E2 • Frequency of runs largely dictated by LHe supply

  4. Magnet Training (cont’d) • Numerous issues have arisen during the training that delayed progress but, for the most part, have been solved • These include: LHe supply, level gauges wiring problem, cold mass leaks to atmosphere, inadvertent quench triggered by QP system, circuit breaker trips, power supply stability • The most severe problem was a burnout of one of the six high-current HTS leads

  5. HTS Lead Burnout • During the 7/3/12 training run, it was discovered that the ‘E’ HTS lead connected to one of the end coils had burned out • Subsequent review of the test data revealed that the lead had exhibited a constant resistance of ~100mW during all of the recent training runs • The voltage across the lead had never reached a level sufficient to trip the quench system until it spiked above the 100 mV threshold at 245 A • The quenched lead burned out before the system could sufficiently reduce the magnet current

  6. HTS Lead Burnout Top: recently failed lead; middle: previously failed lead; bottom: new lead

  7. HTS Lead Resistances Failed Lead 10x better, but worrisome New Lead In the noise HTS lead resistances measured over numerous training cycles

  8. 2nd Series of Training Runs • The magnet was warmed up in order to replace the failed lead thru an access port • Pumpout of the insulating vacuum and cooldown completed 8/9/12 • Four training quenches carried out so far: • M1=110 A, M2=134A, E1/C/E2=135A • M1=132 A, M2=163A, E1/C/E2=161A • M1=141 A, M2=168A, E1/C/E2=169A • M1=144 A, M2=174A, E1/C/E2=174A • Another training run to be carried out today

  9. 2nd Series of Training Runs • The reason for the lower current quenches is not known • Our analysis of the data suggests that these are normal training quenches that are similar in nature to the previous series • The fast DAQ/QP system appears to be functioning normally, and the power supplies are stable (in manual mode)

  10. Schedule • The schedule is a bit uncertain due to the unpredictability of the training • Once the training and warmup are complete, the support feet need to be welded on and the magnet prepared for shipping • LBNL on site technical manpower has been limited in recent weeks due to budget issues • Progress on the second unit has been somewhat slowed as well

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