Spectrometer Solenoid Update

Steve Virostek - LBNL

MICE VC 150

August 23, 2012

LBNL

MICE VC 15023 August 2012

- 2 -Spectrometer Solenoid Update Steve Virostek LBNL

Topics

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

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MICE VC 15023 August 2012

- 3 -Spectrometer Solenoid Update Steve Virostek LBNL

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

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MICE VC 15023 August 2012

- 4 -Spectrometer Solenoid Update Steve Virostek LBNL

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

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MICE VC 15023 August 2012

- 5 -Spectrometer Solenoid Update Steve Virostek LBNL

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

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MICE VC 15023 August 2012

- 6 -Spectrometer Solenoid Update Steve Virostek LBNL

HTS Lead Burnout

Top: recently failed lead; middle: previously failed lead; bottom: new lead

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MICE VC 15023 August 2012

- 7 -Spectrometer Solenoid Update Steve Virostek LBNL

HTS Lead Resistances

HTS lead resistances measured over numerous training cycles

Failed Lead

New Lead

10x better,but worrisome

In the noise

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MICE VC 15023 August 2012

- 8 -Spectrometer Solenoid Update Steve Virostek LBNL

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

LBNL

MICE VC 15023 August 2012

- 9 -Spectrometer Solenoid Update Steve Virostek LBNL

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)

LBNL

MICE VC 15023 August 2012

- 10 -Spectrometer Solenoid Update Steve Virostek LBNL

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