Spectrometer Solenoid Update

Steve Virostek - LBNL

MICE Video Conference #129February 25, 2010

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Magnet 2 Modification Summary

•A modification to Magnet 2 has been carried out which adds a single stage cryocooler to provide additional cooling to the HTS leads and won’t require full magnet disassembly

•The single-stage Cryomech AL330 cooler provides 170 W at 55 K and required modifications only in the “turret” area

•The added cooling power should lower the HTS lead temperature sufficiently to train to full current

•The new cooler could remove enough heat to permit the other 3 two-stage coolers to maintain the cold mass LHe level (i.e. closed system)

•Additional instrumentation has also been incorporated

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Magnet 2 with Added Cryocooler

Single-stage cooler

Thermal link

HTS leads

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Modification Details

Added turret space

Access port

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Current Status of Magnet 2

•The Magnet 2 turret area has been modified to allow installation of the single stage cooler

•New HTS and warm leads have been tested in an off line apparatus and have been installed in the magnet

•Additional temperature sensors on the cold heads (1st and 2nd stages) and voltage taps on the lower HTS leads have been added

•Initial pumpdown and leak check of the magnet insulating vacuum has been carried out

•Several leaks in the new turret welds were found and are expected to be repaired today

•Cooldown will start in one week if leak repairs go well

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Magnet 2 Single Stage Cooler

Single stage cooler and flexible copper thermal link during fit installation in Magnet 2

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Vacuum Pumping of the Magnet

Reassembled turret (single stage cooler on right)

Mechanical pump with cold trap and increased diameter connection

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Magnet Leads Testing

•A series of off line lead tests were conducted in order to characterize the warm leads and verify the performance of the HTS leads

•The tests were delayed by a vacuum leak in one of the ceramic feedthroughs that was not readily located

•The resistive heating in the warm leads was found to be higher than originally predicted; a modified design has been incorporated into Magnet 2

•Lead tests for Magnet 1 are under way and near complete

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Magnet Lead Test

HTS lead

1st stageplate

Thermalconnection

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Installed Leads in Magnet 2