Spectrometer Solenoid Update

Steve VirostekLawrence Berkeley National Lab

MICE Video Conference 120

May 7, 2009

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•Second magnet assembly including all fixes and modifications has been completed

•Second magnet had been cooled to 5K (cold mass) and transfer of LHe was under way

•An internal leak developed between the cryostat and the insulating vacuum (1 week ago)

•Magnet has been warmed up and leak checking is under way•Leak is likely in either the cryostat fill or vent lines

•LN cooldown system developed at FNAL has been installed

•Temperature logging system developed at LBNL is working

•First magnet is completely disassembled and fixes are well under way in preparation for reassembly

•Additional cryostat penetrations and extra vent line added•Modifications to vent line are nearly complete

Summary

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LN Cooldown of Magnet

Cooler He lines

Transfer line

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LHe Transfer into Cold Mass

Fill line turret

Transfer lineVent line

turret

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Steps Leading up to Leak•Magnet had been cooled to 5K (cold mass) and transfer of LHe was under way

•LHe dewar was changed, and no flow through the system could be attained

•Vendor suspected an ice blockage and attempted to thaw out fill line with heated helium gas

•Blockage remained, so vendor attempted to transfer LHe through the vent line containing an unprotected bellows

•An internal leak developed between the cryostat and the insulating vacuum causing the cold mass temperature to rise and the external vacuum vessel surfaces to frost

•Leak is likely in either the cryostat fill or vent lines

•A leak near or in the vent line bellows is the easiest repair

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Possible Leak LocationsConflat seal

Al/SS transition

Weld joints

Bellows

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FNAL LN Cooldown Control System

Heaters

Thermocouple

Control system chassis

Flow control valve

LN

•System was successfully operated during cooldown

•Modifications to control circuitry under way to optimize performance

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Temperature Logging System in Use

•System now operating

•16 channels being logged

•User can specify logging time increment

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Temperature Logging System Screen Shot

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First Magnet Cold Mass Modification

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Power Supply Racks

•Two power supply racks have arrived from RAL

•Installation of power supplies and discharge circuits are under way

•Spec supplied by RAL dictates locations of components

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•Locate exact location of vacuum leak (today or tomorrow)

•Develop plan to make necessary repairs (depends on the accessibility of the leak location)

•Make the repair while maintaining the integrity of the magnet insulation (subject to review by LBNL)

•Initiate cool down of the magnet (~1.5 week process)

•Run the system at operating temperature for ~24 hours to ensure recondensing system is functional

•Power the magnet and train coils•Warm up for shipping to FNAL

Upcoming Tasks