Quench Variability

Purpose

Evaluate the reason(s) for increased quenching from June to September and provide suggestions/solutions to reduce/eliminate magnet quenching during this time period. 

Background

• MRI Superconducting magnet cooled with liquid helium to 4K
• Quenching is a massive helium boil off
• Caused by small increase in temperature
• Slips in wire-epoxy create frictional heat
• More common during humid summer
• Quenching costs time and money

Accomplishments

• Statistically supported hypotheses for quench variability
• Determined how the surface finish of the wire correlates to slippage
• Analyzed how environmental humidity affects the wire-to-epoxy bond strength
• Measured moisture build up within the epoxy and test how this affects bonding capabilities 

Results

• Humidity is absorbed into epoxy and DMD
• Humidity reduces wire-epoxy bond strength, determined by slip testing
• Wire suppliers have chemically similar surfaces, determined by spectroscopy
• Supplier with roughest wire provided highest bond strength, determined by microscopy