A versatile 4 K insert for characterization of the superconducting joints

Area of Science:

• Superconducting magnet technology
• Magnetic Resonance Imaging (MRI) instrumentation

Background:

• Superconducting magnets are essential for MRI, requiring highly stable magnetic fields.
• Temporal field stability is directly impacted by the electrical resistance of inter-coil joints and superconducting switch connections.
• Accurate characterization of these joints necessitates specialized testing equipment operating at cryogenic temperatures.

Purpose of the Study:

• To introduce a versatile 4 K insert developed at IUAC for characterizing superconducting joints.
• To detail the capabilities of the test rig for measuring joint resistance using the field-decay method.
• To assess the performance of superconducting joints under varying conditions, including background magnetic fields.

Main Methods:

• Development and utilization of a versatile 4 K insert for joint characterization.
• Employing the field-decay measurement technique to determine joint resistance.
• Testing straight or spiral joint configurations up to 150 mm in length with currents exceeding 600 A.

Main Results:

• The 4 K insert can measure joint resistance in the range of approximately 10⁻¹⁵ Ω.
• Joint resistance characterization is feasible in the presence of a 1.5 T background magnetic field.
• The lowest measured joint resistance was 8 × 10⁻¹⁵ Ω at zero field.

Conclusions:

• The developed 4 K insert is a versatile tool for characterizing superconducting joints critical for MRI magnets.
• The system enables the study of joint behavior under relevant operating conditions, including background fields.
• This technology aids in establishing reliable joint technology for improved MRI performance and stability.