A (RE)BCO Pancake Winding With Metal-as-Insulation

Area of Science:

• High-temperature superconductivity (HTS)
• Superconducting magnet technology
• Electrical engineering

Background:

• No-insulation (NI) winding technique is a proven method for HTS pancake coils.
• Protection and stability are critical parameters for superconducting coil operation.
• The metal-as-insulation (MI) winding technique is a novel variant of NI.

Purpose of the Study:

• To experimentally investigate the protection capabilities of REBCO pancake coils using the MI winding technique.
• To compare the performance of MI coils against the established NI technique.
• To assess the viability and advantages of MI winding for HTS pancake coils.

Main Methods:

• Experimental testing of two REBCO pancake coils: one NI and one MI.
• Operation and analysis at 77 K.
• Comparison of stability, quench parameters, and charging-delay time constants.
• Circuit modeling to evaluate the effect of metallic tape thickness.

Main Results:

• MI technique is viable for HTS pancake coils, offering nearly self-protecting features.
• MI coils exhibit a significantly smaller charging-delay time constant compared to NI coils.
• Stable operation at 97% of quench current was achieved with MI coils.
• Metallic tape thickness was found to have minimal detrimental effect on MI coil self-protection.

Conclusions:

• The MI winding technique presents a promising alternative to NI for HTS pancake coils.
• MI coils offer enhanced self-protection, faster charging, and better parameter control.
• The MI technique allows for stable operation closer to the critical current, improving overall performance.