A Feasibility Study of High-Strength Bi-2223 Conductor for High-Field Solenoids

Area of Science:

• Materials Science
• Condensed Matter Physics
• Superconductivity

Background:

• High-field solenoid magnets require advanced superconducting materials capable of withstanding significant mechanical stress.
• Bismuth-based cuprate superconductors, specifically Bi-2223 tapes, are candidates for such applications due to their high critical temperatures.

Purpose of the Study:

• To assess the electro-mechanical feasibility of a high-strength DI-BSCCO Type HT-XX (a precursor to HT-NX) tape conductor for high-field solenoid applications.
• To determine the critical stress and strain limits of the conductor under various magnet-relevant conditions.

Main Methods:

• Conducted stress-strain characterizations at 77 K.
• Performed single- and double-bend tests on coil-turns at various radii.
• Evaluated straight and helical samples in high magnetic fields (up to 31.2 T) and tested small coils (20-turn) in fields up to 17 T.
• Investigated the effect of combined bending and Lorentz forces on allowable strain.

Main Results:

• Longitudinal tensile tests at 77 K yielded critical stress and strain levels of 516 MPa and 0.57%, respectively.
• Combined bending and Lorentz loading experiments demonstrated an amplified allowable strain of ≥ 0.92% (outer tape edge).
• The conductor is multi-filamentary and supplied in a reacted and insulated state.

Conclusions:

• The high-strength DI-BSCCO HT-NX conductor exhibits significant strain tolerance, particularly under combined mechanical and electromagnetic loads.
• Its electro-mechanical properties make it highly suitable for constructing very high-field solenoids, enabling high current densities within manageable magnet dimensions.