Interpretation of time-dependent current and resistance of HTS closed loop with superconducting joint considering flux creep

Takeda, Yasuaki; Tsuchiya, Yuji; Nishijima, Gen

doi:10.35848/1882-0786/acf7a9

Cited by 1 publication

(1 citation statement)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…If superconducting joints must be used in regions (ii) or (iii), additional efforts must be made to achieve a lower R j . A recent study has shown that when I loop is close to I cj , R j is almost inversely proportional to the elapsed time and decreases with an increase in the pinning potential of a superconducting joint [49]. This may be effective for achieving a lower R j .…”

Section: Discussionmentioning

confidence: 99%

Angular dependence of resistance and critical current of a Bi-2223 superconducting joint

Takeda,

Nishijima,

Nakai

et al. 2023

Supercond. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

Low resistance and high critical current are prerequisites for superconducting joints used in persistent-mode magnets. Herein, we use a joint resistance evaluation system, previously developed by us, to systematically evaluate the angular dependence of resistance and critical current of a Bi-2223 superconducting joint in a closed-loop sample. The current decay is measured by rotating the sample incrementally. The time dependence of the loop current is evaluated at 4 K, 0.15–0.28 T, and magnetic field angles ranging from 90° to 0, wherein 90° corresponds to the direction parallel to the tape surface. The results suggest that the resistance and critical current of the joint depend on the angle of the magnetic field. The evaluated critical current increases as the angle increases. The angular dependence of resistance can be divided into three regions: low-resistance, transition, and high-resistance regions. The low-resistance region exists at high angles close to 90°. In this region, the decay of the loop current is small, and the persistent current continues to flow. Furthermore, the joint resistance is less than 1.4 × 10−13 Ω. In the transition region, the joint resistance significantly increases by three orders of magnitude with sample rotation. This significant increase is attributed to an increase in the perpendicular component of the magnetic field, which decreases the critical current of the joint. At lower angles, the joint resistance remains high, ranging from 10−11 to 10−10 Ω. A significant decay in the loop current is observed in the high-resistance region. Based on these findings, we conclude that the design of a persistent-mode magnet must consider not only the magnitude but also the direction of the magnetic field applied to superconducting joints.

show abstract

Section: Discussionmentioning

confidence: 99%