Earticle

Superconductivity has the characteristics of zero resistance, where electricity flows without resistance, and perfect diamagnetism, where magnetic fields are repelled. Zero resistance increases the efficiency of power management technologies such as power transmission, high-magnetic field superconducting magnets, and current limiters, etc. These devices are manufactured by winding superconducting wires in the shape of a solenoid. The perfect diamagnetism can be utilized in contactless bearings, high-efficiency energy storage, and magnetic levitation transportation, etc. The superconductors of a bulk form are used in these devices. In addition, high-temperature superconductors, which are type II superconductors, can trap large magnetic fields inside the superconductor. This characteristic can be utilized to manufacture high-magnetic bulk magnets. Superconducting bulk magnets can be used as portable magnets, wastewater purification magnets, and bioanalysis magnets. This review describes the fabrication process and bulk applications of YBCO superconductors suitable for magnetic levitation and superconducting bulk magnets.

This study explores the enhancement of magnetic field homogeneity in Nuclear Magnetic Resonance (NMR) magnets through optimized ferromagnetic shimming design. Traditional shimming techniques, which involve attaching ferromagnetic materials to the magnet bore, often lack manufacturability considerations, limiting their effectiveness in real-world applications. To address this, we employ a topology optimization (TO) approach using the Solid Isotropic Material with Penalization (SIMP) scheme for design parametrization. The proposed optimization framework includes volume and perimeter constraints to improve the practical manufacturability of the shim. Numerical analysis demonstrates that the TO-based design method achieves superior magnetic field homogeneity, achieving 0.45 ppm with integer thickness shims, compared to conventional designs. This approach also effectively reduces manufacturing complexity by minimizing design sensitivity to the thickness and placement of individual shimming elements. The proposed design framework is broadly applicable to superconducting magnets in NMR and MRI systems, where high magnetic field homogeneity is essential. This study presents a significant advancement in ferromagnetic shimming technology, offering a viable solution for enhancing the performance and manufacturability of high-precision magnetic field devices.

The superconducting accelerator's liquid or superfluid helium cryogenic system requires numerous temperature sensors to precisely monitor key components and ensure the device's safe and stable operation. Uncalibrated temperature sensors are widely used in large scientific facilities owing to their low cost and short supply cycles. This study developed a temperature sensor calibration system suitable for the superfluid helium temperature region. This system combines the comparison method and dynamic calibration while optimizing the calibration approach for different temperature ranges. A total of 20 uncalibrated temperature sensors were calibrated over a temperature range of 300 K to 2 K. Experimental results show that the system can simultaneously calibrate numerous temperature sensors, significantly improving calibration efficiency. In the 4.2 K-2 K temperature region, the calibration accuracy is ±6.035 mK, which meets the engineering application requirements of large scientific facilities.