Design of a superconducting magnet system using a cryogenic magnetic coupler for contactless current charging
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General-purpose electromagnets are widely used to measure and analyze the magnetic properties of various materials. The performance of these electromagnets depends mainly on the magnitude and uniformity of the magnetic field. As the allowable current density of copper wires, which are generally used in these electromagnets, does not exceed 5 A/mm2 at room temperature, it is difficult to generate a high magnetic field, and water-cooling is required to mitigate the temperature rise at higher current densities. High-temperature superconductors (HTSs) have significantly higher current-carrying capacity than copper; thus, general-purpose electro-magnets based on HTS coils can generate higher magnetic fields and are more compact than conventional electromagnets that use copper coils. However, given that the use of a superconducting joint is not feasible in an HTS coil, it should always be physically connected to an external power source at room temperature for current charging. This places a large thermal load on the cryogenic cooling system for the HTS coil, which may decrease the operating stability of the coil over time. This study proposes a general-purpose HTS electromagnet based on a contactless current-charging method. The proposed electromagnet is composed of a ferromag-netic iron yoke, HTS coils, cryogenic cooling system, and contactless charging system. The HTS electromagnet was designed and analyzed using finite element analysis coupled with electrical circuit analysis. The HTS electromagnet offers better field performance than a conventional general-purpose electromagnet even though it is only half the weight of the latter. We expect that the proposed HTS electromagnet can be applied in fields that require excellent magnetic field performance but also have size limitations.
Abstract
General-purpose electromagnets are widely used to measure and analyze the magnetic properties of various materials. The performance of these electromagnets depends mainly on the magnitude and uniformity of the magnetic field. As the allowable current density of copper wires, which are generally used in these electromagnets, does not exceed 5 A/mm2 at room temperature, it is difficult to generate a high magnetic field, and water-cooling is required to mitigate the temperature rise at higher current densities. High-temperature superconductors (HTSs) have significantly higher current-carrying capacity than copper; thus, general-purpose electro-magnets based on HTS coils can generate higher magnetic fields and are more compact than conventional electromagnets that use copper coils. However, given that the use of a superconducting joint is not feasible in an HTS coil, it should always be physically connected to an external power source at room temperature for current charging. This places a large thermal load on the cryogenic cooling system for the HTS coil, which may decrease the operating stability of the coil over time. This study proposes a general-purpose HTS electromagnet based on a contactless current-charging method. The proposed electromagnet is composed of a ferromag-netic iron yoke, HTS coils, cryogenic cooling system, and contactless charging system. The HTS electromagnet was designed and analyzed using finite element analysis coupled with electrical circuit analysis. The HTS electromagnet offers better field performance than a conventional general-purpose electromagnet even though it is only half the weight of the latter. We expect that the proposed HTS electromagnet can be applied in fields that require excellent magnetic field performance but also have size limitations.
참고문헌 (19)
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