No-insulation High-temperature Superconducting Coils Research Articles

Experimental Study on Low-Pass Filtering Characteristic of Axial Magnetic Field of No-Insulation and Partial-Insulation HTS Coils Carrying a DC-Biased AC Current

This paper deals with the low-pass filtering characteristic of the axial magnetic field of no-insulation and partial-insulation high temperature superconducting (HTS) coils carrying a dc-biased ac current. Recently, the no-insulation winding technique has been issued as a key technique to enhance the performance of HTS coils in terms of the overall current density, thermal stability, and mechanical integrity. In this paper, to verify the effect of time-varying external distortion on no-insulation HTS coils, an experimental analysis is carried on three HTS coils-insulation, no-insulation, and partial-insulation coils. To simulate the environment in which time-varying external distortion influences the HTS coils, a dc-biased ac current is carried by the HTS coils. The axial magnetic fields of no-insulation, partial insulation, and insulation HTS coils are experimentally tested and analyzed. When the coils carry a dc-biased ac current, the no-insulation and partial-insulation coils have a tendency to attenuate the high-frequency components and to act as a low-pass filter on the axial magnetic field; however, the insulation coil does not attenuate the high-frequency components of the axial magnetic field. The analysis of the experimental results can be useful data for the adoption of no-insulation and partial-insulation windings in superconducting applications.

No-insulation 기법을 적용한 소용량 고온 초전도 코일의 영구전류 특성에 관한 연구

This paper aims to evaluate the feasibility of using no-insulation High Temperature Superconducting (HTS) coil in persistent current mode system. A HTS coil in persistent current mode system usually includes one or more non-superconducting joints in its circuit. And the current decaying rate of the coil is affected by the resistance of joint in persistent current circuit. If the resistance of joint is large, decaying rate of the current drastically increases. Therefore, reducing the joint resistance of the HTS coil is very important in persistent current mode system. In this paper, the no-insulation HTS coil is suggested as a way to reduce the joint resistance with the embedded parallel contact resistance naturally made by no-insulation winding method. Two small coils are fabricated with insulation and no-insulation winding method, and persistent current mode system experiment of each coil is preformed and analyzed.