Investigations on a Passive Real-Time Magnetic Flux Density Amplifier Made From Eight-Shaped HTS Loops

Abstract

The superconducting devices made by high temperature superconducting (HTS) tapes attract great significance in high magnetic fields and at low temperature. A configuration of the magnetic flux density amplifier (MFDA) composed of rare earth-Ba-Cu-O (REBCO) HTS tapes with one central slit and twisted to form an “eight-shaped” loop with two different sizes of “closed-loops” is reported by our group in recent years. However, it can only achieve the fixed amplified function of magnetic flux density. This article proposes a passive dynamic MFDA made by the same HTS tape as an “eight-shaped” loop, which abides by the principle of flux conservation. An experimental setup is established to investigate the real-time amplification of magnetic flux density, and numerical method is used to simulate the process of dynamic magnetic flux density. Five kinds of multipulse excitation amplitudes are utilized in the experiment and a real-time process of magnetic flux density is displayed within a period. The feasibility of amplified magnetic flux density in the HTS loop is separately verified by experiment and simulation in 77 K. In order to improve the accuracy of ac loss calculation, analytical method and finite element method are compared with each other. Temperature distribution of the real-time MFDA is obtained and thermal stability is also analyzed by comparing the effects of different transmission currents and frequencies to the HTS loop. The results show that REBCO loops achieve the real-time amplified function of magnetic flux density and it has the ability of passive long-term stable operation, which is potential for sensor of flux density.