[AP8] Magnet science and technology 2

4:16 PM - 4:31 PM JST(7:16 AM - 7:31 AM UTC)

[AP8-07] Study on a Stationary Metamagnetic AMR System Using AC Superconducting Magnet

*Haruumi Yamamoto¹, Daiki Kobayashi¹, Kyohei Natsume¹, Koji Kamiya¹ (1. National Institute for Materials Science (Japan))

Keywords:

Magnetic Refrigeration,Superconducting Magnet,AC Loss

Magnetic refrigeration is a cooling technology that utilizes the magnetocaloric effect, in which a change in the magnetic field applied to a magnetic material induces a temperature change. Compared with gas-based refrigeration, it offers higher theoretical efficiency and fewer restrictions related to refrigerant gases. Active Magnetic Refrigeration (AMR) employs magnetic materials as both regenerator and refrigerant to cover a wide temperature range. However, the requirement of a large magnetic field variation exceeding 1 T and the necessity of stacking multiple materials to broaden the operating temperature range remain significant challenges toward practical implementation. Most magnetic refrigeration systems currently realize field variation by mechanically moving the magnetic material [1]. From a system perspective, however, it is more desirable to keep the material stationary and vary the field using superconducting magnets. Yet, conventional AMR typically requires fields of ~5 T, and varying 0–5 T at ~0.1 Hz would cause severe AC losses, making this approach impractical.In this study, we focus on metamagnetic materials, which, compared with conventional ferromagnets, exhibit a large magnetocaloric effect with a small change in magnetic field and whose transition field strongly depends on temperature. As illustrated in Figure 1, we designed a stationary magnetic refrigeration system composed of an AC superconducting magnet to generate the alternating magnetic field required for the cycle, a DC superconducting magnet to control the operating temperature range, and the magnetic refrigerant. Therefore, we propose a stationary magnetic refrigeration system employing metamagnetic materials, which can exhibit a large magnetocaloric effect even under a field variation of only about 1 T.We constructed a numerical simulation model of metamagnetic refrigeration and evaluated the cooling capacity. The results will be reported, along with discussions on the AC losses caused by alternating fields and the possibility of expanding the operating temperature range by applying a DC gradient magnetic field.