HTS Vector Magnet for Magnetic Circular Dichroism Measurement

In this study, we developed a two-dimensional vector magnet with Y-Ba-Cu-O (YBCO) tape conductors for use in an X-ray magnetic circular dichroism measurement system. The characteristics of this high- T_c superconducting vector magnet are as follows: (a) it is a split magnet comprising four unit coils that enable an X-ray magnetic circular dichroism system to access the center sample space along three axes; (b) it is compact with a high magnetic field, and it exhibits a cone-shaped design to enable the split unit coils to come close together and to achieve a maximum magnetic field up to 1 T at the center; and (c) it is conduction-cooled by a cryocooler and a cryogen-free system. We fabricated four unit coils with YBCO tape conductors (manufactured by SuperPower Inc.). Two pairs of the unit coils were configured at right angles to each other in a cryostat and cooled below 30 K by the cryocooler. We confirmed that the magnetic field orientation can be controlled by adjusting the current of the unit coils. However, we observed hysteresis and drift of the magnetic field owing to the screening current induced in the YBCO tape conductors. Here, we design a high- T_c superconducting vector magnet and present its excitation test results.