Characteristics of Magnets Depending on the Width of High Temperature Superconducting Tapes Applied to the Outer Pancake Windings

In a High Temperature Superconducting (HTS) magnet consisting of pancake windings, HTS tape with the same width has been used for all pancake windings. If a wider HTS tape is used for the outer pancake windings, the critical current of the HTS magnet can be increased. This paper shows the properties of BSCCO magnets in which the outer pancake windings are wound with a wider HTS tape. In order to examine the effects of a wider HTS tape, a HTS magnet with an inner radius of 20 mm and a height of 202.4 mm was used. The number of turns of each pancake winding was 150, and the number of pancake windings was 46. The critical current of the pancake winding was determined by using E-J relation. Results of calculation show that the critical current was higher in the HTS magnet with a wider HTS tape at the outer pancake windings than in the HTS magnet with the same width of HTS tape for all pancake windings.

I. Introduction

The number of devices demanding high magnetic fields is on a constant increase along with the industrial development. Some examples of such devices are as follows: Nuclear Magnetic Resonance (NMR) (used for the analysis of compounds), Magnetic Resonance Imaging (MRI) (used for medical diagnosis), magnetic separator (used to separate metals or impurities), magnetic refrigerator (used for refrigeration)[1]–[4].