Electromagnetic Design of 1.5 T No-Insulation REBCO Coil System Charged by Multiflux Pumps for Dedicated MRI

This paper presents an electromagnetic design of a 1.5 T REBCO magnet for dedicated orthopedic magnetic resonance imaging (MRI). This design makes MRI portable as well as cheaper. Due to the application of no-insulation high temperature superconductor (HTS) technology, the magnet composed of double-pancake coils (DPC) is highly compact; its outer diameter and axial length are both less than 300 mm, diameter of room-temperature bore of the magnet is 200 mm. On the other hand, we used multiflux pumps to charge the DPCs separately to reduce tape consumption and costs of power sources. In our optimized magnet, four HTS flux pumps were designed to charge the MRI magnet, while the overall tape consumption was decreased by 29.7% compared to that charged by a single dc current source. This multiple dc current sources method avoids the current limiting effect of the DPCs located at the end of the magnet, which has the highest field normal to the surface of the 2G HTS wire. Moreover, by using the HTS flux pump, the current leads which cause heat leakage were eliminated, while the HTS magnet was operated in a persistent mode, with its decayed current been constantly fed by the HTS flux pump. Although the whole cost is not able to compete with LTS MRI, high-field portable MRI are in great demand.