Research On Micro Magnetic Flux Pump For High Temperature Superconducting Magnet

High temperature superconductors (HTS) have been found for many years, but the intrinsic property of low n-index value result in high dissipation of current in closed loop. And applicable superconducting joint has not been realized. So HTS is hard to work in persistent mode, which is one of the biggest obstacles for widely usage of HTS. This thesis works against this obstacle. According to the development of magnetic flux pump (MFP) at home and abroad, the research on the pumping performance of a newly developed pulse MFP is performed. The research aims to improving the magnetic field stability of HTS magnets.This thesis introduces the structure and operational principle of the pulse MFP. One-ring superconducting loads made of Bi-2223and MgB2are made. Four different pulse waves are added to original MFP control system, and the pumping performance of each pulse wave is investigated. The magnetic field distribution of each pulse wave is measured under room temperature. MFPs that have7poles and4poles are constructed, and magnetic yoke made of si-steel and amorphous steel are also constructed. The control circuit of MFP based on C8051F350single-chip and the drive circuit based on MJE3055T transistor are studied. The program of single-chip and the corresponding PC program are written. And the programs work well.The pumping performance of each MFP is investigated. The saturation pumping currents on Bi-2223load and MgB2load are129A and43A respectively. The inductance of both load is1μH. The MFPs can pump current bidirectionally. The calculating result shows that the current ripple of the MFP is2.3×105for a1.3mH load at100Aloop current. So the conclusion is that this new pulse MFP can compensate current decay to superconducting load and that this new MFP is promising to be used and bidirectional current supply.