Measuring the Output Voltage of a Linear-Motor Type Flux Pump With an Insulated HTS Coil

High-temperature superconducting (HTS) flux pump can supply DC current into the superconducting magnet coil in a contactless manner. The flux pump works similarly as a DC power supply, with low output voltage and high output current. In this paper, based on the linear-motor type flux pump previously introduced from our laboratory (W. Wang et al. 2018), we miniaturized it and measured its the output DC voltage. By using different peak values and frequencies of the applied AC travelling magnetic wave, we obtained the pumping characteristics of this linear-motor type flux pump. With the same applied magnetic strength, it was found that the pumped current is not directly proportional to the frequency, we interpret that the critical current of the HTS stator was likely deteriorated by the heat generated in the stator due to high magnetic field amplitude and frequency. From the pumping current curve, a voltage-current relationship of the HTS flux pump was obtained. This method mentioned in this paper can directly derive the output voltage of the HTS flux pump, and could also be applicable for all other types of flux pumps. The method helps further optimizing HTS flux pumps which will be applied in the dedicated MRI and the brushless superconducting motor under developing.