Experimental study on quench current of superconducting coils for 50-60 Hz use

The quench current of a superconducting coil wound with a multifilamentary superconducting wire for 50-60 Hz use was measured for various frequencies by using a variable-voltage variable-frequency power supply composed of a cycloconverter or an inverter circuit to investigate characteristics of the superconducting AC coil and solve the current degradation problem. The test coil was wound by using wire containing no copper. Because of the instability of the wire, the effect of wire motion was observed, and quench current of the coil varied significantly. Generally, superconducting wires for AC use are unstable because the copper content of the wire is lower than for wires for DC or pulse use. From experimental results, it has become clear that a fixing method for wires to a bobbin keeping a good cooling condition is the key to solving the current degradation problem.<
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