A trapped magnetic field of greater than 3 T has been achieved in a single grain GdBa$_2$Cu$_3$O$_{7-}$$_delta$ (GdBaCuO) bulk superconductor of diameter 30 mm by employing pulsed field magnetization. The magnet system is portable and operates at temperatures between 50 K and 60 K. Flux jump behaviour was observed consistently during magnetization when the applied pulsed field, $B_a$, exceeded a critical value (e.g., 3.78 T at 60 K). A sharp d$B_a$/d$t$ is essential to this phenomenon. This flux jump behaviour enables the magnetic flux to penetrate fully to the centre of the bulk superconductor, resulting in full magnetization of the sample without requiring an applied field as large as that predicted by the Bean model. We show that this flux jump behaviour can occur over a wide range of fields and temperatures, and that it can be exploited in a practical quasi-permanent magnet system.
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机译：通过使用脉冲场，在直径为30 mm的单晶粒GdBa $ _2 $ Cu $ _3 $ O $ _ {7-} $$ _ delta $（GdBaCuO）块状超导体中实现了大于3 T的俘获磁场磁化。该磁体系统是便携式的并且在50 K和60 K之间的温度下运行。当施加的脉冲磁场$ B_a $超过临界值（例如60 K下的3.78 T）时，在磁化过程中始终观察到磁通跳跃行为。急剧的d $ B_a $ / d $ t $对于这种现象至关重要。这种通量跳跃行为使磁通量可以完全渗透到块状超导体的中心，从而使样品完全磁化，而无需像Bean模型所预测的那样大的施加磁场。我们证明了这种磁通跳跃行为可以在很宽的磁场和温度范围内发生，并且可以在实际的准永磁系统中加以利用。
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