Electric motors and actuators are most promising future applications of HTS bulks. The HTS bulks in these electric machines are exposed to AC magnetic field perturbations. The perturbations cause AC losses in the bulks and also affect the magnetic field trapped in the bulks. In a previous work we measured AC losses in a YBCO bulk subject to the AC magnetic field and found the loss characteristics well followed the Bean model. In this work we experimentally studied the influence of the AC perturbations of the external magnetic field on the trapped field in a YBCO bulk. The experimental results showed that the application of the AC magnetic field decreased the trapped magnetic field even to zero. In this paper, the experimental results are presented and a reason for the decay of the trapped magnetic field is discussed based on the Bean model.
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