Time evolution and spatial distribution of temperature in YBCO bulk superconductor after pulse field magnetizing

Abstract

The time evolutions of temperature rise T (t) after pulse field magnetizing have been measured on the surface of a cryo-cooled YBaCuO bulk superconductor. The temperature rise T increases with increasing pulse field strength, and a quite large temperature rise (T max ∼ 18.8 K) is observed just before the trapped magnetic flux reaches the central region of the bulk. The epoxy resin, impregnated and coated to the bulk crystal for mechanical reinforcement, prevents the heat exhaust towards the cold stage of the refrigerator and it needs much time to recover its initial temperature. The spatial distribution of T (t) has indicated that the magnetic fluxes tend to enter into the bulk, avoiding the 4-fold growth sector boundaries of the bulk crystal.

Modelling and comparison of trapped fields in (RE)BCO bulk superconductors for activation using pulsed field magnetization

“…The field required to fully magnetise the bulk sample will be hereafter referred to as the 'activation field' (for example, the activation field in Figure 7 is around 3.4 T). There is no significant increase in trapped field for larger applied fields than the activation field, and, in fact, the trapped field begins to reduce for a sufficiently large field due to the temperature rise in the bulk generated by the rapid movement of flux lines in the sample interior [11].…”

Simulation and experiments of stacks of high temperature superconducting coated conductors magnetized by pulsed field magnetization with multi-pulse technique

“…However, the trapped field obtained by PFM is generally lower than that by FC or ZFC, especially at lower temperatures [10]. This is due to the fast flux motions during PFM which generate substantial heat and increase the temperature [11] [12]. Effort has been devoted to optimize the PFM process to improve the trapped field, which can be found in the recent review [10].…”

Local measurements of the magnetization process of bulk superconductors induced by a pulsed magnetic field

“…From application perspective, pulse field magnetization (PFM) is more feasible because a large current has to be fed only for a very short time and the magnetizing coil can be made small [2; 3]. PFM is, however, less effective than the FC method because of the heat that is generated by the dissipative motion of flux lines [2][3][4][5][6]. Most significantly, the difference in the trapped field with the FC method tends to escalate when the ability of trapping flux lines increases by improving the material characteristic or by decreasing the temperature.…”