Pulsed magnetization of HTS bulk parts atT<77 K

Abstract

Various pulsed magnetization experiments employing peak fields of up to 2 T and pulse durations of 30 ms and 3 ms were carried out on YBCO samples at temperatures between 20 and 80 K. Trapped magnetic flux profiles were recorded. The highest remanent magnetizations were obtained for a multi-pulse technique with step-wise cooling. The shape and the absolute values of the trapped flux profile are discussed in terms of the dynamics of such pulsed magnetization processes.

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

“…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. Therefore, many efforts have been devoted to overcome this problem and to increase the trapped field by the PFM method [7][8][9][10][11]. Fujishiro et al have achieved a record high trapped field of 5.2 T by PFM for a 46 mm diameter Gd-Ba-Cu-O bulk superconductor that was cooled by a cryogenic refrigerator, which is however still lower than the trapped field achieved by FC magnetization [11].…”

Theoretical simulation studies of pulsed field magnetisation of (RE)BCO bulk superconductors

“…The pulsed field magnetisation (PFM) technique has been applied to (RE)BCO bulk superconductors since 1996 [1,2], and is considered more suitable and convenient for in situ magnetisation of these materials compared to conventional techniques of static field magnetisation such as 'field cooling' (FC) and 'zero field cooling' (ZFC). Several multi-pulse magnetisation techniques have been developed since the late 1990s [3][4][5], where repeated pulses of lower intensity are applied to bulk HTS mainly in the temperature range 30-60 K in order to suppress the heat generation associated with rapid flux motion in the samples. A trapped field of 5.20 T was achieved in a GdBCO bulk at 30 K in 2006 [6], which is the highest trapped field by the PFM processes reported to-date.…”

Enhancement of total trapped fluxes on φ65mm GdBaCuO bulk by multi-pulse techniques

“…The trapped field B T P by PFM was, however, pretty smaller than the trapped field B T FC attained by FCM below 77 K because of the large temperature rise caused by the dynamical motion of magnetic fluxes in the bulk. Several approaches have been performed and succeeded to enhance B T P around 77 K such as an iteratively magnetizing pulsed-field method with reducing amplitude (IMRA) [3] and a multi-pulse technique with stepwise cooling (MPSC) [4]. We have systematically studied the time and spatial dependences of the temperature T(t, x), the local field B L (t) and the trapped field B T P on the surface of cryo-cooled REBaCuO bulks [5].…”