Presentation Information
[WBP2-07]Trapping, shielding, and focusing properties of the magnetic field in large MgB2 ring-bulk superconductors prepared by a premix-infiltration method
Shuta Abe1, *Tomoyuki Naito1 (1. Iwate University (Japan))
Keywords:
MgB2,Trapped Field,Magnetic Shielding,Focusing Field
[Purpose]
We are now attempting to achieve a high magnetic field in the bore of the MgB2 ring-bulks by combining the MgB2 bulk magnet and MgB2 magnetic lens. In this paper, we report the trapping, shielding, and focusing properties of the magnetic field for the large MgB2 ring-bulk superconductors.
[Method]
MgB2 ring-bulks were prepared from the B with 10-50mol%MgB2 and Mg precursor pellets by the infiltration method; the premixed MgB2 can suppress the cracking in the MgB2 bulk.Trapped field was measured by the Hall probes at various temperatures after the field-cooled magnetization. The magnetic shielding and focusing effects were also evaluated by the Hall probe method in the zero-field cooling mode.
[Results]
We successfully fabricated reproducibly the large MgB2 ring-bulks with 60 mm outer diameter, 40 mm inner diameter, and 10 mm thickness. The trapped field of 1.3 T at 20 K was obtained at the center of the bore by the field-cooled magnetization from the applied magnetic field, Happ, of 2 T. On the other hand, in the zero-field cooling mode, the external magnetic field of 1 T was reduced to approximately 0.1 T at the same temperature and position by the shielding effect. After the evaluation of the trapping and shielding properties, we made a single slit in the MgB2 ring-bulk by machining. The applied magnetic field of 1 T was enhanced to about 1.2 T at 20 K by the lens effect; however, the flux jumps occurred at Happ=1.2 T.
[Consideration]
The present magnetic properties of the MgB2 ring-bulks were superior to those reported previously. This originated from the high quality of the present MgB2 ring-bulks. A more precise discussion will be performed with the critical current density properties and the microstructural analysis in the presentation; the evaluation of these properties is now in progress.
[Conclusion]We successfully fabricated reproducibly the large MgB2 ring-bulks, and the good three magnetic properties were achieved for the identical MgB2bulk. Therefore, we can achieve a high magnetic field in the bore of the MgB2 ring-bulks by combining the MgB2 bulk magnet and MgB2 magnetic lens.
We are now attempting to achieve a high magnetic field in the bore of the MgB2 ring-bulks by combining the MgB2 bulk magnet and MgB2 magnetic lens. In this paper, we report the trapping, shielding, and focusing properties of the magnetic field for the large MgB2 ring-bulk superconductors.
[Method]
MgB2 ring-bulks were prepared from the B with 10-50mol%MgB2 and Mg precursor pellets by the infiltration method; the premixed MgB2 can suppress the cracking in the MgB2 bulk.Trapped field was measured by the Hall probes at various temperatures after the field-cooled magnetization. The magnetic shielding and focusing effects were also evaluated by the Hall probe method in the zero-field cooling mode.
[Results]
We successfully fabricated reproducibly the large MgB2 ring-bulks with 60 mm outer diameter, 40 mm inner diameter, and 10 mm thickness. The trapped field of 1.3 T at 20 K was obtained at the center of the bore by the field-cooled magnetization from the applied magnetic field, Happ, of 2 T. On the other hand, in the zero-field cooling mode, the external magnetic field of 1 T was reduced to approximately 0.1 T at the same temperature and position by the shielding effect. After the evaluation of the trapping and shielding properties, we made a single slit in the MgB2 ring-bulk by machining. The applied magnetic field of 1 T was enhanced to about 1.2 T at 20 K by the lens effect; however, the flux jumps occurred at Happ=1.2 T.
[Consideration]
The present magnetic properties of the MgB2 ring-bulks were superior to those reported previously. This originated from the high quality of the present MgB2 ring-bulks. A more precise discussion will be performed with the critical current density properties and the microstructural analysis in the presentation; the evaluation of these properties is now in progress.
[Conclusion]We successfully fabricated reproducibly the large MgB2 ring-bulks, and the good three magnetic properties were achieved for the identical MgB2bulk. Therefore, we can achieve a high magnetic field in the bore of the MgB2 ring-bulks by combining the MgB2 bulk magnet and MgB2 magnetic lens.