Trapped Field Profiles on Square GdBaCuO Bulks with Different Arrangement of Growth Sector Boundaries

Mochizuki

Ainslie

et al. 2016

MgB 2 superconducting bulks have promising potential as trapped field magnets. We have achieved a trapped field of B z =1.1 T on a high-J c MgB 2 bulk at 13 K without flux jumps by pulsed field magnetization (PFM) using a split-type coil with a soft iron yoke, which is a recordhigh trapped field by PFM for bulk MgB 2 to date. The flux jumps, which frequently took place using a solenoid-type coil during PFM, were avoided by using the split-type coil, and the B z value was enhanced by the insertion of soft iron yoke. The flux dynamics and heat generation/ propagation were analyzed during PFM using a numerical simulation, in which the magnetic flux intruded and attenuated slowly in the bulk and tended to align along the axial direction due to the presence of soft iron yoke. The advantages of the split-type coil and the simultaneous use of a soft iron yoke are discussed.

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Trapped field of 1.1 T without flux jumps in an MgB₂bulk during pulsed field magnetization using a split coil with a soft iron yoke

Mochizuki

Ainslie

et al. 2016

“…T s J c0 (A/m 2 ) B 0 (T) a in eqn (5) α (A/m 2 ) in eqn (6) Bulk-A 10 K × 6.01 10 9 1.50 1.50 × 6.70 10 9 20 K × 4.31 10 9 1.05 1.50 Bulk-B 10 K × 2.36 10 9 1.30 1.40 × 2.70 10 9 20 K × 1.71 10 9 0.95 1.50 position z r ( , ) and at any temperature T s using the simulation. figure 2.…”

Section: Bulkmentioning

confidence: 99%

Numerical simulation of the trapped field in MgB₂bulk disks magnetized by field cooling

Naito

Yoshida

2014

Self Cite

We performed a numerical simulation of the trapped field properties of MgB 2 bulk disks with different superconducting characteristics magnetized by field cooling. The temperature dependence of the trapped field B T () z , and the time dependence of the local field B t () z and temperature T (t) were calculated, and compared with experimental results. Since the measured critical current density J T B (,) c was used in the simulation, the results of the simulation reproduce the experimental results well. These results suggest that the value of B z and the trapped field profile can be estimated precisely for bulks of any shape and under any conditions, such as the operating temperature and applied field, using the measured J T B (,) c characteristics. The diameter and thickness dependence of B z was also calculated.

“…Giunchi [13] developed MgB 2 bulks using the reactive Mg-liquid infiltration (Mg-RLI) technique, which is preferable to fabricate dense and large MgB 2 bulk with any form, such as disks, cylinders, rings and so on, where the maximum B z value was about 1.3 T at 15 K by FCM on the MgB 2 bulk with 55 mm diameter and 15 mm thickness at the center hole of 6 mm. We magnetized the Mg-RLI MgB 2 bulk by PFM and measured the trapped field profile 1 mm above the bulk surface, where the precise trapped field inhomogeneity can be measured [14,15]. However, the trapped field profile on the MgB 2 polycrystalline bulk magnetized by PFM is not necessarily concentric circled, even though the profile by FCM is nearly conical shaped.…”

Section: Introductionmentioning

confidence: 99%

Trapped field properties of a concentric-circled MgB₂bulk composite magnetized by pulsed field and field cooling

Mochizuki

Naito

et al. 2015

We investigated the trapped field properties of the concentric-circled MgB 2 bulk composite disk by pulsed field magnetization (PFM), which consists of 36 MgB 2 thin rings for both surfaces of the disk and a small MgB 2 central cylinder in the stainless steel disk. MgB 2 parts were fabricated by a reactive Mg-liquid infiltration (Mg-RLI) method. The trapped field profile just above the composite surface was very concentric circled, which suggested that the superconducting current flows along the azimuthal direction in the MgB 2 rings and the cylinder independently, even though the magnetic flux dynamically moves in the composite during PFM. The trapped field properties by PFM were reproduced qualitatively by the numerical simulation using the critical current density J c (B) of the MgB 2 parts estimated by the trapped field B z by the field-cooled magnetization (FCM). The composite disk is a promising candidate to realize the MgB 2 bulk magnet with concentric-circled trapped field distribution magnetized by PFM.