6.3 Levitation forces of HTS bulk above PMG Ë 157Tab. 6.2:Levitation forces of different arrays of four YBCO [25].
Gap/mm Levitation forces (N)
Array 1 Array 2 Array 3 Array 4
5 267.0 221.1 203.8 279.5
10 200.0 167.5 168.4 213.4
15 139.7 119.6 126.3 152.2
20 96.7 84.2 92.8 106.2
25 67.0 59.3 66.0 73.7
30 45.0 41.2 46.9 49.8
35 28.7 28.7 32.5 35.4
40 19.1 21.1 22.1 22.0With the increase of the levitation gap, more and more YBCO bulks were in a lower
magnetic field region, and the effective areas of the different arrays were approxima-
tely the same. At 5-mm gap, the effective area of array 4 was maximum, arrays 1 and
2 had smaller effect area, and array 3 had the smallest. Those effective areas were in
accordance with the levitation forces at a 5-mm gap, that is, the levitation force of array
4 was maximal. At 40-mm gap, the levitation forces were very close and consistent
with the almost same effective areas for different arrays.
6.3.3Levitation forces of seven-HTS bulks array [25]
The levitation forces of seven-block HTS YBCO over a PMG were investigated. The
melt-textured YBCO bulks were made in the Beijing General Research Institute for
Nonferrous Metals. The samples shared a diameter of 30 mm and a thickness of
14 mm. The YBCO bulks are arrayed in Fig. 6.4. In this measurement, the HTS YBCO
bulks were cooled into superconducting state in a zero magnetic field. The measure-
ment results for levitation forces of each YBCO sample and the total levitation forces
of a seven-block YBCO sample are shown in Figs. 6.5 and Fig. 6.6, respectively. The
levitation forces of each sample were similar to each other. The best measurement
results of total levitation forces of seven HTS YBCO bulks are shown in Fig. 6.7.
Fig. 6.4:Different array of multi-block YBCO HTS bulks [25].