182 Ë 6 First manned HTS Maglev vehicle in the world
Fig. 6.37:Levitation forces comparison of YBCO bulk with different hollow holes [43]. (a) A hole with
8 mm in diameter. (b) A hole with 12 mm in diameter. (c) A hole with 18 mm in diameter.
Fig. 6.38:Guidance forces vs. lateral displacement with different holes in FCH 5 mm (left) and 10 mm
(right) [43].
than the inner part. In some cases, we can substitute a cylindrical YBCO bulk with
a ring-shaped YBCO bulk in order to achieve a lightweight Maglev system.
While the hole did not cause much difference in the levitation forces, it had much
more influence on the guidance forces. When the hole was small enough, i.e. a hole
with diameter of 4 mm, the influence on guidance forces was not clear. As the diameter
of the hole increased, the guidance forces decreased rapidly (Fig. 6.38).
The reason was that the guidance forces originates from the interaction between
trapped flux and applied field. The trapped flux depended on the pinning centers. As
the hole enlarged, the number of pinning center decreased, which resulted in smaller
trapped flux and led to a smaller guidance force.
6.11 Early scheme consideration
Both rare-earth materials yttrium (Y) and neodymium (Nd) are used in a HTS bulk
Maglev system, and these resources are abundant in China. After the HTS magnetic