6.7 Guidance forces of HTS bulks over PMG Ë 169
epoxy bulk had the same geometry as the HTS bulk, the position of each HTS bulk
was kept the same in every measurement so that the measured results of the additive
(epoxy bulks) method could be reasonably compared with that of the direct method.
The guidance forces of each HTS bulk in array 1 are drawn as a function of lateral
displacement in Fig. 6.20a–d [34]. Figure 6.20e shows the results of the additive
(epoxy bulks) method and the direct method. With respect to each lateral displace-
ment of the PMG where the guidance forces are sampled, we subtract GFadditivefrom
GFdirectand the difference, denoted by d, is shown as a function of lateral displacement
in the inset of Fig. 6.20e.
6.7.2Guidance forces of YBCO bulks over two parallel PMG [31]
In order to test the guidance forces over the two parallel PM guideway, Wang et al. [31]
designed and produced another special test apparatus. It was the special apparatus
composed of two cryogenic vessels over two parallel PMGs. This test apparatus was
equivalent to the frame of a quarter of the “Century” vehicle on the PMG. It could hold
two onboard HTS Maglev equipments (see Section 6.16) in this framework.
A sketch of the apparatus measuring guidance forces is shown in Fig. 6.21 [31]. The
guidance forces of the YBCO bulk over the PMG were measured using the measuring
equipment of the guidance forces for the entire HTS Maglev vehicle (see Section 5.4).
Here, the measuring equipment of the guidance forces was split into two parts, and
they were placed on both sides of the PMG. The bottom center of the liquid nitrogen
vessel was aligned to the center line along the PMG length. During the experiment,
the onboard HTS Maglev equipments were moving component relative to the PMG,
and the guiding force was measured directly.
The guidance forces (lateral forces returning to the initial position) depend on the
field-cooling height (FCH). Guidance forces for a single YBCO bulk over two parallel
PMG were measured by the guidance force test apparatus (Fig. 6.21) in two FCH cases.
Fig. 6.21:Schematic diagram and photograph of guidance force test apparatus of YBCO arrays
on two parallel PM guideways [31]. (1) Horizontal propulsion arm. (2) Force transducer. (3) Liquid
nitrogen vessel. (4) Rigid link. (5) HTS arrays. (6) PMG.