154 Ë 6 First manned HTS Maglev vehicle in the world
“National 863 Program Strategy Development Report (Superconducting Materials
and Technology)” pointed out: China had developed the manned HTS Maglev system
technology, and it had expanded the possibility to cross over the development of HTS
Maglev technology. HTS Maglev system technology had bright Chinese characteristic.
This Maglev technology was a new transport vehicle which will have high energy
efficiency, environment-friendly, safe, and comfortable.
6.3 Levitation forces of HTS bulk above PMG
6.3.1Levitation forces of single HTS bulk above PMG
A HTS Maglev measurement system was developed (see Section 5.3) in order to realize
the real-time, high-precise measurement of HTS Maglev performance and to develop
the manned HTS Maglev vehicle. This measurement system (Fig. 5.7) is different from
the previous one, i.e. measuring the levitation forces of HTS bulk over PMG (see
Section 5.2.1). Thus, a special thin-bottom liquid nitrogen vessel [23] (see Section
5.2.2) was needed. The outside and inside diameters of the thin-bottom liquid nitrogen
vessel were 200 and 150 mm, and the height was 250 mm. The liquid nitrogen vessel
can operate continuously for over 16 hours and can hold a 7-YBLO-bulks unit, where
each bulk shares the 30-mm diameter. The PMG was composed of NdFeB PMs and an
iron plate whose function is concentrating field in the center of the surface was up to
1.2 and 0.4 T at a height of 20 mm above it. The length of the PMG was 920 mm.
A series of the magnetic levitation properties, for example, levitation force, gui-
dance force, levitation stiffness, trapping flux, and influence of HTS bulk shape, thick-
ness, etc., of the HTS YBCO bulk above PMG have been systematically investigated by
this HTS Maglev measurement system SCML-01. These research will be presented in
this chapter.
The levitation forces of a HTS YBCO bulk over the PMG was measured by the
SCML-01 HTS Maglev measurement system (see Section 5.3). In our measurement,
the measured YBCO bulks were fixed at the bottom of the thin-bottom liquid nitrogen
vessel, then they were cooled into the superconducting state in zero magnetic field.
Second, the vessel was fixed at a connecting fixture with a servo electromotor. In order
to avoid collision between the bottom of the vessel and the surface of the PMG, there
was still a gap of 1.5 mm between them when the vessel moved to the closest position,
so the minimum gap was 5 mm between the bottom of the HTS bulk sample and the
surface of the PMG. The vessel first moved downward, after reaching the lowest point
of 1.5 mm, then moved upward at a speed of 2 mm/s, and the computer collected data
every 0.5 second.
First, we measured the levitation forces of the HTS YBCO bulk over the single-
NdFeB PM and the PMG. Figure 6.1 shows the measured results of the levitation
forces over the NdFeB PMG (its surface magnetic flux density was 1.2 T) and over the