210 Ë 6 First manned HTS Maglev vehicle in the world
6.20 Long-term stability of YBCO bulks in 2001–2009 [63]
In order to evaluate the long-term stability of the single HTS bulks for practical
application, the levitation performance of single bulk YBCO samples were investigated
with the SCML-02.
The 43 YBCO bulk pieces were packaged in the No. 6 on-board HTS Maglev
equipment in “Century” in 2000. The YBCO bulk samples were not opened, but they
were measured independently in separate tests while running for nine years. After
opening the seal cover and removing the YBCO bulks, the levitation forces of each
YBCO bulk were measured in 2009. These YBCO samples were signed A 15 , B 14 , and
C 14 , and included 15 pieces over the center of the PMG and 14 pieces over both sides
of the center of the PMG. Table 6.18 lists the average values of measurements for A 15 ,
B 14 , and C 14 of 45 YBCO bulks.
From the test results, the average levitation forces of the three groups, A 15 , B 14 , and
C 14 YBCO bulk, were close. The A 15 group was slightly higher than that of the other two
groups. The better YBCO bulks in the same batch were located in the strong magnetic
field at the PMG center line in 2000. This was consistent with the measured results.
This showed that, after the long-term operation in about 9 years, the performance of
A 15 group bulk were not degraded at the work environment of the high magnetic field.
The single piece of A5 YBCO bulk over the center of the PMG had the maximum
levitation force. The YBCO bulk 07-1 was produced in 2007, and old-1 was an old YBCO
bulk produced in 2001 and not loaded for operation. Table 6.19 lists the comparison of
long-term stability of single YBCO bulk. It shows that the maximum levitation forces
of the A5 bulk and the old-1 bulk sample at a gap of 10 mm were very close. However,
the levitation force of the A5 bulk and the old-1 bulk were higher than the 07-1 bulk.
This was due to the smaller thickness of the 07-1 bulk.
Tab. 6.18:Average values of A 15 , B 14 , and C 14 [63].
A 15 B 14 C 14Average levitation forces (N) 30.95 29.10 28.54
Maximum levitation forceFmax(N) 33.59 31.9 30.2
Piece number ofFmax A5 B1 C4
Tab. 6.19:Comparison of long-term stability of single YBCO bulk [63].
A5 07-1 Old-1Diameter (mm) 31 31 30
Thickness (mm) 17.5 13 18.5
Fmax(N) 33.59 28.5 33.25
Levitation forces of unit volume (N/mm^3 ) 2.544× 10 −^3 2.906× 10 −^3 2.544× 10 −^3