U.S. patent application number 15/069086 was filed with the patent office on 2016-09-15 for superconducting power transmission system.
This patent application is currently assigned to CHUBU UNIVERSITY EDUCATIONAL FOUNDATION. The applicant listed for this patent is CHUBU UNIVERSITY EDUCATIONAL FOUNDATION. Invention is credited to Hirofumi Watanabe, Sataro YAMAGUCHI.
Application Number | 20160265839 15/069086 |
Document ID | / |
Family ID | 45810803 |
Filed Date | 2016-09-15 |
United States Patent
Application |
20160265839 |
Kind Code |
A1 |
YAMAGUCHI; Sataro ; et
al. |
September 15, 2016 |
SUPERCONDUCTING POWER TRANSMISSION SYSTEM
Abstract
In a thermally insulated double pipe, a structure is provided in
which an inner pipe may be prevented from being appreciably offset
relative to an outer pipe due to thermal contraction. The structure
includes an inner pipe 101, within which a superconducting cable is
mounted, an outer pipe 103 within which the inner pipe is housed,
with the inner and outer pipes constituting a thermally insulated
double pipe, and an inner pipe support member 104 supporting the
inner pipe. The inner pipe support member 104 is secured to the
inner and outer pipes.
Inventors: |
YAMAGUCHI; Sataro; (Aichi,
JP) ; Watanabe; Hirofumi; (Aichi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CHUBU UNIVERSITY EDUCATIONAL FOUNDATION |
Kasugai-shi |
|
JP |
|
|
Assignee: |
CHUBU UNIVERSITY EDUCATIONAL
FOUNDATION
Kasugai-shi
JP
|
Family ID: |
45810803 |
Appl. No.: |
15/069086 |
Filed: |
March 14, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13821277 |
May 24, 2013 |
9318242 |
|
|
PCT/JP2011/070663 |
Sep 5, 2011 |
|
|
|
15069086 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y02E 40/60 20130101;
H01B 12/00 20130101; H02G 15/34 20130101; F25J 1/0022 20130101;
H01B 12/16 20130101 |
International
Class: |
F25J 1/00 20060101
F25J001/00; H01B 12/16 20060101 H01B012/16 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 7, 2010 |
JP |
2010-200333 |
Claims
1. A method for evacuation to vacuum for a thermally insulated
double pipe, comprising: introducing a pre-set sort of gas into a
region defined between an inner pipe and an outer pipe composing a
thermally insulated double pipe, thereby effecting gas replacement,
with a superconducting cable being installed within the inner pipe,
with the inner pipe being housed within the outer pipe; evacuating
said region to vacuum; and subsequently cooling the inner pipe.
2. The method for vacuum evacuation for a thermally insulated
double pipe according to claim 1, wherein, the pre-set sort of gas
comprises a carbon oxide gas.
3. The method for vacuum evacuation for a thermally insulated
double pipe according to claim 1, wherein, the pre-set sort of gas
is a gas that solidifies at a temperature higher than a liquid
nitrogen temperature, having a low saturated vapor pressure upon
solidification, that is gaseous at ambient temperature and ambient
pressure, that is relatively low in viscosity and in dipolar
moment, and that has a relatively high mass number.
4. The method for vacuum evacuation for a thermally insulated
double pipe according to claim 1, wherein, the pre-set sort of gas
is a rare gas comprising argon and xenon, excerpt for neon, a
chlorofluorocarbon (CFC) gas, a hydrocarbon-based gas, or a
mixture(s) thereof.
Description
[0001] This is a Divisional of application Ser. No. 13/821,277
filed May 24, 2013, claiming priority based on International
Application No. PCT/JP2011/070663 filed Sep. 5, 2011, claiming
priority based on Japanese Patent Application No. 2010-200333 filed
on Sep. 7, 2010, the entire disclosure thereof being incorporated
herein by reference thereto. This invention relates to a
superconducting electrical power transmission system.
FIELD
Background
[0002] In a power transmission system, employing a superconducting
cable, such configuration that assures a facilitated laying-down
operation and that operates as measures against heat intrusion has
been proposed in Patent Literatures 1 and 2, as examples, by
Satarou Yamaguchi, one of the present inventors.
[0003] Patent Literature 1 shows a configuration including a first
pipe, within which a superconducting cable is housed, and a second
pipe of a ferromagnetic material, disposed on an outer side of the
first pipe. In the disclosed configuration, an end part(s) of a
straight-shaped pipe section of the superconducting cable is
connected by a bellows pipe, and the first pipe includes the
bellows pipe.
[0004] Patent Literature 2 shows a superconducting power
transmission cable at least including a first pipe, within which a
superconducting conductor part is disposed, and a second pipe
arranged on the outer side of the first pipe. A vacuum thermally
insulating section is provided between the first and second pipes.
A first pipe support ring that bears against an outer wall section
of the first pipe is also provided between the first and second
pipes, and a second pipe support ring is fitted on the inner wall
section side of the second pipe. A support member is arranged
between the first and second pipe support rings. FIG. 6 shows a
configuration of a thermally insulated double-shell pipe. A cooling
medium passage section 11, a superconducting conductor section 12
and an electrical insulation section 13 are provided in the
superconducting conductor part which is housed within the first
pipe 15 (see FIG. 6). The term "double-shell pipe" is termed herein
as "double pipe".
CITATION LIST
Patent Literature
[0005] [Patent Literature 1] JP Patent Kokai JP-A-2006-210263
[0006] [Patent Literature 2] JP Patent Kokai JP-A-2006-32186
SUMMARY
[0007] The present inventors conducted eager searches, and arrived
at the present invention which is proposed herewith.
[0008] In one aspect of the present invention, there is provided a
superconducting power transmission system. The system includes a
thermally insulated double pipe composed by an inner pipe within
which a superconducting cable is installed and by an outer pipe
within which the inner pipe is housed, and an inner pipe support
member(s) supporting the inner pipe. The inner pipe support
member(s) is secured to the inner and outer pipes.
[0009] According to the present invention, the superconducting
power transmission system further includes a bellows pipe housed
within the outer pipe. The bellows pipe is connected to an end(s)
of the inner pipe. The superconducting cable is housed within the
inside of the bellows pipe.
[0010] In another aspect of the present invention, there is
provided a superconducting power transmission system further
including an object to be imaged by a camera, with the object being
connected to an end part of the superconducting cable within a
cryostat. The camera is installed at a site thermally insulated
from the cryostat and is configured for imaging the object within
the cryostat through a window. A control device analyzes picture
image data of the object acquired by the camera to detect an
object's displacement. On detection of the displacement by the
control device, a driving device causes movement of the cryostat in
its entirety.
[0011] According to the present invention, the superconducting
power transmission system further includes an illumination device
that illuminates the object.
[0012] According to the present invention, the object is arranged
at an end part of a straight-shaped connection member, which
straight-shaped connection member is connected to a support section
at an end part of the superconducting cable and is further extended
along a length of the cable.
[0013] In another aspect of the present invention, both ends of the
superconducting cable are provided with free supported terminal
ends movable along the length of the cable.
[0014] In another aspect of the present invention, the
superconducting cable is fixedly supported by the inner pipe at a
mid part between both ends of the superconducting cable.
[0015] In another aspect of the present invention, there is
provided a superconducting power transmission system, wherein a
pre-set sort of gas is introduced into a vacuum region between the
inner and outer pipes of the thermally insulated double pipe to
effect gas replacement to perform evacuation to vacuum.
[0016] According to the present invention, the inner pipe is cooled
following the evacuation to vacuum.
[0017] According to the present invention, the preset sort of gas
is inclusive of a carbon oxide gas. The pre-set sort of gas is such
a gas that solidifies at a temperature higher than the liquid
nitrogen temperature, with a saturated vapor pressure at such time
being low, that is gaseous at ambient temperature and ambient
pressure, that is relatively low in viscosity and in dipolar
moment, and that has a relatively high mass number.
[0018] According to the present invention, the pre-set sort of gas
is a carbon oxide gas, a rare gas including argon and xenon, to the
exclusion of neon, a chlorofluorocarbon (CFC) gas matched to the
above conditions, a hydrocarbon-based gas, or a mixture(s)
thereof.
[0019] In another aspect of the present invention, the
superconducting cable includes a plurality of superconducting wire
tape materials, the outer pipe includes a first feed-through, and
the inner pipe includes a second feed-through [facing the first
feed-through]. There are provided one or a plurality of first leads
electrically insulated one from another. One end(s) of the first
lead(s) are connected to a vacuum side electrode of the first
feed-through and the other end(s) of the first lead(s) are
connected to one side of the facing second feed-through. There are
also provided a plurality of second leads electrically insulated
one from another. Each of the second leads has one end connected to
each first lead on the opposite side of the second feed-through,
while having the other opposite end connected to one end of each of
the plurality of the superconducting wire tape materials. A
connection portion between the plurality of the second leads and
the plurality of the superconducting wire tape materials is formed
of a retention structure.
[0020] In yet another aspect of the present invention, there is
provided a method for evacuation to vacuum for a thermally
insulated double pipe, in which the method comprises: introducing a
pre-set sort of gas into a vacuum region defined between an inner
pipe and an outer pipe composing a thermally insulated double pipe,
such as to effect gas replacement, evacuating to vacuum, and
subsequently cooling the inner pipe. A superconducting cable is
installed within the inner pipe, and the inner pipe is housed
within the outer pipe.
[0021] According to the present invention, there is no risk that
the inner pipe becomes appreciably displaced (or offset) on thermal
contraction from the outer pipe, or that a multi-layered radiation
shield film which covers up the inner pipe becomes injured.
[0022] Moreover, according to the present invention, in which an
object attached to the end part of the superconducting cable is
monitored on a picture image, contraction or expansion of the
superconducting cable may be monitored. The driving device causes
movement of the cryostat in its entirety in response to such
contraction or expansion of the superconducting cable. It is thus
possible to alleviate thermal stress that might be generated in the
superconducting cable due to its contraction or expansion caused by
changes in temperature.
[0023] According to the present invention, both ends of the
superconducting cable are displaceable along the longitudinal
direction, owing to the free supported terminal ends, thereby
alleviating any thermal stress that might be generated with the
contraction or expansion of the superconducting cable.
[0024] Moreover, according to the present invention, the pre-set
sort of gas is introduced in the vacuum region of the thermally
insulated double pipe by way of gas replacement. Evacuation to
vacuum and cooling are then carried out in this order to achieve a
high degree of vacuum.
BRIEF DESCRIPTION OF DRAWINGS
[0025] FIG. 1 is a schematic view showing an illustrative exemplary
embodiment 1 of the present invention.
[0026] FIG. 2 is a schematic view showing an illustrative exemplary
embodiment 2 of the present invention.
[0027] FIG. 3 is a schematic view showing an illustrative exemplary
embodiment 3 of the present invention.
[0028] FIG. 4 is a schematic view showing an illustrative exemplary
embodiment 4 of the present invention.
[0029] FIG. 5(A) is a graph showing changes over time of the degree
of vacuum as from the start of cooling of the inner pipe.
[0030] FIG. 5(B) is a graph showing the results of mass analysis of
residual gases in vacuum.
[0031] FIG. 6 is a schematic view showing the configuration of a
thermally insulated double pipe.
[0032] FIG. 7 is a schematic view showing a cross-sectional
configuration of the exemplary embodiment 1 of the present
invention shown in FIG. 1.
[0033] FIG. 8 is a schematic view showing an illustrative exemplary
embodiment 5 of the present invention.
PREFERRED MODES
[0034] In the description to follow, proposed are:
1) supporting an inner pipe of a thermally insulated double pipe of
the superconducting transmission system; 2) a picture image
processing device responsive to cable contraction and a movable
rack; 3) securing the superconducting cable; 4) evacuation to
vacuum for the thermally insulated double pipe, and 5) rendering
uniform the current through the superconducting wire tape
materials.
<Supporting an Inner Pipe of a Thermally Insulated Double
Pipe>
[0035] FIG. 1 depicts a diagrammatic view showing an illustrative
configuration of an exemplary embodiment 1 according to the present
invention, and shows a configuration designed for supporting an
inner pipe of a thermally insulated double pipe. FIG. 7 depicts a
schematic view showing a cross-sectional configuration of the
exemplary embodiment 1 of the present invention shown in FIG. 1.
The inner pipe is composed by a straight-shaped inner pipe section
101 and by a bellows pipe 102 connecting to an end of the
straight-shaped inner pipe section 101. An outer pipe 103 is a
straight-shaped pipe. A multi-layered radiation shielding film, not
shown, composed by a plurality of sheets, coated with aluminum, as
an example, is provided in a vacuum thermally insulating section
105 defined between the inner and outer pipes. A superconducting
cable, formed of an equi-high-temperature superconductor material,
such as an oxide material, may be disposed on an inner side of the
inner pipe, via an electric insulation section, so that a cooling
medium at a liquid nitrogen temperature may be passed through the
inner side of the cable.
[0036] An inner pipe support section 104, supporting the inner pipe
from the outer pipe 103, is secured to the outer pipe 103 and to
the straight-shaped inner pipe section 101.
[0037] The outer pipe 103 is not subjected to thermal contraction,
so that there is no change in a distance D before and after
cooling. However, the straight-shaped inner pipe section 101 is
thermally contracted after cooling due to the low temperature. This
thermal contraction is absorbed (taken up) by extension of the
bellows pipe 102.
[0038] Where a power transmission pipe is bent, a bent pipe may be
used in place of a straight-shaped pipe, or a bellows or corrugated
pipe may sometimes be used. In this case, the inner pipe support
section 104 is also secured to both the outer pipe 103 and the
[straight-shaped] inner pipe [section] 101. It is noted that, in
FIG. 7, two of the inner pipe support sections 104, each being a
member extending radially between an outer wall section of the
[straight-shaped] inner pipe [section] 101 and an inner wall
section of the outer pipe 103, are disposed at diametrically
opposite positions of the inner pipe, that is, at an angular
spacing of 180.degree. from each other. Alternatively, three or
four of the inner pipe support sections 104 may be provided at
angular spacing of 120.degree. or 90.degree., respectively.
[0039] In the thermally insulated double pipe, the outer pipe 103
is at an ambient temperature. However, the inner pipe is cooled
down to the liquid nitrogen temperature, and hence is subjected to
thermal contraction. The bellows pipe or the corrugated pipe is
welded to the end of the straight-shaped pipe section of the
straight-shaped inner pipe section 101. Owing to the inner pipe
support section 104, the inner pipe is not offset (displaced)
appreciably by thermal contraction with respect to the outer pipe
103, such that there is no risk of injuries to the multi-layered
radiation shielding film, not shown, applied to the straight-shaped
inner pipe section 101.
<Picture Image Processing Device Responsive to Cable Contraction
and Movable Rack>
[0040] FIG. 2 depicts a schematic view showing a configuration of
an illustrative exemplary embodiment 2 of the present invention. A
camera 220 images a camera target object 212 which is arranged in a
cryostat 210 (thermally insulated vacuum vessel) and moved
(displaced) with contraction/expansion of a superconducting cable
201. The image information as imaged (digital image information) is
sent to a control device 230 in order to monitor the position of
the camera target object 212. The camera target object 212 is
connected to an end part of a straight-shaped connection member 216
which is connected to a terminal support section 211 at a terminal
end of the superconducting cable and which is aerially extended
along the longitudinal direction of the superconducting cable. When
the camera target object 212 is displaced, a picture image
processing software, executed by a CPU, not shown, within the
control device 230, recognizes such displacement of the camera
target object 212 and instructs a driving device 240 to perform a
movement, indicating the direction as well as the distance of the
movement. The driving device 240 accordingly causes the movement of
the cryostat 210 in its pre-set movement direction under
instructions from the control device 230. If the superconducting
cable 201 is contracted such that the camera target object 212 is
displaced towards right in FIG. 2, the driving device 240 causes
movement of the cryostat 210 as a whole, inclusive of the camera
220, towards right in the drawing. If the superconducting cable 201
is expanded such that the camera target object 212 is displaced
towards left in FIG. 2, the driving device 240 causes movement of
the cryostat 210 as a whole, inclusive of the camera 220, towards
left in the drawing. This prevents any thermal stress, attendant on
the contraction or expansion due to changes in temperature of the
superconducting cable 201, from being generated in the
superconducting cable 201. Since the cryostat 210 is cooled down
to, for example, the liquid nitrogen temperature, and since the
camera 220 does not operate at lower temperatures, the camera is
mounted on an ambient temperature side via a thermal insulation
member (partition chamber) 214 from the superconducting cable 201,
and images the camera target object 212 through a window 215
provided in the thermal insulation member 214. The cryostat 210
includes an illumination device 213, such as an LED, for
illuminating the camera target object 212. It should be noted that
the illumination device 213, such as an LED, may be provided in the
thermal insulation member (partition chamber) 214 to illuminate
along the imaging direction of the camera 220.
[0041] Although the outer pipe of the thermally insulated double
pipe is at ambient temperature, its inner pipe is cooled down to
the liquid nitrogen temperature, and hence is subjected to thermal
contraction. For this reason, the inner pipe is composed by a
straight-shaped pipe welded to a bellows pipe or a corrugated pipe
designed to absorb the thermal contraction. Among the devices
subjected to thermal contraction, other than the inner pipe of the
thermally insulated double pipe, there is a superconducting
cable.
[0042] To absorb the thermal contraction of the inner pipe, the
bellows pipe 102 may be used, as described above in connection with
the exemplary embodiment 1. However, a bellows pipe, such as 203,
for example, may not be used to cope with thermal contraction of
the superconducting cable 201. Hence, there is no alternative but
to absorb the contraction thereof at (or by) the terminal section
of the superconducting cable 201.
[0043] For this reason, the cryostat 210, in which the terminal
part of the superconducting cable 201 is housed, is movable along
the longitudinal direction of the superconducting cable 201 in
order to absorb the thermal contraction or expansion of the
superconducting cable 201.
[0044] In FIG. 2, the bellows pipe 203 is connected also to the
outer pipe of the thermally insulated double pipe, and a distal end
portion of the bellows pipe is fixed. However, the terminal end
side of the superconducting cable 201 as a whole is movable. The
thermal contraction as well as expansion of the superconducting
cable 201 can automatically be dealt with by exploiting the control
device 230 (picture image processing device). The terminal end part
of the superconducting cable 201 is housed within the cryostat 210
and connections are made as necessary. The camera target object
212, observed by the camera, is connected to an end part of the
superconducting cable 201 via a terminal support section 211. The
camera target object 212 is displaced to follow the thermal
contraction or expansion of the superconducting cable 201. The
camera 220 observes this displacement, that is, observes that the
camera target object 212 is displaced to follow thermal contraction
or expansion of the superconducting cable 201. The camera 220
observes this, viz., it observes that the superconducting cable is
contracted and expanded during temperature lowering time and
temperature rising time, respectively. The control device 230
performs picture image processing and causes movement of the
cryostat 210 via the driving device 240 so that no thermal stress
will be generated in the superconducting cable 201.
<Securing the Superconducting Cable 201>
[0045] FIG. 3 depicts a schematic view showing an illustrative
configuration of an exemplary embodiment 3 according to the present
invention. A superconducting cable 301 has its mid portion along
the cable length affixed to the inner pipe (101 of FIG. 1). The
superconducting cable 301 is installed in the inner pipe (inner
pipe 1 and in bellows pipe 102 of FIG. 1) of the thermally
insulated double pipe (202 of FIG. 2), as shown in FIG. 1.
[0046] The superconducting cable 301 is repeatedly subjected to
thermal contraction and expansion during cooling (low temperature)
and during temperature rise (ambient temperature). To prevent
thermal stress from being generated in the superconducting cable
301, the superconducting cable 301 has its both ends formed as free
supported terminal ends 302, 303 so that it is movable in the
longitudinal direction. In case both ends of the superconducting
cable 301 are movable, in this manner, the superconducting cable in
its entirety may be moved, by way of an inchworm-like movement, in
one or the opposite direction. Hence, the superconducting cable 301
is secured to the inner pipe at a mid portion along the length of
the superconducting cable 301, as indicated by a fixed support part
to the inner pipe shown for example in FIG. 3.
<Evacuation to Vacuum for Thermally Insulated Double
Pipe>
[0047] FIG. 4 depicts a schematic view showing a configuration of
an illustrative exemplary embodiment 4 of the present invention. A
carbon oxide gas is introduced into a vacuum thermally insulating
section 405 of the thermally insulated double pipe, which is a
spacing outside the inner pipe and inside the outer pipe, by way of
performing gas replacement with a carbon oxide gas. By carrying out
such gas replacement twice, thrice or so, the vacuum thermally
insulating section 405 is substantially charged with carbon oxide
gas. The vacuum thermally insulating section is then cooled. Since
carbon oxide gas solidifies at the liquid nitrogen temperature, a
high degree of vacuum is established.
[0048] Such a gas that solidifies at a temperature higher than the
liquid nitrogen temperature, with a saturated vapor pressure at
such time being low, that is gaseous at ambient temperature and
ambient pressure, that is relatively low in viscosity and in
dipolar moment and that has a relatively high mass number, is
suited for use as this sort of gas for replacement. Thus, the
following gases:
a) rare gases, such as argon or xenon, to the exclusion of neon; b)
chlorofluorocarbon CFC (Freon) gases, providing that, in view of
there being many sorts of the gases, such a gas that matches to the
above conditions should be selected; c) hydrocarbon based gases,
such as ethane, propane or butane; and d) a mixture(s) of the above
gases are suited as a gas(es) for gas replacement in addition to
the carbon oxide gas.
[0049] In view of longer length of the thermally insulated double
pipe, evacuation to vacuum for the thermally insulated double pipe
is an extremely time-consuming operation. As an example, in a 500 m
cable project of NEDO, it took one month in evacuating to vacuum.
If this distance is increased in future to several to several tens
of kms, it would be necessary to finish evacuating to vacuum in a
shorter time. Additionally, to improve the vacuum thermal
insulation performance, a high degree of vacuum must be set. It is
noted that a technique known as `baking` is used for such case. In
this technique, a vacuum vessel is heated from outside to maintain
a temperature of 100.degree. C. or more for several hours, during
which time evacuation to vacuum is carried out by a vacuum pump.
However, it is technically almost impossible to bake a pipe several
to several tens of kms long. For this reason, in an experiment on a
cable 200 m long, evacuation to vacuum was performed without
initial baking.
[0050] On the other hand, most of residual gases are turned in
known manner into `water`. At this time, any remaining matter in
the vacuum vessel is replaced by nitrogen. Such replacement with
nitrogen is normally performed twice or thrice. By so doing, water
in the vacuum vessel is absorbed by the nitrogen gas and exhausted
to raise the degree of vacuum. After replacement with nitrogen, any
remaining matter was evacuated to vacuum by the vacuum pump down to
a vacuum pressure of 10.sup.-1 Pa, that is, 0.1 Pa. If the inner
pipe is cooled, a vacuum pressure of 10.sup.-3 Pa, that is, 0.001
Pa, should be reached, so that it should be possible to realize a
degree of vacuum necessary for vacuum thermal insulation. However,
in an experiment conducted in March 2010, the degree of vacuum
could hardly be increased, even after cooling, such that a vacuum
pressure of a fraction of Pa at most was obtained. This is not the
vacuum pressure necessary for vacuum thermal insulation.
[0051] We searched into grounds therefor, and arrived at a
conclusion that the above mentioned generally accepted common sense
may hold valid for a thermally insulated vacuum vessel exploiting
liquid helium, and that, if the inner pipe temperature is the
liquid nitrogen temperature, the probability is high that a
nitrogen gas is left in vacuum at a high pressure. Actually, we
analyzed the gas left in vacuum and found that the nitrogen gas was
the principal component in vacuum.
[0052] We thus arrived at the above mentioned technique. That is,
replacement with a gas that solidifies at a liquid nitrogen
temperature and that is low in saturation vapor pressure at such
temperature, and cooling the inner pipe, are carried out in this
order. This causes the gas to solidify and adhere to the inner
pipe, thus improving the degree of vacuum. The results of the
experiment will now be described as an Example.
<Evacuation to Vacuum for Thermally Insulated Double Pipe
(Experimental Data)>
[0053] FIG. 5(A) depicts a graph showing changes over time of the
degree of vacuum at an A-point, a U-shape and at a B-point of the
thermally insulated double pipe after replacement by a carbon oxide
gas followed by cooling the inner pipe down to the liquid nitrogen
temperature. The A-point is a site where liquid nitrogen is
introduced, with its vicinity, the U-shape is a turn-around site,
and the B-point is a site where liquid nitrogen flows out, with its
vicinity. FIG. 5(B) depicts a graph showing results of mass
analysis of residual gases in vacuum. The graph of FIG. 5(A) shows
changes in the degree of vacuum as found by an experiment conducted
as from June 1 until June 5 of 2010. The abscissa stands for time
and the ordinate stands for the degree of vacuum in Pa. Also, in
the figure, a solid line denotes a degree of vacuum at the A-point,
a broken line a degree of vacuum at the U-point, a double dotted
chain line a degree of vacuum at the B-point and a dotted chain
line denotes the temperature. When cooling is commenced (Cooling
Down), the degree of vacuum becomes higher until ultimately it
reaches 3.7.times.10.sup.-4 Pa, that is, 0.00037 Pa. This value is
higher by one order of magnitude than a value obtained with the
conventional method, thus testifying to an extremely high thermal
insulation performance of the proposed method.
[0054] FIG. 5(B) shows the results of analysis of residual gases
after reaching the high degree of vacuum. In the figure, the
abscissa denotes the mass number and the ordinate the partial
pressure. These values testify to a degree of vacuum which is
rather high as compared to the values obtained with the
conventional method of replacement with the nitrogen gas.
<Preventing Superconducting Wire Tape Materials from Current
Imbalance>
[0055] FIG. 8 depicts a schematic view showing a configuration of
an illustrative exemplary embodiment 5 according to the present
invention. A terminal 501, connecting to a copper cable at ambient
temperature, is connected to a first feed-through 502 between the
atmospheric side and vacuum, with the inside being a vacuum 504. A
plurality of first copper leads 503, connected to the first
terminal 501, is connected to an electrode 512 on the vacuum side
of the first feed-through 502 attached to an outer pipe 511 in
which a superconducting cable is housed. Note that respective first
leads 503 are electrically insulated from one another. The
superconducting cable is disposed within a cooling medium, such as
liquid nitrogen, and is composed by a plurality of superconducting
wire tape materials 507. Due to its shape, each of the
superconducting wire tape materials 507 has only a pre-set bending
direction, such that it cannot flexibly adapt itself to a
particular site of placement (i.e., routing) in layout. In the
subject exemplary embodiment, each of the superconducting wire tape
materials 507 is connected to each of a plurality of second copper
leads 506. By so doing, any desired target portion of the
superconducting wire tape materials may be bent via the second
copper leads 506 to effect desired connection. The fact that the
copper leads of uniform length and uniform cross-sectional region
can be connected in this manner to the respective superconducting
wire tape materials 507 is crucial. This structure has been adopted
in all experimental devices of the Chubu University.
[0056] It is necessary for a connection portion 508 between the
second copper leads 506 and the superconducting wire tape materials
507 to provide a stabilized fixing structure. To this end, the
connection portion 508 is designed as a retention structure to
provide a stabilized strong fixing without exerting stress to a
solder connection portion interconnecting the second copper leads
506 and the superconducting wire tape materials 507. Although the
retention structure may be of any desired suitable configuration,
it may be composed by a first plate having a plurality of grooves
or holes in its surface and a second plate placed on top of the
first plate. Each of the second copper leads 506 and each of the
superconducting linear tape materials 507 are adapted to be guided
and moved from opposing lateral sides of the first and second
plates into each groove or hole so as to be housed therein. The two
plates are then secured together by bolts. It is noted that the
surface of the second plate facing the surface of the first plate
may also be provided with a plurality of grooves in register with
those of the first plate.
[0057] The second copper leads 506 are connected to a second
feed-through 505 acting as vacuum sealing and electrical
insulation. This configuration may assure connection from the power
supply cable at the ambient temperature section to the
superconducting wire tape materials 507. In such structure, an
electrical resistance is partially connected in series with an
electric circuit of (any one of) the superconducting wire tape
materials 507 by the copper lead(s) connected to the
superconducting wire tape material(s) 507. This enables uniform
current to flow through an electrical circuit of the
superconducting wire tape materials 507. As to this issue, it is
possible to avoid that the current flowing through the
superconducting wire tape materials is non-uniformly generated due
to variations in the connection resistances, in case a long
superconducting cable is manufactured or connected in the future.
It is noted that, although a plurality of first copper leads 503
are used in FIG. 8, just one first copper lead may also be used.
However, in this case, the current may be made uniform solely by
the electrical resistances of the second leads.
[0058] The disclosures of the aforementioned Patent Publications
are incorporated herein by reference thereto. The exemplary
embodiments or examples may be modified or adjusted within the
scope of the entire disclosure of the present invention, inclusive
of claims, based on the fundamental technical concept of the
invention. Further, various combinations or selections of the
elements disclosed herein may be made within the ambit of the
claims. The present invention may encompass various modifications
or corrections that may occur to those skilled in the art within
the scope of the entire disclosure of the present invention,
inclusive of claims and the technical concept of the present
invention.
REFERENCE SIGNS LIST
[0059] 11 cooling medium passage section [0060] 12 superconducting
conductor section [0061] 13 electric insulation section [0062] 14
vacuum thermal insulation section [0063] 15 inner pipe (first pipe)
[0064] 16 outer pipe (second pipe) [0065] 17 PVC anti-corrosion
layer [0066] 101 straight-shaped inner pipe section [0067] 102
bellows pipe [0068] 103 outer pipe [0069] 104 inner pipe support
section [0070] 105 vacuum thermally insulating section [0071] 201
superconducting (SC) cable [0072] 202 thermally insulated double
pipe (double-shell pipe) [0073] 203 bellows pipe [0074] 210
cryostat [0075] 211 terminal support section [0076] 212 camera
target object [0077] 213 illumination device [0078] 214 thermal
insulation member (partition chamber) [0079] 215 window [0080] 216
connection member [0081] 220 camera [0082] 230 control device
[0083] 240 driving device [0084] 301 superconducting cable [0085]
302, 303 free supported terminal ends [0086] 304 fixed support part
to inner pipe [0087] 401 inner pipe [0088] 402 bellows pipe [0089]
403 outer pipe [0090] 404 inner pipe support section [0091] 405
vacuum thermal insulation section [0092] 501 terminal [0093] 502
first feed-through [0094] 503 first copper leads [0095] 504 vacuum
[0096] 505 second feed-through [0097] 506 second copper leads
[0098] 507 superconducting wire tape materials [0099] 508
connection portion [0100] 509 cooling medium [0101] 510 inner pipe
[0102] 511 outer pipe [0103] 512 electrode
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