JPH0836074A - Vacuum container for nuclear fusion device - Google Patents

Abstract

PURPOSE:To apply electromagnetic force generated by halo current flowing in a vacuum container to a rib part which has a sufficiently high mechanical strength. CONSTITUTION:In the vacuum container having a double wall structure, a rib 7 is put at a position where plasma is brought into contact with, halo current 9 possibly flows in, and a protective tile 1 and a limiter are to be set. Or, for the position where a rib 7 can not be set, the protective time 1 is set in an electrically insulated state and with that condition, the rib 7 is set while being electrically connected with the rib 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a nuclear fusion device, and more particularly to a vacuum for a nuclear fusion device in which a structure in a vacuum container, a structural material directly facing plasma and a protective tile are fixed more reliably. Regarding the container.

[0002]

2. Description of the Related Art In a nuclear fusion device, a dilute hydrogen gas is placed in a donut-shaped vacuum container and an electric current (plasma current) is applied to the gas.
To make hydrogen gas a high temperature plasma. Energy is generated by causing a nuclear fusion reaction in this plasma. The plasma is isolated from the wall of the vacuum vessel by the magnetic field,
Sometimes the plasma becomes unstable and may come into direct contact with the vacuum vessel wall. At this time, the plasma gives a large amount of heat to the wall of the vacuum container, which may damage the wall. To prevent such damage, a protective tile is placed on the plasma facing surface of the vacuum container. This tile is made of light element materials such as carbon. This is because light elements have a low rate of deteriorating the plasma performance even if they are mixed as impurities in the plasma. A large amount of heat flows into the tile during plasma operation.
For this reason, the method of installing the tiles takes the heat removal into consideration.

For example, technical papers (T. Ando et al., Proceedin
g of the 17-thFusion Technology, Rome Italy, 199
2, Elsevier Science Publishers BV, 1993, P.161.)
As shown in FIG. 2, the installation method shown in FIG. 2 is conventionally used. The protective tiles 1 are grouped together and fixed to the substrate 2. At this time, it is installed so as to have a large contact area for removing heat. Further, this is fixed to the cooling plate 3, and this cooling plate 3 is fixed to the inner wall 4 of the vacuum container. The cooling plate 3 is provided with a coolant passage 5. The vacuum container has an inner wall 4 and an outer wall 6, and ribs 7 are arranged between them. The location of tiles and the location of ribs were not particularly considered.

It is during disruption that the plasma strikes the vacuum vessel wall most intensely. At this time, not only heat from the plasma to the tiles, but also the current flowing in the plasma will flow, it has been found in recent experiments with the fusion device. This current is called halo current and interacts with the magnetic field that confine the plasma in the fusion device to generate a large electromagnetic force. This electromagnetic force is applied to tiles and vacuum containers,
Damage this part. Therefore, it is necessary to set aside a method of installing tiles that minimizes this electromagnetic force.

[0005]

DISCLOSURE OF THE INVENTION The present invention proposes, when installing a protective tile, a structure in which a force due to a current (halo current) flowing from plasma is applied to a high-strength portion such as a rib portion. is there. FIG. 3 shows how the halo current 9 flows in the poloidal cross section. The halo current 9 is flowing in the plasma in the poloidal direction as indicated by the dotted arrow. The toroidal magnetic field is in the direction perpendicular to the paper surface, and forms a spiral magnetic field line together with the magnetic field generated by the plasma 20 and the external coil. An electric current flows along these lines of magnetic force. The current flowing around the plasma also flows into the vacuum container. When projected onto the poloidal section, it flows in the poloidal section as shown in FIG. The halo current 9 thus flowing interacts with the toroidal magnetic field 8 in the direction perpendicular to the plane of the drawing to generate an electromagnetic force 11 like a thick arrow in the plasma 20 and the vacuum container 10.

In FIG. 3, the strong magnetic field in the nuclear fusion device is directed in the toroidal direction (large radius direction) perpendicular to the paper surface. Therefore, when a current flows in the protective tile or in a weak portion, it should be arranged so as to flow in the toroidal direction. Since the magnetic field and the current are parallel, the electromagnetic force becomes weak. The vacuum container 10 is often a double wall as shown in FIG. 2, but the structure of this wall is strong at the rib 7. Therefore, when a current is passed in the poloidal direction, this portion should flow. In particular, in the fusion reactor, in order to reduce the activation of the vacuum vessel, the wall thickness on the plasma side should be thin and the wall thickness on the atmosphere side should be thick. Between the two walls, in addition to the ribs, there is filled with a substance that is highly effective in blocking water and the like. In the case of such a structure, when a halo current flows on the thin plasma side surface, the thin portion is damaged by the electromagnetic force 11.

Therefore, the present invention provides a structure in which the tile installation position is associated with the position of the rib structure portion so that the current flowing as a halo current flows through the rib structure portion and the electromagnetic force applied to the thin portion can be reduced. .

[0008]

In order to solve the problems, a structure is adopted in which a halo current does not flow as much as possible in a thin portion having a weak strength. That is, after the halo current flows into the vacuum container, the halo current flows through the vacuum container rib. The rib has high strength, so there is no problem. Consider a case where the position where the protective tile is installed in the vacuum container matches the position of the rib structure. In this case, the halo current flowing into the protective tile flows into the vacuum container from the supporting portion of the tile, but the rib portion has a lower resistance than the thin plate portion on the plasma side, and therefore flows through this portion. Therefore, the support of the protective tile is performed from the rib portion as much as possible and electrically connected to this portion.

If the rib spacing is large, it becomes necessary to install protective tiles even at the intermediate positions of the ribs. For those placed in the middle of the rib, mechanical support is provided from the thin wall of the vacuum vessel and electrically connected to the protective tile connected to the rib through toroidal wiring. The reason for wiring in the toroidal direction is to weaken the electromagnetic force. With this structure, the location where the halo current flows into the wall of the vacuum container is limited to the rib portion, and the electrical resistance at the rib portion is smaller than that at the thin wall portion. Concentrate on the ribs and flow. As a result, the current flowing through the thin portion can be reduced, and the electromagnetic force acting on the thin portion can be weakened.

[0010]

When the protective tile is installed and electrically connected as described above, the protective tile functions as a collecting electrode that collects an electric current in the rib portion. Therefore, current does not flow into the thin portion. In this case, the current that flows in as a halo current concentrates in the rib portion, and the electromagnetic force is not generated in the thin portion of the vacuum container but is applied to the rib portion having high mechanical strength. As a result, the risk of the vacuum container being damaged by the halo current flowing from the plasma through the tile into the vacuum container is reduced.

[0011]

FIG. 1 shows an embodiment of the present invention. It is sectional drawing which cut | disconnected in the toroidal direction between the outer wall 6 of a vacuum container, and the protective tile 1. The upper side is the plasma side, and the protective tile 1 is placed on it. When viewed from the plasma side, the protective tiles (1 and 15) have a square shape of about 10 cm square. The tiles are lined up against the plasma without any unevenness. There is a support structure on the side of the vacuum tile wall of the protective tile. This protective tile 1 is mechanically supported by a support rod 12 or 14 by a vacuum container. The vacuum container has a double wall, and the plasma side is thin due to low emission. Water 18 is filled between the double walls, mainly for neutron shielding and cooling.

There are two types of protective tile support structures of the present invention. The protective tiles installed on the rib structure are electrically connected directly to the vacuum vessel. Of the halo current 9 flowing into the protective tile, the current flowing into the protective tile connected to the rib portion flows directly from the protective tile to the rib 7 portion as shown by the curve and arrow.
On the other hand, the protective tiles 15 installed between the ribs are supported by the insulating support rods 14, and electrically connected to the protective tiles 1 installed on the ribs by the short-circuit plate 13. This connection is in the toroidal direction. Therefore, the halo current 9 that has flowed into the protective tile 15 supported by this insulating support rod also flows in the toroidal direction into the rib 7.
The rib 7 runs in the poloidal direction. As shown in FIG. 3, the inflowing current flows in the direction of the porodile and enters the plasma again from another point. At this time, if the arrangement is such that the protective tile is electrically connected to the rib portion as shown in FIG. 1, the current that has flowed in due to the halo current mainly flows through the rib portion, and the electromagnetic force due to this flows in the rib 7 as well. Mainly join the part. The force applied by the halo current 9 to the inner surface (plasma side) 4 of the double wall of the vacuum container having insufficient mechanical strength becomes weak. As a result, soundness can be maintained against the electromagnetic force due to the halo current received by the vacuum container.

FIG. 4 shows the installation situation of the protective tile (1 or 15) embodying the present invention as a view of the vacuum vessel wall viewed from the plasma side. It is assumed that you have seen the bottom surface of the vacuum vessel. In the drawing, the upper part is inside the main radius, and the left-right direction is the toroidal direction. The black circle indicates the position of the support rod 12, and this portion is electrically connected to the vacuum vessel. White circles indicate the positions of the insulating support rods 14. A short-circuit plate 13 electrically connects the insulating support rod 14 position to the normal support rod 12 position in the toroidal direction. This is on the vacuum container wall side from the protective tile 1, but is shown by a solid line here for convenience. FIG. 1 shows a cross section taken along the line AA ′ in the drawing.
Equivalent to.

The ribs 7 running in the poloidal direction are often installed at equal toroidal angular intervals. Therefore, inside the main radius, each protective tile is installed at the position of the rib. However, the rib spacing becomes large outside the main radius, and there is also the protective tile 15 placed in the middle because it cannot be installed at the rib position. Such a protective tile is installed on the wall of the vacuum container insulatively, and is electrically connected to the protective tile installed at the position of the rib running in the adjacent poloidal direction. Depending on the position, the ribs also run in the toroidal direction, and if there is no rib in the poloidal direction, it can be installed at the position of this toroidal rib.
In this case, since the current flowing as a halo current flows through a portion having a small resistance, it first flows in the toroidal direction up to the location of the poloidal rib, and then flows in the poloidal direction.

FIG. 5 shows a case in which some protective tiles 1 are collectively installed on the inner wall 4 of the vacuum container. Although the structure is similar to that of the conventional example of FIG. 2, the ribs are placed on the thin plasma-side vacuum vessel wall where the entire protective tiles are put together, and they are electrically and mechanically connected and supported. According to such a structure,
Not only does the halo current 9 not flow into the thin portion 16,
Since the protective tile 1 is in full contact with the installation substrate 2,
The heat removal performance from the protective tile to the installation substrate 2 can also be secured. Further, since the heat is dissipated to the water between the double walls through the rib 7 by installing the rib 7 in the portion, the heat dissipation area for water is effectively increased. As a result, the heat dissipation from the installation substrate to water is improved, and it is not necessary to cool the installation substrate in particular.

FIG. 6 shows a case where a limiter is installed. The halo current 9 also flows into the limiter 17. Therefore, it is desirable to install it on the rib like the protective tile. In FIG. 6, the limiter is divided and installed on one poloidal section, and is electrically connected. In the same cross section, the poloidal ribs run in the poloidal direction.
The halo current 9 flowing from the plasma flows through the rib 7 in the poloidal direction as shown by the arrow and returns to the plasma 20. Since the rib 7 flows through the high-strength portion, the electromagnetic force applied to the thin portion is reduced, and damage can be prevented. Since the halo current 9 is more likely to flow into the limiter than the protective tile, it is better to install a particularly strong rib. In other words, only ribs having a poloidal cross-section to which the limiter is attached have large and strong ribs in the toroidal direction.

It has been described with reference to FIGS. 1 and 4 that the ribs may be installed between the ribs when the rib spacing is large. The tiles installed between the ribs are electrically connected in the toroidal direction so that the halo current flows into the ribs because they are tapped separately.
FIG. 7 is an example of a method for electrically connecting protective tiles placed at positions between ribs. In FIG. 1, the support portion of the protective tile is connected to the adjacent tile, but in this example, the plasma tile side surface of the protective tile 1 is cut out, and the short-circuit plate 13 is installed at this portion. In this case, the protective tile 1 between the ribs
The halo current 9 flowing into 5 flows into the protective tile 1 arranged on the rib through the short-circuit plate 13, and then flows into the rib 7. As compared with the previous example (FIG. 1), the flow path of the current flowing as the halo current 9 becomes shorter, and therefore the electromagnetic force also becomes smaller. That is, the halo current 9 that has flowed into the protective tile 15 provided between the ribs flows through the protective tile in the toroidal direction as it is, passes through the short-circuit plate 13, and flows into the adjacent protective tile. This method is also advantageous in that the short-circuit plate can be maintained even after the protection tile is installed.

The advantages of installing the protective tiles on the ribs have been described above in terms of electromagnetic force due to halo current. However, the advantage of such an arrangement is also that the deformation of the inner surface of the vacuum container can be reduced. There will always be a welded part and a machined part in the installed part. For example, in FIG. 5, the nut is welded to the wall of the vacuum vessel, and the installation substrate is bolted to this. If this welding is performed at the thin portion 16, the deformation due to welding becomes large and the installation accuracy of the protective tile 1 becomes poor. If the installation accuracy deteriorates, there will be protective tiles protruding against the plasma. If there is such a protective tile, the tile will be selectively damaged by heat or halo current flowing from the plasma, leading to damage of the protective tile. However, if the ribs are selectively installed on the ribs as in the present invention, this deformation is reduced, and selective damage to a specific protective tile can be avoided. From this point as well, damage to the vacuum container and the plasma facing wall can be reduced.

[0019]

According to the present invention, the halo current flowing into the vacuum container from the protective tile or the like facing the plasma in the vacuum container does not easily flow to the thin portion of the vacuum container, and the damage of the vacuum container wall due to the halo current can be prevented. . Further, the deformation of the vacuum vessel wall is reduced, and it is possible to prevent a specific protective tile from being selectively damaged.

[Brief description of drawings]

FIG. 1 is a poloidal cross-sectional view showing an installation situation of a protective tile embodying the present invention.

FIG. 2 is a perspective view of a conventional protective tile installation situation.

FIG. 3 is an explanatory diagram showing a relationship between a halo current flowing in a nuclear fusion device and an electromagnetic force.

FIG. 4 is an explanatory diagram showing a state of a plasma facing wall in which the present invention is implemented.

FIG. 5 is a perspective view showing an example in which the present invention is applied to protective tiles assembled on a cooling substrate in an embodiment of the present invention.

FIG. 6 is an explanatory diagram of an embodiment of the present invention for installing a limiter.

FIG. 7 is an explanatory diagram of an embodiment in which tiles are electrically connected in a toroidal direction.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Protective tile, 4 ... Vacuum container inner wall, 6 ... Vacuum container outer wall, 7 ... Rib, 9 ... Hello electric current, 12 ... Support rod, 13 ...
Short-circuit plate, 14 ... Insulated support rod, 15 ... Protective tile, 18
…water.

Claims (5)

[Claims] 1. When installing a protective tile and a limiter, which are located in a vacuum container of a nuclear fusion device and face a plasma, to which a current may directly flow from the plasma, in the vacuum container, A vacuum container for a nuclear fusion device, which is electrically connected to a portion having high mechanical strength. 2. A protective tile or limiter, which is located in a vacuum vessel of a nuclear fusion device and faces a plasma and to which a current may directly flow from the plasma, is installed in a double-walled vacuum vessel having a rib structure. In this case, the vacuum container for a nuclear fusion device is characterized in that it is selectively electrically connected to a rib portion having high mechanical strength. 3. The plasma counter object according to claim 1 or 2, which cannot be installed in a portion having high mechanical strength, is arranged insulatively in the vacuum container, and is electrically connected to a nearby portion having high mechanical strength. Vacuum container for nuclear fusion equipment. 4. The vacuum container for a nuclear fusion device according to claim 3, wherein the protective tiles are electrically connected in a toroidal direction with a plasma facing object built therein. 5. The vacuum container for a nuclear fusion device according to claim 2, wherein the limiter is arranged on a rib running in the same poloidal direction.