JPH0659063A - Nuclear fusion device - Google Patents

Abstract

PURPOSE:To acquire sufficient vibration amplitude and speed in a collisional range by way of reducing fluctuation of the magnetic field of a diverter coil. CONSTITUTION:A shielding body 105 and a first wall 106 are provided in a to rus type vacuum vessel 1, a diverter 1 is provided below the first wall 106, and on this diverter 1, a protruded part 4 protruding in the direction of an X point 119 of a separatrix. 117 of a magnetic field is formed. Consequently, the X point 119 is vibrated against the diverter 1 or the position of the X point 119 is vibrated in the vertical direction or in the roughly vertical direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fusion device having an improved diverter for removing impurities in plasma in a fusion device such as a tokamak.

[0002]

2. Description of the Related Art A tokamak type fusion device shown in FIG. 4 is known as one of the fusion devices that confine plasma by using a magnetic field. The structure of this tokamak fusion device will be described later, but as shown in FIG. 5, a vertical magnetic field Bv perpendicular to the plasma 100, a radial toroidal magnetic field Bt along the circumferential direction, and the inside of the plasma 100 are shown. Flowing plasma current I
Plasma 100 due to the poloidal magnetic field Bp created by p
Is confined in a torus.

A vertical magnetic field Bv is arranged along the annular plasma 100 as shown in FIG.
3, the toroidal coil magnetic field Bt is generated by the toroidal coil 102 arranged so as to form an annular solenoid coil. Also, the plasma current Ip
Is generated by electromagnetic induction.

That is, the plasma current Ip induces an electric field in the plasma 100 due to a temporal change in magnetic flux caused by a rapid change in the current of the induction coil 104 arranged at the center of the tokamak-type fusion device, and the electric field is generated. To accelerate and generate electrons.

The structure of the nuclear fusion device showing an example of the configuration of the plasma and the coil will be described with reference to FIG. That is, in FIG. 4, the outer circumference of the vacuum vessel 101, which is a torus (ring) -shaped furnace that stores plasma such as deuterium and tritium, is arranged in a small circumferential direction (toroidal direction) with a small circular cross section.
Toroidal coil 102 that forms a toroidal magnetic field Bt at
And a poloidal coil 103 that forms a vertical magnetic field Bv in the circumferential direction (torus direction) of the torus ring.
Is wound. Further, an induction coil 104 is arranged in the central portion to generate a plasma current Ip.

These toroidal coil 102 and poloidal coil 103 are plasma 10 generated by a fusion reaction.
0 is suspended and held in the vacuum container 101 by electromagnetic force. Normally, these coils are composed of superconducting coils, so in order to avoid the effect of heat conduction through air, the entire superconducting coils are airtightly covered with a cryostat (not shown), and the inside is evacuated to a vacuum for superconducting. It secures a very low temperature to maintain.

The vacuum container 101 has an inner peripheral surface directly exposed to the plasma 100 entirely covered with a shield 106, and the inner peripheral surface of the shield 105 is referred to as a first wall 106. 101 is mounted on the floor 108 by the support 107.

The vacuum vessel 101 has a diverter 109 for removing impurities in the plasma 100 on a part of the inner wall of the shield 105.
Is provided. The impurities removed by the diverter 109 are exhausted to the outside through a vacuum exhaust duct 110 connected to the lower part of the vacuum container 101.

As shown in FIG. 7, a composite magnetic field 113 in which a poloidal coil magnetic field 112 generated by a plasma current and a toroidal magnetic field 111 generated by a toroidal coil are added together has a spirally twisted shape. This synthetic magnetic field
When 113 is projected on a cross section perpendicular to the axis along the torus direction, it can be seen that the magnetic field lines 114 closed at a density according to the distribution of the plasma current form a layered structure, as shown in FIG.

When the diverter coil 116 shown in FIG. 9 is provided for the closed magnetic field line 114 having such a structure and a current in the same direction as the plasma current is passed, a diverter coil magnetic field 115 and a closed magnetic field line 114 are generated. Further, the combined magnetic field has a shape in which two spirals are in contact with each other.

At the outside of the line of magnetic force around the plasma 100, the line of magnetic force is re-connected, and the line of magnetic force does not become a closed line of magnetic force interlinking with the plasma 100, but a structure open to the plasma 100. Next, plasma 100
And magnetic field lines 118 interlinking with both the diverter coil 116. The boundary at which the lines of magnetic force 118 are changed is called Separatrix 117. The contact point at the boundary where the closed magnetic field lines 114 and the diverter coil magnetic field 115 are changed is the X point 11
Call it 9.

The diverter 109 is made of a high melting point material and is placed at a position intersecting the magnetic field lines 118. Ions and electrons 120 that make up the plasma move toward the outside from the center due to collisions between particles in addition to moving along the lines of magnetic force while entraining the lines of magnetic force and making a turning motion.

As shown in FIG. 10, the particles 121 that have come out of the separatrix 117 move along the magnetic field lines 118 and collide with the diverter 109 to become neutralized particles 122 such as neutral atoms and distributions. . By exhausting these neutralized particles 122 through the vacuum exhaust duct 110, plasma is generated.
It is possible to prevent impurities from entering the 100
0 can be kept at a high temperature.

By the way, most of the particles 121 emitted from the surface of the plasma 100 to the outside are concentrated and incident on the collision area 123 of the diverter 109, which is a narrow area shown in black, so that it is unavoidable that the temperature becomes high locally. However, even if a high melting point material is used, there is a risk of melting and evaporation.

In order to avoid this, the diverter coil 116
By varying the current in the constant period and changing the magnetic field, the separatrix 117 near the divertor 109 and the X point 119 are spatially oscillated as indicated by the arrow 124 as shown in FIG. Collision area of particles 123
A method to reduce the heat load was proposed by periodically moving.

[0016]

However, in the conventional fusion apparatus, since the collision area is vibrated by about 20 to 30 cm per second, it is necessary to greatly change the magnetic field of the diverter coil 116.

This magnetic field fluctuation causes a large AC loss in the superconductor forming the toroidal coil 102, and there is a problem that the superconducting state is lost due to the heat.

The present invention has been made to solve the above problems, and it is an object of the present invention to provide a fusion device capable of obtaining a sufficient vibration width and velocity in the collision region by reducing the magnetic field fluctuation of the diverter coil. .

[0019]

According to the present invention, a shield, a first wall and a diverter are provided in a torus-shaped vacuum container, a toroidal coil and a poloidal coil are wound around the outer periphery of the vacuum container, and a central part of the vacuum container is provided. In a fusion device in which an induction coil is arranged and plasma generated by a fusion reaction is suspended and held in the vacuum chamber by electromagnetic force and is confined, a convex portion protruding in the direction of point X of the magnetic field separatrix is formed in the diverter. The X point is vibrated with respect to the diverter.

Further, according to the present invention, the diverter is provided with a protrusion protruding in the direction of the magnetic field's separatrix, and a protrusion continuous in the toroidal direction from the first wall to the point X so as to be perpendicular to the diverter. The position of the point X is oscillated in the vertical and substantially vertical directions.

[0021]

When the moving widths of the shapes of the diverters are compared, the convex shape is the longest. Therefore, the same X
When the point is convex with respect to the moving time and the moving width, the sweep speed of the collision area is the highest and the moving width can be increased. Therefore,
The magnetic field fluctuation of the diverter coil can be relatively reduced.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the nuclear fusion device according to the present invention will be described with reference to FIG. In addition, FIG. 1 shows the basic structure of the present embodiment (excluding the coils, etc.).
Since the first wall 106 and other parts are similar to the structure of the conventional nuclear fusion device shown in FIG. 4, description of other parts will be omitted and only the main part of the present invention will be described.

The fusion device in FIG. 1 is different from the conventional example in that the diverter 1 is formed with a convex portion 4 projecting in the direction of the point X of the magnetic field separation. That is, the diverter 1 of the present embodiment in which the convex portion 4 is formed has the X point 11
It has a structure that bends so as to project toward 9 and is constructed by laying a plate made of a high melting point material such as tungsten on the surface.

Next, the operation of the above embodiment will be described. FIG. 2 shows the difference between the moving width of the X-point and the moving width of the separatrix on the diverter surface with respect to the shape of the diverter of the convex shape of the present embodiment, the conventional flat shape and the concave shape.

That is, FIG. 2 shows the convex diverter 1 of the present embodiment when the current of the diverter coil 116 is changed and the position of the X point 119 is vibrated, the conventional flat plate diverter 2,
With respect to the X point 119, it shows the difference in the moving width of the high-heat receiving portion of the particle collision region on each diverter surface of the concave diverter 3 having a concave shape. Here, for the sake of simplicity, the high heat receiving portion is represented by the intersection with the Separatrix 117.

In FIG. 2, δx6 indicates the vibration width when the X point 119 is vibrated in the horizontal direction, and δy7 indicates the vibration width when the X point 119 is vibrated in the vertical direction. L ₁ is the X point
When 119 is vibrated, the moving width of the intersection of the separatrix 117 on the surface of the convex divertor 117 of the present embodiment, l ₂ is the separatrix 11 on the surface of the flat plate diverter 11 in the same case.
7 shows the movement width of the intersection, and l ₃ shows the movement width of the intersection of Separatrix 117 on the concave diverter 3 surface in the same case. As is clear from FIG. 2, it is clear that l ₁ is the longest for the same change width in the horizontal direction and the vertical direction of the X point 119. That is, in the case of the convex diverter 1 of the present embodiment, the high heat receiving portion can be swung to the largest and quickest.

On the contrary, considering the vibration width of the X point 119 which makes the moving width of the intersection of the separatrix 117 on each diverter surface the same, in the case of the convex diverter 1 of this embodiment, It can be seen that the smallest vibration width of X point 119 is obtained.

Therefore, in the nuclear fusion device according to this embodiment, a diverter coil for vibrating the X point 119 is used.
The magnitude of the change in the current of 116 can be reduced.
Moreover, AC loss of the superconducting wire of the toroidal coil can be reduced, and stable operation of the coil without a quencich can be secured. Furthermore, since the high heat-receiving part on the diverter plate can be swept quickly, a reliable fusion device without melting of the diverter plate can be obtained.

Next, another embodiment of the present invention will be described with reference to FIG. 3, those parts that are the same as those corresponding parts in FIG. 1 are designated by the same reference numerals, and a description of the overlapping parts will be omitted. The present embodiment is different from the embodiment of FIG. 1 in that it has an eave-shaped protrusion 5 from the first wall 106 toward the X point 119. This protruding portion 5 is assumed to continue one round in the torus direction. When the X point 119 is vibrated in the vertical direction in such an arrangement, the crossing state between the protruding portion 5 and the magnetic field lines 118 interlinking the two hardly changes, so that the sudden collision of plasma particles with the protruding portion 5 increases. Does not happen in particular.

Therefore, even when the position of the X point 119 is vibrated, the diverter 1 called the closed diverter is used.
It is possible to adopt a structure in which the protrusions 5 are partially expanded, and it is possible to further reduce the mixing of impurities into the plasma 100.

[0031]

According to the present invention, the high heat receiving portion on the diverter surface can be moved sufficiently large and fast with a small vibration width at the X point. Therefore, it is possible to suppress the AC loss of the superconductor of the toroidal coil and maintain a stable superconducting state,
Further, melting of the diverter can be avoided, and a reliable fusion device can be realized.

[Brief description of drawings]

FIG. 1 is a basic structural diagram showing an embodiment of a nuclear fusion device according to the present invention.

FIG. 2 is a conceptual diagram illustrating the operation of the present invention and a conventional diverter.

FIG. 3 is a basic structural diagram showing another embodiment of the nuclear fusion device according to the present invention.

FIG. 4 is a sectional view showing a structure of a conventional tokamak nuclear fusion device.

5 is a schematic diagram showing the relationship between the magnetic field and the plasma current of the nuclear fusion device in FIG.

6 is a perspective view showing each coil arrangement of the nuclear fusion device in FIG. 4. FIG.

FIG. 7 is a conceptual diagram showing a combined state of magnetic fields of the nuclear fusion device in FIG.

FIG. 8 is a schematic diagram showing closed magnetic force lines due to a plasma current of the nuclear fusion device in FIG.

FIG. 9 is a basic structural diagram of a conventional tokamak fusion device having a diverter coil.

10 is an enlarged structural view showing magnetic lines of force in the vicinity of the diverter of the nuclear fusion device in FIG. 9.

11 is a schematic diagram showing movement of a collision region when horizontally vibrating point X of the nuclear fusion device in FIG. 9. FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Diverter (present invention), 2 ... Flat plate type diverter, 3
… Concave diverter, 4… Projection, 5… Projection, 6… X
Horizontal vibration width of point, 7 ... Vertical vibration width of X point,
100 ... Plasma, 101 ... Vacuum container, 102 ... Toroidal coil, 103 ... Poloidal coil, 104 ... Induction coil,
105 ... Shield, 106 ... First wall, 107 ... Support, 108 ...
Floor, 109… Diverter (conventional), 110… Vacuum exhaust duct, 111… Toroidal magnetic field, 112… Poloidal magnetic field, 1
13 ... Synthetic magnetic field, 114 ... Closed magnetic field lines, 115 ... Divertor coil magnetic field, 116 ... Divertor coil, 117 ... Separatrix, 118 ... Magnetic field lines interlinking with each other, 119 ... X point, 1
20 ... Ions and electrons, 121 ... Outgoing particles, 122 ... Neutronized particles, 123 ... Collision area, 124 ... Arrows.

Claims (1)

[Claims] 1. A torus-shaped vacuum container is provided with a shield, a first wall and a diverter, a toroidal coil and a poloidal coil are wound around the outer periphery of the vacuum container, and an induction coil is arranged at the center of the vacuum container to form a core. In a nuclear fusion device for floatingly holding and confining plasma generated by a fusion reaction in the vacuum vessel by an electromagnetic force, the diverter is formed with a convex portion protruding in a direction of a point X of a magnetic field separatrix. Fusion device.