JPS6333111B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to torus type, mirror type, etc. nuclear fusion devices, and particularly to a toroidal coil thereof.

Nuclear fusion devices use magnetic fields to confine plasma within a vacuum vessel. For example, in a torus-type fusion device, a toroidal coil provides a magnetic field parallel to the longitudinal direction of an annular vacuum chamber.
Stabilizes plasma confinement. but,
At this time, if a magnetic field that is not parallel to the longitudinal direction of the vacuum vessel is generated, the toroidal magnetic field will be disturbed and the plasma confinement characteristics will be degraded. This means that even among torus types, the lines of magnetic force do not have twists like bumpy torus types, in other words, the lines of magnetic force start from a certain point in the annular vacuum container, go around the torus direction, and return to their original position. This is particularly noticeable in nuclear fusion devices that have a magnetic field arrangement that follows, and due to the irregular magnetic field that is not parallel to the longitudinal direction of the vacuum vessel, the charged particles that move along the magnetic field lines return to their original positions after orbiting in the torus direction. The plasma drifts and deteriorates the plasma confinement characteristics. Therefore, it is extremely important to minimize the irregular magnetic field generated by the toroidal coil.

FIG. 1 shows the arrangement and connection state of each toroidal coil in a conventional torus-type fusion device. A plurality of toroidal coils 1 are wound in the same direction so as to surround an annular vacuum vessel (not shown) that confines plasma. The toroidal coils 1 are arranged at equal intervals and connected in series by an inner feeder wire 2 and an outer feeder wire 3 so that the magnetic polarity of each toroidal coil 1 is in the same direction.

As for the current flow, as shown by the arrow, the inner feeder wire 2 and the toroidal coil 1
After circulating in the interior clockwise alternately, it turns around,
It flows counterclockwise through the outer peripheral feeder wire 3 and returns to its original position. At this time, an asymmetric magnetic field that is not parallel to the longitudinal direction of the vacuum container, that is, the torus direction T, is generated by the current loop that flows in the clockwise direction and the current loop that flows in the counterclockwise direction. Among these, each irregular magnetic field generated by the current flowing through the inner feeder wire 2 and the outer feeder wire 3 can be mutually suppressed by arranging the feeder wires 2 and 3 so that the gap between them is sufficiently small. By canceling, the adverse effects of these misaligned magnetic fields can be substantially eliminated. However, it is difficult to make the current loop small for the irregular magnetic field generated by the current I ₀ flowing across the inner circumference of each toroidal coil 1, that is, through the stepped part, and it exists in a position close to the plasma. Because of this, the impact is significant.

Therefore, as shown in FIGS. 2 and 3, a toroidal coil 1a consisting of a stacked body of, for example, four double pancake coils 4a ₁ to 4a ₄ wound in a right-handed direction, and a toroidal coil 1a wound in a left-handed direction. For example, toroidal coils 1b made of a laminate of four double pancake coils 4b ₁ to 4b ₄ are arranged alternately, and each toroidal coil 1a wound in a right-handed direction is connected to the inner peripheral feeder wire 2. In addition, a method has been proposed in which each toroidal coil 1b wound in the left-handed thread direction is connected in series by an outer peripheral feeder wire 3 (Japanese Patent Publication No. 49-46038).

According to this method, toroidal coils 1a, 1
In order to generate a toroidal magnetic field in the same direction with the magnetic polarity direction of b being the same, as shown in FIG.
a and toroidal coil 1 wound in the left-handed direction
Since the _directions of the currents flowing through the terminals b are opposite to each other, as shown in _FIG . The directions of the flowing current components I ₀ a ₁ to I ₀ a ₄ are the same, and the current I ₀ a (= I ₀ a ₁ + I ₀ a ₂ +I ₀ a ₃ +I ₀ a ₄ ) and I ₀ b
The directions of (=I ₀ b ₁ + I ₀ b ₂ + I ₀ b ₃ + I ₀ b ₄ ) are opposite to each other. That is, the directions of currents flowing through the stepped portions of the toroidal coils 1a and 1b arranged at intervals in the torus direction T are alternately reversed, such as I ₀ a and I ₀ b. Therefore, as shown in FIG. 3b, the magnitude of the irregular magnetic field δB directly under the toroidal coil cannot be particularly reduced compared to the conventional example shown in FIG. Since the direction of the irregular magnetic field δB is alternately reversed for each coil, if the irregular magnetic field component δB of each toroidal coil is averaged over the entire circumference in the torus direction, the average irregular magnetic field <δB> = δBd/d
(is the circumferential length of the vacuum container in the torus direction T) can be brought close to zero. The fact that the circulating average asymmetric magnetic field <δB> in the torus direction T is almost zero means that when a charged particle moves in the torus direction T along the lines of magnetic force, the influence of the asymmetric magnetic field is suppressed at each location. As a result, the orbit deviates from the magnetic field lines, but it is always displaced in the opposite direction, and once it goes around in the torus direction T, it is canceled out and returns to its original position, which leads to improved plasma confinement characteristics. However, this method only brings the average irregular magnetic field <δB>=δBd/d closer to zero, and does not contribute much to lowering the absolute value of the irregular magnetic field at individual locations.

The present invention was made in view of this point, and its purpose is not only to bring the average irregular magnetic field of the entire device close to zero, but also to minimize the absolute value of the irregular magnetic field at each location, so that plasma An object of the present invention is to provide a nuclear fusion device that can further improve confinement characteristics.

In order to achieve this object, the present invention alternately reverses the winding direction of a plurality of double pancake coils constituting a toroidal coil in the stacking direction, so that an irregular magnetic field is generated by a coil winding part in each toroidal coil. It is characterized by being made to approach zero.

An embodiment of the present invention will be described below with reference to FIG. In FIG. 4, the same reference numerals as in FIGS. 1 to 3 indicate the same or equivalent components.

In this embodiment, as shown in FIG. 4a, each toroidal coil 5 is arranged in the torus direction T.
are a double pancake coil 4a ₁ wound in a right-handed direction, a double pancake coil 4b ₁ wound in a left-handed direction, a double pancake coil 4a ₂ wound in a right-handed direction, and a left-handed threaded coil. It is constructed by sequentially stacking double pancake coils 4b ₂ wound in the torus direction T, and each double pancake coil 4a ₁ , 4b ₁ ,
4a ₂ and 4b ₂ are double pancake coils 4a ₁ and 4a ₂ wound in a right-handed direction and double pancake coil 4b wound in a left-handed direction in order to have the same magnetic polarity direction. ₁ and _4b2 are connected so that the directions of current flowing through them are opposite to each other.

Therefore, double pancake coils 4 with different winding directions within the same toroidal coil 5
The directions of the current components I ₀ a ₁ , I ₀ a _{2 and I 0 b 1 , I 0 b 2 flowing in the stepped portions of a 1 , 4 a 2 and 4 b 1 , 4 b 2} are opposite to each other,
Each irregular magnetic field δB due to these current components is the fourth
As shown in Figure b, the directions are alternately reversed for each double pancake coil and cancel each other out within the same toroidal coil 5, and their absolute values are also significantly smaller than in the method shown in Figure 3. .

For example, large radius 1400mm, average coil radius 130mm,
In a toroidal fusion device with a coil cross section of 98 mm x 85 mm and 24 toroidal coils, when the toroidal coil is made of four double pancake coils, the maximum asymmetric magnetic field δB generated by the current flowing in the coil section The value δBmax is when the conducting current is 7000A (the average magnetic field in the toroidal direction T at this time is 1.6 terraces), and in the conventional example shown in Fig. 3,
While δBmax = 15.0 Gauss, the fourth
In the example shown in the figure, δBmax=1.2 Gauss, which was able to be reduced to 1/10 or less.

In the above embodiment, the toroidal coil is composed of four double pancake coils, and one double pancake coil is used as one coil element, but the number of double pancakes is not limited to four.
An even number is sufficient, and the larger the number, the smaller the absolute value of the irregular magnetic field due to the coil winding section.For example, two double pancake coils wound in the same direction can be It may also be one coil element.

In addition, in the above embodiments, the case where the present invention is applied to a torus type nuclear fusion device has been described, but the present invention is not limited to this, but can be widely applied to nuclear fusion devices such as a mirror type where the vacuum vessel is linear. Is possible.

As explained above, according to the present invention, the winding direction of the plurality of double pancake coils in the toroidal coil is alternately reversed in the stacking direction, and the irregular magnetic field due to the coil recessed portion is reduced in each toroidal coil. By making it close to zero, not only can the average irregular magnetic field for the entire device be brought close to zero, but also the absolute value of the irregular magnetic field at each location can be significantly reduced, resulting in improved plasma confinement characteristics. It becomes possible to further improve the

[Brief explanation of the drawing]

Figures 1 and 2 are schematic configuration diagrams showing examples of the arrangement and connection state of each toroidal coil in a conventional torus-type fusion device, and Figures 3a and b are in the fusion device shown in Figure 2. A schematic configuration diagram showing the internal configuration of the toroidal coil and its connection state, and a characteristic diagram showing the irregular magnetic field distribution due to the stepped portion of the toroidal coil, Figures 4a and 4b are torus-shaped nuclei according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram showing the internal configuration of a toroidal coil and its connection state in a fusion device, and a characteristic diagram showing an irregular magnetic field distribution due to a stepped portion of the toroidal coil. 4a ₁ , 4b ₁ , 4a ₂ , 4b ₂ ... double pancake coil (coil element), 5 ... toroidal coil.

Claims (1)

[Claims] 1 Equipped with a vacuum container containing plasma, and a plurality of toroidal coils wound around the vacuum container and arranged at intervals in the longitudinal direction of the vacuum container, each of these toroidal coils In the case where the coil is constructed by laminating a plurality of double pancake coils and the magnetic polarities thereof are set in the same direction, the winding direction of the plurality of double pancake coils in the toroidal coil is the lamination direction. A nuclear fusion device characterized in that the fusion devices are alternately reversed.