JPH0746151B2 - High frequency heating antenna - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to improvement of a high-frequency heating antenna used for plasma heating of a nuclear fusion device.

[Technical background of the invention]

A nuclear fusion device utilizing the DT reaction of deuterium (D) and tritium (T) is constructed, for example, as shown in FIG. In the figure, reference numeral 101 is a torus-shaped vacuum container for enclosing the plasma 102 therein and maintaining a high vacuum state. A blanket 103 is integrally provided inside the vacuum container 101 so as to surround the plasma 102. Has been.
The blanket 103 contains lithium as a tritium breeding material inside and is provided with a coolant passage (not shown) for cooling the lithium. The blanket 103 reacts the high energy neutrons emitted from the plasma 102 with the lithium to generate tritium,
The thermal energy generated at this time is taken out to the outside via the coolant flowing through the coolant channel.

Around the vacuum container 101, a toroidal coil 104 is arranged in the toroidal direction of the vacuum container 101, and a poloidal coil 105 is arranged in the poloidal direction. The toroidal coil 104 and the poloidal coil 105 form a magnetic field generating coil, and the coils 104 and 105 and the vacuum container 101 are installed on a pedestal 106.

On the other hand, in the center of the vacuum container 101, the center support 107 is a vacuum container.
The hollow part of 101 is vertically erected. A current transformer coil 108 is wound around the center column 107, and constitutes a current transformer together with the magnetic field generating coil. This current transformer supplies a large current to the magnetic field generating coil to generate a magnetic field inside the vacuum container 101, and the plasma 102 in the vacuum container 101 is Joule heated by the current generated by the magnetic field. .

A high-frequency secondary heating device 109 called an ion cyclotron resonance heating (ICRF) device is installed around the vacuum container 1. This high frequency secondary heating device 109 includes a plurality of high frequency heating antennas (hereinafter,
Loop antennas) are provided, and high-frequency current is supplied to these loop antennas via a coaxial power supply line to further heat the plasma 102 in the vacuum container 101. In FIG. 6, 110 is a vacuum exhaust device, 1
11 indicates a shield.

7 to 9 show the basic structure of a conventional loop antenna. This loop antenna 501 has a center conductor 502,
It is composed of a return conductor 503 and a Faraday shield 504. The center conductor 502 is installed so as to face the plasma 102, and is connected to the inner conductor 302 of the coaxial power supply line 301. The return conductor 503 is installed behind the center conductor 502 and is connected to the outer conductor 303 of the coaxial power supply line 301.

The center conductor 502 and the return conductor 503 are connected by a short-circuit conductor 505 at the terminal end thereof as shown in FIG. 8, and the return conductor 503 is a return path of the high frequency current supplied from the high frequency secondary heating device 109. Has become. And
The Faraday shield 504 short-circuits unnecessary electric field components that do not contribute to plasma heating, is formed in a U shape so as to surround the central conductor 502, and both ends thereof are fixed to the return conductor 503.

The loop antenna 501 having such a basic structure is used for the plasma 1
It is installed outside the first wall 112 of the fusion device to reduce the heat load due to the collision of neutrons from 02. And
Inside the Faraday shield 504, a cooling flow path 403 is formed to cool the heat load from the plasma 102, γ-rays, or nuclear heat generated by neutrons, and a cooling medium (for example, water) is flown through the cooling flow path 403. It has a structure that reduces the heat load.

As shown in FIG. 9, the cooling medium is supplied from the cooling medium supply pipe 401 connected to the return conductor 503 to the cooling flow passage 403 in the Faraday shield 504 through the cooling medium supply channel 402 in the return conductor 503. . Then, after flowing through the cooling flow path 403, it flows into the cooling medium discharge channel 404 in the return conductor 503, and is further discharged from the cooling medium discharge pipe 405 connected to the return conductor 503 to the outside. It should be noted that a part of the cooling medium in the cooling medium supply channel 402 flows through the cooling channel 406 formed in the return conductor 503 to the cooling channel 407 in the central conductor 502, and further the cooling flow in the return conductor 503. It is adapted to flow to the cooling medium discharge channel 404 via a passage 408.

[Problems of background technology]

By the way, in such a conventional loop antenna, since the Faraday shield 504 is fixed to the return conductor 503, a short circuit that links the poloidal magnetic field of the plasma 102 is formed.

Fig. 10 shows a short circuit that is formed for each Faraday shield.
A current I is induced by a sudden change in the poloidal magnetic field B _P during the disruption (a phenomenon in which plasma abruptly disappears). The induced current I acts on the toroidal magnetic field B _T and the poloidal magnetic field B _P to generate large electromagnetic forces F ₁ and F ₂ . In particular, the electromagnetic force F ₁ due to the toroidal magnetic field B _T causes the entire Faraday shield to largely deform in the poloidal direction, so a large stress is generated in the joint with the return conductor 503, and the Faraday shield 504 is cracked or broken in combination with the thermal load. And so on. In order to prevent deformation of the Faraday shield due to electromagnetic force, shortening the length of both ends of the Faraday shield will prevent deformation of the Faraday shield to some extent, but shortening the length of both ends of the Faraday shield will reduce the length of the Faraday shield. Thermal stress due to thermal expansion of the shield in the axial direction is undesirably generated at the joint between the Faraday shield and the return conductor.

[Object of the Invention]

The present invention has been made in view of such circumstances, and its purpose is to generate a U-shaped Faraday shield in the poloidal direction without causing excessive thermal stress in the coupling portion between the Faraday shield and the return conductor. Another object of the present invention is to provide an antenna for high frequency heating which can prevent deformation.

[Outline of Invention]

In order to achieve the above-mentioned object, the present invention is provided with a central conductor which is installed facing a plasma and to which a high-frequency current is supplied from a high-frequency secondary heating device through a coaxial feeder line, and a central conductor disposed behind the central conductor. In a high frequency heating antenna comprising a return conductor and a plurality of Faraday shields which are connected to the front face of the return conductor at both ends and are formed in a U shape so as to surround the central conductor, a plurality of antennas are provided on the front face of the return conductor. The plate-shaped supports are extended in the poloidal direction at intervals, and both ends of the Faraday shield are sandwiched by the supports from the poloidal direction.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

1 to 4 show an embodiment of a loop antenna according to the present invention. The loop antenna 201 includes a central conductor 202 installed facing the plasma and a central conductor 202.
And a Faraday shield 204 that short-circuits unnecessary electric field components that do not contribute to plasma heating. The inner conductor 302 of the coaxial feed line 301 is connected to the center conductor 202, and the outer conductor 303 of the coaxial feed line 301 is connected to the return conductor 203. Further, the center conductor 202 and the return conductor 203 are connected by a short-circuit conductor 205 (see FIG. 2) at the terminal end thereof, and the return conductor 203 receives the high frequency current supplied from the high frequency secondary heating device 109. It is on the way back.

On the other hand, the Faraday shield 204 is formed in a U shape so as to surround the center conductor 202, and both ends thereof are fixed to the return conductor 203. This Faraday Shield 204
A plate-shaped Faraday shield support 206 is provided between the Faraday shields near the coupling portion of the return conductor 203 and the return conductor 203. This Faraday Shield Support 20
The reference numeral 6 is integrated with the return conductor 203, and the potential difference generated between the Faraday shields 206 and the Faraday shields 206 and 204 is short-circuited as shown in FIG. A good electrical contact gasket 207 is installed.

Further, the loop antenna 201 is housed in the antenna case 208 and installed outside the first wall 112 of the nuclear fusion device. A cooling channel 403 is formed inside the Faraday shield 204, and a cooling medium (for example, water) is caused to flow through the cooling channel 403 to reduce the heat load.

As shown in FIG. 3, the cooling medium is supplied from the cooling medium supply pipe 401 connected to the return conductor 203 to the cooling channel 403 in the Faraday shield 204 through the cooling medium supply channel 402 in the return conductor 203. . Then, after flowing in the cooling flow path 403, it flows into the cooling medium discharge channel 404 in the return conductor 203, and is further discharged to the outside from the cooling medium discharge pipe 405 connected to the return conductor 203. It should be noted that a part of the cooling medium in the cooling medium supply channel 402 flows through the cooling flow passage 406 formed in the return conductor 203 to the cooling flow passage 407 in the central conductor 202, and further the cooling flow in the return conductor 203. It is adapted to flow to the cooling medium discharge channel 404 via a passage 408.

As shown in FIG. 5, the loop antenna 201 configured as described above forms a short circuit that makes an electrical circuit by interlinking with the poloidal magnetic field B _{P of} the plasma, and the induced current I flows during the plasma disruption. . As described above, the induced current I acts on the toroidal magnetic field B _T and the poloidal magnetic field B _P to generate large electromagnetic forces F ₁ and F ₂ , which largely deform the Faraday shield 204 in the poloidal direction. However, in this embodiment, the Faraday shield 204
Is supported by the Faraday shield support 206, so that deformation in the poloidal direction can be suppressed. Note that the Faraday shield 204 is also subjected to thermal expansion in the toroidal direction due to heat load, but since the Faraday shield support 206 is not constrained in the toroidal direction at all, no stress is generated due to thermal expansion.

〔The invention's effect〕

As described above, according to the present invention, a plurality of plate-shaped supports are provided on the front surface of the return conductor at intervals in the poloidal direction, and both ends of the Faraday shield are sandwiched by the supports from the poloidal direction. This prevents the Faraday shield from deforming in the poloidal direction even when electromagnetic force acts on the Faraday shield in the poloidal direction, and does not generate excessive thermal stress in the joint between the Faraday shield and the return conductor. Deformation can be prevented.

Further, according to the present invention, since the Faraday shield may be installed between the Faraday shield and the support during assembly, it is expected that the dimensional accuracy can be improved and the manufacturing cost can be reduced.

[Brief description of drawings]

1 to 5 show an embodiment of a loop antenna according to the present invention. FIG. 1 is an overall perspective view, FIG. 2 is a longitudinal sectional view, FIG. 3 is a transverse sectional view, and FIG. 4 is a Faraday shield. Fig. 5 is a perspective view showing the vicinity of the coupling portion of the return conductor, Fig. 5 is a perspective view showing the electromagnetic force acting on the loop antenna, Fig. 6 is a schematic diagram of the nuclear fusion device, and Figs. 7 to 10 are conventional loops. FIG. 7 is an overall perspective view of the antenna, FIG. 8 is a longitudinal sectional view, FIG. 9 is a transverse sectional view, and FIG. 10 is a perspective view showing electromagnetic force acting on the loop antenna. 102 …… plasma, 109 …… high frequency secondary heating device, 201 ……
Loop antenna, 202 …… Center conductor, 203 …… Return conductor, 204 …… Faraday shield, 205 …… Short conductor, 206
...... Faraday shield support, 207 …… Electrical contact gasket, 301 …… Coaxial power supply line.

Front page continuation (72) Inventor Yoshitaka Ikeda 2-2 Uchisaiwaicho, Chiyoda-ku, Tokyo Inside Japan Nuclear Research Institute (72) Inventor Yasushi Saito 1-1-1 Shibaura, Minato-ku, Tokyo Toshiba Headquarters Office (72) Inventor Nobuo Tachikawa 1-1-1, Shibaura, Minato-ku, Tokyo Inside Toshiba Headquarters Co., Ltd. (72) Inventor Kunio Wakabayashi 1-1-1, Shibaura, Minato-ku, Tokyo Inside Toshiba Headquarters Co., Ltd. ( 72) Inventor Omori, 1-1 1-1 Shibaura, Minato-ku, Tokyo TOSHIBA CORPORATION Head Office (56) References JAERI-M-83-214 "Conceptual design of fusion experimental reactor (FER) (Option B)" (February 1984) Japan Atomic Energy Research Institute P.P. 411-431

Claims (1)

[Claims] 1. A center conductor, which is installed facing a plasma and to which a high-frequency current is supplied from a high-frequency secondary heating device via a coaxial power supply line, a return conductor arranged behind the center conductor, and this return conductor. A high frequency heating antenna having a plurality of Faraday shields formed in a U-shape so as to surround both ends of the center conductor with the front surface of the return conductor, and a plurality of plate-shaped supports are provided on the front surface of the return conductor in a poloidal direction. An antenna for high frequency heating, characterized in that it is extended with a space between the two ends and both ends of the Faraday shield are sandwiched by these supports from the poloidal direction.