JPH0789155B2 - High frequency heating device - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a high frequency heating device for plasma heating in a nuclear fusion (experimental) device and the like, and more particularly to a reduced hybrid wave band high frequency heating device.

[Technical background of the invention]

Plasma heating in the nuclear fusion (experimental) apparatus is performed by the second step heating method such as a neutral particle heating method or a high frequency heating method in addition to the Joule heating in which an electric current is passed through plasma. Here, the high frequency heating method is a method of increasing the temperature of the plasma by absorbing the energy of the high frequency electromagnetic wave in the plasma, and there are various methods depending on the frequency used, and one of them is the reduced hybrid wave high frequency heating. One example is shown in FIG.

That is, a high-frequency oscillator 1 that generates and amplifies high-power electromagnetic waves, a high-frequency transmission system 3 that transmits the electromagnetic waves generated by this high-frequency oscillator 1 to a nuclear fusion (experimental) device 2, and a plasma 4 that emits electromagnetic waves from the terminals of the transmission system 3. It is composed of a high-frequency coupling system 5 that emits to the.

Above all, since the high frequency coupling system 5 is inserted from the port 2a of the nuclear fusion (experimental) device 2, it must be provided in a narrow space because of size restrictions.

FIG. 5 shows a more detailed structure of the high frequency coupling system 5. Fifth
In the figure, 6 is a rectangular waveguide, and usually a plurality of waveguides 6 are arranged in a grid. The electromagnetic wave is transmitted through the respective waveguides 6 and is emitted to the plasma 4. These waveguides 6 are entirely covered with a waveguide bundle container 7. Further, the waveguide container 7 is provided with a cooling passage 8,
In some cases, a coolant such as gas may flow in the passage 8 to cool the waveguide bundle container 7 and the waveguide 6. A connection waveguide 9 is connected to the rear end of the coupling system 5 and is connected to the transmission system 3.

[Problems of background technology]

On the plasma front end side, however, the waveguide 6 is
It is desirable to make the pitch of the waveguides 6 narrower because the electromagnetic waves can be efficiently injected into the plasma by making the gap between the adjacent waveguides 6 small.

On the other hand, the output of the incident electromagnetic wave is increased to satisfy each fusion condition, and the high frequency loss generated in the waveguide 6 is also increased. In this case, considering the incident heat from the plasma 4 as well, it becomes difficult to cool the waveguide 6. Usually, the waveguide 6 is made of stainless steel, and its thermal conductivity is poor, and when the surroundings are air-cooled, it is difficult for a fluid to flow in the gaps between the waveguides 6 and the temperature of the waveguide 6 is low. Can reach hundreds of degrees. Therefore, the thermal stress generated in the waveguide 6 also becomes large, which causes a problem in mechanical strength.

In addition, recently, in order to efficiently enter electromagnetic waves, it has been considered that the long sides of the rectangular waveguide 6 are closely contacted in a horizontal row. In that case, cooling of the waveguide 6 is becoming more and more difficult.

[Object of the Invention]

The present invention has been made based on the above circumstances, and an object thereof is to provide a high-frequency heating device capable of efficiently cooling a waveguide bundle in the reduced hybrid wave band, and thus capable of plasma heating with high output and high efficiency. It is in.

[Outline of Invention]

In order to achieve such an object, a high-frequency heating apparatus according to the present invention is a high-frequency heating apparatus having a coupling system composed of a plurality of waveguides, wherein at least gap pieces of a good heat conductor are introduced between the waveguides. It is characterized in that it is inserted so as to be in close contact with the horizontal side wall of the wave guide, and a cooling means for indirectly cooling the waveguide is provided at the end of the extending portion of the spacing piece.

According to such a configuration, the spacing piece is used as the heat conducting medium without circulating the cooling material between the waveguides, and the waveguide is cooled by the cooling means provided at the end of the extension portion of the spacing piece. An indirect cooling method is realized, whereby Joule heat generated in the waveguide can be removed by indirect cooling using heat conduction through the spacer. Moreover, since the waveguide can be efficiently cooled without flowing a coolant between the waveguides, it is possible to make the gap between the side walls of the waveguide in the vertical direction small and to bring them into close contact with each other. Therefore, electromagnetic waves can be more efficiently incident in a limited space.

[Embodiment of the Invention] An embodiment of the high-frequency heating apparatus according to the present invention will be described below with reference to FIG. FIG. 1 is a sectional view of a plurality of waveguides 6.

As shown in FIG. 1, a spacing piece 10 is sandwiched between the upper and lower waveguides 6. In addition, the spacing piece 10 extends to both sides of the waveguide 6,
The pipe 11 is fixed to both ends 10a by welding or brazing.

In FIG. 2, a space piece 12 is housed between the upper and lower waveguides 6, and an extension 12a is formed in the space between the adjacent waveguides 6 in the space piece 12 to form the extension portion 12a. This is an example in which the pipe 11 is housed in the portion 12a.

In FIG. 3, the spacing piece 13 is housed between the waveguides 6,
The end of 13 is extended, and this extension 13a is bolted to the waveguide container 7 with a bolt 14. This waveguide container 7 is provided with a cooling passage 8 to cool itself. That is, the spacing piece 13 is connected to the cooling passage 8 via the waveguide container 7.
Since it is thermally connected to the spacing piece 13, the spacing piece 13 can be indirectly cooled.

In the above, the spacing pieces 10, 12, 13 may have a flat cross section so as to be sandwiched between the upper and lower waveguides 6, or the extending portions 12a, 13b so that the waveguide 6 can be accommodated as shown in the figure. Therefore, irregularities may be provided. In this case, the waveguide 6 fits in the recess. The length of the spacer pieces 10, 12, 13 may be appropriately determined by the amount of heat load.

Next, the operation of this embodiment configured as described above will be described.

That is, since a high frequency current flows through the waveguide 6, heat is generated due to Joule loss. Further, heat is input from the plasma 4 due to the tip portion on the plasma side. The generated heat is transmitted to the spacer pieces 10, 12, 13 made of a good heat conductor material, for example, copper.

Further, heat removal is performed by the pipe 11 provided on the spacing piece 10 in FIG.
Let the refrigerant flow in. In FIG. 2, a coolant such as water is flowed through the pipe 11 provided on the spacing piece 12. In the case of FIG. 3, the amount of heat is transferred from the spacing piece 13 to the waveguide container 7 by heat conduction, and the refrigerant is passed through the cooling passage 8 provided in the waveguide container 7 to remove heat.

Also, if hot gas is passed through the pipe 11 or the cooling passage 8,
The waveguide 6 can also be heated. By performing this heating when a high frequency is not passed, it has an effect of reducing the gas released from the inner surface of the waveguide 6. This helps to reduce the inflow of impurities into the plasma 4.

In this way, it is possible to play both roles of cooling and heating by changing the refrigerant.

As described above, according to this embodiment, the following operational effects are obtained.

According to this embodiment, since the waveguides 6 can be effectively cooled, the gap G between the adjacent waveguides 6 shown in FIG.
Is small, that is, the waveguide 6 has a high arrangement efficiency. Therefore, it is possible to increase the number of waveguides 6 per unit space. This is because a large number of waveguides 6 can be inserted by the relatively small port 2a of the nuclear fusion (experimental) device, and high frequency input is possible. The efficiency can be improved.

Here, the difference between the method of indirectly cooling the waveguide 6 using the spacing piece of the present embodiment and the conventional method of directly cooling the waveguide 6 will be described.

That is, the smaller the gap G between the adjacent waveguides 6, the better the spatial efficiency, and the higher the efficiency of high frequency input. In that case, assuming that the outer circumference of the waveguide 6 is gas-cooled as in the conventional case, its thermal conductivity is about several W / m ² h ° C. Further, the heat generation of the waveguide 6 is about several hundred W / m ² h ° C. even if the high frequency is pulsed through the plasma 4. This indicates that the temperature of the gas and the temperature of the waveguide 6 have a temperature difference of up to several hundred degrees.

On the other hand, when the spacing pieces 10, 12, 13 are interposed between the waveguides 6, if the material is copper, the thermal conductivity is about 380 W / m ² h ° C. Further, the amount of heat generated by the waveguide 6 is about 100 W / m ² h ° C even when the pulse operation is performed. Assuming that the temperature difference between the heat receiving surfaces of the interval pieces 10, 12, 13 and the pipe 11 is 20 ° C, the heat transfer amount can be specified by the following equation.

Q = λ ・ (ΔT / l) ・ S Now, ΔT: Temperature difference to pipe 11 (= 20 ° C) l: Distance from center of waveguide 6 to pipe 11 (= 0.1m) λ = Heat conduction Rate (= 380W / m ² h ° C) S = Gap between upper and lower waveguides 6 (0.005m) and unit length (1m)
Then (= 0.005 m ² ), the heat quantity Q is Q = 380 W / mh.

This is sufficient to cool the heat generation rate W / mh per unit length of the waveguide 6.

That is, it has been proved that the method of indirectly cooling the waveguide 6 using the spacing piece of the present embodiment is a better cooling method than the conventional method of directly cooling the waveguide 6 with gas.

In particular, as shown in FIG. 3, the gap G is small and the waveguide 6
When the two are in close contact with each other, the amount of heat transfer is increased, which is effective. Further, since the heat input to the waveguide 6 is increased in the portion of the tip end of the waveguide 6 which is close to the plasma 4, it can be said that the cooling efficiency is improved in this portion.

〔The invention's effect〕

As described in detail above, the high-frequency heating device of the present invention is a high-frequency heating device provided with a coupling system composed of a plurality of waveguides, in which at least a gap piece of a good thermal conductor is provided between the waveguides. It is characterized in that it is inserted so as to be in close contact with the horizontal side wall of the tube, and a cooling means for indirectly cooling the waveguide is provided at the end of the extending portion of the spacing piece.

According to such a configuration, the spacing piece is used as the heat conducting medium without flowing the coolant between the waveguides, and the waveguide is cooled by the cooling means provided at the end of the extension portion of the spacing piece. An indirect cooling method is realized, whereby Joule heat generated in the waveguide can be removed by indirect cooling using heat conduction through the spacer. Moreover, since the waveguide can be efficiently cooled without flowing a coolant between the waveguides, it is possible to make the gap between the side walls of the waveguide in the vertical direction small and to bring them into close contact with each other. Therefore, electromagnetic waves can be more efficiently incident in a limited space.

[Brief description of drawings]

1 to 3 are views showing the essential parts of an embodiment of a high-frequency heating device according to the present invention, FIG. 4 is a view showing a coupling system of the high-frequency heating device, and FIG. 5 is a view showing a conventional example. There is. 1 ... High-frequency oscillator, 2 ... Nuclear fusion (experimental) device, 3 ...
High frequency transmission system, 4 Plasma, 5 High frequency coupling system, 6 Waveguide, 7 Waveguide bundle container, 8 Cooling passage, 9 Connection waveguide, 10, 12 , 13 …… Spacing piece, 11 ……
Piping.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenzo Masuda, 2-4 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa, Kanagawa Prefecture (72) Inside the Keihin Office, Toshiba Corporation (72) Issei Nakamoto, Suehiro-cho, Tsurumi-ku, Yokohama 2-4, Toshiba Keihin Office (56) References JP-A-61-245499 (JP, A)

Claims (1)

[Claims] 1. A high-frequency heating apparatus having a coupling system composed of a plurality of waveguides, wherein a gap piece of a good heat conductor is adhered between said waveguides at least with a horizontal side wall of each waveguide. A high-frequency heating device, characterized in that it is inserted as described above, and a cooling means for indirectly cooling the waveguide is provided at the end of the extending portion of the spacing piece.