JPH1048369A - Neutral particle injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce thermal load injected in a beam damp and reduce the size of the beam damp. SOLUTION: This device has a neutralizing cell 4 converting ion beam 2 emitted from an ion source 1 to neutral particles, a biasing magnet 11 biasing the orbit of the ion beam 2 remaining after passing the neutralizing cell 4 and beam dumps 13a, 13b, 14a and 14b eliminating the remaining ion biased by the magnetic field of the bias magnet 11 as heat. Between the magnetic poles of the bias magnet 11, the beam dumps 13a and 13b are arranged so that the ion beam 2 goes into the beam dumps 13a and 13b before completely reflected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a neutral beam injector which is a heating device for a nuclear fusion device.

[0002]

2. Description of the Related Art FIG. 5 is a sectional view showing the structure of a conventional neutral particle injector. As shown in FIG. 5, the ion beam 2 extracted from the ion source 1 is neutralized by passing through a vacuum cell 3 and a neutralization cell 4. Only the neutral particles neutralized by the neutralization cell 4 are supplied to the vacuum vessel 5
Through the drift tube 6 and into the plasma 8 of the fusion device main body 7.

A cryopump 9 for evacuating the vacuum is provided in the vacuum vessel 3, while a calorie meter 10 and a deflecting magnet 11 for deflecting the path of the ion beam 2 are provided in the vacuum vessel 5. And beam dumps 12 for removing residual ions deflected by the deflection magnet 11 as heat.

When the ion beam 2 passes through the neutralization cell 4 and is converted into a neutral particle beam, a part of the ion beam remains as an ion. The ion trajectory of the residual ions is bent by the magnetic field of the deflecting magnet 11 installed in the vacuum vessel 5, enters the beam dumps 12, 12 as a thermal load, and is removed.

Here, a method of deflecting an ion beam will be described. Ion beam deflection methods are classified into a transmission type and a reflection type. FIG. 6 shows the configuration of a conventional transmission type ion beam orbit and a beam dump, and FIG. 7 shows a conventional reflection type ion beam. The configuration of the orbit and the beam dump are shown respectively. However, FIGS. 6 and 7 show only the trajectory of the negative ion beam, and the positive ions are not shown because they are vertically symmetric with respect to the beam axis.

In the case of the transmission type, the trajectory of the ion beam 2 is bent by the deflecting magnet 11 as shown in FIG. The transmission type beam dumps 12, 12 are arranged at positions substantially parallel to the beam axis to receive the beams.

[0007] In the case of the reflection type, as shown in FIG.
Due to the deflection, the beam dumps 12, 12 are arranged at positions perpendicular to the beam axis.

The beam dumps 12 and 12 are provided with cooling pipes arranged side by side in the ion beam incident area, and when a straight pipe is used depending on the value of the incident heat load, a twisting tape is inserted into the cooling pipe to reduce the heat removal ability. In some cases, an increased swirl tube is used.

[0009]

However, in the above-described conventional neutral particle injector, the beam dump 1
In the structures 2 and 12, the heat load of the incident ion beam 2 and the arrangement of the beam dumps 12 and 12 receiving the heat load pose a problem. Problems will be described for each of the beam deflection methods described above.

In the case of the transmission type deflection method, the ion beam 2 that has passed through the neutralization cell 4 is converged by the magnetic field of the deflection magnet 11 after passing through the deflection magnet 11 as shown in FIG. Therefore, the heat load per unit area when entering the beam dumps 12 and 12 increases. In order to reduce the heat load, it is necessary to reduce the intensity of the magnetic field of the deflecting magnet 11 and make the incident angle of the ion beam 2 incident on the beam dumps 12, 12 shallow.

In this case, since the beam area expands in the beam axis direction, the length of the beam dumps 12, 12 must be increased. In addition, long beam dumps 12, 12
Therefore, the size of the vacuum vessel 5 must be increased. Further, when the length of the beam dumps 12 and 12 increases, the pressure loss when flowing the cooling water increases, and there is a problem that the pump capacity of the entire apparatus increases. And beam dump 1
When the length of the beam 2 or 12 is increased, there is also a problem that thermal deformation caused by a temperature rise at the time of beam incidence becomes large.

In the case of the reflection type deflection method, as shown in FIG. 7, the ion beam 2 converges in the magnetic field region of the deflecting magnet 11, then diverges again, and has a beam shape almost similar to the beam distribution at the time of incidence. The light enters the dumps 12, 12. Therefore, although the heat load can be kept low, the ion beam 2
Requires a magnetic field region to deflect the beam by 180 °, and there is a problem that the deflection magnet 11 and the beam dumps 12 are enlarged accordingly.

The present invention has been made in view of the above-described circumstances, and has as its object to provide a neutral particle injector that reduces the heat load incident on the beam dump and reduces the size of the beam dump. And

[0014]

In order to solve the above-mentioned problems, a first aspect of the present invention is an ion source for generating an ion beam, and an ion beam emitted from the ion source is converted into neutral particles. Neutralizing cell, a deflecting magnet that deflects the trajectory of the ion beam remaining after passing through the neutralizing cell, and a beam dump that removes residual ions deflected by the magnetic field of the deflecting magnet as heat. In the incident device, the beam dump may be arranged between the magnetic poles of the deflection magnet, and may be incident on the beam dump before the ion beam is completely reflected.

According to a second aspect of the present invention, the beam dump according to the first aspect is divided into a plurality of parts, a horizontal beam dump installed between the magnetic poles of the deflecting magnet substantially parallel to the beam axis, and a beam dump installed perpendicular to the beam axis. And a vertical beam dump.

A third aspect of the present invention is characterized in that the beam dump according to the first or second aspect has a cooling pipe structure in which a swirl pipe is provided in a high heat load part by an ion beam and a straight pipe is provided in a low heat load part.

A fourth aspect of the present invention is characterized in that the cooling pipe provided in the low heat load portion according to the third aspect has a double pipe structure.

A fifth aspect of the present invention is characterized in that the cooling water flowing to the beam dump receiving the high heat load and the cooling water of the beam dump receiving the low thermal load flow in series.

A sixth aspect of the present invention is characterized in that an anticorrosion coating is applied to the inner surface of the cooling pipe of the beam dump according to the first aspect.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a first embodiment of a neutral particle injector according to the present invention. Note that the same parts as those in the conventional configuration are denoted by the same reference numerals as in FIG.

As shown in FIG. 1, the neutral particle injector is
An ion source 1 for generating an ion beam 2, a neutralization cell 4 for converting the ion beam 2 emitted from the ion source 1 into neutral particles, and ions remaining after passing through the neutralization cell 4 are removed. Magnet 11 for deflecting the trajectory of the ion beam 2 and a horizontal beam dump 13 for removing residual ions deflected by the deflection magnet 11 as heat.
a, 13b and vertical beam dumps 14a, 14b;
And a drift tube 6 through which the neutral particles pass before being incident on the plasma 8 of the fusion device main body 7.

A cryopump 9 for evacuating the vacuum is provided in the vacuum vessel 3, and a deflecting magnet 11, horizontal beam dumps 13 a and 13 b, and vertical beam dumps 14 a and 14 b are provided in the vacuum vessel 5. ing.

Here, 13a is a horizontal beam dump for negative ions, 13b is a horizontal beam dump for positive ions,
a indicates a vertical beam dump for negative ions, and 14b indicates a vertical beam dump for positive ions. The horizontal beam dumps 13a, 13b are installed in the magnetic pole gap of the deflecting magnet 11, and the vertical beam dumps 14a,
14b is provided on the neutralization cell 4 side of the deflection magnet 11.

Next, the operation of the present embodiment will be described.

The ion beam 2 extracted from the ion source 1 is converted into neutral particles through a neutralization cell 4. However, a part thereof remains as ions, and FIG. 1 shows only the remaining ion beam 2. Then, when the converted neutral particles enter the plasma 8 of the fusion device 7,
After passing through the neutralization cell 4, the trajectory of the remaining ion beam 2 is bent by the magnetic field generated by the deflection magnet 11. The bent ions are then transferred to horizontal beam dumps 13a, 13a.
b, incident on the vertical beam dumps 14a, 14b and removed as heat.

Also, the deflected ion beam 2 is approximately 9
When the beam is deflected by 0 °, the beam is incident on a horizontal beam dump 13 a placed horizontally between the magnetic poles of the deflecting magnet 11 and the beam orbit. Horizontal beam dumps 13a, 13 between the deflecting magnets 11
By installing b, the ion beam 2 enters the horizontal beam dump 13a at a time point of distribution that is slightly narrower than the spread point at the time of leaving the neutralization cell 4, so that the height dimension of the deflecting magnet 11 is reflected. It can be shorter than the mold.

However, the horizontal beam dump 13a alone cannot receive all of the deflected ion beam 2.
Therefore, the ion beam 2 is further deflected to receive the unacceptable ion beam 2, and a vertical beam dump 14a is arranged in a portion perpendicular to the beam axis in a portion passing through the magnet region. Since the vertical beam dump 14a receives only the ion beam 2 that has not previously entered the horizontal beam dump 13a, it is sufficient to cover an area shorter than the beam dump length in the case of the complete reflection type.

There are two types of ions, positive and negative, depending on the charge in the ion beam. Although FIG. 1 does not show only one type of ion beam trajectory, the other one type of ion beam has the opposite polarity, so that the deflection method is reversed. Therefore, the horizontal ion beam dump 13 described above is used.
b and the vertical ion beam dump 14b are similarly arranged at positions where the beam axis is a symmetry axis.

Therefore, a horizontal beam dump 13b for positive ions and a horizontal beam dump 13a for negative ions are provided in the gap of the deflecting magnet 11,
Vertical beam dump 14b for positive ions on the neutralization cell 4 side
And a vertical beam dump 14a for negative ions.

As described above, according to the present embodiment, the horizontal beam dumps 13a and 13b are provided between the magnetic poles of the deflecting magnet 11, and are incident on the horizontal beam dump 13a before the ion beam 2 is completely reflected. The heat can be removed by the horizontal beam dump 13a without converging the beam 2. Further, the size of the deflecting magnet 11 can be reduced and the vacuum vessel 5 can be reduced in size as compared with the case of a completely reflective type.

Horizontal beam dumps 13a and 13b are provided between the deflecting magnet 11 and the horizontal axis of the beam axis, and vertical beam dumps 14a and 14b are provided perpendicular to the beam axis.
The length of each beam dump can be shortened by installing. Thereby, the pressure loss of the cooling water flowing in the beam dump can be reduced, and the thermal deformation due to the beam incidence can be suppressed.

Further, two beam dumps are added to the horizontal beam dumps 13a and 13b and the vertical beam dumps 14a and 14b.
By adopting the divided structure, the unit can be made into a unit, and the weight of one unit at the time of assembly can be reduced. As a result, it is possible to increase the work efficiency during assembly and disassembly.

That is, by dividing the beam dump, if there is a difference in the heat load due to each beam incidence, it is possible to adopt a cooling structure that matches each heat load. In addition, when assembling and disassembling, the deflection magnet 11, the vertical beam dumps 14a and 14b, and the horizontal beam dumps 13a and 13b are each a unit.
The weight and shape of the unit are reduced.

FIGS. 2A and 2B are perspective views showing a cooling pipe of a beam dump in a second embodiment of the neutral particle injector according to the present invention. Parts corresponding to those in the first embodiment will be described with the same reference numerals. In the second embodiment, the configurations of the deflecting magnet and the beam dump are the same as those of the first embodiment.

By the way, since the ion beam 2 that has passed through the neutralization cell 4 has a distribution, it does not have a uniform heat load in the beam region. Therefore, horizontal beam dump 1
The incident thermal loads differ between 3a and 13b and the vertical beam dumps 14a and 14b. When the difference in the heat load value is large, the beam dump subjected to the high heat load uses a swirl tube 16 in which the torsion tape 15 is inserted into the inside of the cooling pipe to increase the cooling capacity as shown in FIG.

Although the swirl pipe 16 has an extremely high heat removal ability as compared with a straight pipe, the pressure loss when flowing cooling water is large. For this reason, as shown in FIG. 1, by dividing into horizontal beam dumps 13a and 13b and vertical beam dumps 14a and 14b, the length per one can be shortened and the pressure loss in each cooling unit can be reduced. .

When the difference in heat load between the horizontal beam dumps 13a, 13b and the vertical beam dumps 14a, 14b is large, the swirl tube 16 is used for the beam dump receiving a high heat load, and the beam dump having a low incident heat load is used. A straight pipe 17 as shown in FIG. By changing the cooling structure for each unit as described above, it is possible to optimize the cooling water amount and the cooling water pressure.

As described above, according to the present embodiment, the swirl pipe 16 is provided in the high heat load part, and the straight pipe 17 is provided in the low heat load part.
By using a beam dump configuration using the above, a cooling configuration that matches the incident thermal load can be achieved, the loss can be reduced, and the cooling structure can be optimized.

Further, by employing a structure in which the cooling water of the divided beam dump is flowed in series from the high heat load portion to the low heat load portion, the required cooling water flow rate can be reduced while the cooling capacity is secured. Can be achieved.

FIGS. 3A and 3B are a perspective view showing a beam dump in a third embodiment of a neutral particle injector according to the present invention, and a sectional view showing a cooling pipe thereof.

In this embodiment, a double tube is used as a beam dump for a low-temperature heat load, and FIGS. 3A and 3B are used.
Is installed between the deflection magnets 11, and a header 19 is installed outside the deflection magnet 11.

As described above, according to the present embodiment, the use of the double-tube beam dump 18 in the low heat load portion requires a header for cooling water only on one side of the cooling pipe, resulting in a compact structure as a whole. In addition, the configuration of the cooling pipe in the vacuum vessel 5 can be simplified. In addition, since only one side restricts thermal expansion, stress due to thermal deformation is reduced.

FIG. 4 is a cross-sectional view showing a cooling pipe of a beam dump in a fourth embodiment of the neutral particle injector according to the present invention.

In this embodiment, when copper is used as the material of the cooling pipe 20, the inner surface of the cooling pipe 20 is coated with an anticorrosive thin film 21 such as titanium (Ti). By forming the thin film 21, erosion of the inner wall surface of the cooling pipe 20 can be prevented while the cooling water flows. The life of the beam dump is determined by the erosion in the cooling pipe described above, in addition to the repeated thermal stress. Therefore, by coating the cooling pipe 20 with the thin film 21 of titanium (Ti), the replacement period of the beam dump can be extended, and the maintenance period can be lengthened.

[0046]

As described above, according to the first aspect of the present invention,
According to, the beam dump is arranged between the magnetic poles of the deflection magnet and the ion beam is made to enter the beam dump before it is completely reflected, so that the heat load on the beam dump is reduced without converging the ion beam. While removing heat. In addition, the size of the deflection magnet and the beam dump can be reduced, and the size of the vacuum container can be reduced, as compared with the case of the complete reflection type.

According to the second aspect, the beam dump according to the first aspect is divided into a plurality of parts, and the horizontal beam dump is installed between the magnetic poles of the deflecting magnet substantially in parallel with the beam axis, and is installed perpendicular to the beam axis. With the provided vertical beam dump, the length per beam dump can be reduced. This can reduce the pressure loss of the cooling water,
Thermal deformation due to beam incidence can also be suppressed. Also,
By forming the beam dump into a divided structure, the beam dump can be unitized, and the weight of one unit at the time of assembly can be reduced.
As a result, work efficiency during assembly and disassembly can be increased.

According to the third aspect, the beam dump according to the first or second aspect has a cooling pipe structure in which a swirl pipe is provided in a high heat load part by an ion beam and a straight pipe is provided in a low heat load part. Thus, a cooling configuration that matches the heat load to be performed can be achieved, loss can be reduced, and the cooling structure can be optimized.

According to the fourth aspect, the cooling pipe provided in the low heat load portion according to the third aspect has a double pipe structure,
The cooling pipe header of this cooling pipe is needed only on one side,
Cooling piping can be simplified. In addition, since only one side restricts thermal expansion, stress due to thermal deformation is reduced.

According to the fifth aspect of the present invention, the cooling water flowing to the beam dump receiving the high heat load and the cooling water of the beam dump receiving the low thermal load are flowed in series to secure the cooling capacity. In addition, the required cooling water flow rate can be reduced, and the cooling structure can be made compact.

According to the sixth aspect of the present invention, since the inner surface of the cooling pipe of the beam dump according to the first aspect is provided with an anticorrosion coating, the erosion of the pipe wall by the cooling water flow of the beam dump can be prevented. The use period is extended, and the maintenance period can be lengthened.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of a neutral particle injector according to the present invention.

FIGS. 2A and 2B are perspective views showing a cooling pipe of a beam dump in a second embodiment of the neutral particle injector according to the present invention.

FIGS. 3A and 3B are perspective views showing a beam dump in a third embodiment of the neutral particle injector according to the present invention;
Sectional drawing which shows the cooling pipe.

FIG. 4 is a sectional view showing a cooling tube of a beam dump in a fourth embodiment of the neutral particle injector according to the present invention.

FIG. 5 is a sectional view showing a configuration of a conventional neutral particle injector.

FIG. 6 is a cross-sectional view showing a transmission type beam dump configuration in a conventional neutral particle injector.

FIG. 7 is a cross-sectional view showing a reflection type beam dump configuration in a conventional neutral particle injector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ion source 2 Ion beam 3 Vacuum container 4 Neutralization cell 5 Vacuum container 6 Drift tube 7 Fusion device main body 8 Plasma 9 Cryopump 11 Deflection magnet 13a, 13b Horizontal beam dump 14a, 14b Vertical beam dump 15 Twist tape 16 Swirl Pipe 17 Straight pipe 18 Double pipe beam dump 19 Header 20 Cooling pipe 21 Thin film

Claims (6)

[Claims] 1. An ion source for generating an ion beam, a neutralization cell for converting an ion beam emitted from the ion source into neutral particles, and a trajectory of an ion beam remaining after passing through the neutralization cell. In a neutral particle injector having a deflecting magnet to deflect and a beam dump for removing residual ions deflected by the magnetic field of the deflecting magnet as heat,
A neutral particle injector, wherein the beam dump is arranged between magnetic poles of the deflection magnet, and is incident on the beam dump before the ion beam is completely reflected. 2. The beam dump is divided into a plurality of parts.
2. The neutral particle injector according to claim 1, further comprising a horizontal beam dump installed between the magnetic poles of the deflection magnet substantially parallel to the beam axis, and a vertical beam dump installed perpendicular to the beam axis. . 3. The beam dump has a cooling pipe structure in which a swirl pipe is provided in a high heat load part by an ion beam, and a straight pipe is provided in a low heat load part.
Or the neutral particle injector according to 2 above. 4. The neutral particle injector according to claim 3, wherein the cooling pipe provided in the low heat load portion has a double pipe structure. 5. The neutral particle injector according to claim 3, wherein cooling water flowing to the beam dump receiving a high heat load and cooling water of the beam dump receiving a low heat load flow in series. 6. The neutral particle injector according to claim 1, wherein the beam dump is provided with an anticorrosion coating on an inner surface of the cooling pipe.