JP5019200B2 - Ion source electrode - Google Patents

Description

The present invention relates to an ion source electrode for generating a high-speed ion beam by accelerating ions in plasma in an ion source applied to a neutral particle injection device, an ion mixing device, or the like of a fusion apparatus.

  In a neutral particle injection device or ion mixing device of a fusion device, an ion source that generates a high-speed ion beam from plasma is used.

  For example, as shown in FIG. 8, an ion source 32 of a neutral particle injection device 31 used in a fusion apparatus has a gas 33 such as hydrogen introduced therein, and a plasma generation unit 35 having a filament 34 passes through the filament 34. Plasma is generated by arc discharge. Then, the ions in which the gas in the plasma is ionized are extracted from the plasma by an electric field formed by applying a high voltage to the electrode 36 by a high voltage power source 37 and accelerated to generate a high-speed ion beam 40 having high energy. It is what happens.

  Since the ion beam 40 is bent by the magnetic field of the coil of the fusion apparatus as it is, the neutron beam 41 is passed through the neutron cell 39 filled with gas and the kinetic energy is preserved by collision reaction between ions and gas. Into the core plasma 42.

  The electrode 36 for accelerating ions in the ion source described above is composed of three stages or five stages (not shown) as shown in the figure, and draws out the ion beam from the plasma through ion beam extraction holes formed in a large number on the electrode. In particular, the first-stage electrode closest to the ion source is in direct contact with the high-temperature ion beam. For this reason, the electrode is formed with a cooling channel that lowers the thermal load of the electrode itself and improves the durability.

  Usually, the cooling channel is provided between a plurality of ion beam extraction holes formed in order to effectively perform cooling.

  FIG. 9 is a cross-sectional view showing an example of a conventional first-stage ion source electrode.

  That is, the ion source electrode 43 is provided with a number of beam extraction holes 44 formed so as to penetrate through electrode plates 43a and 43b made of molybdenum material, which has high heat resistance, a small linear expansion coefficient, and is easily available. A cooling channel 45 through which the refrigerant flows is formed adjacent to the beam extraction hole 44.

  The structure of the ion source electrode 43 will be described in more detail. Two electrode plates 43a and 43b made of molybdenum are processed on one plate, a cooling channel 45 is processed on one plate, and a flat plate is used on the other plate. A plate made of molybdenum is diffusion-bonded using a hot press apparatus capable of pressurizing at a high temperature in a vacuum, and has a structure having a beam extraction hole 44 through electrode plates 43a and 43b.

  By the way, when an ion beam is extracted using the ion source electrode 43 having the above-described configuration, pure water as a coolant is passed through the cooling channel 45 in order to reduce the heat load of the ion source electrode itself. .

  However, molybdenum is used as a material for the electrode plate because it can withstand high heat load and maintain the accuracy of the position due to the heat load of the beam extraction hole. However, this molybdenum material has a drawback that it is corroded by cooling water such as pure water because the material is made of sintered metal. Therefore, according to the experience of the present inventors, the lifetime as an electrode is as short as 1 to 2 years. For this reason, an ion source power source that is resistant to corrosion and has excellent corrosion resistance and a long lifetime is desired.

  Therefore, as a countermeasure, the following ion source power supply manufacturing method has been proposed.

(1) The groove surface of the grooved molybdenum plate provided with grooves for cooling water passages is coated with nickel to prevent corrosion due to cooling water, and a molybdenum flat plate coated with nickel is overlaid thereon to perform diffusion bonding. A method of forming a cooling water passage hole covered with nickel, and then processing an ion beam hole (PTL 1). In particular, this electrode is mounted on the opening side of the plasma generation unit and is made of molybdenum, which is a refractory metal and a high melting point material suitable for an electrode for forming an electric field.

(2) In the same manner as described above, in the ion source electrode mainly composed of a molybdenum plate, a superposed plate structure in which the molybdenum plate is integrated by diffusion bonding, and the inner peripheral surface of the cooling hole for the cooling water passage is a ceramic coating layer. In this case, a method of forming a ceramic coating layer by vapor deposition of ceramics (Patent Document 2).

(3) The ion source electrode for accelerating the ion beam is mainly composed of a superposed tantalum plate with diffusion bonding of the tantalum plate. When diffusion bonding of the tantalum plate, diffusion is performed on the bonding surface via titanium. Joining method (Patent Document 3).

(4) In a vacuum vessel provided with a heater capable of diffusion bonding in a vacuum or gas atmosphere, the electrode element is provided between a grooved plate and a flat plate, which are a pair of electrode elements facing each other. A method in which a liquid phase is generated by a eutectic reaction at a temperature lower than the melting point of the material to form a thin film layer that is solid-solved with the electrode element, and integrated by diffusion bonding using the eutectic reaction (Patent Document 4). In this case, the grooved plate is formed with a narrow groove that constitutes a cooling hole for allowing the coolant to flow and a beam extraction hole for extracting the ion beam.

The feature of this method is that by using the liquid phase generated by the eutectic reaction, diffusion bonding can be performed only by applying a relatively small pressure, so that the liquid phase diffuses and solidifies, and gaps and voids disappear. It is possible to obtain a good bonding surface with excellent adhesion on the entire bonding surfaces of both electrode elements without deforming the entire electrode, deforming or filling the cooling holes of the grooved plate. In addition, there is an advantage that the narrow groove formed for the cooling hole is deformed by the applied pressure, so that the cooling efficiency is reduced and the dimensional accuracy as a product is hardly lowered.
Japanese Patent Application No. 3-129638 Japanese Patent Application No. 5-029093 Japanese Patent Application No. 6-314600 Japanese Patent No. 2523742

  The ion source electrode manufactured by the above method (1) is designed to prevent the molybdenum electrode plate from being corroded by cooling water and to extend the life of the product by coating nickel on the molybdenum electrode plate. However, it is difficult to have a sound coating of nickel in the water channel of the electrode plate made of molybdenum, and sometimes it corrodes from the unhealthy part of the coating, causing a leakage of cooling water itself.

  The reason why the soundness of the coating is difficult to obtain is that the groove to be a water channel is very thin, 2 mm to 3 mm, and coating inside such a thin groove is required. Even if a state-of-the-art coating technique such as electroplating, PVD (physical vapor deposition), or CVD (chemical vapor deposition) is used as the coating method or means, it is difficult to coat the inside of the narrow groove. Further, the groove shape is a square groove in order to increase the cooling efficiency, and it is very difficult to coat the groove so that the coating thickness in the groove and in the corner portion is uniform and sound.

  The ion source electrodes manufactured by the above methods (1), (2), and (3) are all made of molybdenum or tantalum, which is a high melting point material, and the structure is a grooved plate and a flat plate. Are integrated by diffusion bonding. In order to perform diffusion bonding of a grooved plate made of molybdenum or tantalum, which is a high melting point material, and a flat plate, it is required to strictly observe the conditions regarding the temperature, atmosphere, and pressure during the bonding. Furthermore, these conditions must be kept stable for a fixed time.

  The temperature required for diffusion bonding is generally said to be at least 0.7 times the melting point of the material or higher than the recrystallization temperature of the material. The atmosphere should be an atmosphere that does not cause problems such as surface oxidation of the material to be joined at the temperature required for diffusion bonding. Therefore, bonding in a high vacuum or an inert gas atmosphere such as argon or helium is required. The appropriate pressure is determined by the surface roughness of the bonding surface and the bonding temperature. If the temperature is high, the applied pressure is small. If the temperature is low, the applied pressure must be set large. Further, regarding the surface roughness, the pressurizing force must be set low when the surface to be joined is fine, and conversely, the pressurizing force must be set high when the joint surface is rough.

  In short, contact (adhesion) between the joint surfaces is important. The time for maintaining this condition depends on the temperature, atmosphere, and pressure. That is, if the temperature is high and the pressure is high, the interdiffusion proceeds positively and the holding time is short.

  However, in ion source electrode plate bonding by diffusion bonding, when the accuracy of the bonding surface that facilitates bonding, for example, the surface roughness is maintained at 5S or less, buffing is required after machining, and the flatness In order to maintain the degree of cleanliness, and also cleanliness, care must be taken during storage and after processing. In particular, the plate thickness of the ion source electrode plate is as thin as about 3 to 10 mm, for example, and it is difficult to control the pressure while uniformly pressing the entire joint surface of this member and suppressing the deformation of the groove. Even if the device is made, it becomes a very complicated and expensive facility. Such diffusion bonding has a high manufacturing cost, its reliability is low, and when the area is large like an ion source electrode plate, uniform bonding over the entire bonding surface is considered difficult.

  The ion source electrode manufactured by the method of (4) is integrated by diffusion bonding using a eutectic reaction, and the feature is that it uses a liquid crystal generated by the eutectic reaction. Diffusion bonding is possible with a relatively small pressure applied.

  However, in order to integrate the members by diffusion bonding, it is necessary to heat all the members to a temperature range where diffusion bonding or a eutectic reaction occurs. In this method, when a flat surface is not obtained on the bonding surface and the bonding surface is not sufficiently adhered in the heated state, no eutectic reaction occurs and no liquid phase is generated. May occur.

  On the other hand, this method may face the same problem as described in the joining of the electrode plates by the methods (1) to (3) described above. That is, in the ion source electrode by diffusion bonding, when the accuracy of the bonding surface for facilitating the bonding, for example, the surface roughness is kept at 5S or less, buffing is necessary after machining, and after such a process is obtained. But care must be taken to keep flatness and cleanliness.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an ion source electrode having high cooling efficiency, excellent corrosion resistance, and a long lifetime.

In order to achieve the above object, the present invention comprises an ion source electrode by the following means .

According to a first aspect of the present invention, there is provided an ion source electrode having a structure in which a flat plate and a grooved flat plate provided with a cooling groove are joined together. A brazing material is applied and melted by heating, and the molten brazing material is cut and formed to form barriers having a thickness of 0.1 to 0.2 mm. Are joined and integrated.

According to a second aspect of the present invention, in the ion source electrode according to the first aspect of the present invention, the flat plate and the grooved flat plate are made of a material mainly composed of molybdenum or tantalum .

  According to the present invention, it is possible to obtain an ion source electrode having high cooling efficiency, excellent corrosion resistance due to the molten layer, less risk of cooling water leakage, and high cooling efficiency.

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

  FIG. 1 is a diagram showing the shape of a part before production constituting the ion source electrode according to the first embodiment of the present invention, and FIGS. 2 and 3 are diagrams showing the production process.

  As a method for manufacturing this ion source electrode, as shown in FIGS. 1A and 1B, a flat plate 1 made of molybdenum and a plurality of grooves 2 each having a width and a depth of about 2 mm are parallel to each other at a predetermined interval. A grooved flat plate 3 made of molybdenum is formed.

Next, as shown in FIG. 2, nickel brazing powder 4, 5 is applied to one surface of the flat plate 1, one surface of the grooved flat plate 3, and the inside of the groove, and inserted into a vacuum furnace 7 in which a heater 6 is built. After that, the flat plate 1 and the grooved flat plate 3 coated with nickel brazing powder 4 and 5 are heated by an exhaust pump 8 to 1050 to 1100 ° C. which is a temperature at which the brazing material melts in a vacuum atmosphere of 10 ⁻² Pa or less. Hold for at least 10 minutes.

  Thereafter, the flat plate 1 and the grooved flat plate 3 are taken out from the vacuum furnace 7, and after joining one surface (joint surface) of the flat plate 1 and one surface (joint surface) of the grooved flat plate 3, the inside of the groove serving as a cooling hole is melted. The brazing material is machined to finish the groove 11 and the flat surface in which the barriers 9 and 10 are formed. In particular, in the present embodiment, the barriers 9 and 10 are cut to a thickness of about 0.1 to 0.2 mm as a target to obtain a predetermined thickness, and the flat finish is performed so that the subsequent bonding can be performed. In addition, machining was performed with great care.

  The flat plate 1 and the grooved flat plate 3 having a predetermined flatness in this way are set so as to overlap each other in the vacuum furnace 7 with the configuration shown in FIG. 3, and a vacuum atmosphere is used using a predetermined weight or the like. By heating inside, it joins and integrates through the barriers 9 and 10 of the flat plate 1 and the grooved flat plate 3.

  The bonding conditions such as the heating temperature were 1050 to 1100 ° C., which is the same as the barrier generation temperature, and the heating time was 10 minutes or more.

  FIG. 4 shows a cross-sectional view of the ion source electrode after the flat plate 1 and the grooved flat plate 3 are joined through the barriers 9 and 10 and then the beam hole 12 for extracting the ion beam is processed by the NC processing machine. .

  In FIG. 4, the alternate long and short dash line indicates the joining surface 14 of the flat plate 1 and the grooved flat plate 3 joined through the molten layer, and the cooling hole obtained by joining and integrating the flat plate 1 and the grooved flat plate 3. 12 respectively.

  If the ion source electrode is manufactured by such a method, the cooling efficiency can be increased by passing pure water through the cooling hole 13 as shown in the sectional view of FIG. There is no change in the dimensions of the beam hole 12 during operation, and the cooling hole 13 is covered with a barrier, and the molybdenum material is not in direct contact, so there is no concern about leakage of cooling water due to corrosion by pure water cooling medium. Absent. Therefore, it is possible to improve the reliability of the ion source electrode made of molybdenum, which is assumed to be operated at a high heat load, and to achieve heat resistance and long life.

  In the present embodiment, a method using nickel brazing for producing a molten layer has been described. However, in addition to nickel brazing, wetting with molybdenum can be achieved by using gold brazing, titanium brazing silver brazing, palladium brazing, and the like. Similar effects can be obtained from the viewpoint of reactivity.

  As described above, in the first embodiment of the present invention, the ion source electrode made of forced cooling type molybdenum is reactive with molybdenum on the joint surfaces of the flat plate 1 and the grooved flat plate 3 and the groove inner surface of the grooved flat plate 3. Since the barrier is formed of a good metal, the pure water of the cooling medium does not come into direct contact with the molybdenum material. For this reason, corrosion of the molybdenum material due to cooling water is eliminated, so that a longer life can be realized as compared with a conventional diffusion bonding type molybdenum electrode. In addition, as compared with a diffusion bonding method that requires a large and special bonding device as a manufacturing method, a highly reliable ion electrode can be manufactured at low cost by a simple manufacturing method using only a device such as a vacuum furnace. .

  FIG. 5 is a cross-sectional view of parts constituting an ion electrode for explaining a second embodiment of the present invention.

  In the second embodiment, two flat plates made of a clad material obtained by rolling a metal having a small thermal expansion coefficient and a metal having high corrosion resistance with respect to pure water in a vacuum are used, and one of the flat plates has excellent corrosion resistance. Grooving is performed below the thickness of the metal to form a grooved flat plate, and the flat plate and the grooved flat plate are joined and integrated in a vacuum furnace or atmospheric gas to produce an ion electrode.

  Here, the manufacturing method of the said ion electrode plate is demonstrated concretely with FIG. 5 (a), (b).

  As shown in FIGS. 5A and 5B, flat plates 15 and 16 made of molybdenum, which is a metal having a small thermal expansion coefficient, have different thicknesses, and flat plates made of nickel having high corrosion resistance against pure water. 17 and 18 are rolled in a vacuum atmosphere using a vacuum rolling apparatus (not shown), and the flat plates 15 and 17 and the flat plates 16 and 18 are joined and integrated, respectively, and a clad material 19 composed of molybdenum and nickel is formed. 20 is produced.

  As the clad materials 19 and 20 made of molybdenum and nickel, the clad material 19 shown in FIG. 5 (a) is 0.3 mm in molybdenum, 0.2 mm in nickel, and 0.5 mm in total plate thickness. The clad material 20 of b) is 0.8 mm of molybdenum, 0.7 mm of nickel and 1.5 mm in total plate thickness in order to perform groove processing for cooling holes of the ion source electrode.

  With respect to the clad material 20 shown in FIG. 5B, cooling grooves 21 having a width of 2 mm and a depth of 0.5 mm are processed at a pitch of about 20 mm on the nickel side.

  FIG. 6 is a cross-sectional view of the clad material 20 after performing the groove processing that becomes the cooling hole of the ion source.

  In order to join the clad material 20 thus grooved with the clad material 19 shown in FIG. 5 (a), the clad materials 19 and 20 are overlapped, as shown in FIG. 2 or FIG. In a vacuum furnace, vacuum brazing is performed using a brazing material such as titanium brazing silver brazing or titanium brazing silver brazing containing indium, which is a relatively low temperature brazing material, and a flat clad material 19 and a grooved clad material 20. Are joined and integrated to produce an ion source electrode having a cooling hole 23 shown in FIG.

  Thereafter, similarly to the cross-sectional view of the ion source electrode shown in FIG. 4 shown in the first embodiment, although not shown, the beam hole 12 for extracting the ion beam is processed by an NC processing machine to obtain a predetermined structure and shape. The ion source electrode is finished.

  Thus, the clad material 19 made of molybdenum and nickel shown in FIG. 5 (a) and the clad material 20 made of molybdenum and nickel with grooves 21 processed on the nickel side shown in FIG. 6 were joined and integrated in a vacuum furnace. The ion source electrode is made of nickel with excellent corrosion resistance. Since it is covered, molybdenum does not come into direct contact with pure water, and there is no risk of leakage of cooling water due to corrosion. Therefore, it is possible to improve the reliability of the molybdenum ion source electrode assumed to operate at a high heat load, and to extend the life.

  In addition, since the clad material made of molybdenum and nickel, which is excellent in heat resistance and corrosion resistance, is manufactured by vacuum rolling, it has excellent reliability from the viewpoint of the bondability of molybdenum and nickel and the results of rolling clad. Reliability is also improved.

  In this embodiment, the clad material of molybdenum and nickel is used. However, the present invention is not limited to the combination of molybdenum and nickel as long as it is a combination of metals having heat resistance and corrosion resistance. For example, the same effect as the combination of molybdenum and nickel can be obtained with a clad material of molybdenum and copper.

  Also, clad materials such as molybdenum and nickel have high bonding reliability even in a manufacturing method using HIP (hot isostatic pressing), and even if the clad material is used, the same heat resistance and corrosion resistance as in this embodiment. Can be obtained.

  As described above, in the second embodiment of the present invention, the forced cooling type molybdenum ion source electrode plate does not directly contact the molybdenum and the material with pure water of the cooling medium, so that the molybdenum material is not corroded by the cooling water. As compared with the conventional diffusion bonding type molybdenum electrode, the life can be extended. In addition, as compared with the diffusion bonding method that requires a large and special bonding device as a manufacturing method, a highly reliable ion electrode can be manufactured at a low cost by a simple method using only a simple device such as a vacuum furnace. it can.

Sectional drawing which shows the components before manufacture which comprise the ion source electrode plate which concerns on the 1st Embodiment of this invention. Sectional drawing which shows the manufacturing process to the middle of the ion source electrode plate in the embodiment. Sectional drawing which shows the last manufacturing process of an ion source electrode plate in the embodiment. Sectional drawing which shows the ion source electrode of the embodiment Sectional drawing which shows the components before manufacture which comprise the ion source electrode which concerns on the 2nd Embodiment of this invention. Sectional drawing which shows the manufacturing process to the middle of the ion source electrode plate in the embodiment. Sectional drawing which shows the last manufacturing process of an ion source electrode plate in the embodiment. Sectional drawing which shows schematic structure of a neutral particle injection apparatus. Sectional drawing which shows the conventional ion source electrode plate.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Flat plate, 2 ... Groove, 3 ... Flat plate with groove, 4, 5 ... Powder, 6 ... Heater, 7 ... Vacuum furnace, 8 ... Exhaust pump, 9, 10 ... Barrier, 11 ... Cooling hole groove, 12 ... Beam hole , 13 ... cooling hole, 14 ... joint surface, 15 ... molybdenum plate, 16, 18 ... nickel plate, 17 ... molybdenum, 19, 20 ... cladding material, 21 ... cooling groove, 23 ... cooling hole

Claims (2)

In an ion source electrode having a structure in which a flat plate and a grooved flat plate provided with a cooling groove are joined,
Wherein the powdery brazing material is heated and melted by applying the groove within each of the joint surface and the grooved flat plate of the flat plate and the grooved flat plate, 0.1 to 0.2 mm thickness by cutting shaping the molten brazing material An ion source electrode comprising: a barrier plate, and a flat plate having grooves and a flat plate with grooves joined together through the barrier. The ion source electrode according to claim 1.
The ion source electrode according to claim 1, wherein the flat plate and the grooved flat plate are made of a material mainly composed of molybdenum or tantalum.

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