JP2003307598A - Electron beam emission tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electron beam emission tube having such effects that an electron emission tube can be constituted comparatively small, that an irradiation window and a peripheral part of the irradiation window can be cooled effectively, and that the service life span of the electron beam emission tube determined by damage to the irradiation window can be elongated. <P>SOLUTION: This tube is constituted as follows: a head part 12 is constituted so as to have a cylindrical body 15 having the irradiation window 11, and a ring body 16 interfitted with the cylindrical body at the center part; a recessed part working as a cooling water channel 17 is formed over the outer periphery near the irradiation window of the cylindrical body; the cylindrical body is constituted so as to have a channel check plate on a part of the recessed part; a cooling water introduction channel and a drainage channel are formed on the ring body; and the cylindrical body is interfitted with the ring body so that the channel check plate is positioned between the cooling water introduction channel and a distribution channel, to thereby form a continuous cooling water channel from the cooling water introduction channel to the drainage channel via the periphery of the irradiation window. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an electron beam emission device for generating and utilizing high energy electrons, and more particularly to an electron beam emission tube with a relatively small and low output cooling mechanism.

[0002]

2. Description of the Related Art An electron beam emitting device has an accelerating voltage of 150 k.
V or more, and the area of the electron irradiation window is 80 cm ² or more is generally used. To cool the irradiation window, a method is used in which a cooling fluid is passed through a hole in a metal (mainly copper) block that supports the window material made of a thin film. Many. When the irradiation current is large and block cooling alone is insufficient, a method of directly blowing a cooling gas from the cooling nozzle to the irradiation window is used.

As a method for improving the cooling efficiency when the irradiation window is relatively small, for example, in Japanese Patent Laid-Open No. 2000-346998, as shown in FIG. 2 of the same patent, a cooling fluid is provided on the inner circumference of the mounting flange around the irradiation window. A method has been reported in which a channel having a complicated cross-sectional shape is formed by processing a channel groove and then closing it with a lid.

Further, as shown in FIGS. 1 to 7 of Japanese Patent Laid-Open No. 2001-323369, a method of blowing a cooling gas to the irradiation window of the electron emission tube and bringing a cooling block into contact with the vicinity of the irradiation window has also been reported. .

[0005]

As described above, it has been common knowledge to cool the electron-irradiated surface and its periphery, but there is a problem when these methods are applied to a small electron beam emission tube. . First, there is no dimensional allowance for adopting the cooling block in the general method. Also, if an air-cooling nozzle is installed on the outside, it will be a hindrance when attaching and detaching the electron beam emitting tube, which does not fit the concept of downsizing.

[0006] Instead of the cooling block, the above-mentioned Japanese Patent
The method of 2000-346998 can be used, but in the case of further miniaturization, it becomes difficult to form a groove on the inner circumference of the flange, for example, with an electron beam emission tube for spot irradiation having an irradiation window with a diameter of 10 mm or less. Become.

In the method of bringing the cooling block into contact with the vicinity of the electron emission tube irradiation window as in the above-mentioned Japanese Patent Laid-Open No. 2001-323369, contact heat transfer between solids between the electron irradiation surface and the cooling block results in heat transfer efficiency. It will be a disadvantage. In addition, JP 2001-323
In 369, there is described an example in which a cooling pipe is provided around the cooling block or the head portion and a means for blowing the cooling gas to the irradiation window is added, but with this method, it is difficult to take a large size of the cooling gas pipe. , Pressure loss is large.
Moreover, only the flow of the gas near the surface to be cooled is considered, and there is no consideration for increasing the flow velocity of the cooling gas on the electron irradiation surface. In this method, the cooling gas blown out from the blowing port diffuses, and the flow velocity of the cooling gas on the electron irradiation surface cannot be increased. As a result, since the cooling capacity of the irradiation window is small, it is difficult to obtain a large electron beam output, and the usable fields are limited.

The present invention has been made in view of the above points, and the electron emission tube can be constructed in a relatively small size, and the irradiation window and its vicinity can be effectively cooled.
Another object of the present invention is to provide an electron beam emitting tube with a cooling mechanism, which has effects such as prolonging the life of the electron beam emitting tube caused by damage to the irradiation window.

[0009]

In order to solve the above problems, according to the present invention as set forth in claim 1, a head portion having an irradiation window made of a material that transmits an electron beam, and the head portion are opposed to each other. In an electron beam emission tube including an electron generating portion at a position and a body portion made of an electrically insulating material, the head portion has a cylindrical body having an irradiation window and the cylindrical body at the center thereof. It has a ring-shaped body that fits in, and also has a concave portion that serves as a cooling water channel formed all around the outer periphery of the cylindrical body near the irradiation window. A plate having a plate, on the other hand, a cooling water introducing passage and a drainage passage are formed in the annular body, and the cylindrical body and the annular body are arranged so that a passage stop plate is located between the cooling water introducing passage and the drainage passage. By fitting the body, continuous cooling from the cooling water introduction path to the drainage path through the vicinity of the irradiation window Waterways are configured to be configured.

According to a second aspect of the present invention, a head portion having an irradiation window made of a material that transmits an electron beam, and an electron generating portion provided at a position facing the head portion are made of an electrically insulating material. In the electron beam emission tube composed of the body part, the part for fixing the irradiation window to the head part in a part of the head part, and having a built-in mechanism for sending cooling air to the irradiation window. Is configured.

According to a third aspect of the present invention, a head portion having an irradiation window made of a material that transmits an electron beam, and an electron generating portion provided at a position facing the head portion are made of an electrically insulating material. In the electron beam emission tube including a body part, the head part has a tubular body having an irradiation window and an annular body into which the tubular body is fitted, and the head body has a tubular body. In the outer periphery of the irradiation window near the entire circumference, a concave portion to be a cooling water channel is formed, and the cylindrical body has a flow path stop plate in a part of the concave portion, while cooling water is introduced into the annular body. A pipe and a drainage path, and by fitting the tubular body and the annular body so that the flow path stop plate is located between the cooling water introduction path and the drainage path, the cooling water introduction path and the vicinity of the irradiation window A continuous cooling water channel that leads to the drainage channel is formed and part of the head part Have configured irradiation window has a component with a built-in mechanism for sending cooling air to a component in irradiation window for fixing the head portion.

According to the present invention as set forth in claims 1 to 3, the electron emission tube can be constructed in a relatively small size, and the irradiation window and / or the vicinity thereof can be effectively cooled. It is possible to extend the life of the electron beam emitting tube due to the damage of the window.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to FIGS. 1 to 5 are schematic front views of an embodiment according to the present invention of claim 1. FIG. 1 is a front view, and FIG. 2 is a plan view showing a cross section of a cooling water channel portion.

In FIG. 1, the upper portion is a head portion 12, and the lower portion is a body portion 14 having an electron generating portion 13 therein. Reference numeral 11 denotes an irradiation window, which normally uses a thin metal foil or a silicon thin film for emitting electrons to the outside. Reference numeral 21 is a portion near the irradiation window, and it is important to cool this portion.

In the head portion 12, 15 is a cylindrical body, 16
Is a ring-shaped body, and both are integrated to form the head portion 12, as described later.

FIG. 3 is a schematic view of the cylindrical body 15 portion. Figure 3
In, the reference numeral 18 denotes a concave portion which is formed over the entire circumference of the side surface. This recess can be formed as close to the irradiation window 11 as possible in consideration of the material strength. This portion becomes the cooling water passage 17 after the annular body 16 is fitted.
After processing the recess in the cylindrical body 15, the separately processed flow path stop plate 20 is joined to a part of the recess.

FIG. 4 is a schematic view of the annular body 16 portion. In FIG. 4, reference numerals 19a and 19b denote a cooling water introducing passage and a cooling water draining passage, respectively, which are arranged at appropriate intervals in consideration of cooling efficiency and workability, as shown in FIG.
The cylindrical body 15 is provided with a cooling water introduction passage 19a and a cooling water drainage passage 19b.
So that the flow path stop plate 20 is located between
As shown in FIGS. 5 and 2, a continuous cooling water passage extending from the cooling water introduction passage to the drainage passage through the vicinity of the irradiation window is formed by fitting in the central portion of the.

FIG. 6 and FIG. 7 are schematic views of another embodiment according to the present invention of claim 1. In FIG. 6, the upper portion is a head portion 32 and the lower portion is a body portion 34 in which an electron generating portion 33 is housed.
Is. Reference numeral 31 is an irradiation window, and the entire structure is almost the same as that of the embodiment of FIG. Similarly, 32 is a head portion, 35 is a cylindrical body, 36 is an annular body, 37 is a cooling water channel, 38 is a recessed portion, 3
Reference numeral 9a is a cooling water introduction passage, 39b is a cooling water drainage passage, and 40 is a passage stop plate.

Reference numeral 41 is a tightening bolt, and 42 is a pressing plate for fixing the irradiation window 31 to the head portion 32. Further, 44 is an O-ring and 45 is an O-ring retainer, which hermetically seals the body portion 34 of the electron beam emitting tube to the head portion 32. Reference numeral 43 denotes a vacuum pipe joint, which is configured to maintain a high vacuum inside the electron beam emission tube by connecting to a high vacuum exhaust system (not shown).

8 and 9 are schematic views of an embodiment according to the present invention of claim 2. In FIG. 8 as well, the structure is similar to that of the embodiment of FIG. 6, 51 is an irradiation window, 52 is a head part, 53 is an electron generating part, 54 is a body part, 61 is a tightening bolt, and 62 is a holding plate. , 64 is an O-ring, 65 is an O-ring
It is a ring holder.

Although the embodiment of FIG. 8 does not have a mechanism for cooling the vicinity of the irradiation window 51 with water, a mechanism for sending cooling air to the irradiation window 51 is built in the pressing plate 62. FIG. 9 is an enlarged view of the pressing plate 62 in the embodiment of FIG. 6
Reference numeral 6 is a cooling air blowing portion, 67 is an inclined surface, 68 is a cooling nozzle, and a flow path for sending cooling air from a cooling gas pipe (not shown) to the irradiation surface 51 is formed.

FIG. 10 is a schematic view of an embodiment according to the present invention of claim 3. In FIG. 10 as well, the structure is similar to that of the embodiment shown in FIGS. 6 and 8, and 71 is an irradiation window and 72
Is a head portion, 73 is an electron generating portion, 74 is a body portion, 75 is a cylindrical body, 76 is an annular body, 77 is a cooling water channel, 78 is a concave portion, 79
a is a cooling water introduction passage, 79b is a cooling water drainage passage, 80 is a flow path stop plate, 81 is a tightening bolt, 82 is a holding plate, 84 is an O-ring, 85 is an O-ring holding member, and 86 is a cooling air blowing portion. , 87 are inclined surfaces, and 88 is a cooling nozzle, which has both a mechanism for water cooling the vicinity of the irradiation window 71 and a mechanism for air cooling the irradiation window 71.

The operation of the electron beam emitting tube according to the present invention will be described below. In the electron beam emission tube, an electric field is created between the electron generation section and the head section to accelerate electrons generated in the electron generation section to high energy and emit the electrons from the irradiation window to the outside of the electron beam emission tube. Some of the high-energy electrons are absorbed in the irradiation window, generate a small amount of X-rays, and are mostly converted into thermal energy. Therefore, while the electron beam emission tube is operating, the temperature of the irradiation window rises and the temperature near the irradiation window also rises due to heat conduction, which causes adverse effects such as deterioration of the irradiation window material and internal discharge due to gas emission inside the electron beam emission tube. . In order to prevent this adverse effect, it is necessary to cool the irradiation window and the vicinity of the irradiation window.

The operation of cooling the vicinity of the irradiation window according to the present invention described in claim 1 is as follows. As described above, in FIG. 1, the head portion 12 has a configuration in which the tubular body 15 is fitted in the central portion of the annular body 16, but the cooling water path after the fitting of both parts is as follows. External piping (not shown)
The cooling water that is introduced from the cooling water introduction path 19a proceeds to the irradiation window vicinity 21 through the path shown by the arrow in FIG.
It is discharged to (not shown). The cooling water introducing passage 19a and the cooling water draining passage 19b are provided in substantially the same direction, but since the shortest path is closed by the passage stop plate 20 provided between them, the cooling fluid is irradiated as described above. It flows so as to go around the window vicinity 21 almost once. In this way, since the cooling water passes very close to the irradiation window 11, the heat in the vicinity 21 of the irradiation window is quickly transferred to the cooling water and radiated to the outside of the electron beam emitting tube.

The heat generated near the center of the irradiation window 11 is radiated by heat radiation from the irradiation window itself and natural convection heat transfer with the outside air.

In the embodiment shown in FIG. 6, the head portion is provided with an exhaust pipe for evacuating the inside of the electron beam emitting pipe,
It is used while exhausting the inside of the pipe with a vacuum pump or the like. The present invention can be applied to this embodiment in the same manner as the embodiment of FIG.

The operation of directly air-cooling the irradiation window according to the present invention described in claim 2 is as follows. In the embodiment shown in FIG. 8, a pressure plate 62 for fixing the irradiation window 51 is provided with a flow path for guiding the cooling gas to the irradiation window 51 so that the irradiation window 51 can be cooled. In FIG. 9, the gas introduced from a cooling gas pipe (not shown) is blown out from the cooling air blowing portion 66 to the irradiation window 51 through the cooling nozzle 68. At that time, the surrounding gas can be taken in from the inclined surface 67, and the cooling air multiplied by the flow rate of the introduced gas can be sent. The pressing plate 62 corresponds to the pressing plate 42 in the embodiment of FIG. 6 and is a component necessary even when the cooling air is not blown directly to the irradiation window. Therefore, the outer diameter of the electron beam emitting tube and the protruding size from the irradiation window are measured. Is not increased by applying the present invention.

According to the present invention described in claim 3, FIG.
It is possible to use both the mechanism of water cooling near the irradiation window and the mechanism of air cooling the irradiation window itself, as in the embodiment shown in FIG. 1, and the temperature rise of the irradiation window is increased by the synergistic effect of the above two actions. It becomes possible to further reduce.

When the electron irradiation current is small, the heat generated near the center of the irradiation window is released by radiative heat transfer and natural convection heat transfer with the outside air, so that the equilibrium temperature of the irradiation surface does not deteriorate the irradiation window. Fits inside. For example, in the embodiment shown in FIG. 6, when water cooling in the vicinity of the irradiation window is not performed, the anode current is 0.2 mA / cm ² or less, and the cooling water amount is ² L /
Even at min, it was about 0.4 mA / cm ² . However, the temperature of the irradiation window may rise to a dangerous range when it is necessary to further increase the current value due to usage requirements. In this case, it is necessary to blow cooling air directly onto the irradiation window for forced air cooling.

In the embodiment shown in FIG. 10, when the irradiation window is not water-cooled or air-cooled, the anode current is 1.0 mA / c.
When the temperature is m ² , the temperature of the irradiation window 51 is 1700 ° C. with natural air cooling.
With the above (instantaneous burning), 30 L of nitrogen even with the conventional air cooling method.
/ Min was passed and the irradiation window temperature was about 450 ° C. When water cooling and air cooling were performed with the configuration according to the embodiment shown in FIG. 10, the temperature of the irradiation window 51 was about 300 ° C. at a cooling water amount of 2 L / min and a nitrogen flow rate of 20 L / min, and cooling was achieved at a practical level.

[0031]

As described above, according to the present invention of claim 1, the electron emission tube of a relatively small size is as high as or more than the case where an external cooling device is attached without increasing the outer diameter dimension. The irradiation window and its vicinity can be cooled with cooling efficiency. Therefore, the occurrence of in-tube discharge due to the temperature rise in the electron beam emitting tube is reduced. Further, deterioration of the electron beam irradiation window material due to high temperature is reduced, and it becomes possible to remarkably extend the life of the electron beam emitting tube which causes damage to the irradiation window.

According to the second aspect of the present invention, for a relatively small-sized electron emission tube, the size equal to or more than that in the case where the external cooling device is attached without increasing the outer diameter size and the projection size from the irradiation surface. It is possible to directly cool the irradiation window with high cooling efficiency. Therefore, the deterioration of the electron beam irradiation window material due to the high temperature is further reduced, and it becomes possible to emit high-power electrons from the electron beam emission tube of claim 1.

Furthermore, according to the present invention of claim 3, by combining the inventions of claims 1 and 2, the outer diameter dimension and the projection dimension from the irradiation surface are increased for a relatively small electron emission tube. Without this, it is possible to cool the irradiation window and its vicinity with high cooling efficiency equal to or higher than the case where the external cooling device is attached, and it is possible to directly cool the irradiation window. Therefore, the deterioration of the electron beam irradiation window material due to the high temperature is further reduced, and it becomes possible to emit electrons with a higher output than the electron beam emitting tubes according to the first and second aspects.

[Brief description of drawings]

FIG. 1 is a schematic front view of an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a cooling water channel in the embodiment of FIG.

FIG. 3 is a schematic view of a cylindrical portion in the embodiment of FIG.

FIG. 4 is a schematic view of an annular body portion in the embodiment of FIG.

FIG. 5 is a schematic view when the cylindrical body and the annular body are fitted in the embodiment of FIG.

FIG. 6 is a schematic front view of another embodiment of the present invention.

FIG. 7 is a schematic sectional view of a cooling water channel in the embodiment of FIG.

FIG. 8 is a schematic view of an embodiment of the present invention according to claim 2.

9 is a schematic view of a pressing plate portion in the embodiment of FIG.

FIG. 10 is a schematic view of an embodiment of the present invention according to claim 3.

[Explanation of symbols]

11 irradiation window 12 head 13 Electron generator 14 torso 15 cylinder 16 ring 17 Cooling channel 31 irradiation window 32 head 33 Electron generator 34 torso 35 cylinder 36 ring 37 Cooling channel 42 Press plate 51 irradiation window 52 head 53 Electron generator 54 torso 62 Press plate 66 Cooling air outlet 71 irradiation window 72 Head 73 Electron generator 74 torso 75 cylinder 76 ring 77 Cooling channel 86 Cooling air outlet 87 Inclined surface

Claims (3)

[Claims] 1. A head portion having an irradiation window made of a material that transmits an electron beam, and a body portion having an electron generating portion internally provided at a position facing the head portion and made of an electrically insulating material. In the electron beam emitting tube according to claim 1, the head portion is configured to have a tubular body having an irradiation window and an annular body in which the tubular body is fitted in a central portion thereof, and the head portion has an outer periphery in the vicinity of the irradiation window. A concave portion to be a cooling water passage is formed all around, and the cylindrical body is configured to have a flow path stop plate in a part of the concave portion, while a cooling water introduction passage and a drainage passage are formed in the annular body. By continuously fitting the cylindrical body and the annular body so that the flow path stop plate is located between the cooling water introduction passage and the drainage passage, the cooling water introduction passage continuously passes through the irradiation window and reaches the drainage passage. An electron beam emitting tube, characterized in that a cooling water channel is formed. 2. A head portion having an irradiation window made of a material that transmits an electron beam, and a body portion having an electron generating portion internally provided at a position facing the head portion and made of an electrically insulating material. In the electron beam emitting tube according to claim 1, a part of the head part has a part for fixing the irradiation window to the head part and a part including a mechanism for sending cooling air to the irradiation window. Electron beam emitting tube. 3. A head portion having an irradiation window made of a material which transmits an electron beam, and a body portion having an electron generating portion internally provided at a position facing the head portion and made of an electrically insulating material. In the electron beam emission tube according to the first aspect, the head portion is configured to have a tubular body having an irradiation window and an annular body in which the tubular body is fitted in the central portion thereof, A concave portion to be a cooling water passage is formed all around, and the cylindrical body is configured to have a flow path stop plate in a part of the concave portion, while a cooling water introduction passage and a drainage passage are formed in the annular body. By continuously fitting the cylindrical body and the annular body so that the flow path stop plate is located between the cooling water introduction passage and the drainage passage, the cooling water introduction passage continuously passes through the irradiation window and reaches the drainage passage. The cooling water channel is configured, and the irradiation window is fixed to the head part in a part of the head part. Electron beam discharge tube equipped with a cooling mechanism, characterized in that it comprises a component with a built-in mechanism for sending cooling air to the irradiation window be because part.