JP2004361195A - Electron beam irradiation device and its monitoring system - Google Patents

Abstract

An electron beam irradiation apparatus in which a plurality of electron beams are connected so as to overlap each other to obtain a large irradiation processing width is to obtain an irradiation intensity distribution with good uniformity over the entire irradiation processing width. .
A plurality of electron beam tubes (2, 2,...) Each containing an electron generating unit (3) are irradiated so as to collectively transmit electron beams emitted from the tube end openings (4). It is airtightly mounted in a side-by-side state with respect to a head portion (5) provided with a window (6).
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electron beam irradiation device and a radiation irradiation device monitoring system that monitors the operation status of the device.
[0002]
[Prior art]
Recently, in order to reduce the size of the electron beam irradiation device, an electron beam tube consisting of a glass tube containing an electron generation unit having a cathode and a grid, and an electron beam placed at a position facing the electron generation unit. 2. Description of the Related Art A vacuum tube type electron beam emission tube formed in a high vacuum hermetic container such as a vacuum tube by inseparably combining a head portion provided with an irradiation window through which light is transmitted (see Patent Document 1).
This vacuum tube type electron beam emission tube has the advantages of being small in size and easy to replace, etc., but has to be disposed of if any of the irradiation window or the cathode is broken down or deteriorated. It is an unusable disposable product, which has the disadvantage of not contributing to resource and cost savings, and the processing width of electron beam irradiation that can be used alone is only a few cm at most, so it is extremely small. There is a drawback that only the object can be processed.
The processing width can be increased by enlarging the size of the electron beam tube and the head portion and increasing the size of the irradiation window provided in the head portion, but the electron beam tube made of glass has the entire size. There is a problem that when the size is increased, it is easily broken.
For this reason, a plurality of electron beam emitting tubes are juxtaposed in a processing chamber for irradiating an object to be processed, and the electron beams emitted from the electron beam emitting tubes are superimposed on each other to provide a large irradiation. There has been a proposal to obtain a processing width (see Patent Document 2).
[0006]
[Patent Document 1]
Japanese Patent Publication No. 10-512092 [Patent Document 2]
JP 2002-182000 A
[Problems to be solved by the invention]
However, when a plurality of electron beam emission tubes are juxtaposed to obtain a large irradiation processing width as described above, the size of the irradiation window provided in the head portion of each electron beam emission tube is smaller than that of the electron beam tube. Since the electron beam generated by the electron beam tube is smaller than the diameter and transmitted through each irradiation window, the electron beams are superimposed on each other to obtain an overall uniform irradiation intensity distribution. However, there is a limit in increasing the uniformity of the irradiation intensity distribution.
Therefore, the invention according to claim 1 provides an electron beam capable of obtaining a large irradiation processing width by overlapping the electron beams with each other, and obtaining a uniform irradiation intensity distribution over the entire irradiation processing width. It is a technical object to provide a beam irradiation device.
When the electron beam emitted from a plurality of electron beam emission tubes is overlapped with each other as described above to increase the irradiation processing width of an object to be processed, one of the electron beam emission tubes may fail. When the deterioration occurs, the uniformity of the irradiation intensity distribution is impaired, and for example, a large-sized electron beam irradiation apparatus in which a plurality of filaments serving as cathodes are provided in parallel in a vacuum chamber evacuated to a high vacuum, the If one of the wires breaks, the uniformity of the irradiation intensity distribution is impaired, and in any case, if left unchecked, the product defect rate of the workpiece may increase.
Therefore, the invention according to claim 7 accurately detects the irradiation intensity of the electron beam emitted from the electron beam irradiation device by simple and inexpensive means, and when the illuminance intensity changes, the electron beam irradiation device is used. An object of the present invention is to provide a monitoring system for a radiation irradiation apparatus that can stop operation or activate an alarm device.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a method in which a plurality of electron beam tubes each containing an electron generating unit are used to collectively transmit an electron beam emitted from a tube end opening. An electron beam irradiating apparatus characterized in that the electron beam irradiating apparatus is hermetically mounted in a side-by-side state with respect to a head section provided with a window.
In the electron beam irradiation apparatus of the present invention, the electron beams are emitted from the tube end openings of the electron beam tubes each containing the electron generating section, and the electron beams are passed through the electron beam tubes in parallel. The light is collectively transmitted through an irradiation window provided in a head portion which is hermetically attached, and is irradiated to the outside. At this time, since it is easy to enlarge the emission area of the electron beam emitted from the tube end opening of each electron beam tube, the electron beams emitted from the adjacent electron beam tubes are overlapped with each other. At the same time, it is easy to obtain a large irradiation width, and it is also easy to adjust the degree of overlap between the electron beams so as to equalize the irradiation intensity over the entire irradiation width. In addition, since irradiation is performed through the irradiation windows provided in the head unit without being transmitted through the individual irradiation windows, the irradiation intensity distribution can be extremely uniform.
A seventh aspect of the present invention is a monitoring system for monitoring the operation status of a radiation irradiating apparatus such as an electron beam irradiating apparatus. Is characterized by comprising an optical sensor for detecting plasma emission generated by excitation of the light emitting device, and a controller for outputting a control signal in accordance with the amount of plasma emission detected by the optical sensor.
According to the monitoring system of the present invention, the irradiation intensity of the electron beam irradiated from the electron beam irradiation device is easily and accurately detected by a relatively inexpensive optical sensor, and for example, the irradiation intensity is reduced to a certain value or less. In some cases, the controller can stop the operation of the electron beam irradiation device or output a control signal for activating various notification devices such as an alarm device, thereby significantly reducing the product defect rate of the workpiece.
That is, according to the present invention, the irradiation intensity of the electron beam is detected based on the amount of plasma emission generated by exciting gas molecules by the electron beam irradiated from the electron beam irradiation device, and the irradiation illuminance is reduced by a certain amount or more. At this time, a control signal or the like for stopping the operation of the electron beam irradiation device is output from the controller, so that it is possible to reliably prevent the occurrence of processing failure due to a decrease in the irradiation intensity of the electron beam. If two or more optical sensors having different plasma emission detection points are provided, the uniformity of the irradiation intensity distribution can be monitored, and the operation of the electron beam irradiation device can be stopped when the uniformity is impaired.
As a conventional technique for detecting the irradiation intensity of the electron beam irradiated from the electron beam irradiation apparatus, there are known means for measuring the amount of X-rays generated when the electron beam hits the irradiation window, There has been proposed a means for measuring the amount of fluorescence emitted from the object when the object is irradiated with the object, but the former means is not practical because the cost is remarkably increased, and the latter means is not practical. Since the amount of fluorescence generated varies depending on the shape and position of the processed object, it has been difficult to accurately detect the irradiation intensity of the electron beam based on the amount of fluorescence. On the other hand, according to the present invention, the optical sensor detects the amount of plasma emission generated when gas molecules are excited by the electron beam irradiated from the electron beam irradiation apparatus, so that the cost is not increased and the irradiation intensity of the electron beam is increased. Can be easily and accurately measured.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
FIG. 1 is a diagram showing an example of an electron beam irradiation device according to the present invention and an irradiation intensity distribution thereof, and FIG. 2 is a diagram showing an example of a monitoring system for monitoring an operation state of the electron beam irradiation device.
In the electron beam irradiation apparatus 1 shown in FIG. 1, a plurality of electron beam tubes 2, 2... Each containing an electron generating section 3 collectively emit an electron beam emitted from a tube end opening 4. It is air-tightly mounted in a side-by-side state with respect to the head section 5 provided with an irradiation window 6 for transmitting light.
The electron beam tube 2 is formed of an electrically insulating material such as glass, and serves as a wiring port for connecting a high voltage cable 7 for supplying a high voltage to the electron generating section 3 having a cathode and a grid. One end is hermetically sealed by sealing or the like, and a bracket 9 is provided on one end of the bracket 9 for mounting and supporting a connector 8 for detachably connecting the high-voltage cable 7 and the electron generator 3.
The head section 5 is formed of a metal such as stainless steel which is difficult to transmit an electron beam. A plurality of mounting holes 10, 10... An O-ring 11 and an O-ring retainer 12 are provided in the mounting hole 10 so as to hermetically and detachably attach the electron beam tube 2 to the mounting hole 10. On the other hand, the lower surface side of the head portion 5 is opened almost entirely, and the opening collectively transmits electron beams emitted from the tube end openings 4, 4,... Of the electron beam tubes 2, 2,. It is hermetically sealed by the irradiation window 6. The irradiation window 6 is detachably attached to the head unit 5, and each electron beam tube 2 attached to the head unit 5 has an electron beam emission area between the adjacent electron beam tube 2 and each other. Are arranged so as to partially overlap each other.
On the side surface of the head portion 5, there is evacuated to evacuate an internal space 13 formed by the head portion 5 and the electron beam tubes 2, 2,. A pipe connection port 14 for an apparatus (not shown) is provided, and an airtight valve 15 that opens and closes the pipe connection port 14 is interposed in the pipe connection port 14.
Further, an insulating oil case 16 for collectively housing the electron beam tubes 2, 2,... Mounted on the upper surface of the head portion 5 is mounted. The case 16 is filled with insulating oil for preventing a high voltage supplied from the high-voltage cable 7 to the electron generating unit 3 of the electron beam tube 2 from leaking to the head unit 5 along the surface of the electron beam tube 2. , And a cover 18 that seals the case body 17. The cover 18 has an insulating bushing 19 through which the high-voltage cables 7 are routed. Is provided.
The electron beam irradiating apparatus 1 having the above structure is evacuated from the pipe connection port 14 provided in the head section 5 to make the internal space 13 a high vacuum, and connect the electron beam tubes from the high voltage cables 7 to the respective electron beam tubes. When a high voltage is supplied to the electron generating units 3 to emit electron beams simultaneously from the tube end openings 4 of the electron beam tubes 2, 2,..., The electron beams are arranged in the electron beam tubes 2, 2,. The electron beams are overlapped so as to be continuously connected along the direction and collectively pass through the irradiation window 6 of the head unit 5 to obtain an electron beam having a wide irradiation processing width and a good uniformity of the irradiation intensity distribution as shown in FIG. Therefore, it is possible to irradiate a large object to be processed, and at the same time, it is possible to significantly reduce the product defect rate due to uneven processing.
The electron beam irradiating apparatus 1 is, for example, operated by a manufacturer in a trial manner in the same procedure as described above to perform pretreatments such as conditioning, and then to perform an airtight operation provided at the pipe connection port 10. By shipping the valve with the valve 15 closed and the internal space 13 kept in a vacuum state, or by introducing an inert gas into the internal space 13 and closing the airtight valve 15, the user can perform a troublesome conditioning operation. There is an advantage that it can be used immediately without performing.
Most of the causes of failure of the electron beam irradiation apparatus are caused by failure or deterioration of the irradiation window and the cathode. In general, the durability life of the cathode is about 5000 hours, whereas the durability of the irradiation window is about 5000 hours. Since it takes about 2000 hours, even if the irradiation window 6 shown in FIG. 1 breaks down or deteriorates, the cathode of the electron generating unit 3 is still often usable. In this case, the electron beam irradiating apparatus 1 is brought to a maker or the like in a state where the airtight valve 15 is closed and the internal space 13 is maintained in a vacuum state or in an inert gas atmosphere, and failure or deterioration is caused. By replacing only the irradiation window 6 that has caused the problem with a new one and reusing the cathode of the electron generating unit 3 without replacing it, it is possible to contribute to resource saving and cost saving. That is, in the electron beam irradiation apparatus 1, the internal space 13 formed by the head unit 5 and the electron beam tubes 2, 2,... May be formed in a high vacuum hermetic space like a vacuum tube. However, as long as the internal space 13 is evacuated and used as shown in FIG. 1, there is an advantage that it can be recycled.
If any of the electron beam tubes 2, 2,... Causes a failure in the cathode of the electron generating unit 3 while the electron beam irradiation device 1 is operating, the abnormality is determined as shown in FIG. And the operation of the electron beam irradiation apparatus 1 can be immediately stopped.
That is, FIG. 2 shows an optical sensor 20 for detecting plasma emission generated when gas molecules in the irradiation area are excited by radiation irradiated from a radiation irradiation apparatus such as the electron beam irradiation apparatus 1, and the like. And a controller 21 that outputs a control signal in accordance with the amount of plasma emission detected by the controller 21.
This monitoring system is widely applicable not only to an electron beam irradiation apparatus but also to a gamma ray irradiation apparatus and other apparatuses for irradiating high-energy radiation. This monitoring system is applied to, for example, the electron beam irradiation apparatus 1 shown in FIG. In this case, as shown in FIG. 2, a plasma emission P generated by exciting gas molecules in the irradiation area by an electron beam irradiated through the irradiation window 3 of the apparatus 1 is detected by an optical sensor 20 such as a photodiode or a CMOS. When the amount of plasma emission detected by the sensor 20 exceeds a certain range, the controller 21 outputs a control signal or the like to the electron beam irradiation device 1 to immediately stop the operation of the device. .
The monitoring system shown in FIG. 2 monitors the uniformity of the irradiation intensity distribution formed by connecting a plurality of electron beams emitted from the electron beam tubes 2, 2,... As shown in FIG. Are provided with two or more optical sensors 20, 20... Having different detection points A to C of the light emission P, and a controller 21 detects the detected values of the optical sensors 20, 20,. And outputs a control signal for stopping the operation of the electron beam irradiation device 1 or a control signal for activating the alarm device when the difference value exceeds a certain range.
Each set value preset for each of the optical sensors 20, 20... Corresponds to the plasma emission P at each of the detection points A to C when the irradiation intensity distribution of the electron beam irradiation apparatus 1 has a desired distribution. ., The irradiation intensity distribution collapses due to the deterioration of the cathode of the electron generating unit 3 provided in any one of the electron beam tubes 2, and the above set values and the optical sensors 20, 20,... When the difference value from the detected value exceeds a certain range, the controller 21 outputs a control signal for stopping the operation of the electron beam irradiation device 1.
The optical sensors 20, 20,... May be installed so as to directly face the detection points A to C of the plasma light emission P. However, as shown in FIG. Is detected via the reflection mirrors 22, 22,..., The degree of freedom of the installation location is remarkably increased, and more changes in the irradiation intensity distribution can be accurately detected using more optical sensors 20. Becomes possible. Note that the present invention is not limited to the reflection mirror, and the plasma light emission P may be detected by the optical sensor 20 via a prism or an optical fiber.
Further, a radiation shielding glass 23 which does not hinder the detection of plasma emission P by the optical sensor 20 is provided between devices such as the optical sensor 20 and the controller 21 and a radiation irradiating device such as the electron beam irradiating device 1. If the installation location of the devices such as the optical sensor 20 and the controller 21 is protected by the radiation shielding glass 23, the devices may be deteriorated by X-rays or the like generated when the electron beam hits the irradiation window 6. Can be prevented, and at the same time, the inspection and adjustment work of those devices can be performed safely.
When the reflection mirrors 22, 22,... And the radiation shielding glass 23 are used, compressed air is periodically used so that the detection accuracy of the optical sensor 20 is not impaired by dirt attached to the surfaces. It is desirable to blow dirt or nitrogen gas to wipe off dirt attached to the surface.
[0034]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, while a several irradiation electron beam continues so that it may mutually overlap, a large irradiation processing width is obtained and the small-sized electron beam irradiation which can obtain the irradiation intensity distribution with good uniformity over the whole irradiation processing width is obtained. It is possible to provide an apparatus, and to monitor the irradiation intensity and the uniformity of the irradiation intensity distribution to prevent the processing unevenness of the processing target and to significantly reduce the product defect rate of the processing target. Has an excellent effect.
[Brief description of the drawings]
FIG. 1 shows an example of an electron beam irradiation apparatus according to the present invention and an irradiation intensity distribution thereof. FIG. 2 shows an example of a monitoring system of the irradiation apparatus according to the present invention.
1 Electron beam irradiation device 2 Electron beam tube 3 Electron generator 4 Tube end opening 5 of electron beam tube … Head part 6… Irradiation window 13… Internal space 14… Piping connection port 15… Airtight valve 20… Optical Sensor 21 Controller 22 Reflecting mirror

Claims (10)

A plurality of electron beam tubes each containing an electron generating unit are air-tightly mounted in parallel with a head unit provided with an irradiation window through which electron beams emitted from the tube end openings are collectively transmitted. An electron beam irradiation apparatus, comprising: The electron beam irradiation apparatus according to claim 1, wherein an internal space formed by the head section and each of the electron beam tubes is formed in a high vacuum hermetic space. 2. The electron beam irradiation apparatus according to claim 1, wherein the head section is provided with a pipe connection port to a vacuum exhaust device for exhausting an internal space formed by the head section and the electron beam tubes to a high vacuum. The electron beam irradiation apparatus according to claim 3, wherein an airtight valve that opens and closes the pipe connection port is interposed at the pipe connection port. The electron beam irradiation device according to claim 3, wherein each of the electron beam tubes is detachably attached to the head unit. The electron according to claim 1, 2, 3, 4, or 5, wherein each of the electron beam tubes is arranged such that an adjacent electron beam tube and an electron beam emission area of each other partially overlap on the surface of the irradiation window. Beam irradiation device. A monitoring system for monitoring the operation status of a radiation irradiation apparatus such as an electron beam irradiation apparatus, and an optical sensor for detecting plasma emission generated by exciting gas molecules in the irradiation area by radiation irradiated from the radiation irradiation apparatus, A monitoring system for a radiation irradiation apparatus, comprising: a controller that outputs a control signal according to the amount of plasma emission detected by the optical sensor. The apparatus further comprises two or more optical sensors having different plasma emission detection points, wherein the controller compares a detection value of each of the optical sensors with a preset value set for each of the optical sensors, and calculates a difference value between the values. The monitoring system according to claim 7, wherein a control signal for stopping operation of the radiation irradiation device or a control signal for activating an alarm device is output when the value exceeds a predetermined range. 9. The monitoring system according to claim 7, wherein the plasma emission is detected by the optical sensor via a reflection mirror, a prism, or an optical fiber. The monitoring system according to claim 7, wherein the optical sensor and the controller are separated from the radiation irradiation device by a radiation shielding glass that does not prevent the optical sensor from detecting the plasma emission.

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