JP4130694B2 - Radiation irradiation device monitoring system - Google Patents

Description

  The present invention relates to a monitoring system for a radiation irradiating apparatus that monitors the operation status of the radiation irradiating apparatus.

  Recently, in order to reduce the size of the electron beam irradiation apparatus, an electron beam tube made of a glass tube with an electron generator having a cathode and a grid and an electron beam at a position facing the electron generator. A vacuum tube type electron beam emission tube formed in a high-vacuum hermetic container such as a vacuum tube is used in which a head portion provided with an irradiation window to be transmitted is unseparably combined (see Patent Document 1).

  While this vacuum tube type electron beam emission tube has the advantage of being small and easy to replace, it cannot be recycled if either the irradiation window or the cathode fails or deteriorates. It is a disposable product and has the disadvantage that it cannot contribute to resource and cost savings, and the processing width that can be irradiated with an electron beam with a single product is only a few centimeters at the maximum. Only had the disadvantage of being able to handle only.

  If the electron beam tube and the head portion are enlarged and the size of the irradiation window provided in the head portion is increased, the processing width can be increased, but the glass electron beam tube is increased in its overall size. There is a problem that it becomes easy to break.

  For this reason, a large irradiation processing width can be obtained by arranging a plurality of electron beam emission tubes in parallel in a processing chamber for irradiating an object to be processed and superimposing the electron beams emitted from the electron beam emission tubes on each other. A proposal to be obtained has been made (see Patent Document 2).

Japanese National Patent Publication No. 10-512092 Japanese Patent Laid-Open No. 2002-182000

  However, when it is intended to obtain a large irradiation processing width by arranging a plurality of electron beam emission tubes in parallel as described above, each electron beam emission tube has an irradiation window size in the head portion of the electron beam tube. In addition to being smaller than the diameter, the electron beam generated in the electron beam tube is irradiated through each irradiation window, so that the electron beams are superposed on each other to obtain a generally uniform irradiation intensity distribution. However, since there is a limit in increasing the degree of uniformity of the irradiation intensity distribution, there is a possibility that processing unevenness may occur in the object to be processed.

  Therefore, in order to obtain a well-balanced irradiation intensity distribution over the entire irradiation processing width, the irradiation processing width of the object to be processed is increased by superimposing electron beams irradiated from a plurality of electron beam emission tubes. However, there is a problem that the uniformity of the irradiation intensity distribution is impaired when one of the electron beam emission tubes fails or deteriorates.

  Therefore, the present invention accurately detects the irradiation intensity of radiation emitted from a radiation irradiation apparatus such as an electron beam irradiation apparatus by a simple and inexpensive means, and stops the operation of the irradiation apparatus when the illuminance intensity changes. It is a technical problem to provide a radiation irradiation apparatus monitoring system that can output a control signal for operating an alarm device.

In order to solve this problem, the present invention is a monitoring system for monitoring the operating status of a radiation irradiation apparatus such as an electron beam irradiation apparatus, and gas molecules in the irradiation region are excited by radiation irradiated from the radiation irradiation apparatus. An optical sensor for detecting the plasma emission generated and a controller for outputting a control signal for stopping the operation of the radiation irradiating apparatus or a control signal for operating the alarm device according to the amount of plasma emission detected by the optical sensor. It is characterized by.

  The monitoring system of the present invention detects the irradiation intensity of the electron beam irradiated from the electron beam irradiation apparatus simply and accurately with a relatively inexpensive optical sensor, and when the irradiation intensity is reduced below a certain value, for example, The controller can stop the operation of the electron beam irradiation device, or can output a control signal for operating various alarm devices such as an alarm device, thereby significantly reducing the product defect rate of the object to be processed.

  That is, according to the present invention, when the irradiation intensity of the electron beam is detected by the amount of plasma emission generated by exciting the gas molecules by the electron beam irradiated from the electron beam irradiation apparatus, and the irradiation illuminance is reduced more than a certain level. A control signal or the like for stopping the operation of the electron beam irradiation apparatus can be output from the controller, so that it is possible to reliably prevent the occurrence of processing failure due to a decrease in electron beam irradiation intensity. Further, when two or more optical sensors having different detection points of plasma emission are provided, the uniformity of the irradiation intensity distribution can be monitored, and the operation of the electron beam irradiation apparatus 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 means for measuring the amount of X-rays generated when the electron beam hits the irradiation window, and the electron beam is processed. Means for measuring the amount of fluorescence emitted from an object to be processed when irradiated on the object have been proposed, but the former means is not practical because it is extremely expensive, and the latter means is not suitable for the object to be processed. Since the amount of fluorescence generated differs depending on the shape and position, it is difficult to accurately detect the irradiation intensity of the electron beam based on the amount of fluorescence. On the other hand, the present invention detects the amount of plasma emission generated by the excitation of gas molecules by the electron beam irradiated from the electron beam irradiation apparatus with an optical sensor, so that the cost is not high and the irradiation intensity of the electron beam is high. Can be measured easily and accurately.

Embodiments of the present invention will be specifically described below with reference to the drawings.
FIG. 1 is a view showing an example of an electron beam irradiation apparatus (radiation irradiation apparatus) and its irradiation intensity distribution, and FIG. 2 is a view showing an example of a monitoring system for the electron beam irradiation apparatus (radiation irradiation apparatus) according to the present invention.

  1 is an irradiation in which a plurality of electron beam tubes 2, 2... Each having an electron generation unit 3 are collectively transmitted through an electron beam emitted from the tube end opening 4. The head portion 5 provided with the window 6 is airtightly attached in a parallel state.

  The electron beam tube 2 is formed of an electrically insulating material such as glass, and one end side serving as a wiring port for connecting a high voltage cable 7 for supplying a high voltage to the electron generator 3 having a cathode and a grid is melted. A bracket 9 for mounting and supporting a connector 8 for detachably connecting the high voltage cable 7 and the electron generating portion 3 is provided at one end of the airtight seal by sealing or the like.

  The head portion 5 is formed of a metal such as stainless steel that is difficult to transmit an electron beam, and a plurality of mounting holes 10, 10... At the same time, an O-ring 11 and an O-ring retainer 12 for attaching the electron beam tube 2 in an airtight and detachable manner are provided in the mounting hole 10. On the other hand, the lower surface side of the head portion 5 is opened substantially entirely, and the opening portion collectively transmits the electron beams emitted from the tube end openings 4, 4... Of the electron beam tubes 2, 2,. The irradiation window 6 is hermetically sealed. 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 irradiation window 6 in which the adjacent electron beam tube 2 and the electron beam emission area of each electron beam tube 2 are arranged. Are arranged so as to partially overlap each other.

  Further, on the side surface of the head unit 5, a vacuum evacuation device (see FIG. 5) for evacuating the internal space 13 formed by the head unit 5 and the electron beam tubes 2, 2. (Not shown) is provided with a pipe connection port 14, and an airtight valve 15 for opening and closing the pipe connection port 14 is interposed in the pipe connection port 14.

  Further, an insulating oil case 16 that collectively accommodates the electron beam tubes 2 attached to the upper surface of the head portion 5 is attached. The case 16 is filled with insulating oil for preventing a high voltage supplied from the high voltage cable 7 to the electron generator 3 of the electron beam tube 2 from leaking to the head unit 5 along the surface of the electron beam tube 2. A case main body 17 and a lid 18 that seals the case main body 17, and the lid 18 has an insulating bushing 19 through which the high voltage cables 7, 7. Is provided.

  When an abnormality such as a failure of one of the electron beam tubes 2, 2... Occurs in the cathode of the electron generator 3 during operation of the electron beam irradiation apparatus 1, the abnormality is monitored as shown in FIG. It is detected by the system, and the operation of the electron beam irradiation apparatus 1 can be stopped immediately.

  That is, FIG. 2 is a radiation irradiation apparatus monitoring system according to the present invention, and emits plasma light generated by excitation of gas molecules in the irradiation area by radiation irradiated from a radiation irradiation apparatus such as the electron beam irradiation apparatus 1. An optical sensor 20 for detection and a controller 21 for outputting a control signal according to the amount of plasma emission detected by the optical sensor 20 are provided.

  This monitoring system can be widely applied not only to an electron beam irradiation apparatus but also to a gamma ray irradiation apparatus or other apparatus that irradiates high-energy radiation. For example, when this is applied to the electron beam irradiation apparatus 1 of FIG. As shown in FIG. 2, plasma emission P generated by the excitation of gas molecules in the irradiation region by the electron beam transmitted through the irradiation window 3 of the apparatus 1 is detected by an optical sensor 20 such as a photodiode or 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 for immediately stopping the operation of the apparatus to the electron beam irradiation apparatus 1.

  Further, the monitoring system of FIG. 2 particularly monitors the uniformity of the irradiation intensity distribution composed of a plurality of electron beams emitted from the electron beam tubes 2, 2... As shown in FIG. Two or more optical sensors 20, 20... Having different detection points A to C are provided, and the controller 21 compares the detection value of each optical sensor 20, 20... With the set value preset for each sensor. When the difference value exceeds a certain range, a control signal for stopping the operation of the electron beam irradiation apparatus 1 or a control signal for operating the alarm device is output.

  Each set value set in advance for each optical sensor 20, 20... Is the amount of plasma emission P at each detection point A to C when the irradiation intensity distribution of the electron beam irradiation apparatus 1 forms a desired distribution. The irradiation intensity distribution collapses due to deterioration of the cathode of the electron generator 3 provided in any one of the electron beam tubes 2, and the set values and the detection values of the optical sensors 20, 20,. When the difference value exceeds a certain range, the controller 21 outputs a control signal for stopping the operation of the electron beam irradiation apparatus 1.

  Each of the optical sensors 20, 20... May be installed so as to directly face the detection points A to C of the plasma emission P, but the plasma emission P at each detection point A to C as shown in FIG. If it detects via 22, 22, ..., the freedom degree of the installation place will increase remarkably, and it will be possible to detect the fine change of irradiation intensity distribution correctly using more optical sensors 20. Become. In addition to the reflection mirror, the plasma emission P may be detected by the optical sensor 20 via a prism or an optical fiber.

  Further, the devices such as the optical sensor 20 and the controller 21 and the radiation irradiation device such as the electron beam irradiation device 1 are separated from each other by a radiation shielding glass 23 that does not interfere with the detection of the plasma emission P by the optical sensor 20. If the installation place of the devices such as the optical sensor 20 and the controller 21 is protected by the radiation shielding glass 23, the devices are prevented from being deteriorated by X-rays or the like generated when the electron beam hits the irradiation window 6. At the same time, it is possible to safely carry out inspection and adjustment operations of these devices.

  When the reflection mirrors 22, 22... And the radiation shielding glass 23 are used, in order to prevent the detection accuracy of the optical sensor 20 from being impaired by dirt adhering to the surfaces, compressed air or nitrogen gas is regularly used. It is desirable to wipe off dirt adhering to the surface by spraying.

  According to the present invention, the irradiation intensity of the radiation irradiated from the radiation irradiation apparatus is easily and accurately detected by a relatively inexpensive optical sensor, and the irradiation intensity and the degree of uniformity of the irradiation intensity distribution are monitored. For example, when the irradiation intensity drops below a certain value, the controller stops the operation of the radiation irradiation device or outputs a control signal for operating various alarm devices such as an alarm device. There is a very excellent effect that the product defect rate of the object to be processed can be remarkably reduced.

  As described above, the present invention can be applied to an application in which the irradiation intensity of radiation irradiated from a radiation irradiation apparatus is accurately detected by a simple and inexpensive means and the operation status is monitored.

The figure which shows an example of an electron beam irradiation apparatus (radiation irradiation apparatus), and its irradiation intensity distribution. The figure which shows an example of the monitoring system of the electron beam irradiation apparatus (radiation irradiation apparatus) which concerns on this invention.

Explanation of symbols

1. Electron beam irradiation device 2. Electron beam tube 3. Electron generating unit 4. Tube end opening of electron beam tube 5 .... …………………………………………………………………………………………………………………………………………………………………………………… Piping connection port 15 …………… Airtight valve 20 …………… Optics Sensor 21 ……………… Controller 22 ……………… Reflective mirror

Claims (4)

An optical sensor that monitors the operating status of a radiation irradiation device such as an electron beam irradiation device, and detects plasma emission generated by exciting gas molecules in the irradiation region by radiation irradiated from the radiation irradiation device; And a controller for outputting a control signal for stopping the operation of the radiation irradiation apparatus or a control signal for operating the alarm device according to the amount of plasma emission detected by the optical sensor. system.   The two or more optical sensors having different detection points of the plasma emission are provided, and the controller compares a detection value of each optical sensor with a preset value set for each optical sensor, and the difference value thereof. 2. The radiation irradiation apparatus monitoring system according to claim 1, wherein a control signal for stopping the operation of the radiation irradiation apparatus or a control signal for operating the alarm device is output when the value exceeds a certain range.   The radiation irradiation apparatus monitoring system according to claim 1, wherein the plasma emission is detected by the optical sensor via a reflection mirror, a prism, or an optical fiber. 4. The radiation irradiation apparatus according to claim 1, wherein the optical sensor and the controller are separated from the radiation irradiation apparatus by radiation shielding glass that does not interfere with detection of the plasma emission by the optical sensor. Monitoring system.

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