JPH03134600A - Terminal point of electron beam irradiation device - Google Patents

Abstract

PURPOSE:To reduce the opening width of an irradiation window without inducing any abnormal electric discharge due to the acceleration voltage by providing a net shaped grid placed on the side surface of a case, in a denting condition toward the inner side of the case. CONSTITUTION:When a grid voltage is charged between a filament 11, a gun structure 12 and a grid 14, and an acceleration voltage is charged between the structure d12 and an irradiation window 3, an electron beam 15 generated by the filament 11 is accelerated in an acceleration space 4 of an electron accelerating tube 2 and irradiates an irradiation object through a metal foil 3a of the window 3. Cross section of the grid 14 is formed to be shape of an arc and is placed in a denting condition toward the inside of a case 13. By this reason, an iso-electric potential curve, which is generated concentrically around the filament 11, is recessed in the direction toward the filament 11 immediately below the grid 14. Therefore, the electrons that tend to progress rectangularly to the iso-electric potential curve actually progress so as to be concentrated in the direction toward the center of electron irradiation, as shown by a dotted line in the figure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a terminal for an electron beam irradiation device that performs treatments such as crosslinking and curing by irradiating a workpiece with an electron beam.

[Conventional technology]

FIG. 6 is a schematic cross-sectional view of an electron beam generating section in a conventional electron beam irradiation device. The electron beam generating unit 10 includes a cylindrical terminal 1 that generates an electron beam, an electron acceleration tube 2 that accelerates the electron beam generated by the terminal 1, and an irradiation window 3 that irradiates the object to be processed with the electron beam. It is something that

The terminal l includes a filament (for example, a linear cathode) 11 that is an electron source, a gun structure 12 that supports the filament 11, a cylindrical case 13 that houses the gun structure 12 that supports the filament 11, and a case. It consists of a wire-shaped grid 54 provided on the side surface of 13 and a force.

When a grid voltage is applied between the filament 11, the gun structure 12, and the grid 54 by a power supply device (not shown), and an acceleration voltage is applied between the gun structure 12 and the irradiation window 3, the filament 11 The generated electron beam 15 is accelerated in the acceleration space 4 of the electron acceleration tube 2 and is irradiated onto the object to be processed through the metal foil 3a of the irradiation window 3.

In one electron beam irradiation bag, the diameters of the electron accelerating tube 2 and the terminal 1 (the diameter of the case 13) increase in accordance with the value of the acceleration voltage. Fig. 6 shows the case where the accelerating voltage is low, but when the accelerating voltage is high, as shown in Fig. 7, the diameters of the terminal 1 and the electron accelerating tube 2 become larger, and the object to be processed increases. As the width of the electron beam irradiated increases, the width C of the opening 3b of the irradiation window 3 also increases accordingly.

Also, b is the ratio of the diameters of the terminal 1 and the electron acceleration tube 2.
H/a1 and S,/ax are determined depending on the accelerating voltage, and generally, as the diameter of the electron accelerating tube 2 increases, the diameter of the terminal 1 also increases.

[Problem to be solved by the invention]

The electrons emitted by the filament 11 float as thermoelectrons,
The electron beams are drawn in all directions by the grid voltage, and only those that pass through the wire-shaped grid 54 placed below are effectively extracted as electron beams. Therefore, the number of electrons that can be used as an electron beam is limited to only d + /360 degrees out of all the electrons released from the filament 11. As shown in Fig. 7, the acceleration voltage is high and the electron accelerating tube 2
And even if terminal 1 is large, the middle I shown in Figure 6
In order to allow electrons having the same central angle as the angle d1 to pass through, the width of the grid 54 and the width of the opening 3b of the irradiation window 3 must be increased.By the way,
When electrons penetrate the metal foil 3a provided in the opening 3b of the irradiation window 3, the temperature of the metal foil 3a increases. In order to prevent the temperature from rising, a cooling device using, for example, air or water is provided. However, when the width C2 of the opening 3b of the irradiation window 3 becomes large, it becomes difficult to prevent the temperature of the metal foil 3a from rising with the cooling device, and there is a problem that preventing the temperature rise increases the manufacturing cost. .

Also, while maintaining the central angle d of the irradiated electron beam,
In addition, in order to increase the acceleration voltage without increasing the width C3 of the opening 3b of the irradiation window 3, only the diameter of the electron accelerating tube 2 is increased and the diameter of the terminal 1 is increased as shown in FIG. It would be fine if it were not done, but with this method, the general ratio of b/a to the applied accelerating voltage would be disrupted, and there is a risk of inducing abnormal discharge.

The present invention has been made based on the above circumstances, and aims to provide a terminal for an electron beam irradiation device that can reduce the width of the opening of the irradiation window without inducing abnormal discharge due to the accelerating voltage. This is the purpose.

[Means to solve the problem]

To achieve the above object, the present invention includes a gun structure that supports a filament that is an electron source, a case that houses the gun structure, and a case that is provided on a side of the case to take out electrons from the filament. In the terminal of an electron beam irradiation device having a cross-shaped grid, the grid is provided in a recessed state inside the case.

[Effect]

With the above-described configuration, the present invention has a shape in which the equipotential curve, which originally occurs on concentric circles, cuts into the direction of the filament, so that the equipotential curve tends to advance perpendicularly to the equipotential curve. The electrons become focused in the direction of the irradiation center of the electron beam. Thereby, the width of the opening of the irradiation window can be made smaller than that of the conventional one.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 is a schematic cross-sectional view of an electron beam generating section of an electron beam irradiation apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of an electron beam irradiation apparatus according to an embodiment of the present invention. The electron beam irradiation device includes an electron beam generation unit IO that generates a curtain-shaped electron beam, a transport path 20 that includes an irradiation space that irradiates the object to be processed with the electron beam, an acceleration space of the electron acceleration tube 2, and the transport path 20.
An irradiation window 3 having a metal foil 3a separating the processing cloud from the inside
Equipped with. Note that the side walls of the electron accelerator tube 2 and the transport path 20 are coated with metal such as lead to prevent X-rays from leaking outside.
X-ray shielding is provided by b.

FIG. 3 is an enlarged sectional view of the cylindrical terminal 1, and FIG. 4 is a bottom view thereof. As shown in FIG. 3, in the terminal 1 of this embodiment, the cross-sectional shape of the mesh-like grid 14 is formed into an arc shape, and the terminal 1 is provided in a recessed state inside a cylindrical case 13. In addition, if the same acceleration voltage as the conventional electron beam irradiation device shown in FIG. 7 is required, the irradiation angle should be the same as or larger than the irradiation angle d2 shown in the same figure. A width E of the grid 14 is formed. Although not shown, the area near the irradiation window 3 is a metal F! through which the electron beam passes. 3a is water-cooled to prevent the temperature from rising. Furthermore, in this embodiment, components having the same functions as those of the conventional system are designated by the same reference numerals, and detailed explanation thereof will be omitted.

When a grid voltage is applied between the filament 11, the gun structure 12, and the grid 14 by a power supply device (not shown), and an acceleration voltage is applied between the gun structure 12 and the irradiation window 3, the filament 11 The generated electron beam 15 is accelerated in the acceleration space 4 of the electron acceleration tube 2, and is irradiated onto the object to be processed through the metal foil 3a of the irradiation window 3.

By the way, the grid 54 of the conventional electron beam irradiation device has a flat cross section, but the grid 14 of this embodiment has an arc cross section and is recessed inside the case 13. It is being Therefore, the equipotential curves, which originally occur concentrically around the filament 11, take a shape that cuts into the direction of the filament 11 directly below the grid 14, as shown in FIG. Therefore, an electron trying to move perpendicular to the equipotential curve is
As shown by the dotted line in FIG. 1, the electron beam advances in a convergent direction towards the irradiation center. Therefore, when the accelerating voltage is the same, the structure of the cooling device using water etc. to prevent the temperature of the electronic metal foil 3a from the terminal 1 from rising is better than that of the conventional electron beam irradiation device. It becomes something simple.

According to the above embodiment, when the acceleration voltage is the same, the width C of the opening 3b of the irradiation window 3 can be formed narrower than in the conventional electron beam irradiation device. Compared to an electron beam irradiation device, the cooling device for the attachment member for attaching the metal foil 3a of the irradiation window 3 may have a simple structure, and the device can be made inexpensive.

In the above embodiment, a case has been described in which the cross-sectional shape of the grid 14 is formed into an arc shape, but it may be formed into a substantially arc shape by combining a plurality of planes.

FIG. 5 is a schematic sectional view of an electron beam generating section showing a modification of the above embodiment. The terminal of this modification shown in the fifth leap is different from the terminal of the electron beam generating section shown in FIG. It is provided in a recessed state in the direction and has the same function and effect as the terminal of the device.

Therefore, in this modification, when an acceleration voltage equivalent to the acceleration voltage shown in FIG. 7 is required, the diameter of the terminal 1 (diameter of the case) and the diameter of the electron acceleration tube 2 The width C of the opening 3b of the irradiation window 3 is the same as that of the conventional electron beam irradiation device shown in the figure.
can be made smaller than the width c2 of the opening 3b of the irradiation window 3 shown in the figure.

In addition, the joint part between the case 13 and the grid 14 or the grid 24 of the terminal 1 is
It is preferable to form it into a gently curved shape without making any sharp bends.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a terminal for an electron beam irradiation device in which the width of the opening of the irradiation window can be reduced without using a grid.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of an electron beam generating part of an electron beam irradiation device which is an embodiment of the present invention, FIG. 2 is a schematic sectional view of an electron beam irradiation device which is an embodiment of the present invention, and FIG. is an enlarged sectional view of the terminal, FIG. 4 is a bottom view thereof, FIG. 5 is a schematic sectional view of an electron beam generating section showing a modification of the above embodiment, and FIG.
8 are schematic cross-sectional views of an electron beam generating section in a conventional electron beam irradiation device. DESCRIPTION OF SYMBOLS 1... Terminal, 2... Electron accelerator tube, 3... Irradiation window, 3a... Metal foil, 3b... Aperture source 4... Irradiation space, 10... Electron beam generation part, DESCRIPTION OF SYMBOLS 11... Filament, 12... Gun structure, 13... Case, 14
．． 24... Grid, 20... Conveyance path, A... Processed object.

Claims (1)

[Claims] An electron beam irradiation device comprising: a gun structure that supports a filament that is an electron source; a case that houses the gun structure; and a grid-like grid provided on a side surface of the case to extract electrons from the filament. 2. A terminal for an electron beam irradiation device, wherein the grid is recessed inside the case.