JP2005241521A - Device and method for electron beam irradiation and method for manufacturing electron beam acceleration plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To primarily adjust the distribution of the density of electron beams by adjusting the distribution of the strength of electric fields. <P>SOLUTION: An electron beam irradiation device comprises an electron beam source (2) located in a vacuum container (1) and an electron beam transmission film (6) mounted on an opening region. The electron beam source (2) includes an initial acceleration electric field generating curved-face body (4) which maintains an electric potential for initially accelerating electrons. The curved-face body (4) has an initial acceleration voltage making face (7) and an electron beam transmission opening (12) which has a specified numerical aperture as an opposed face opposite to the electron beam transmission film (6). When the electron beam transmission film (6) of a thin film is supported in a window part of the vacuum container (1), it is difficult to curve the surface of the film (6). It is more difficult to increase the curvature of the curved surface of the electron beam transmission film (6) which receives the energy of an electron beam and emits high-temperature heat. The space distribution of the density of the electron beams can be optimized by imparting the curvature other than 0 to the initial acceleration electric field generating curved-face body (4) opposite to the electron beam transmission film (6). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electron beam irradiation apparatus, an electron beam irradiation method, and an electron beam acceleration plate manufacturing method, and in particular, an electron beam irradiation apparatus, an electron beam irradiation method, and an electron beam acceleration plate that optimize an electron beam density. It relates to the manufacturing method.

  The electron beam irradiation apparatus is expected to be developed for sterilization, physical property modification, chemical property modification, and other various uses. The electron beam irradiation apparatus projects an electron beam generated in a vacuum container onto a processing target through an electron beam extraction window (see Patent Document 1 described later) formed as a part of the vacuum container. The electron beam is formed in a fan shape, a curtain shape, or a cone shape.

  In order to improve the processing performance, it is important to adjust the spatial distribution ratio of the electron beam beam density. A technique for adjusting the aperture ratio distribution of the electron beam passage window two-dimensionally for adjusting the electron beam density is known from Patent Document 1 described later. In the known technique, as shown in FIG. 4, a mesh-shaped electron beam passage plate 103 is disposed in an opening portion of a cylindrical casing (sleeve) 102 disposed in the vacuum vessel 101. Electrons that ooze from the metal surface near the sleeve 102 undergo initial acceleration near the surface of the sleeve 102. The initial acceleration direction is an important cause for determining the electron beam trajectory after acceleration.

  Since the electron beam density is extremely small, the electron beam density is primarily influenced strongly by the accelerating electric field strength distribution. The aperture ratio distribution adjusts the density of electrons entering the acceleration region with respect to the electron beam whose acceleration direction distribution is adjusted by the adjusted electric field strength distribution.

  It is primarily required to adjust the energy distribution by adjusting the electric field intensity distribution. It is important that the aperture ratio distribution is devised secondarily.

JP-A-9-166700

An object of the present invention is to provide an electron beam irradiation apparatus, an electron beam irradiation method, and a method for manufacturing an electron beam acceleration plate that primarily adjust an electron beam density distribution by adjusting an electric field intensity distribution.
Another object of the present invention is to provide an electron beam irradiation apparatus, an electron beam irradiation method, and an electron beam acceleration plate manufacturing method that correct the electron beam density distribution by secondarily adjusting the aperture ratio distribution. There is.
Still another object of the present invention is to provide an electron beam irradiation apparatus, an electron beam irradiation method, and a method for manufacturing an electron beam acceleration plate that increase the electron beam density distribution.
Still another object of the present invention is to provide an electron beam irradiation apparatus, an electron beam irradiation method, and a method for manufacturing an electron beam acceleration plate that can increase the energy as a result.
Still another object of the present invention is to provide an electron beam irradiation apparatus, an electron beam irradiation method, and a method for manufacturing an electron beam acceleration plate, which consequently reduce the apparatus cost.

  An electron beam irradiation apparatus according to the present invention includes a vacuum vessel (1), an electron beam source (2) disposed in the vacuum vessel (1), and an electron beam transmission film attached to an opening portion of the vacuum vessel (1). (6). The electron beam source (2) includes an accelerating electric field generating curved surface body (4) that holds a potential for accelerating electrons, particularly an initial accelerating electric field generating curved surface body (4) that defines initial acceleration. The initial acceleration electric field generating curved surface (4) has an initial acceleration voltage forming surface (7) and an electron beam passage opening (12 or 14) having a specified aperture ratio as opposed surfaces facing the electron beam transmission film (6). have. Since the equipotential surface is formed along the metal surface, the initial acceleration potential surface is easily shaped by bending the metal plate (eg, cylindrical surface), and the potential surface can be easily adjusted. In particular, the electron beam density can be easily adjusted, and cost reduction can be easily realized.

  The electron beam permeable film (6) is formed of a thin Ti thin film of about 10 μm or less. In order to support such a thin Ti thin film on the window portion of the vacuum vessel, a crosspiece that supports the electron beam permeable film is used. By applying a non-zero curvature to the accelerating electric field generating curved surface (4) facing the electron beam permeable film, the spatial distribution of the electron beam density is optimized, and the electron beam incident on the electron beam transmissive film and the support beam is incident. The angle can be optimized. As the projected cross-sectional area of the support beam with respect to the electron beam flow increases, the number of electrons incident on the support beam increases, and the energy of effective electrons decreases. In order to reduce such energy loss, it is important to adjust the incident angle at which the electron beam enters the transmission film.

  It is practically important that the initial acceleration electric field generating curved surface (4) is formed as a perforated plate. A punching plate is particularly practical in terms of accuracy as the perforated plate. The punching plate has a uniform thickness and is supplied in large quantities to the free market, and the initial acceleration voltage forming surface (7) can be easily and inexpensively formed into a smooth curved surface. If the initial acceleration voltage forming surface (7) is smoothed, the initial acceleration direction of the electron beam can be designed with high accuracy. In this case, the specified numerical aperture is determined by the in-plane distribution of the size of the electron beam passage opening formed in the punching plate, and is determined by the in-plane distribution of the numerical aperture density, or the size and numerical aperture density surface. It is easily determined by the internal distribution.

  Both sides of the initial acceleration voltage forming surface (7) are formed on a corrected acceleration voltage forming projection surface (4 ') for forming a corrected acceleration electric field (8') for directing the electron beam toward the center. By changing the shape of the surface, the initial acceleration direction of electrons can be easily defined according to the application.

  An electron beam irradiation method according to the present invention is an electron beam irradiation method for irradiating a processing target with an electron beam using the above-described electron beam irradiation apparatus. Producing initial acceleration electric field generation curved body with finished punching plate, attaching initial acceleration electric field generation curved body to specified position of electron beam source, initial acceleration electric field generation corresponding to processing object change It consists of replacing the curved body. Although an electron beam irradiation apparatus is very expensive, its application is wide. By a simple device such as replacement of plates, there is an economic effect that many devices can be purchased, and the spread of expensive devices can be promoted.

  An electron beam acceleration plate manufacturing method according to the present invention is an electron beam acceleration plate manufacturing method for manufacturing an electron beam acceleration plate that is attached to an electron beam irradiation device and initially accelerates electrons, and has a smooth plane. Manufacturing a plate for use (synonymous with carrying into a factory), punching an electron beam passage opening with a specified aperture ratio in a plate, a curved surface with a non-zero curvature on a plate with an electron beam passage opening already opened And is made up of. A high-definition electron beam density can be obtained at low cost.

  The electron beam irradiation apparatus, the electron beam irradiation method, and the electron beam accelerating plate manufacturing method according to the present invention can primarily adjust the electron beam density distribution by adjusting the electric field intensity distribution. The electron beam density distribution can be corrected by secondarily adjusting the rate distribution. The cost reduction of expensive devices promotes the spread of useful devices.

  The implementation state of the electron beam irradiation apparatus according to the present invention will be described in detail with reference to the drawings. An electron beam source 2 is disposed in the vacuum container 1 of the electron beam irradiation apparatus. The electron beam source 2 forms an electron pump container that discharges electrons from a metal surface into a vacuum. The electronic pump container is formed in a substantially cylindrical body 3. An initial accelerating electric field generating curved body 4 that holds a potential for accelerating electrons is attached to the opening portion of the substantially cylindrical body 3. An electron beam extraction window 5 is attached to the opening portion of the vacuum vessel 1. The electron beam extraction window 5 includes a Ti thin film 6. The Ti thin film 6 is planarly formed for structural reasons. The initial acceleration electric field generating curved surface 4 has a large number of small radius openings distributed with an appropriate aperture ratio distribution.

  Examples of the initial acceleration voltage forming surface 7 of the initial acceleration electric field generating curved surface 4 include a cylindrical surface, an elliptical surface, and a saddle-shaped surface. The initial acceleration voltage forming surface 7 is formed on the initial acceleration electric field generating curved surface 4 on the transmission film side as the transmission film facing surface facing the Ti thin film 6. A plurality of initial acceleration electric field generating curved bodies 4 having various curved surfaces are prepared. A number of initial acceleration electric field generating curved bodies 4 are attached to the substantially cylindrical body 3 so as to be interchangeable with each other in accordance with the processing purpose. The initial acceleration voltage forming surface 7 is finished to be a smooth surface. The initial acceleration electric field generating curved surface body 4 is easily manufactured as a punching plate in which a large number of electron beam passage openings are opened by a high-definition mold on a thin metal plate finished with a smooth surface.

  If a specified voltage is applied to the initial acceleration electric field generating curved surface 4, the entire initial acceleration electric field generating curved surface 4 is applied to a constant specified voltage, and the initial acceleration voltage forming surface 7 also forms an equipotential surface. If the initial acceleration voltage forming surface 7 is a spherical surface having the center point O as the center, or if the initial acceleration voltage forming surface 7 is a cylindrical surface having the center line O as the central axis, the radial direction from the initial acceleration voltage forming surface 7 The virtual spherical surface or the virtual cylindrical surface separated by a certain distance forms an equipotential surface 8 on which the electric field distribution on the surface is uniformly equipotential. Electrons existing at an arbitrary position on the equipotential surface 8 are accelerated in the radial direction R by receiving a voltage action in the radial direction (radial direction, radiation direction) of the equipotential surface 8. The radial energy density (in particular, dose density) of the electron beam is generally defined as a function of the curved surface shape of the initial acceleration voltage forming surface 7.

  Electrons on the initial acceleration voltage forming surface 7 are accelerated in a substantially linear direction (generally radiating direction) by a voltage drop between the potential of the initial acceleration electric field generating curved surface body 4 and the Ti thin film 6 or other acceleration potential forming body. The electron trajectory in the acceleration region is greatly influenced by the initial acceleration electric field, and is greatly related to the transmission film or the beam distribution after passing through. Since the initial acceleration is received at the initial acceleration voltage forming surface 7 and the initial acceleration direction is positively defined, the beam can be directed in the direction almost as designed. Such setting of the initial acceleration potential surface makes it possible to irradiate the processing target with an electron beam uniformly or with an electron dose density as designed, and as a result, high energy can be realized.

  FIG. 2 shows another embodiment of the electron beam irradiation apparatus according to the present invention. In this modified example of the beam shape, trajectory correction protrusions (potential correction protrusions) 4 ′ are arranged on both sides of the aforementioned initial acceleration electric field generating curved surface 4 in FIG. 1. The trajectory correction protrusion 4 ′ correctively forms initial voltage correction formation surfaces 8 ′ on both sides of the equipotential surface 8. The trajectory correction protrusion 4 ′ can be manufactured integrally with the initial acceleration electric field generating curved surface body 4 by forming a single punching rectangular plate. The initial voltage correction forming surface 8 ′ is formed in a convex shape in a direction from the initial acceleration voltage forming surface 7 toward the Ti thin film 6. The initial voltage correction forming surface 8 ′ can direct both side portions of the electron beam toward the center. Thus, the spatial density of the electron beam can be freely adjusted by adjusting the curvature distribution of the initial acceleration voltage forming surface 7. This means that the magnetic field generator for correcting the trajectory can be eliminated.

  FIG. 3 shows an embodiment that allows a wide distribution of electron beam density. In the present embodiment, the electron beam current is divided into two beams. The initial acceleration electric field generating curved body (punching plate) 4 is divided into two regions. The one-side rectangular region 11 is formed as a high-density region where the small-diameter openings 12 are opened at high density, and the other-side rectangular region 13 is formed as a low-density region where the large-diameter openings are formed at low density. Here, the magnitude relationship and the elevation relationship are expressions for comparison. Such density can vary continuously on the surface. When the object to be processed (example: film) is continuously conveyed in the conveyance direction A, the object to be processed is irradiated with the high-density electron beam first in time, and then the low-density electron beam after time. It can be irradiated and modified in physical properties in stages.

  A plurality of initial acceleration electric field generating curved bodies 4 are produced. The plural bodies are manufactured in various ways by combinations of aperture ratio, aperture ratio distribution, curvature, and curvature distribution. A plurality of bodies are exchanged with each other so as to be plugged in or detachable in accordance with the characteristics, physical properties, and processing problems of the processing target.

  Punching plates having a smooth flat surface are provided in large quantities on the free market. An electron beam passage opening with a prescribed aperture ratio is opened in such a plate by punching of a well-known technique. A curved surface with a non-zero curvature is given to a plate in which an electron beam passage opening has already been opened. The punching technique can form a large number of smooth openings. The smoothness of the opening smoothes the surface of the acceleration voltage. Due to the smoothness, the initial acceleration direction distribution can be obtained as designed with high accuracy. Opening an opening in a curved surface makes the shape of the opening inaccurate.

FIG. 1 is a cross-sectional view showing an implementation of an electron beam irradiation apparatus according to the present invention. FIG. 2 is a cross-sectional view showing another embodiment of the electron beam irradiation apparatus according to the present invention. FIG. 3 is a plan view showing an embodiment of a punching plate. FIG. 4 is a cross-sectional view showing a known technique.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vacuum container 2 ... Electron beam source 4 ... Initial acceleration electric field production | generation curved surface 4 '... Correction acceleration voltage formation projection surface 6 ... Electron beam permeable film 7 ... Initial acceleration voltage formation surface 8' ... Correction acceleration electric field 12 ... Electron beam passage Opening 14 ... Electron beam passage opening

Claims (10)

A vacuum vessel;
An electron beam source disposed in the vacuum vessel;
Comprising an electron beam transmission window attached to the opening of the vacuum vessel;
The electron beam source includes an initial acceleration electric field generating curved body that holds a potential for accelerating electrons,
The acceleration electric field generating curved body is
An electron beam irradiation apparatus having an initial acceleration voltage forming surface and an electron beam passage opening having a specified aperture ratio as opposing surfaces facing the electron beam transmission film. The electron beam irradiation apparatus according to claim 1, wherein the initial acceleration electric field generating curved surface is formed as a perforated plate, the thickness of the perforated plate is uniform, and the initial acceleration voltage forming surface is formed as a smooth curved surface. . The electron beam irradiation apparatus according to claim 2, wherein the perforated plate is a punching plate. The electron beam irradiation apparatus according to claim 2, wherein the prescribed aperture ratio is determined by an in-plane distribution of the size of the electron beam passage aperture formed in the perforated plate. The electron beam irradiation apparatus according to claim 2, wherein the prescribed aperture ratio is determined by an in-plane distribution of a numerical aperture density of the electron beam passage aperture formed in the perforated plate. The electron beam irradiation apparatus according to claim 2, wherein the prescribed aperture ratio is determined by an in-plane distribution of a size and a numerical aperture density of the electron beam passage aperture formed in the perforated plate. The electron beam irradiation apparatus according to claim 1, wherein both sides of the initial acceleration voltage forming surface are formed on a correction acceleration voltage forming projection surface that forms a correction acceleration voltage that directs the electron beam toward the center. The electron beam irradiation apparatus according to claim 1, wherein the electron beam permeable film is formed in a plane. An electron beam irradiation method for irradiating a processing object with an electron beam using the electron beam irradiation apparatus according to claim 1,
Arranging the electron beam irradiation apparatus in a processing facility;
Producing a plurality of the initial accelerating electric field generating curved body with a punching plate finished to a smooth surface;
Attaching the initial acceleration electric field generating curved body to a prescribed position of the electron beam source;
An electron beam irradiation method comprising: replacing the initial acceleration electric field generating curved body in response to the change of the processing target. An electron beam initial acceleration plate manufacturing method for manufacturing an electron beam initial acceleration plate that is attached to an electron beam irradiation apparatus and initially accelerates electrons,
Producing a plate for punching with a smooth plane;
Opening an electron beam passage opening with a specified aperture ratio in the plate by punching;
A method of manufacturing an electron beam acceleration plate comprising: providing a curved surface with a non-zero curvature on a plate in which the electron beam passage opening has already been opened.

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