JP5036376B2 - Electron beam irradiation device - Google Patents

Description

  The present invention relates to an electron beam irradiation apparatus that generates an electron beam by field emission from a field emission type cold cathode and irradiates the generated electron beam from a window foil part to the outside.

  Electron beams are used in many fields such as medical, industrial, and analytical purposes. For example, in addition to being used for pattern evaluation purposes such as inspection and measurement of fine patterns of semiconductor devices, it is used for various applications from material evaluation to cell morphology observation (Patent Documents 1 and 2). Further, X-rays are generated when an electron beam collides with an X-ray target such as a metal or a fluorescent material (Patent Documents 2 and 3).

  Many electron beam irradiation apparatuses that perform sterilization, sterilization, modification, fine processing, and the like of an external irradiation object from an electron beam irradiation window foil have been proposed in the past (Patent Document 4). etc).

  In this conventional electron beam irradiation apparatus, for example, a cold cathode is heated to a high temperature with a heater to generate thermoelectrons in the cold cathode, and the electron extraction electrode draws thermoelectrons from the cold cathode to form an electron beam. There has been proposed a technique in which an electron beam accelerated by an annular anode is transmitted through an electron transmission window after passing the electron beam through an annular gap (Patent Document 5). In the electron beam irradiation apparatus according to this proposal, the cold cathode has an electron emitting element such as lanthanum hexaboride, and emits thermoelectrons by heating with a heater inside the cold cathode.

  However, the electron beam irradiation apparatus according to Patent Document 5 has many problems such as short lifetime, slow electron emission timing unless preheated, complicated structure, high cost and large weight because a heater is required. It has become something that has.

  Further, as shown in FIG. 5, the cathode 2 is arranged concentrically with the outer diameter side and the anode 3 as the inner diameter side, the cathode 2 is made of copper or stainless steel, and carbon nanotubes are formed on the entire inner peripheral surface of the cathode 2. A brazing layer of powder is formed, and an electron beam transmission window 6 made of a metal foil such as titanium is provided in a transfer tube 5 arranged on the inner diameter side of the cathode 2, and an electron is transmitted to an irradiation object transferred in the transfer tube 5. There has also been proposed a technique in which sterilization or the like can be performed by irradiating a line (Patent Document 6).

However, in the electron beam irradiation apparatus according to Patent Document 6, carbon nanotubes are brazed to the inner peripheral surface in order to limit the direction of electron beam irradiation from the cathode 2, but in this configuration, in FIG. It is considered that the electron beam cannot be irradiated with high efficiency through the anode 3 having a large number of slits as described by the arrow B1 and to the window foil portion 6 located at a considerable distance from the anode 3.
JP 2001-338600 A JP2003-1000024 Special Table 2002-517882 JP2007-010450 JP 2003-279698 A JP 2004-239819 A

  In the present invention, long life, quick response, simple, small size and light weight can be achieved, while an electron beam from a cold cathode can be irradiated to the window foil portion with high efficiency, medical, industrial, analytical, etc. It is an object of the present invention to provide an electron beam irradiation apparatus that can be used more efficiently in the field.

  An electron beam irradiation apparatus according to the present invention comprises a double cylinder having an inner and outer concentric cylinders and a circumferential annular vacuum sealing space inside, and an anode is circumferentially annular on the inner cylinder. A window foil portion having electron beam permeability is formed on a part of the anode and a cold cathode with a carbon film for electric field emission is disposed in a circumferential direction at a position facing the window foil portion in the double cylinder. It is characterized by being arranged in an annular shape.

  Preferably, an electron beam shielding member for shielding an electron beam from the cold cathode at substantially the same potential as the cold cathode is disposed around the cold cathode.

  In the present invention, since the window foil portion is provided on the inner cylindrical body and the anode is disposed around the window foil portion, the electron beam emitted from the cold cathode can be focused only on the window foil and irradiated with high efficiency. It becomes possible. In this case, if the periphery of the cold cathode is covered with the electron beam shielding member, the electron beam emitted from the cold cathode can be concentrated only on the window foil and irradiated with higher efficiency.

  Examples of the form of the electron beam shielding member include an annular plate structure that sandwiches the cold cathode in the axial direction and a cylindrical structure that covers the outer diameter side of the cold cathode.

  Also, the carbon film has fine nm-order protrusions such as carbon nanotubes, carbon nanowalls, carbon nanofibers, diamond-like carbon, amorphous diamond, crystalline diamond, graphite, fullerene, acicular carbon film, carbon fine particles, etc. What has is preferable. There may be one cold cathode or a plurality of cold cathodes.

  The anode may be in the form of a ring in the circumferential direction, or it may be discontinuous in the ring in the circumferential direction.

  You may comprise the said window foil part by providing an opening part in a part of anode and providing metal foil in this opening part.

  The window foil is made of a foil material that can transmit an electron beam, and the material is not particularly limited, and examples thereof include silicon, beryllium, titanium, glass, and diamond.

  The power source used in the electron beam irradiation apparatus of the present invention is preferably a power source capable of applying a direct current, an alternating current, or a pulse voltage between the anode and the cold cathode with the anode side having a higher potential than the cold cathode side.

  An electron acceleration means may be arranged between the cold cathode and the anode.

  Moreover, you may accelerate an electron according to the distance from a cold cathode to an anode.

  The cold cathode may be solid or hollow.

  According to the present invention, a double cylinder having an inner and outer concentric cylinders and a vacuum sealed space is formed, and an anode is provided on the inner cylinder in an annular shape in the circumferential direction, and electrons are formed in a part of the anode. While forming a window foil portion having line permeability, a cold cathode with a carbon film for electric field emission is arranged in a ring shape in the circumferential direction at a position facing the window foil portion in the double cylinder. It becomes possible to irradiate the window foil part with the electron beam from

  Hereinafter, an electron beam irradiation apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings. 1 is a sectional view of the electron beam irradiation apparatus, FIG. 2 is a partially cutaway perspective view of the electron beam irradiation apparatus of FIG. 1, FIG. 3 is a diagram for explaining the operation, and FIG. 4 is an enlarged view of the main part of FIG. FIG.

  1 and 2, an electron beam irradiation apparatus 10 according to an embodiment includes an inner cylinder 14 having a window foil portion 12 for electron beam irradiation, and an outer cylinder arranged concentrically with the inner cylinder 14. 16 constitutes a double cylinder 20 having a vacuum sealing space 18 in the circumferential annular shape and in the axial direction.

  The inner cylindrical body 14 has a configuration in which a cylindrical anode 22 is sandwiched between two cylindrical bodies 14a and 14b divided into two. Window foil portions 12 are formed on the anode 22 at several locations in the circumferential direction. As described above, the anode 22 is arranged in a circumferential annular shape with respect to the double cylinder 20.

  The window foil portion 12 is configured by opening a part of the anode 22 and providing a foil material having electron beam transparency in the opening portion. Examples of the foil material include silicon, beryllium, titanium, glass, diamond and the like.

  In the circumferential annular space 18 in the double cylinder 20, cold cathodes 24 are circumferentially arranged at positions facing the window foil portion 12.

  The cold cathode 24 is formed by coating a carbon film 24b as an electron beam emitting layer on the surface of a conductive wire 24a.

  The cross section of the cold cathode 24 is not limited to a circle but may be a rectangle, an ellipse, or the like.

  The carbon film 24b may be formed only on the inner diameter side of the conductive wire 24a.

  The cold cathode 24 generates an electron beam due to electric field concentration at the tips of the fine protrusions included in the carbon film 24b by electric field radiation by applying an electric field between the anode 22 and the generated electron beam through the window foil portion 12 inside. Irradiation is performed in a duct space 26 surrounded by the inner peripheral surface of the cylindrical body 14.

  The carbon film 24b has carbon nanometers, carbon nanowalls, carbon nanofibers, diamond-like carbon, amorphous diamond, crystalline diamond, graphite, fullerene, acicular carbon film, carbon fine particles, and the like having fine nm order protrusions. It can be illustrated.

  Around the outer diameter side of the cold cathode 24, an electron beam shielding member 28 that shields an electron beam that has substantially the same potential as the cold cathode 24 and is emitted from the cold cathode 24 is disposed. The electron beam shielding member 28 includes a pair of annular plate portions 28a and a cylindrical body portion 28b that couples both annular plate portions 28a on the outer diameter side. Ends on the inner diameter side of both annular plate portions 28a preferably extend toward the inner diameter side than the cold cathode 24, and shield the electron beams from being emitted from the cold cathode 24 to other than the window foil portion 12. Thus, the window foil 12 can be irradiated with an electron beam with high efficiency.

  The anode 22 is grounded, and a negative potential is applied to the cold cathode 24 and the electron beam shielding member 28. The negative potential power source may be a DC power source or a pulse power source. When the electron beam irradiation device is driven by a pulse power source, heat generation due to the electron beam irradiation of the window foil portion 12 can be suppressed. On the other hand, when the window foil portion 12 is continuously driven by a DC power source, a cooling mechanism may be provided in the window foil portion 12.

  In the electron beam irradiation apparatus 10 of the embodiment having the above-described configuration, when a negative potential is applied to the cold cathode 24, electrons are emitted from the surface of the carbon film 24b of the cold cathode 24 by field emission, and the electrons A line 32 is irradiated from the window foil 12 into the duct space 26. And this electron beam irradiation apparatus 10 is interposed between irradiation object conveyance path | routes A and B, and irradiation target object is carried out from the one side shown by the arrow in the duct space 26 in the electron beam irradiation apparatus 10 from the path A side to the other side. When 30 is carried in, the irradiation object 30 is irradiated with the electron beam 32, sterilization / sterilization, modification, fine processing and the like are performed, and the other object B is carried out. .

  In this case, as a result of the electron beam shielding member 28 regulating the electron beam irradiation direction from the cold cathode 24, the electron beam 32 is not irradiated in the direction indicated by the broken line 34, and the window foil 12 is irradiated with high efficiency. .

  As shown in FIG. 4, the anode 22 may be disposed along the periphery of the window foil portion 12 so as to constitute a part of the inner cylinder 14. However, in this case, since the anode 22 is exposed to the duct space 26, it is preferable that the anode 22 is grounded and the cold cathode 24 is applied with a negative high potential.

  The present invention is not limited to the above-described embodiment, and includes various changes or modifications within the scope described in the claims.

FIG. 1 is a sectional view of an electron beam irradiation apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view of the electron beam irradiation apparatus of FIG. 3 is a cross-sectional view corresponding to FIG. 1 for explaining the operation of the electron beam irradiation apparatus of FIG. FIG. 4 is an enlarged cross-sectional view showing a main part of FIG. FIG. 5 is a diagram showing the configuration of the electron beam irradiation apparatus described in Patent Document 6. In FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electron beam irradiation apparatus 12 Window foil part 14 Inner cylinder 16 Outer cylinder 18 Vacuum sealed space 20 Double cylinder 22 Anode 24 Cold cathode 24a Conductive wire 24b Carbon film 26 Duct space 28 Electron beam shielding member 30 Irradiation object Item 32 Electron Beam

Claims (2)

A double cylinder having an inner and outer concentric cylinders and having a circumferential annular vacuum sealed space is formed, and an anode is provided on the inner cylinder in an annular shape in the circumferential direction. while forming the window foil portion with the line transparency, in the above vacuum-sealed space arranged cold cathode with carbon film for field emission circumferentially annularly position facing the window foil portion, the cold cathode An electron beam irradiation apparatus comprising: an electron beam shielding member that shields an electron beam from the cold cathode at substantially the same potential as the cold cathode around a portion other than the portion facing the window foil portion . The electron beam irradiation apparatus according to claim 1, wherein a part of the inner cylindrical body is formed of an anode.

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