WO2016114107A1

WO2016114107A1 - Small pitch multi-nozzle electron beam emitter and sterilization system

Info

Publication number: WO2016114107A1
Application number: PCT/JP2016/000036
Authority: WO
Inventors: Kaveh Bakhtari
Original assignee: Hitachi Zosen Corporation
Priority date: 2015-01-14
Filing date: 2016-01-06
Publication date: 2016-07-21
Also published as: WO2016113807A1; WO2016114108A1; JP2018503565A; JP2018508933A; JP2018502020A

Abstract

The present invention has its objective to reduce the size of an electron beam sterilization system so as to lower the cost and complexity of the overall system. An electron beam emitter according to the present invention includes a power supply (11), a cathode (12) connected to the power supply (11), an electron lens (13) that surrounds the cathode (12) and has a plurality of apertures (13a), a flange (14) having a plurality of nozzles (14a), and a chamber (15) that keeps a vacuum, with the flange (14), around the electron lens (13) and the cathode (12). The cathode (12) is partially provided on a straight line passing through the aperture (13a) and the nozzle (14a).

Description

SMALL PITCH MULTI-NOZZLE ELECTRON BEAM EMITTER AND STERILIZATION SYSTEM

The present invention relates to an electron beam emitter for sterilizing containers in the food, beverage and pharmaceutical packaging industry, and an electron beam sterilization system.

Sterilization is the process of killing, disabling or removing microorganisms. In the food and beverage industries the objectives of sterilization are the destruction of any pathogens to extend shelf life of the products; making the distribution process safe and easy. Thus, safe sterilization is necessary for containers for beverages and foods, as well as pharmaceutical containers.

Sterilization with electrons has significant advantages over other methods of sterilization currently in use. The process using the electron beam emitter is quick, reliable, and compatible with most materials. Since chemicals are not used in an electron beam sterilization system including such an electron beam emitter, no chemical residues are left in sterilized containers, achieving high safety.

For example, an electron beam sterilization system for sterilizing containers for beverage, food and pharmaceutical is described in Patent Literature 1. As shown in FIG. 16, an electron beam sterilization system 6 described in Patent Literature 1 includes external electron beam emitters E1 and E2, an internal electron beam emitter having nozzles 24a, conveyors M1 to M4, and a radiation shield S. Black dots in FIG. 16 indicate the nozzles 24a of the internal electron beam emitter. In FIGS. 16 and 18, only the portions of the nozzles 24a of the internal electron beam emitter are illustrated and other portions thereof are omitted.

The conveyors M1 to M4 have retainer arms A. Containers C retained by the retainer arms A are continuously transported along a transport path R. The electron beam emitter includes the first external electron beam emitter E1, the second external electron beam emitter E2, and multiple internal electron beam emitters. As shown in FIG. 17, the first and second external electron beam emitters E1 and E2 sterilize the external surfaces of the containers C with electron beam radiation in a state in which the containers C are retained by the retainer arms A of the conveyor M1. As shown in FIG. 18, the internal electron beam emitter has the nozzles 24a. The nozzle 24a is inserted into the container C to sterilize the internal surface of the container C.

In this configuration, electron beams emitted from the external electron beam emitters E1 and E2 and the internal electron beam emitter may cause radiation harmful to human bodies, for example, X-rays. The radiation shield S surrounds the conveyors M1 to M4, the external electron beam emitters E1 and E2, and the internal electron beam emitter in order to block such radiation. FIG. 19 is a schematic cross-sectional view showing conventional internal electron beam emitters E3'. The conventional internal electron beam emitter E3' includes a power supply 21, a cathode 22, an electron lens 23, a flange 24, and a chamber 25. The cathode 22 is connected to the power supply 21 while the flange 24 is electrically grounded. The nozzle 24a is formed on the flange 24. A space surrounded by the flange 24 and the chamber 25 is kept under vacuum by a vacuum pump 25a. The electron lens 23 and cathode 22 are set at a negative potential provided by a voltage supplied from the power supply 21. This generates an electric field between the duality of ‘electron lens 23 and cathode 22’ and the grounded flange 24 and accelerates the electrons in a form of a beam from the cathode 22 to the nozzle 24a of the flange 24. The electron beam emitters E3' are sequentially disposed along the transport path R of the containers C, sequentially sterilizing the internal surfaces of the containers C transported in a continuous manner.

[Patent Literature 1] Japanese Patent Publication No. 2013-106956

In order to maintain the voltage gradient between the electron lens 23 and the grounded chamber 25, a certain clearance (hereinafter will be referred to as a stand-off D) is necessary between the electron lens 23 and the chamber 25. The stand-off D increases the pitches of the electron beam emitters E3' continuously disposed along the transport path of the containers C, thereby also increasing a pitch P2 between the nozzles 24a of the electron beam emitters E3'. This increases the size of the electron beam sterilization system 6, disadvantageously leading to higher cost and complexity for the overall system.
An object of the present invention is to reduce system cost by downsizing an electron beam sterilization system.

An electron beam emitter of the present invention has been devised to solve the problem. The electron beam emitter includes: a power supply; a cathode connected to the power supply; an electron lens that surrounds the cathode and has a plurality of apertures; a flange having a plurality of nozzles; and a chamber that keeps a vacuum, with the flange, around the electron lens and the cathode. The cathode is partially provided on a straight line passing through the aperture and the nozzle.

Advantageous Effect of Invention

The electron beam emitter of the present invention can reduce the size of an electron beam sterilization system, achieving lower system cost and complexity.

FIG. 1 is a schematic top view showing an electron beam sterilization system according to a first embodiment.

FIG. 2 is a schematic diagram showing an electron beam sterilization method according to the first embodiment.

FIG. 3 is a schematic cross-sectional view showing an electron beam emitter according to the first embodiment and a second embodiment.

FIG. 4 is a principal-part perspective view showing an example of the electron beam emitter according to the first and second embodiments.

FIG. 5 is a principal-part perspective view showing an example of the electron beam emitter according to the first and second embodiments.

FIG. 6 is a principal-part perspective view showing an example of the electron beam emitter according to the first and second embodiments.

FIG. 7 is a principal-part perspective view showing an example of the electron beam emitter according to the first and second embodiments.

FIG. 8 is a principal-part perspective view showing an example of the electron beam emitter according to the first and second embodiments.

FIG. 9 is a principal-part perspective view showing an example of the electron beam emitter according to the first and second embodiments.

FIG. 10 is a principal-part perspective view showing an example of the electron beam emitter according to the first and second embodiments.

FIG. 11 is a schematic top view showing an example of an electron beam sterilization system according to the second embodiment.

FIG. 12 is a schematic diagram showing an electron beam sterilization method according to the second embodiment.

FIG. 13 is a schematic top view showing an example of the electron beam sterilization system according to the second embodiment.

FIG. 14 is a top cross-sectional view showing an example of the electron beam sterilization system according to the second embodiment.

FIG. 15 is a top cross-sectional view showing an example of the electron beam sterilization system according to the second embodiment.

FIG. 16 is a schematic top view showing a conventional electron beam sterilization system.

FIG. 17 is a schematic diagram showing a conventional electron beam sterilization method.

FIG. 18 is a schematic diagram showing the conventional electron beam sterilization method.

FIG. 19 is a schematic cross-sectional view showing conventional electron beam emitters.

(First Embodiment)
First, an electron beam sterilization system and an electron beam sterilizing method according to a first embodiment of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, an electron beam sterilization system 1 according to the first embodiment of the present invention includes first and second external electron beam emitters E1 and E2, an internal electron beam emitter having nozzles 14a, a radiation shield S, and first to fourth conveyors M1 to M4. Black dots in FIG. 1 indicate the nozzles 14a of external electron beam emitters. In FIGS. 1 and 2, only portions of the nozzles 14a of the internal electron beam emitter are illustrated and other portions thereof are omitted.

The external electron beam emitters E1 and E2 and the internal electron beam emitter emit electron beams to sterilize sterilization objects C. The sterilization objects C are, for example, formed or pre-formed containers for food, beverage, and pharmaceutical. As shown in FIG. 17, the external electron beam emitters E1 and E2 are flat emitters that can widely emit electron beams. Meanwhile, the internal electron beam emitter is, as shown in FIG. 2, a nozzle emitter having the nozzles 14a.

The first to fourth conveyors M1 to M4 transport the retained sterilization objects C. For example, as shown in FIG. 1, the conveyors M1 to M4 include circular first to fourth turning tables T1 to T4 and retainer arms A connected to the outer peripheries of the turning tables T1 to T4. The turning tables T1 to T4 rotate with the retainer arms A retaining the necks of the sterilization objects C, transporting the sterilization objects C.

An arrow R in FIG. 1 indicates the transport path of the sterilization objects C. As indicated by the transport path R, when the retainer arms A connected to the different turning tables T1 to T4 come close to each other, the sterilization object C is transported from the retainer arm A of one of the turning tables to the retainer arm A of another turning table so as to pass along the circular path. The nozzles 14a of the internal electron beam emitter are continuously disposed on the transport path R around the third turning table T3 and are rotated in synchronization with a rotation of the third turning table T3.

The first external electron beam emitter E1 sterilizes one half of the overall outer surface of the sterilization object C retained by the retainer arm A of the first turning table T1. When the sterilization object C is transported to the retainer arm A of the second turning table T2, the second external electron beam emitter E2 sterilizes the other half of the overall outer surface of the sterilization object C. When the sterilization object C is transported to the retainer arm A of the third turning table T3, the retainer arm A and the nozzle 14a of the internal electron beam emitter relatively move to insert the nozzle 14a into the sterilization object C. Subsequently, as shown in FIG. 2, electron beams emitted in this state from the nozzle 14a scatter, creating a cloud of electrons, sterilizing the inner surface of the sterilization object C.

However, the conveyors are not limited to such a specific configuration as long as the conveyors relatively move in synchronization with the nozzles 14a so as to transport the retained sterilization objects C.

In this case, electron beam radiation from the external electron beam emitters E1 and E2 and the internal electron beam emitter may cause radiation harmful to human bodies, for example, X-rays. The radiation shield S surrounds the external electron beam emitters E1 and E2, the internal electron beam emitter, and the conveyors M1 to M4 so as to block such radiation.

Referring to FIGS. 3 to 10, the specific configuration of the internal electron beam emitter according to the first embodiment will be described below. Hereinafter, the internal electron beam emitter will be simply referred to as an electron beam emitter E3. The electron beam emitter E3 includes a power supply 11, a cathode 12, an electron lens 13, a flange 14, and a chamber 15. Electron beam emitters E31 to E37 shown in FIGS. 4 to 10 are the specific configuration examples of the electron beam emitter E3 according to the present embodiment. In FIGS. 4 to 10, the power supply 11, the front side of the chamber 15, and the front side of the electron lens 13 are omitted.

The cathode 12 is connected to the power supply 11. The duality of the ‘electron lens 13 and cathode 12’ is held at a negative potential in response to a voltage applied from the power supply 11. The cathode 12 is, for example, an annular-shaped filament cathode shown in FIG. 4. Moreover, electrical current supplied from the power supply 11 to the cathode 12 heats the cathode 12. Heat applied to the cathode 12 excites electrons thermionically in the cathode 12.

The flange 14 has the plurality of nozzles 14a. The flange 14 is electrically grounded and has a higher potential than the duality of the ‘electron lens 13 and cathode 12’ that is set at a negative potential in response to the application of a voltage. This generates an electric field directed from the flange 14 toward the cathode 12.

The chamber 15 surrounds the cathode 12 and the electron lens 13. Window portions 14b allowing the passage of electron beams are provided on the distal ends of the nozzles 14a of the flange 14. Furthermore, a space enclosed by the flange 14 and the chamber 15 is formed. The space is kept under vacuum by a vacuum pump 15a connected to the chamber 15.

The electron lens 13 is an electric conductor made of metals and so on. The electron lens 13 surrounds the cathode 12 and has a plurality of apertures 13a. As shown in FIG. 4, the electron lens 13 may be shaped like a cylinder when the cathode 12 is a filament cathode. Alternatively, as shown in FIG. 5, the electron lens 13 may be shaped like a donut with an opening formed at the center of the electron lens 13. As shown in FIG. 3, the electron lens 13 is connected to the power supply 11 like the cathode 12 and is substantially equal in potential to the cathode 12.

Moreover, the cathode 12 is partially provided on straight lines passing through the apertures 13a and the nozzles 14a of the flange 14. In this case, the electron lens 13 that is an electric conductor interrupts an electric field directed from the flange 14 toward the cathode 12 except for the locations of the apertures 13a. In other words, the electric field directed from the flange 14 toward the cathode 12 is only partially applied to the cathode 12 so as to correspond to the locations of the apertures 13a. Moreover, electrons excited on the cathode 12 are emitted from the parts of the cathode 12 where the electric field is applied, and consequently electron beams are emitted to the outside of the electron beam emitter E3 through the aperture 13a, the nozzles 14a, and the window portions 14b.

The electron beam emitter according to the present embodiment can reduce the size of the electron beam sterilization system, achieving cost and complexity reduction of the overall system. The detail will be discussed below.

In a typical electron beam emitter, a certain clearance (stand-off) is required between an electron lens and a chamber to maintain the voltage gradient between the electron lens and the grounded chamber. In the conventional electron beam emitter E3' shown in FIG. 19, the nozzle 24a is provided for the power supply 21, the cathode 22, and the electron lens 23. The electron beam emitters E3' configured thus are continuously disposed along the transport path R of sterilization objects. Thus, the stand-off D is interposed between the continuously disposed electron beam emitters E3' so as to extend the pitch P2 between the nozzles 24a. This increases the size of the electron beam sterilization system, disadvantageously raising the cost of the overall system. Particularly, an increase in the size of the radiation shield S leads to notably high cost. Since the power supplies 21 are provided for the respective nozzles 24a, the power supplies 21 need to be controlled to control electron beams emitted from the nozzles 24a, disadvantageously leading to complicated control.

In contrast, as shown in FIG. 3, the electron beam emitter E3 according to the first embodiment includes the multiple nozzles 14a provided for the single power supply 11, the single cathode 12, and the single electron lens 13. This eliminates the need for providing a stand-off D for each of the nozzles 14a. Thus, a pitch P1 (see FIGS. 2 and 3) between the nozzles 14a is smaller than the pitch P2 (see FIGS. 18 and 19) of the related art. This can reduce the size of the electron beam sterilization system including the radiation shield S surrounding the electron beam emitter E3, thereby achieving cost reduction of the overall system. Moreover, the provision of the single power supply 11 for the multiple nozzles 14a can simplify the control of electron beams emitted from the nozzles 14a.

The electron lens 13 is substantially equal in potential, but not exclusively, to the cathode 12. Rather, the potential of the electron lens 13 is preferably higher than that of the cathode 12. If the electron lens 13 has a higher potential than the cathode 12, the electron lens 13 acts as an extraction electrode, facilitating electron emission from the inside of the cathode 12 to the outside of the cathode.

In this configuration, the cathode 12 preferably has an emission part that facilitates electron emission. For example, the cathode 12 includes an excitation part having a relatively low work function and a non-excitation part having a relatively high work function. In this configuration, the excitation part acts as the emission part that facilitates electron emission. Specifically, as shown in FIG. 6, the annular-shaped filament is used that is partially covered with a coating 12b having a higher work function than the filament, forming the excitation part and the non-excitation part. In this case, a part uncovered with the coating 12b is the excitation part while a part covered with the coating 12b is the non-excitation part. Current supply from the power supply 11 to the cathode 12 applies heat to the excitation part and the non-excitation part. The application of heat to the excitation part excites electrons in the excitation part, whereas heat applied to the non-excitation part is unlikely to excite electrons in the non-excitation part because the non-excitation part has a higher work function than the excitation part.

In this configuration, the excitation part is disposed on the straight line passing through the aperture 13a of the electron lens 13 and the nozzle 14a of the flange 14. Thus, electrons excited in the excitation part are attracted toward the flange 14 by an electric field between the cathode 12 and the flange 14. Electron beams are then emitted to the outside of the electron beam emitter E33 through the apertures 13a and the nozzles 14a.

In this case, the cathode 12 is divided into the excitation parts and the non-excitation parts, thereby efficiently emitting electron beams to the outside of the electron beam emitter E33. For example, if the cathode 12 entirely acts as the excitation part without being divided into the excitation parts and the non-excitation parts, electrons are likely to be excited in the overall cathode 12. However, the electron emission requires only the excitation of electrons from the cathode 12 disposed on the straight line passing through the apertures 13a and the nozzle 14a. Electrons do not need to be excited in other locations.

In this regard, the cathode 12 is divided into the excitation parts and the non-excitation parts. Electrons in the cathode 12 are to be excited in the excitation parts, whereas electrons are not to be excited in the non-excitation parts. This facilitates electron emission from the excitation parts while suppressing electron emission from the non-excitation parts, thereby efficiently emitting electron beams to the outside of the electron beam emitter E33.

In addition to the configuration of FIG. 6, the excitation parts and the non-excitation parts may be specifically configured as shown in FIGS. 7 to 9. In FIG. 7, the non-excitation part is an annular-shaped wire and the excitation parts are discs 12c having a lower work function than the wire. The discs 12c are provided on the wire near the apertures 13a. The disc 12c is disposed on a straight line passing through the aperture 13a and the nozzle 14a.

In FIG. 8, a cable 12d acts as a non-excitation part and the discs 12c acting as excitation parts are connected in series via the cable 12d. The disc 12c is disposed on a straight line passing through the aperture 13a and the nozzle 14a.

In FIG. 9, the cathode 12 includes a disk having a low work function and a high-work function coating covering the disk. At the bottom of the cathode 12, an exposed portion 12f that is not coated is disposed on the disk on a straight line passing through the apertures 13a and the nozzle 14a. In this case, the exposed portions 12f act as excitation parts. Meanwhile, a part other than the exposed portions 12f, that is, a part covered with the high-work function coating acts as a non-excitation part.

In the configurations of FIGS. 4 to 9, a current supplied from the power supply 11 applies heat to the cathode 12 so as to excite, but not exclusively, electrons in the cathode 12. For example, instead of excitation of electrons in the cathode 12, a field emission effect rather than thermionic emission can emit electrons in the cathode 12. Specifically, as shown in FIG. 10, the cathode 12 of the electron beam emitter E37 has a plurality of protrusions 12a that protrude toward the nozzles 14a. The protrusion 12a may be disposed on a straight line passing through the aperture 13a of the electron lens 13 and the nozzle 14a of the flange 14. In this case, the protrusions 12a are closer to the flange 14 than other portions of the cathode 12 and thus electric fields between the cathode 12 and the flange 14 concentrate on the protrusions 12a. Electric fields concentrate on the cathode 12, on the straight lines passing through the nozzles 14a and the apertures 13a, allowing the field emission effect to emit electrons in the cathode 12 to the outside of the cathode 12 without thermionic excitation of electrons. In this case, the protrusions 12a act as emission parts that facilitate electron emission.

In this configuration, the flange 14 is electrically grounded. The present invention is not limited to this configuration. As long as the flange 14 has a higher potential than the cathode 12, electric fields can be generated from the flange 14 toward the cathode 12 to emit electron beams.

(Second Embodiment)
In a second embodiment, the electron beam emitter itself is identical to the electron beam emitter E3 of the first embodiment. The second embodiment is different from the first embodiment in the overall configuration of an electron beam sterilization system. In the first embodiment, as shown in FIG. 1, the outer surface of the sterilization object C is sterilized by the external electron beam emitters E1 and E2, whereas as shown in FIG. 11, an electron beam sterilization system 2 according to the second embodiment does not include the external electron beam emitters E1 and E2 but includes an internal electron beam emitter that also sterilizes the outer surface of a sterilization object C. The detail will be discussed below.

A plurality of nozzles in the electron beam emitter according to the second embodiment include internal sterilizing nozzles 14aa capable of sterilizing the interiors of the sterilization objects C and external sterilizing nozzles 14ab capable of sterilizing the outer surfaces of the sterilization objects. For example, as shown in FIG. 11, the number of retainer arms A is half as many as the nozzles (black dots in FIG. 11) provided on a transport path R. The retainer arm A is disposed on every second nozzle. In this configuration, among the nozzles of the electron beam emitter, the internal sterilizing nozzles 14aa are provided at the locations of the retainer arms A while the external sterilizing nozzles 14ab are provided at other locations.

As shown in FIG. 12, the internal sterilizing nozzle 14aa is inserted into the sterilization object C and emits electron beams in this state so as to sterilize the inner surface of the sterilization object C. Meanwhile, the external sterilizing nozzle 14ab is not inserted into the sterilization object C and emits electron beams in this state so as to sterilize the outer surfaces of the sterilization objects C.

In the electron beam sterilization system 2 according to the second embodiment, the electron beam emitter is identical to the electron beam emitter E3 according to the first embodiment and thus a pitch P1 (see FIG. 12) between the nozzles 14a is smaller than the pitch P2 (see FIGS. 18 and 19) of the related art. This allows the outer surface of the sterilization object C, where the internal sterilizing nozzle 14aa is inserted, to be sterilized by electron beams emitted from the external sterilizing nozzle 14ab adjacent to the internal sterilizing nozzle 14aa. With this configuration, the external electron beam emitters E1 and E2 (see FIG. 16) for sterilizing the outer surfaces of the sterilization objects C do not need to be provided. Furthermore, this configuration eliminates the need for the first conveyor M1 (see FIG. 16) for the external electron beam emitters E1 and E2. Thus, the electron beam sterilization system can be reduced in size, thereby reducing the cost of the overall system. Moreover, the sterilization object C can be internally and externally sterilized at the same time, thereby preventing the already sterilized surfaces of the sterilization object C from being re-contaminated by the not yet sterilized surfaces, between internal sterilization and external sterilization.

In this configuration, the number of retainer arms A is half as many as the nozzles 14a, the retainer arm A being disposed on every second nozzle. The present invention is not limited to this configuration. For example, the retainer arms A may be equal in number to the nozzles 14a and one of the adjacent retainer arms A may be controlled not to hold the sterilization object C. In this case, the internal sterilizing nozzles 14aa are provided for the retainer arms A that retain the sterilization objects C while the external sterilizing nozzles 14ab are provided for the retainer arms A that do not retain the sterilization objects C. Thus, the sterilization object C can be internally and externally sterilized at the same time.

The internal sterilizing nozzle 14aa is disposed, but not exclusively, on every other one of the continuously provided nozzles. For example, two of the external sterilizing nozzles 14ab may be continuously provided for the single internal sterilizing nozzle 14aa. In this case, the internal sterilizing nozzle 14aa is disposed on every two of the continuous nozzles. Since the external sterilizing nozzles 14ab are provided between the internal sterilizing nozzles 14aa, the outer surfaces of the sterilization objects C can be sterilized by electron beams emitted from the external sterilizing nozzles 14ab.

The external sterilizing nozzles 14ab are provided, but not exclusively, on the transport path R of the sterilization objects C. The external sterilizers 14ab may be provided outside the transport path R. For example, as shown in FIG. 13, the four external sterilizing nozzles 14ab may be provided around the internal sterilizing nozzle 14aa in plan view. As shown in FIG. 14, the three external sterilizing nozzles 14ab may be provided around the internal sterilizing nozzle 14aa in plan view. The larger the number of external sterilizing nozzles 14ab surrounding the internal sterilizing nozzle 14aa, the more reliable sterilization on the outer surfaces of the sterilization objects C.

In FIGS. 11, 13, and 14, conveyors M2 to M4 transport the sterilization objects C, but not exclusively, along the circular transport path R. For example, as shown in FIG. 15, the conveyors M2 to M4 may be replaced with a conveyor M5, e.g., a conveyor that transports the sterilization objects C along a linear transport path R'. The internal sterilizing nozzles 14aa are continuously disposed on the linear transport path R'. In the case of the external sterilizing nozzles 14ab, the internal and external sterilizing nozzles 14aa and 14ab may be disposed in a lattice or staggered fashion.

In the electron beam sterilization systems according to the first and second embodiments, the nozzles used for sterilization are all provided, but not exclusively, for the single electron beam emitter E3. For example, the electron beam sterilization system may include a combination of electron beam emitters, each having a plurality of nozzles.

The multiple nozzles 14a may be the same shape or various shapes depending on the intensity of the emission or shape of the emission. For example, If the external sterilizing nozzles 14ab has longer diameters than that of internal sterilizing nozzles 14aa in the second embodiment of the present invention, the cloud of electrons emitted from the external sterilizing nozzles 14ab scatters broadly and the external sterilizing nozzles 14ab can easily sterilize the external surface of the sterilization objects C. Not limited to the diameter of the nozzles, length of the nozzles or shapes of the nozzle tips may be various. Furthermore, the intensity of the emission can be adapted by the various shape of cathode 12, the various resistance of cathode 12 or the various work function of the cathode 12. Materials with corrosion resistance such as stainless or titanium are used as the nozzles. Materials through which the electron can easily transmits such as titanium, silica or aluminum may be used as the window portion 14b. The cooling mechanism such as air cooling or water cooling may be provided since the window portion 14b tend to have a high temperature.

Claims

An electron beam emitter comprising:
a power supply;
a cathode connected to the power supply;
an electron lens that surrounds the cathode and has a plurality of apertures;
a flange having a plurality of nozzles; and
a chamber that keeps a vacuum, with the flange, around the electron lens and the cathode,
the cathode being partially provided on a straight line passing through the aperture and the nozzle.
The electron beam emitter according to claim 1, wherein the cathode has an emission part that facilitates electron emission,
the emission part being provided on the straight line passing through the aperture and the nozzle.
The electron beam emitter according to claim 1, wherein the electron lens has a higher potential than the cathode.
An electron beam sterilization system comprising:
at least one electron beam emitter according to claim 1;
conveyors capable of relatively moving in synchronization with the nozzles of the electron beam emitter and transporting retained sterilization objects; and
a radiation shield surrounding the at least one electron beam emitter and the conveyors.
The electron beam sterilization system according to claim 4, wherein the nozzles include an internal sterilizing nozzle capable of sterilizing an inner surface of the sterilization object and an external sterilizing nozzle capable of sterilizing an outer surface of the sterilization object.
The electron beam sterilization system according to claim 5, wherein the internal sterilizing nozzle is provided on a transport path of the sterilization object, and
the external sterilizing nozzle is provided on and/or outside the transport path.