JP2001242297A - Electron beam irradiation method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron beam irradiation device capable of reducing an energy loss by thinning the thickness of a window foil installed on an irradiation window of an accelerator chamber. SOLUTION: In this electron beam irradiation device, the irradiation window 102a of the accelerator chamber 102 is connected to an irradiation chamber 101, and the window foil 103 is installed on the irradiation window so as to separate the accelerator chamber 102 from the irradiation chamber 101. In the device, a vacuum pump 138 for evacuating the irradiation chamber 101 is installed, to thereby keep the irradiation chamber 101 in the evacuated state when the accelerator chamber 102 is evacuated. And, a vibration applicator 144 for applying vibration on powder 142 as an object to be irradiated is installed, to generate bouncing movement in each particle of the powder during irradiation of the electron beam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam irradiation method for irradiating powders such as grains with an electron beam, and an electron beam irradiation apparatus used for carrying out the method.

[0002]

2. Description of the Related Art In order to sterilize and kill insects such as flour, grain is irradiated with an electron beam. FIG.
FIG. 1 shows the configuration of a conventional electron beam irradiation apparatus used for irradiating powder such as grain with an electron beam. In FIG. The irradiation chamber 2 has an irradiation window 2a connected to the irradiation chamber 1 and has an irradiation window 2a. The irradiation window 2a is closed by a window foil 3 made of a material through which an electron beam can pass. ing. In the accelerator chamber 2,
An electron gun 4 including a filament 4a, a cathode electrode 4b, and the like is arranged, and the electron gun 4 is opposed to the window foil 3. A negative potential is applied to the cathode electrode 4b from a power supply (not shown) with respect to the ground potential portion, and the electron beam B generated from the electron gun 4 is accelerated by the voltage between the cathode electrode 4b and the ground potential portion, so that the window foil is The irradiation chamber 3 is irradiated through the irradiation chamber 1.

[0005] Reference numeral 5 denotes a conveyor arranged in the irradiation chamber 1, which conveys an irradiation tray 7 on which a powder 6 as an object to be irradiated is placed from the entrance 1 a to the exit 1 b. A nitrogen gas supply pipe 9 is connected to the irradiation chamber 1 through a valve 8.

[0004] Shutters 10 and 11 are attached to a carry-in entrance 1a and a carry-out exit 1b of the irradiation chamber 1, respectively.
A carry-out conveyor 13 is arranged behind the shutter 11.

The interior of the accelerator chamber 2 is maintained in a high vacuum state by a vacuum pump (not shown), and the interior of the irradiation chamber 1 is filled with nitrogen gas and maintained at atmospheric pressure. As the window foil 3, a metal foil (for example, a titanium foil) having a thickness (about 20 μm) that can withstand a pressure difference between the accelerator chamber 2 and the irradiation chamber 1 is used.

In the electron beam irradiation apparatus shown in FIG.
The irradiation tray 7 on which the powder 6 is placed is conveyed by the conveyor 12 toward the irradiation chamber 1, the shutter 10 is opened, and the irradiation tray 7 conveyed by the conveyor 12 is transferred to the conveyor 5 in the irradiation chamber 1. . Irradiation chamber 1 with shutters 10 and 11 closed
The inside is filled with nitrogen gas, and while the irradiation tray 7 is being moved toward the carry-out port 1b by the conveyor 5, the electron beam B generated from the electron gun 4 passes through the window foil 2a and the powder on the irradiation tray 7 6 is irradiated. After the irradiation of the electron beam is completed, the shutter 11 is opened, and the irradiation tray 7 on which the powder that has been irradiated with the electron beam is loaded is carried out of the irradiation chamber 1. The irradiation tray 7 carried out of the irradiation chamber 1 is transported by the conveyor 5 to the next step.

In the above description, the irradiation of the electron beam is performed with the shutters 10 and 11 at both ends of the irradiation chamber 1 closed. However, both ends of the irradiation chamber 1 are opened, and N 2 is passed through the irradiation chamber. In some cases, the electron beam is irradiated while flowing gas or the like.

[0008]

In the conventional electron beam irradiation apparatus shown in FIG. 2, the interior of the accelerator chamber 2 is kept in a high vacuum state, the interior of the irradiation chamber 1 is kept at atmospheric pressure, and the Is large, it is necessary to use a thick window foil 3 that can withstand a large differential pressure. Therefore, energy loss generated in the window foil 3 increases,
The number of electrons lost when passing through the window foil 3 increases,
There is a problem that the energy efficiency of the irradiation device is deteriorated and it is necessary to use a high energy electron accelerator.

Further, since the temperature of the window foil 3 rises due to a large loss occurring in the window foil 3, it is necessary to provide a large-scale cooling means such as a water cooling device for cooling the window foil 3, which is troublesome. Was.

When sterilizing powder such as flour or the like, it is desirable to uniformly irradiate the particles of the powder with an electron beam. In a conventional electron beam irradiation apparatus, the electron beam is formed on an irradiation tray 7. The particles located in the vicinity of the surface of the powder layer were mainly irradiated with the electron beam, and the particles located inside the powder layer on the irradiation tray were not irradiated with much electron beam. Was difficult to irradiate.

In a conventional electron beam irradiation apparatus for irradiating food powder such as flour with an electron beam, the inside of the irradiation chamber is purged with nitrogen gas. However, it is possible to completely prevent oxygen from remaining in the irradiation chamber. Therefore, there is a problem that oxygen remaining in the irradiation chamber is ozonized by the irradiation of the electron beam, and the powder is oxidized by the ozone.

An object of the present invention is to reduce the thickness of a window foil attached to an irradiation window of an irradiation chamber so as to reduce a loss generated in the window foil and suppress an increase in the temperature of the window foil. It is an object of the present invention to provide an irradiation method and an electron beam irradiation device used for performing the method.

Another object of the present invention is to provide an electron beam irradiation method capable of uniformly irradiating each particle of a powder with an electron beam and an electron beam irradiation apparatus used for carrying out the method. It is in.

Still another object of the present invention is to provide a method of irradiating an electron beam which eliminates the possibility that an object to be irradiated is oxidized due to generation of ozone in an irradiation chamber and an electron beam irradiation apparatus used for carrying out the method. To provide.

[0015]

According to the electron beam irradiation method of the present invention, an irradiation chamber accommodating an object to be irradiated with an electron beam, an accelerator chamber having an irradiation window connected to the irradiation chamber, and A window foil attached so as to close the irradiation window, and an accelerator having an electron gun arranged in the accelerator chamber and accelerating an electron beam generated from the electron gun and irradiating the inside of the irradiation chamber through the window foil. ,
An irradiation pallet configured to hold powder as an irradiation object and opposed to an irradiation window in the irradiation chamber, a vacuum pump for reducing the pressure in the irradiation chamber, and a vibration applying device for applying vibration to the irradiation pallet; Is provided, and the inside of the accelerator chamber and the inside of the irradiation chamber are simultaneously evacuated to reduce the pressure in both chambers. The inside of the accelerator chamber is in a high vacuum state (for example, 1 × 10 ⁻⁵ [P
a), and the pressure in the irradiation chamber is reduced to a sufficiently low pressure (preferably a pressure of about 10 kPa). In this state, the powder on the irradiation pallet is irradiated with the electron beam from the accelerator chamber through the window foil while applying vibration to the irradiation pallet.

As described above, in order to reduce the pressure in the irradiation chamber to a sufficiently low pressure, it is preferable to use a container that satisfies the conditions of a vacuum container as the irradiation chamber.

If the pressure in the irradiation chamber is also reduced when the pressure in the accelerator chamber is reduced as described above, the pressure difference between the irradiation chamber and the accelerator chamber can be reduced, and the Can be used as a window foil (for example, about 20 μm) which is thinner (for example, about several μm). Therefore, the loss in the window foil can be reduced, the energy efficiency can be improved, and an electron accelerator having lower energy than before can be used as the accelerator.

Further, since the loss occurring in the window foil can be reduced, the temperature rise of the window foil can be suppressed.

Further, as described above, when the electron beam is irradiated in a state where the pressure in the irradiation chamber is reduced, the risk of generation of ozone in the irradiation chamber can be reduced. Oxidation of the irradiated object can be prevented.

Further, as described above, when the electron beam is irradiated while applying vibration to the powder, each particle of the powder can be irradiated with the electron beam while performing a bouncing motion. The electron beam can be irradiated almost uniformly.

The electron beam irradiation apparatus used for carrying out the above method basically includes an irradiation chamber for accommodating an object to be irradiated with an electron beam, and an irradiation window connected to the irradiation chamber. Having an accelerator chamber having a window foil attached so as to cover the irradiation window and an electron gun disposed in the accelerator chamber, and irradiating the electron beam generated from the electron gun to the irradiation chamber through the window foil. An accelerator, an irradiation pallet configured to hold powder as an irradiation object and opposed to the irradiation window in the irradiation chamber, and depressurizing the irradiation chamber when the inside of the accelerator chamber is depressurized. And a vibration applying device for applying vibration to the irradiation pallet.

In order to be able to maintain a reduced pressure to a sufficiently low pressure in the irradiation chamber, the irradiation chamber is provided with a carry-in port for carrying the object to be irradiated and a carry-out port for carrying out the object to be irradiated. It is preferable that the load lock chamber and the load lock chamber are connected to the loading port and the loading port, respectively. In this case, a powder carrying means for carrying the powder carried into the irradiation chamber through the load lock chamber on the carrying side onto the irradiation pallet, and a powder discharging means for carrying the powder on the irradiation pallet to the carry-out port. Means are provided.

Also in the electron beam irradiation apparatus according to the present invention, it is preferable to control the pressure in the reduced irradiation chamber by using an inert gas such as N 2 gas.

It is preferable to use an apparatus having an ultrasonic vibrator and a vibration transmitting member for transmitting the ultrasonic vibration generated by the ultrasonic vibrator to the irradiation pallet.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an electron beam irradiation apparatus according to the present invention. In FIG. 1, reference numeral 101 denotes an irradiation chamber which satisfies the conditions as a vacuum vessel, and 102 is connected to the irradiation chamber 101. This is an accelerator chamber having an irradiation window 102a. The irradiation chamber 101 is formed of a rectangular parallelepiped metal container with its axis oriented in the horizontal direction, and the irradiation window 102a of the accelerator chamber 102 is connected to the upper part of the irradiation chamber.
The irradiation window 2a of the accelerator chamber 102 is closed by a window foil 103 made of a material through which electron beams pass. As the window foil 103, a Kapton foil made of engineering plastic or a metal foil made of a suitable material such as titanium can be used.

An electron gun 104 having a filament 104a, a cathode electrode 104b and the like is arranged in the accelerator chamber 102, and the electron gun 104 is opposed to the window foil 103. The irradiation chamber 101 and the accelerator chamber 102 are maintained at the ground potential, and a negative potential with respect to the ground potential is applied to the cathode electrode 104b from a power supply (not shown), and the electron beam B generated from the electron gun 104 is connected to the cathode electrode 104b. The irradiation is accelerated by the voltage between the ground potential portion and the inside of the irradiation chamber 101 through the window foil 103.

In the example shown, the accelerator chamber 102
, A window foil 103, an electron gun 104, and a power source (not shown) for applying a voltage between the electron gun and a ground potential unit constitute an accelerator.

A loading port 101b is provided at an upper portion of the irradiation chamber 101 near one end in the axial direction, and a loading port 101c is provided at a lower portion at the other end in the axial direction. One end of the load-side load lock chamber 121 is connected to the load entrance 101b through a gate valve 120, and the load lock chamber 1
A gate valve 122 is attached to the other end of 21. A vacuum pump (rotary pump) 124 is connected to the load lock chamber 121 via a valve 123, and N (not shown) is connected via a valve 125 and a pipe 126.
2 The gas supply is connected.

The unloading side load lock chamber 1 is connected to the unloading port 101c of the irradiation chamber 101 through the gate valve 130.
One end of the load lock chamber 131 is connected, and a gate valve 132 is connected to the other end of the load lock chamber 131. A vacuum pump 134 is connected to the load lock chamber 131 through a valve 133.
Is connected, and an N2 gas supply source is connected via a valve 135 and a pipe 136.

A vacuum pump 138 is connected to the irradiation chamber 101 via a valve 137, and N2 (not shown) is connected via a flow control valve 139 and a pipe 140.
A gas supply is connected.

In the illustrated apparatus, during operation, the valve 1
37 is opened to keep the vacuum pump 137 always in operation, and the flow rate of the N2 gas flowing into the irradiation chamber 101 is adjusted by the flow rate adjustment valve 139.
The inside of the irradiation chamber 101 is maintained in a vacuum state of about 10 [kPa].

An irradiation window 10 is provided in the irradiation chamber 101.
2a, the pallet support 141
The irradiation pallet 143 holding the powder 142 as an object to be irradiated is placed on the pallet support table 141.
It is arranged facing the irradiation window 102a.

The pallet support table 141 includes a base 141a.
A movable table 141b rotatably supported by the base 141a; and a drive source (not shown) for rotating the movable table 141b.
The irradiation pallet 143 is fixed on b. The movable table 141b moves at least 90 degrees between a horizontal position where the upper surface is horizontal as shown in the drawing and a standing position where the powder holding surface of the irradiation pallet 143 is raised toward the carry-out port 101c. ° can be rotated.

The movable table 141b is provided with a vibration imparting device 144 having an ultrasonic vibrator and a vibration transmitting member for transmitting the ultrasonic vibration generated by the ultrasonic vibrator to the irradiation pallet 143.

In the irradiation chamber 101, there are provided a powder carrying means 145 and a powder carrying means 146 composed of chutes arranged at a predetermined angle. The conveying means 145 for carrying in the powder has its upper end 1
45a is positioned near the end of the irradiation chamber 101 on the side of the entrance 101b, and the lower end is positioned above the irradiation pallet 143, and is supported by a support device 147 attached to the bottom of the irradiation chamber 101. ing.

The support device 147 includes the irradiation chamber 101
A support 147a fixed to the bottom of the support 147;
a supporting member 147b supported movably in the axial direction of the irradiation chamber by a guide mechanism provided in a, and a driving device (not shown) for moving the supporting member 147b in the axial direction of the irradiation chamber 101. The conveying means 145 for carrying in the powder is supported on the upper end of the supporting member 147b.

The conveying means 145 for carrying in the powder is supported by the supporting device 1
47 allows the reciprocating movement of the irradiation chamber 101 in the axial direction of the irradiation chamber 101. When the powder 142 is supplied to the irradiation pallet 143 by the conveying means 145, the conveying means 145 is moved in the axial direction of the irradiation chamber 101. Thus, the powder 142 is distributed on the irradiation pallet 143 with a substantially uniform thickness.

The conveying means 146 for discharging the powder has one end 1 thereof.
The gate 46a is located at a position higher than the other end 146b, and the one end 146a and the other end 146b are respectively connected below the end of the irradiation pallet 143 on the side of the outlet 101c and to the outlet 101c of the irradiation chamber 101. It is located above the bulb 130 and is supported by a support device 148 fixed to the bottom of the irradiation chamber 101.

An electron beam irradiation method using the electron beam irradiation apparatus shown in FIG. 1 will be described below.

In the electron beam irradiation method of the present invention, as described above, the irradiation chamber 101, the accelerator, and the irradiation pallet 1
43 and a vacuum pump 138 for reducing the pressure in the irradiation chamber
And a vibration imparting device 144 for applying vibration to the irradiation pallet, and the inside of the accelerator chamber 102 and the inside of the irradiation chamber 101 are simultaneously evacuated to reduce the pressure in both the accelerator chamber 102 and the irradiation chamber 101. The powder on the irradiation pallet is irradiated with an electron beam from the accelerator chamber through the window foil 103 while applying vibration to the irradiation pallet 143.

Preferred embodiments of the electron beam irradiation method of the present invention are as follows.

When the powder 142 such as flour is irradiated with an electron beam, the irradiation chamber 101 is first filled with N 2 gas, and then the accelerator chamber 102 and the irradiation chamber 10 are irradiated.
At the same time, the inside of the accelerator chamber 102 is evacuated to a high vacuum state of about 1 × 10 ⁻⁵ [Pa], and the inside of the irradiation chamber 101 is evacuated to about 10 [kPa]. The vacuum pump 138 for evacuating the accelerator chamber and the vacuum pump 138 for evacuating the irradiation chamber are always operated.
01 so that the pressure in the internal pressure 01 is always kept at around 10 [kPa].
2 Adjust the flow control valve 139 to control the gas flow.

After the interior of the irradiation chamber and the interior of the accelerator chamber are decompressed, the gate valve 122 is opened, and the powder to be irradiated with the electron beam is carried into the load-side load lock chamber 121 by carrying means (not shown). Then gate valve 12
2 is closed, the valve 125 is opened, and the load lock chamber 121 is opened.
The N2 gas is injected into the chamber, the valve 123 is opened, and the vacuum pump 124 is operated to reduce the pressure in the load lock chamber 121 to the same pressure as the pressure in the irradiation chamber 101. After the pressure in the load lock chamber 121 is reduced to the same pressure as the pressure in the irradiation chamber 101, the gate valve 120
Is opened, the powder is dropped on the powder carrying conveyance means 145, the powder is caused to flow along the conveyance means 145, and is supplied onto the irradiation pallet 143 supported horizontally on the pallet support table 141. I do. At this time, the powder 142 is distributed with a substantially uniform thickness over the entire surface of the irradiation pallet 143 by appropriately moving the conveying means 145 in the axial direction of the irradiation chamber 101.

After supplying the powder 142 onto the irradiation pallet 143, the gate valve 120 is closed, and the
In a state where ultrasonic vibration is applied to the irradiation pallet 143 by operating the electron gun 4, the electron gun 104 generates an electron beam B,
The powder B on the irradiation pallet 143 is irradiated with the electron beam B through the window foil 103.

After the irradiation of the powder 142 with the electron beam is completed, the generation of the electron beam is stopped, and the vibration applying device 144 is stopped.
Stop the operation of. Next, the vacuum pump 134 is operated while adjusting the supply amount of N2 gas into the load-side load lock chamber 131 by the valve 135 to operate the load lock chamber 1.
After reducing the pressure inside the irradiation chamber 31 to the same pressure as the inside of the irradiation chamber 101, the gate valve 130 is opened and the irradiation pallet 143 is opened.
Is turned 90 °. As a result, the powder 142 in the pallet 143 is dropped onto the conveying means 146, and the powder
2 is caused to flow along the transport means 146 and moved into the load lock chamber 131.

All powders 142 that have been irradiated with the electron beam
Is moved into the load lock chamber 131, and then the gate valve 130 is closed. Next, after the inside of the load lock chamber 131 is set to the atmospheric pressure, the gate valve 132 is opened to discharge the powder in the load lock chamber 131 to the outside.

As described above, when the pressure inside the irradiation chamber is also reduced when the pressure inside the accelerator chamber is reduced, the window foil is reduced as compared with the conventional case where the inside of the irradiation chamber is maintained at the atmospheric pressure. Since the pressure difference acting on the film 103 can be reduced, the window foil 103 can be made sufficiently thinner (of about several μm) than the conventional one (of about 20 μm in thickness). Therefore,
The loss generated in the window foil 103 can be reduced, and an electron accelerator having lower energy than before can be used as an electron beam accelerator.

When the thickness of the window foil 103 is reduced to about several μm, the energy of the electron accelerator is reduced by at least about 50 kV as compared with a conventional electron beam irradiation apparatus which requires a window foil of about 20 μm. can do.

Since the loss in the window foil 103 can be reduced, the temperature rise of the window foil 103 can be suppressed, and the cooling of the window foil 103 can be facilitated.

Further, as described above, when the pressure in the irradiation chamber is reduced and the electron beam is irradiated while controlling the pressure in the irradiation chamber with N 2 gas, the generation of ozone in the irradiation chamber can be suppressed. In addition, the oxidation of food by ozone can be prevented.

Further, as described above, when ultrasonic vibration is applied to the irradiation pallet 143 when irradiating the electron beam, each powder 142 on the pallet performs a free bouncing motion (bouncing). Almost all surfaces of the powder can be uniformly irradiated with the electron beam, and sterilization and insecticide can be completely performed.

In the above example, the vibration imparting device 144 is configured to transmit the ultrasonic vibration generated by the ultrasonic vibrator to the irradiation pallet 143. However, a vibration source other than the ultrasonic vibrator is used. May be used. For example, using a vibration imparting device configured to transmit mechanical vibration generated due to the rotational movement of the eccentric shaft to the irradiation pallet 143 via an appropriate transmission unit, or using a change in magnetic attraction force of an AC electromagnet. A vibration applying device that transmits the generated vibration to the irradiation pallet can also be used. Furthermore, the bouncing motion of the powder can be generated by applying a vibrating electrostatic force to the powder.

In the above example, the powder is supplied onto the irradiation pallet 143 while moving the transporting means 145 in the axial direction of the irradiation chamber 101, so that the irradiation pallet 1
The powder was distributed almost uniformly throughout 43,
Instead of moving the conveying means 145, the irradiation pallet 14
Means for leveling the powder supplied on the irradiation pallet 143 may be provided, or the powder on the irradiation pallet 143 may be leveled by vibration applied from the vibration imparting device 144 to the irradiation pallet 143.

As shown in FIG. 1, when the load lock chambers are provided on both the loading side and the unloading side of the irradiation chamber, and the powder carrying-in means and the powder carrying-out means are provided in the irradiation chamber. A series of processes for irradiating the powder with an electron beam to perform sterilization and insecticidal treatment can be automatically and efficiently performed, but the present invention is not necessarily limited to such a configuration. For example, in the above example, the load lock chambers are provided on both the loading side and the unloading side of the irradiation chamber. However, one load lock chamber is provided in the irradiation chamber, and the object to be irradiated is passed through the one load lock chamber. The apparatus can be configured to carry in and carry out of the apparatus.

[0055]

As described above, according to the present invention, when the accelerator chamber is in a reduced pressure state, the inside of the irradiation chamber is also kept in a reduced pressure state. Can be reduced. For this reason, a thinner window foil than conventionally used can be used as the window foil for partitioning the two chambers, and the loss occurring in the window foil can be reduced, and the energy efficiency can be improved. Further, since the energy lost in the window foil can be reduced, an electron accelerator having lower energy than the conventional one can be used. Further, since the loss occurring in the window foil can be reduced, the temperature rise of the window foil can be suppressed, and the cooling of the window foil can be facilitated.

Further, according to the present invention, since the electron beam is irradiated in a state where the pressure in the irradiation chamber is reduced, the generation of ozone in the irradiation chamber is suppressed, and the oxidation of the object to be irradiated by ozone is extremely reduced. Can be.

Further, according to the present invention, since the powder can be irradiated with the electron beam while vibrating the powder so that each particle of the powder rebounds, the electron can be almost uniformly applied to the entire surface of each particle. Irradiation can be performed, and the reliability of the sterilization treatment and the insecticidal treatment of the powder can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing a configuration of an electron beam irradiation apparatus according to the present invention.

FIG. 2 is a configuration diagram schematically showing a configuration of a conventional electron beam irradiation apparatus.

[Explanation of symbols]

101: irradiation chamber, 102: accelerator chamber,
102a: irradiation window, 103: window foil, 104: electron gun, 1
20, 122: gate valve, 121: load-side load lock chamber, 138: vacuum pump, 142: powder (object to be irradiated), 143: irradiation pallet, 144: vibration applying device,
Reference numerals 130, 132: gate valve, 131: unloading-side load lock chamber, 145: powder carrying means, 146: powder carrying means.

Claims (2)

[Claims] An irradiation chamber accommodating an irradiation object to be irradiated with an electron beam, an accelerator chamber having an irradiation window connected to the irradiation chamber, and a window foil attached so as to cover the irradiation window. An accelerator having an electron gun disposed in the accelerator chamber, for accelerating an electron beam generated from the electron gun, and irradiating the electron beam into the irradiation chamber through the window foil, and holding powder as an object to be irradiated; An irradiation pallet configured so as to be opposed to the irradiation window in the irradiation chamber, a vacuum pump for reducing the pressure in the irradiation chamber, and a vibration applying device for applying vibration to the irradiation pallet are provided. While simultaneously evacuating the inside of the accelerator chamber and the inside of the irradiation chamber and keeping both chambers under reduced pressure, while applying vibration to the irradiation pallet Electron beam irradiation method for irradiating an electron beam to the powder on the irradiation pallet through the window foil from the accelerator chamber. 2. An irradiation chamber accommodating an object to be irradiated with an electron beam, an accelerator chamber having an irradiation window connected to the irradiation chamber, and a window foil attached so as to cover the irradiation window. An accelerator having an electron gun disposed in the accelerator chamber, for accelerating an electron beam generated from the electron gun and irradiating the electron beam into the irradiation chamber through the window foil; and holding powder as an object to be irradiated. An irradiation pallet configured to face the irradiation window in the irradiation chamber; a vacuum pump for reducing the pressure in the irradiation chamber when the pressure in the accelerator chamber is reduced; An electron beam irradiation device comprising: