JP2002148399A - High-energy electron-ray irradiation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron-ray irradiation apparatus capable of properly controlling a (depth × density) directional dose distribution, particularly in the case of irradiation for both sides, in view of drawbacks of conventional techniques. SOLUTION: In the high-energy electron-ray irradiation apparatus, a high- energy electron ray produced when an electron ray produced by an electron gun is accelerated by an accelerating tube is guided to a scanning hone and a subject to be irradiated for sterilization, such as medical equipment, is irradiated with a scanning beam as the beam is deflected by a scanning magnet 8 provided at the scanning hone. A plurality of beam current control means for producing different electron energies are provided at the electron gun. As the plurality of beam current control means are switched from one to another as necessary by a high-speed switch or other means, beam currents emitted from the electron gun are controlled to switch from one to another for each pulse or each group of pulses. Further, the switching of the plurality of beam current control means is effected by a pulse distribution controller and the mixing ratio of the pulses with different energies is set by the pulse distribution controller.

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 apparatus capable of variably controlling irradiation electron energy, and in particular, the present invention relates to a high-energy electron beam generated by accelerating an electron beam generated by an electron gun by an acceleration tube. While guiding the electron beam to the scanning horn, while deflecting and scanning by the scanning magnet provided in the scanning horn,
The present invention relates to a high-energy electron beam irradiation device that irradiates a sterilized irradiation object such as a medical device with a scanning beam.

[0002]

2. Description of the Related Art Electron beam irradiation sterilizers have recently been developed as a method for sterilizing medical equipment such as a dialyzer for hemodialysis. Such an apparatus is capable of sterilizing a medical device or the like by increasing the accelerating voltage of an electron beam, so that there is no need to worry about heat resistance and residual toxicity of an irradiated object, and furthermore, the sterilization processing time is long and short. Processing is possible, and when the power is turned off, irradiation is stopped instantaneously, which has advantages such as high environmental safety and low cost.

The principle configuration of such an electron beam irradiation apparatus will be described with reference to FIG. The charged particle beam irradiation device
An electron gun 1, a pre-buncher 3, an acceleration tube 4, a 270 ° beam deflector 9, and a beam scanning horn 7
Is a cathode 21 (cathode) that emits thermoelectrons, an anode 23 (anode) to which a positive potential is applied relatively to the cathode 21 to extract an electron beam, and is disposed between the cathode 21 and the anode 23. Grid 22 for controlling the amount of electron beam flowing to the anode 23 side by the grid pulse voltage
And so on.

The electron gun 1 generates an electric potential gradient between the cathode 21 and the anode 23 by applying an acceleration voltage to the cathode 21 by an acceleration power supply. Also,
The cathode 21 emits thermoelectrons in an amount corresponding to the heat generation temperature due to the heat generated by the connection of the heating power supply of the cathode. After being extracted by the anode 23 through the grid 22, the thermoelectrons cause the electron beam 1 to enter the pre-buncher 3. The pre-buncher 3 is a buncher for accelerating electrons by a high-frequency electric field supplied from a high-frequency amplification klystron 5 via a phase shifter 6, and compresses a pulse width of an electron beam to be incident on an acceleration tube 4.

The accelerating tube 4 has a number of cavities (bunchers) connected in series via a beam hole, and a scanning magnet 80 and the like for sweeping and focusing the electron beam 1 to an arbitrary length. Are arranged. A high-frequency electric field introduced into the acceleration tube 4 from the high-frequency amplification klystron 5 excites an electromagnetic field in the first acceleration cavity 2. Further, the high frequency sequentially excites the electromagnetic field to the adjacent acceleration cavity, and then sequentially excites the magnetic field in the downstream acceleration cavity. The electron beam is accelerated by the electromagnetic field excited in the accelerating cavity 2, becomes a high energy electron beam of, for example, 10 MeV, and uses the deflecting magnet of the 270 ° beam deflecting unit 9 provided on the emission side thereof to 270 °. After being rotated, it is incident on the beam scanning horn 7.

The beam scanning horn 7 is formed of a flat fan-shaped vacuum vessel, and the irradiation position of the electron beam 1 is set in the longitudinal direction (the transport direction of the irradiation object 2) in order to uniformly irradiate the irradiation object 2 with the electron beam. (In the direction perpendicular to the direction).
A scanning magnet 80 for generating a magnetic field for deflecting and scanning the traveling direction of the scanning horn is provided on both sides of the scanning horn 7. The scanning magnet 80 is an electromagnet, and generates an alternating magnetic field on the trajectory of the electron beam 1 by periodically controlling the amount and direction of energization of an electromagnetic coil (not shown). The alternating magnetic field enables the electron beam to be swept.

FIG. 12 shows another conventional example of an electron beam irradiation apparatus. This electron beam irradiator has substantially the same configuration as the electron beam irradiator shown in FIG. 11 except that the shapes of the extraction window 71 and the vacuum vessel 70 and the arrangement height of the scanning magnet 80 are different.

In this electron beam irradiation apparatus, the accelerated electron beam 1 is deflected in the traveling direction by the alternating magnetic field generated by the scanning magnet 80 when the electron beam 1 accelerates into the flat horn-shaped vacuum vessel 70 for scanning. When an alternating waveform current is applied to the scanning magnet 80, the alternating magnetic field continuously changes, and at this time, the angle at which the deflection is received (indicated by θ in the figure).
(The angle θ depends on the amount of energization). Therefore, when averaging and evaluating on a sufficiently long time scale compared with the period of the energizing current, the shape of the electron beam after passing through the scanning magnet 80 becomes long. The electron beam 1 deflected by the scanning magnet 80 further proceeds in a vacuum, and reaches an extraction window 71 made of a material and a size that can sufficiently withstand a pressure difference between the vacuum and the atmosphere. And after passing through the extraction window 71,
Irradiation is performed on the irradiation object 20 located at a place where the object 20 is opposed to the object.

Such an irradiation method is called a microscan method, and is extremely advantageous when the object to be irradiated is conveyed at a high speed as shown in FIG. 13 as compared with the conventional pulse scan method shown in FIG. It is. That is, FIG.
In the conventional pulse scan method shown in (a), when an object to be irradiated (package) placed on a conveyor is irradiated with an electron beam while being conveyed, the irradiated part is subjected to each pulse as shown in (b). Since each irradiation pattern is circular, even if beam scanning is performed at a slow speed of about 5 pulses per second, if the conveyor speed is slow, the circular pulses overlap vertically and horizontally to form a uniform dose distribution. As the load rises and the baggage flows faster, the irradiation pattern becomes more important, and the variation in dose increases as shown in the calculated dose distribution (50 m / min) in (c).

On the other hand, the micro-scan method shown in FIG. 13A scans a beam at a high speed by a beam scanning width during one pulse. For example, the beam is scanned within 17 μsec corresponding to the irradiation time of one pulse. When the beam is scanned at a high speed, an elliptical slit scan in a direction perpendicular to the transport direction of the load as shown in FIG. With this configuration, the conveyor speed is increased, and even when the luggage flows fast, an elliptical equivalent pulse of 500 Hz or more per second is applied, and the dose distribution calculation value in FIG. As shown, even at a high speed of 50 m / min, dose variation does not occur, which is advantageous for high-speed conveyance.

However, even such an electron beam irradiation apparatus has a problem in the depth direction of an object to be irradiated. That is, such an electron beam irradiation / irradiation apparatus is, for example, in the case of various bacteria such as medical tools, in order to secure a sufficient dose of various bacteria while suppressing the modification (discoloration, embrittlement, etc.) of the member, the over irradiation rate (irradiated It is generally said that it is desirable that the maximum absorbed dose inside the object divided by the minimum absorbed dose) be 1.5 or less, but it is difficult for an electron beam irradiation device to artificially control this. It is possible and depends only on the density of the irradiated object and the electron beam energy, and if these are determined, they will be uniquely determined as shown in FIG. For this reason, an uncontrollable dose difference usually occurs in the irradiation object depth direction.

In order to remedy this drawback, current amount control means for varying the magnitude of the current of electrons emitted from the electron gun 1 by controlling the temperature of the cathode of the electron gun in accordance with the type of object to be irradiated. Japanese Patent Application Laid-Open No. H11-169
438. That is, in FIG. 1 (with the absorbed dose (AU) on the vertical axis and the irradiation depth (ρcm) on the horizontal axis), when the object to be irradiated is irradiated with a conventional electron beam, the energy is 5 MeV. , 6MeV, 8MeV, 1
The energy dependence of the absorbed dose when a high energy electron beam of 0 MeV is irradiated is shown. As is clear from this figure, as the energy increases, the irradiation depth increases.
It is understood that (ρcm) increases in proportion.

Therefore, the amount of energy of the electron beam is controlled by the type of the object to be sterilized, that is, the thickness, by the current amount control means, so that the electron beam suitable for the depth of the object to be sterilized is irradiated, and the speed control means is controlled. When the size and weight of the object 1 to be sterilized exceed the range that can be controlled by the current amount control means by providing the object on the conveyor, the conveyor speed is reduced or increased to irradiate the object 1 to be sterilized. It can be understood from the above-mentioned prior art that the energy value and the irradiation amount of the electron beam become appropriate, so that the electron beam can be sterilized with a more suitable electron beam and deterioration of the conveyor and the like can be prevented. The current amount control means of the prior art controls the temperature of the cathode 21 in accordance with the type of the object to be sterilized by controlling the heating of a heater disposed on the cathode rear side of the electron gun 1.
It is configured to control the magnitude of the current of the electrons emitted from.

[0014]

Such a technique is an electron gun 1
Cathode 2 according to the type of the material to be sterilized.
Since the magnitude of the electron current emitted from the electron gun 1 is controlled by controlling the temperature of the electron gun 1, the energy cannot be instantaneously switched, and the energy can be actually switched only in lot units. Absent. Therefore, depending on the type of the object to be sterilized, the irradiation amount of the object to be sterilized is set to, for example, 5M.
The selection is performed in lot units such as eV, 6 MeV, 8 MeV, and 10 MeV. As can be understood from FIG. 1, in general electron beam bacteria, the irradiation depth (ρ
2), the absorbed dose (AU) decreases in proportion to the ratio, and therefore, as shown in FIG. It is usual to employ double-sided irradiation.

However, if the density of the irradiated object and the size of the box in the depth direction are not optimized with respect to the irradiation energy in the distribution of the double-sided irradiation, as shown in FIG. An over-irradiated part with a large dose is formed.

Accordingly, as in the prior art, high-energy electron beams of 5 MeV, 6 MeV, 8 MeV, 10 M
Even in an electronic energy variable device that can be selected as in each of eV, for example, the irradiation standard is adjusted so that the maximum dose of the combined dose (front and back) is, for example, 1.5, the absorbed dose (AU). In addition, if a high energy electron beam of 5 MeV is selected, sterilization at the minimum dose position will be insufficient, and the irradiation standard will be the absorbed dose where the minimum dose of the combined dose (front and back) is 1.0, for example.
When a high energy electron beam of, for example, 10 MeV is selected in accordance with (AU), as shown in FIG. 2, since the artificial organ is generally made of an organic resin, the maximum dose position is, for example, 2 μm. Absorption dose (AU) of about 0.5 results in excessive irradiation, resulting in deterioration and coloring of the material.

[0017] Therefore, even in the above-mentioned conventional apparatus in which the electron energy can be changed, the electron beam with high energy can be selected. However, if the electron beam with high energy is simply selected, appropriate control corresponding to the thickness of the irradiation object cannot be performed. In particular, in the case of double-sided irradiation, the drawback becomes large.

In view of the drawbacks of the prior art, an object of the present invention is to provide an electron beam irradiation apparatus capable of appropriately controlling the dose distribution in the (depth × density) direction particularly in the case of double-sided irradiation. Another object of the present invention is to provide an electron beam irradiation apparatus that can more appropriately control the dose distribution in the depth direction by combining with a microscan method.

[0019]

According to the present invention, in order to solve the above-mentioned problems, a high-energy electron beam generated by accelerating an electron beam generated by an electron gun by an acceleration tube according to the first aspect of the present invention. Is guided to a scanning horn, and different electron energies are generated in a high-energy electron beam irradiation apparatus that irradiates a scanning beam to an object to be sterilized such as a medical device while deflecting and scanning by a scanning magnet 8 provided in the scanning horn. A plurality of beam current control means are provided on the electron gun side, and the beam current emitted from the electron gun is switched for each pulse or each pulse group while appropriately switching the plurality of beam current control means by a high-speed switch or the like. The method is characterized in that electron beams having different energies are controlled and substantially combined to irradiate an irradiation object.

According to this invention, instead of making the electron energy different for each lot as in the above-described prior art,
Since the object is irradiated with the electron beam with different energy for each pulse or each pulse group, it can effectively cope with an object having a complicated shape. When irradiating a high-energy electron beam to achieve an intended purpose such as sterilization while irradiating a high-energy electron beam from both the front and rear sides, a curve or a peak of an absorbed dose can be arbitrarily set.

This invention can also be applied to a circular pulse irradiation device having a slow beam scanning speed. However, the irradiation beam scans the pulse at high speed at every pulse irradiation interval to form a band-like irradiation beam corresponding to the scanning width. When applied, the belt-like irradiation beams of different energies are superimposed along the conveyor traveling direction to form a pseudo synthetic beam,
preferable.

The invention according to claim 3 is characterized in that the switching of the plurality of beam current control means is performed by a pulse distribution controller, and the mixing ratio of pulses having different energies is set by the pulse distribution controller. It is preferable that the pulse mixing ratio and the mixing order can be arbitrarily set by a control value from a pulse mixing control unit.

According to the present invention, as in the first aspect of the present invention, when a plurality of energies are combined to synthesize irradiation energy in a simulated manner, the order in which pulses having different energies are applied and the mixing ratio are extremely high. The peak value of the absorbed dose formed by the front and back irradiation beams and the absorption curve are different, and when this is irradiated on both the front and back sides, the over-irradiation rate increases significantly. There is. Therefore, it is necessary to precisely control the irradiation order and the mixing ratio of the pulses having different energies so that the peak value and the bottom value of the surface absorbed dose distribution in the traveling direction of the conveyor are hardly and evenly absorbed.

[0024] More preferably, product depth x density)
It is preferable that the beam setting current, the blending ratio and the blending order in the plurality of beam current control means can be arbitrarily set by an externally designated value.

The beam is scanned by scanning magnets arranged on both sides of the scanning horn 7. If the scanning energy is different even when the control value of the AC current of the scanning magnet is constant, it is possible to cope with the energy fluctuation. As a result, the scanning width also varies. Therefore, according to a seventh aspect of the present invention, the control of the energization control value of the scanning magnet provided on the scanning horn is performed in synchronization with the switching of the plurality of beam current control means for generating different electron energies. The constant beam scanning angle is realized by changing the current control value of the AC waveform current every time.

According to an eighth aspect of the present invention, the control target of the plurality of beam current control means for generating electron energy is a grid voltage of a grid provided between a cathode and an anode of an electron gun. If a different grid voltage can be selectively supplied instead of heating the cathode of the electron gun, high-speed switching for each high-speed frequency pulse is also easy.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to an embodiment shown in the drawings. However, unless otherwise specified, dimensions, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the invention, but are merely illustrative examples. 5 to 9
Is an overall view of the electron beam irradiation irradiation apparatus according to each embodiment of the present invention, which is preferably used in a multi-scan type electron beam irradiation apparatus, but is not limited thereto,
It is also applicable to a circular pulse scan method. FIG. 10
FIG. 3 is a block diagram showing a beam current controller incorporated in the electron beam irradiation device. This apparatus comprises an electron gun 1, a pre-buncher 3, an accelerating tube 4, a 270 ° beam deflector 9 (not shown), and a beam scanning horn 7 as described above. The electron gun 1 comprises a cathode 21, a grid 22, and an anode 23.
In the present invention, the ammeter 2 is provided between the electron gun 1 and the pre-buncher 3, and the feedback pulse current from the ammeter 2 is used to increase the grid pulse voltage of the grid 22 disposed between the cathode 21 and the anode 23 at a high speed. A beam current controller 10 is provided which controls the switching in FIG.
The scanning magnets 8 arranged on both sides of the scanning horn 7
An operation magnet control circuit for controlling the angle at which the electron beam is deflected by controlling the application of the AC waveform current is provided.

First, a description will be given based on FIG. 5 which discloses a general outline having a configuration common to each embodiment. 10
Is, for example, 5MeV, 6MeV, 7MeV, 8MeV,
A plurality of beam current controllers 10 and 11 each storing a grid voltage control beam current command value for generating a 10 MeV high-energy electron beam are stored in each of the plurality of beam current controllers. This is a high-speed switching device that performs high-speed switching based on a command from the distribution controller 13. The beam current controller 10 transmits a grid voltage corresponding to one type of irradiation electron energy controlled by the grid 22 to the grid pulser 12 via the high-speed switch 11. In this embodiment, control is performed so that five types of electron beam energy can be obtained. A pulse distribution controller 13 transmits a switching signal of five kinds of electron beam energy to the beam current controller 10 and the high-speed switch 11 for each pulse.

Reference numeral 1 denotes an electron gun.
2 is applied to the grid 22, the grid voltage is controlled based on the pulser voltage signal, and the selected... MeV high energy electron beam is output. A beam ammeter 2 measures a beam current value output from the electron gun 1 and feeds it back to a beam current controller 10.

5 is a klystron for high frequency amplification,
The high-frequency output from the klystron 5 is supplied to the accelerating tube 4 and the pre-buncher 3, and used for accelerating the electron beam. Reference numeral 15 denotes a beam scanning controller, which outputs a beam scanning command value via a high-speed switch 16 interlocked with the high-speed switch 11.
A scanning magnet control circuit (not shown) for controlling the angle at which the electron beam is deflected by controlling the energization of the AC waveform current of the scanning magnet 8 (electromagnet) disposed on both sides of the scanning horn 7 is provided. Beam scanning horn 7
Are applied to the scanning magnets 8 arranged on both sides of the laser beam to realize a beam scanning angle corresponding to each selected pulse having different energy.

The pulse distribution controller shown in FIG. 5 calculates the number of pulses generated in one second based on the optimum irradiation electron energy distribution preset according to the specific gravity of the irradiation object and the depth of the box of the product to be irradiated. Is replaced with a distribution corresponding to the irradiation electron energy distribution described later, and outputs a signal for selecting the beam current controller 10 corresponding to the irradiation electron energy selected for each pulse. The selected beam current controller 10 A control voltage output signal corresponding to a beam current command value corresponding to the irradiation electron energy is input to the grid pulser 12 via a high-speed switch.

The grid pulser 12 applies a grid voltage corresponding to a control voltage signal from the beam current controller 10 to the electron gun 1 of d, and outputs a required beam current value. The output beam current value is measured by the beam ammeter 2,
By feeding back the measured value to the beam current controller 10, stable beam current control is performed. Since a constant high-frequency output is supplied from the high-frequency amplifying klystron 5 to the pre-buncher 3 and the acceleration tube 4, irradiation electron energy corresponding to the beam current value is obtained as the output of the acceleration tube 4.

Next, a beam current controller 1 used in the above-mentioned apparatus.
0 will be described with reference to FIG. The five beam current controllers 10 are provided so as to output respective beam current command values corresponding to the high-energy electron beams of MeV, respectively, and are respectively selected through the high-speed switch 12. Command value is grid pulsar 1
2, the high-speed switch 12 is omitted and only one beam current controller 10 is shown in FIG.

The beam current controller 10 controls 5 MeV, 6 MeV, 7 MeV, 8 MeV based on an internal command.
V and 10 MeV, the initial beam current command value 10a corresponding to the high energy electron beam is taken into the setting unit 10b, and the beam current command corresponding to any high energy electron beam based on the external command value 10f. Both cases when the data is taken into the setting unit 10b are shown.

On the other hand, the ammeter 2 measures the pulsed beam current output from the electron gun 1 and feeds back the measured beam current value to the detection unit 10d. After converting to voltage,
The difference between the initial beam current command value and the beam current measurement value by a differentiator 10c, and the correction value is used as a control unit 1 comprising a PID circuit.
0e. In the control unit 10e, the beam current command value corrected based on the beam current measurement value is input to the grid pulser 12. In the grid pulser 12, positive and negative grid pulse voltages are applied to the grid 22 of the electron gun 1 based on the command value.

In the electron gun 1, when the grid voltage is a minus pulse, the electrons generated by heating the heater on the cathode 21 side repel the electrons and do not pass through the grid 22, but when the grid voltage is a plus pulse, The electrons are attracted to the grid 22 and pass through. Therefore, since the irradiation electron energy is inversely proportional to the beam current value, an arbitrary irradiation electron energy can be obtained by controlling the beam current value output from the electron gun 1 by the grid voltage.

FIG. 3 shows an embodiment in which a box-shaped product is irradiated with an electron beam by a multi-scan method using the above-described apparatus. In this figure, the irradiation electron energies of 10 MeV, 8 MeV, and 6 MeV are combined by a pulse distribution controller,
10MeV: 8MeV: 6MeV = 1: 5: 1 (output ratio)
This is an embodiment in which an electron beam whose energy distribution is optimized so as to be output from the acceleration tube 4 and is irradiated on a box-shaped product flowing on a conveyor by a multi-scan method. The micro-scan method scans a beam at a high speed. For example, if the beam is scanned at a high speed corresponding to the irradiation time of one pulse by 17 μsec / pulse by the beam scanning width, 1: 5 in 0.1 sec: 1
(Combined beam)
Will be irradiated on the product.

In other words, an elliptical, equivalently band-shaped irradiation beam in a direction orthogonal to the carrying direction of the load is 10M.
It is obtained by being synthesized at eV: 8MeV: 6MeV = 1: 5: 1 (output ratio). Then, when such a combined multi-beam is irradiated from the front and back surfaces of the box-shaped product, the combined dose is as shown in FIG. This is the dose distribution in the depth direction when the combined multi-beam is irradiated from both the front and back sides of the box-shaped product. In this case, the over-irradiation rate is within about 1.3 at the maximum, and the 10MeV single color shown in FIG. It can be seen that the irradiation electron energy is significantly improved as compared with the over-irradiation rate maximum value of 2 or more.

In the case where the irradiation energies are synthesized in a pseudo manner by combining a plurality of energies in this manner, the order of irradiating the pulses having the respective energies is very important. When this is irradiated on both the front and back sides, the over-irradiation rate may be greatly increased.

4 is 10 MeV: 8 MeV: 6M.
The energy irradiation order of the combined multi-beam of eV = 2: 1: 5 (output ratio) is summarized for each energy, for example, (10, 1
0,8,6,6,6,6,6) The surface absorbed dose distribution in the traveling direction of the conveyor when MeV is output in the order of MeV, and the peak value and the bottom value of the surface absorbed dose are in the range of 0.94-1. It is understood that it fluctuates.

On the other hand, the right diagram in FIG. 4 shows 10 MeV: 8 MeV:
Conveyor traveling direction when the irradiation order of the combined multi-beam of 6MeV = 2: 1: 5 (output ratio) is dispersed and output for each energy as (6, 10, 6, 8, 6, 6, 10, 6) It can be understood that in the surface absorbed dose distribution with respect to, there is almost no peak value and bottom value of the absorbed dose, and the absorption is uniform.

Therefore, as shown in this figure, the uniformity of the absorbed dose on the surface of the irradiation object may vary depending on the order, and the absorption dose on the surface of the irradiation object may vary.
The absorbed dose inside the irradiated object is further increased, and the over-irradiation rate is naturally increased. For this reason, it is necessary to sufficiently study the irradiation order in advance.

A specific control procedure for each embodiment will be described below. FIG. 6 is a specific example showing a device capable of controlling the beam current for each pulse and switching the irradiation electron energy. In this embodiment, the beam scanning controller and its high-speed switching device are not provided. In this embodiment, micro-scanning is performed at the same beam scanning angle even for selected pulses having different energies.

Then, in the beam current controller 10,
, MeV are provided so as to output respective beam current command values corresponding to the high-energy electron beams, respectively. By performing the high-speed switching in order, the beam current is controlled for each pulse in the order of and the irradiation electron energy is switched and controlled.

FIG. 7 shows a specific example of a device capable of arbitrarily controlling a beam current for each pulse and irradiating an electron beam having a plurality of irradiation electron energies. In this embodiment, a beam scanning controller and its high-speed switching are shown. This embodiment is the same as the previous embodiment in that microscanning is performed at the same beam scanning angle even for selected pulses having different energies, but the beam current shown in FIG. Controller 1
Based on an external command value arbitrarily set to 0, a beam current command corresponding to an arbitrary high-energy electron beam is taken into the setting unit.

According to this embodiment, the beam current controller 1
A beam current controller 103 is provided in which an external command value of 0 is set to an arbitrary beam current command value corresponding to a high energy electron beam of each MeV, and a high-speed switching device based on a signal from a pulse distribution controller. By performing the high-speed switching in the order of →→→..., It is possible to obtain a device having arbitrary irradiation electron energy.

FIG. 8 is a diagram showing an example in which the beam current is arbitrarily controlled for each pulse based on the external command value, and the controlled beam current is pulse-distributed based on the external signal value applied to the pulse distribution controller 13 to perform pulse blending. This is a specific example showing a device in which the ratio can be set arbitrarily, and the beam current corresponding to an arbitrary high-energy electron beam based on an external command value arbitrarily set by the beam current controller 10 in FIG. A command is taken into the setting unit, and an external signal value given to the pulse distribution controller 13 is set to 1: 2: 3,
, .., MeV are set so that the beam current command values corresponding to the high-energy electron beams are distributed with a pulse ratio of 1: 1: 2: 3.

According to such an apparatus, the beam current controller 1
0, by giving a command value to each of the pulse distribution controllers 13, a device capable of irradiating an electron beam with an arbitrary energy and an arbitrary mixing ratio can be obtained.

FIG. 9 shows that the beam current is arbitrarily controlled for each pulse based on the external command value, and the controlled beam current is pulse-distributed based on the external signal value 10f applied to the pulse distribution controller 13. Although the mixing ratio can be set arbitrarily, the pulse mixing ratio is not repeated as in the above-described embodiment, but is controlled non-repetitively according to the shape of the product to be irradiated.

In this embodiment, the pulse mixing ratio and the mixing order are set so that the surface absorbed dose distribution in the traveling direction of the conveyor becomes uniform as shown in the right diagram of FIG. 4 corresponding to the thickness of the product. In this embodiment, a blending order setting circuit 19 is provided. In this embodiment, the arbitrary order is set based on the external command value 10f arbitrarily set by the beam current controller 10 in FIG.
, The beam current command corresponding to the high-energy electron beam is taken into the setting unit 10b, and the external signal value given to the pulse distribution controller 13 is 1: 2:
3, and the beam current command value corresponding to the high-energy electron beam of each MeV is = 1: 2:
The pulse distribution is set so as to be performed at a mixing ratio of 3, and the mixing order is set to be as follows.

According to such an apparatus, the beam current controller 1
0, by giving a command value to each of the pulse distribution controllers 13, it is possible to obtain a device capable of irradiating an electron beam having an arbitrary energy and an arbitrary mixing ratio, and further having an arbitrary mixing order. Also, as shown in the right diagram of FIG. 5, the control can be performed so that the surface absorbed dose distribution in the traveling direction of the conveyor becomes uniform.

FIG. 5 further relates to the improvement of the above-mentioned apparatus. In accordance with the Faraday's left-hand rule, the beam energy is kept constant even when the AC waveform current of the scanning magnet 8 (electromagnet) arranged on both sides of the scanning horn 7 is constant. Are different, the scanning width also changes in accordance with the energy change. Therefore, the beam scanning controller 15 is switched to a beam scanning controller 15 having a beam scanning command value (an energization control value of an AC waveform current) that is changed corresponding to each beam energy by a high-speed switching unit 16 linked to the high-speed switching unit 11. A constant beam scanning angle is realized by switching the control value of the AC waveform current for each selected pulse having a different energy so that the angle at which the electron beam receives deflection is constant. According to this embodiment, a device capable of controlling the same scanning width and the same scanning speed even with a plurality of energy pulses is obtained, which is more preferable. That is, the electron beam pulse and the beam operation control value for scanning the electron beam pulse have a one-to-one correspondence, and a plurality of energy pulses can be controlled to have the same scanning width.

[0053]

As described above, according to the present invention, a plurality of controlled energies within a number of pulses per second (usually about 500 pulses, but there is no limit to the number of pulses) can be obtained.
By generating and irradiating an electron beam of a current amount, a transmission depth profile to an irradiation object can be controlled, and an over irradiation rate can be improved.

[Brief description of the drawings]

FIG. 1 is a graph showing the energy dependence of absorbed dose, where the irradiation depth (ρcm) is plotted on the horizontal axis and the absorbed dose (AU) is plotted on the vertical axis.

FIG. 2 is a graph showing an absorbed dose when a 10 MeV electron beam is irradiated on both sides.

FIG. 3 is a graph showing an absorbed dose when a box-shaped product is irradiated on both sides with an electron beam by a multi-scan method.

Fig. 4 shows the distribution of surface absorbed dose in the traveling direction of the conveyor when the energy irradiation order of the combined multi-beam is output collectively for each energy. The right figure shows the case where the irradiation order of the combined multi-beam is dispersed and output for each energy. Is a surface absorbed dose distribution with respect to the traveling direction of the conveyor.

FIG. 5 shows an embodiment of the best mode of the present invention in which the control value of the beam scanning device is controlled for each pulse according to a plurality of energies (pulses), and the pulse width of any energy can be controlled to the same operation width. The overall diagram of the electron beam irradiation / irradiation apparatus is a time chart in which the lower part shows a beam pulse and a corresponding pulse of a beam scanning control value.

FIG. 6 is an overall view of an electron beam irradiation apparatus capable of controlling a beam current for each pulse and switching irradiation electron energy, and a lower chart is a time chart showing pulse distribution of beam pulses having different energies.

FIG. 7 is an overall view of an electron beam irradiator capable of irradiating a plurality of electron beams having arbitrary energies by controlling each pulse to a different beam current value, and the lower part is a time showing a pulse combination of beam pulses having different energies. It is a chart.

FIG. 8 is an overall view of an electron beam irradiator capable of arbitrarily setting a mixing ratio of a pulse having each energy for an electron beam having a plurality of energies, and a lower row shows a pulse mixing of beam pulses having different energies. It is a time chart.

FIG. 9 is an overall view of an electron beam irradiator capable of arbitrarily setting a mixing order of pulses having each energy for the electron beam having a plurality of energies, and a lower row is a pulse mixing and mixing order of beam pulses having different energies. FIG.

FIG. 10 is a block diagram showing a beam current controller incorporated in the electron beam irradiation device.

FIG. 11 is a diagram showing a basic configuration of a conventional electron beam irradiation apparatus.

FIG. 12 is another conventional example of an electron beam irradiation apparatus.

FIG. 13 shows electron beam irradiation by a conventional pulse scan method.

FIG. 14 shows electron beam irradiation by a microscan method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electron gun 2 Ammeter 3 Pre-buncher 4 Accelerator tube 5 Klystron for high frequency amplification 7 Beam scanning horn 8 Scanning magnet 10 Beam current controller 11 High-speed switch 12 Grid pulsar 13 Pulse distribution controller 15 Beam scan controller 16 High-speed switch 21 Cathode 22 Grid 23 Anode

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G21K 5/10 G21K 5/10 C (72) Inventor Takashi Yamakawa 10 Oecho, Minato-ku, Nagoya-shi Mitsubishi Heavy Industries, Ltd. Nagoya Aerospace Systems Works, Ltd. (72) Inventor Yuichiro Kanna 10 Oecho, Minato-ku, Nagoya City Mitsubishi Heavy Industries, Ltd. Nagoya Aerospace Systems Works F-term (reference) 4C058 AA12 AA17 BB06 CC02 KK03 KK32 4C077 AA05 BB01 GG05 KK09

Claims (8)

[Claims] A high-energy electron beam generated by accelerating an electron beam generated by an electron gun by an acceleration tube is guided to a scanning horn, and the scanning beam is deflected and scanned by a scanning magnet provided on the scanning horn. A plurality of beam current control means for generating different electron energies in a high energy electron beam irradiation apparatus for irradiating an object to be sterilized such as a medical device with electron beams are provided on the electron gun side, and the plurality of beam currents are controlled by a high-speed switcher or other means. An electron beam irradiation apparatus characterized in that a beam current emitted from the electron gun is switched and controlled for each pulse or pulse group while appropriately switching control means, and an object to be irradiated is irradiated with electron beams having different energies. 2. The electron beam irradiation apparatus according to claim 1, wherein the irradiation beam is a band-shaped irradiation beam corresponding to a scanning width by scanning the pulse at high speed at every pulse irradiation interval. 3. The method according to claim 1, wherein the switching of the plurality of beam current control means is performed by a pulse distribution controller, and the mixing ratio of pulses having different energies is set by the pulse distribution controller. Electron beam irradiation equipment. 4. The electron beam irradiation apparatus according to claim 1, wherein a beam setting current in said plurality of beam current control means can be arbitrarily set by an externally designated value. 5. The electron beam irradiation apparatus according to claim 3, wherein the mixing ratio of the pulse is arbitrarily set by an externally designated value. 6. The electron beam irradiation apparatus according to claim 3, wherein the mixing ratio and the mixing order of the pulses can be arbitrarily set by a control value from a pulse mixing control unit. 7. The switching of the power supply control value of the scanning magnet 8 provided on the scanning horn in synchronization with the switching of the plurality of beam current control means for generating different electron energies, and the alternating current for each pulse having a different energy selected. 2. The electron beam irradiation apparatus according to claim 1, wherein a constant beam scanning angle is realized by changing a conduction control value of the waveform current. 8. The electron beam according to claim 1, wherein the control target of the plurality of beam current control means for generating electron energy is a grid voltage of a grid provided between a cathode and an anode of the electron gun. Irradiation device.