JPS6252279B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for preventing a rise in temperature of a window foil of a particle beam irradiation window and an improved apparatus for carrying out the method.

In this specification, a particle beam irradiation window is a particle beam reception port or particle beam extraction port in a reaction device for performing a chemical reaction using particle beam irradiation or a device for generating and extracting particle beams to the outside. The window foil of the irradiation window is a passageway that is attached to these window parts and allows most of the particle beam to pass through while maintaining shielding from the outside and minimizing energy loss. A thin foil, usually made of metal, that provides Furthermore, the term "particle beam" refers to a flow of particles with high energy enough to penetrate substances, and typical examples thereof include electron beams, proton beams, ion beams, and neutron beams.

An example of an industrial method that utilizes reactions that proceed due to particle beam irradiation is a method for treating exhaust gas by electron beam irradiation. Although the method of the present invention can be applied to cases where particle beams other than electron beams are used and methods other than exhaust gas treatment, the principle is the same as when exhaust gas treatment is performed using electron beams, so the following explanation will be given. For convenience, a case will be described using an example in which exhaust gas treatment is performed by electron beam irradiation.

When exhaust gas treatment is performed by electron beam irradiation, the electron beam passes through the metal foil (hereinafter referred to as accelerator window foil) placed over the electron beam outlet of the electron beam accelerator, and then passes between the accelerator and the reactor. The electron beam passes through the space (hereinafter referred to as "intervening space"), passes through the metal foil (hereinafter referred to as "reactor window foil") covered with the electron beam irradiation window of the reactor, and irradiates the exhaust gas inside the reactor. be done. During this time, the electron beam passes through two window foils,
A portion of the electron beam is absorbed as it passes through each window foil. The energy of the absorbed electron beam is converted into heat, raising the temperature of each window foil. In the case of exhaust gas treatment, particularly high-energy electron beam irradiation is performed, so the amount of energy absorbed by the window foil is also large, and therefore the temperature rise of the window foil is also quite large. For this reason, various cooling methods have been used in the past, such as applying cooling air to the accelerator window foil and reactor window foil to remove heat from the window foil, or using a water-cooling jacket to attach the flange where the window foil is attached. As a solution, methods such as flowing cooling water through this system have been adopted.

However, the method of applying cooling air to the window foil has a limit to its cooling capacity, and when the irradiated energy is large, the amount of electron beam energy absorbed by the window foil also increases, resulting in insufficient cooling capacity. However, it was not possible to avoid the occurrence of distortion due to heat-induced hardening of the packing and thermal expansion. Furthermore, using a water-cooled jacket as the flange portion for attaching the window foil has the disadvantage that it is not easy to manufacture and it is extremely inconvenient to replace the window foil.

In order to find a window foil cooling method that does not have these drawbacks, the present inventors conducted extensive research and as a result, came to invent a new window foil cooling method as described below.

In the method of the present invention, the particle beam is cooled at a position that shields only the window foil attachment part and the particle beam that advances outward from it in the path of the particle beam exiting the accelerator window foil and proceeding toward the reactor window foil. This arrangement prevents heat generation due to direct particle beam absorption at the reactor window foil attachment part, and at the same time, the cooling body installed in this way prevents heat generation between the accelerator window foil and the reactor window foil. The purpose is to cool the space sandwiched between the window foils and thereby prevent the window foils from overheating. Therefore,
The cooling body needs to have the ability to continuously cool the space around it and be made of a material that shields or absorbs particle beams. Therefore, the materials that can be used differ depending on the type of particle beam. For example, when using α-rays, it is desirable to use materials with high shielding power, such as lead pipes passed through water, but when using electron beams, materials such as stainless steel pipes passed through water are sufficient for the purpose. can be achieved.

As is clear from the above description, the cooling body used in the method of the present invention should perform both functions as a cooling body and a particle beam shielding body. This is often referred to as a cooling shield. The cooling shield absorbs heat from the surrounding space in the space sandwiched between the accelerator window foil and the reactor window foil (the above-mentioned "intervening space"), and transports the heat to a place other than the intervening space. It should have the function of dissipating heat. Next, some examples will be explained.

FIG. 1 is an explanatory diagram showing a preferred embodiment of the method of the invention by flowing cooling water through a cooling shield. In the figure, 1 is an electron beam accelerator, 2 is an electron beam, 3 is an irradiation container (reactor), 4 is a cooling shield, 5 is cooling water, 6 is a circulation pump, 7 is make-up water,
8 each represents a cooling tower. In the case of this figure, the cooling shield is a hollow tube with water flowing through it, and it does not block the main part of the electron beam emitted from the accelerator window foil, but allows the electrons to proceed toward the reactor window foil mounting area and the outside. The piping is installed in a position that only shields the line.

In one variant of this method, the cooling water always oozes onto the wall of the intervening space or onto the surface of the cooling shield and then evaporates in at least a part of the part passing through said intervening space. The intervening space can be cooled by the heat of vaporization at that time.

FIG. 2 is an explanatory diagram showing another preferred embodiment of the present invention. In this method, a heat pipe is used as a cooling shield. In the figure, 1 to 3 and 5 to 8 are the same as those in FIG. 1, 9 is a heat pipe heat radiation section, and 10 is a water jacket. The mounting position of the heat pipe used as a cooling shield is the same as in the case of FIG. The heat pipe cools the intervening space by absorbing ambient heat in the intervening space and radiating this heat through a portion of the water jacket outside the heat pipe.

A third preferred embodiment of the present invention
As shown in the figure. In Figure 3, 1 is an electron accelerator, 2
is an electron beam, 11 is an accelerator window foil, 12 is a cooling air blowing part, 13 is a cooling water pipe (cooling shield), 14 is a movable flange, 15 is a sealing surface, 16 is an elastic body coating, 17 is an elastic body, and 18 is an Reactor inner wall, 19 is reactor window foil, 20 is finned side wall, 21 is beam diameter, 22 is vacuum, 23 is preliminary reactor window foil, 24 is water-containing part, 25 is water supply part, 26 is cooling air exhaust, 27
represent spacers, respectively.

FIG. 3 shows an example in which the present invention is applied to an electron beam irradiation reaction device including various inventions filed separately by the present inventors, and is one of the most preferred embodiments of the present invention. In addition to the cooling water pipe 13 as a cooling shield disposed in the intervening space, there is a side wall with fins 20 that covers the intervening space from above in a hood shape, and this side wall and the reactor window foil 19 There is an intermediate space in a semi-sealed state in a part surrounded by the movable flange 14 and the spacer 27,
Cooling air is blown into the intervening space from the cooling air inlet 12. The cooling air swirls in the intervening space as shown by the arrow and is discharged to the outside from the cooling air exhaust port 26 while removing heat from the space. A water pipe 25 is provided in contact with the upper edge of the fin on the finned side wall, and a small amount of water is always supplied to the fin from the water pipe 25. Therefore, the upper edge of the fin is The water-containing part 24 is formed. By continuously vaporizing this water, heat is radiated using the heat of vaporization. The fins are provided to increase the heat radiation area. In this way, heat radiation from the finned side wall, cooling of the intervening space by the cooling air and the cooling water pipe 13, and absorption of electron beams by the window foil at the reactor window foil attachment part due to shielding of the electron beam 12 by the cooling water pipe 13. This effectively prevents the accelerator window foil 11 and the reactor window foil 19 from rising in temperature.

FIG. 4 is a plan view taken along the line A--A in FIG. 3.

The method of the present invention can be implemented in combination with the method using rotating cooling air disclosed in Japanese Patent Application No. 51-96485 filed separately by the present inventors, thereby obtaining even more favorable effects. be able to. Furthermore, in order to suppress the temperature of the cooling air from rising, the effect can be improved by blowing in another cooling air to add air volume from a different outlet to the rotating cooling air outlet. In addition, it is also effective to take measures such that a small amount of water is always continuously supplied inside the aforementioned intervening space, and the water is continuously vaporized and cooling is promoted by the heat of vaporization. Can be done. In addition, in order to actively radiate heat from the side wall covering the intervening space, fins are attached to the side wall to increase the heat radiating area, or the fins are constantly wetted to promote cooling by heat of vaporization. You can also walk.

As shown in FIG. 3, the cooling shield disposed in the intervening space according to the present invention is a scattered particle beam generated by collision with the window foil when the particle beam passes through the accelerator window foil. Of these, it is preferable to arrange it at a position where only those with a scattering angle larger than 15° are cut. Further, it is preferable that all the uncut particle beams pass inside the reactor window foil mounting part so that the particle beams do not directly hit the mounting part.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment in which a cooling water pipe through which cooling water flows is used as a cooling shield of the present invention. FIG. 2 is an explanatory diagram showing another preferred embodiment of the present invention using a heat pipe as a cooling shield. FIG. 3 is yet another explanatory diagram showing one of the most preferred embodiments of the present invention. FIG. 4 is a view taken along the line A-A in FIG. 3. The symbols in the diagram indicate the following: 1...Electron beam accelerator, 2...Electron beam, 3...Irradiation container (reactor), 4...Cooling water pipe, 5...Cooling water, 6...Circulation pump, 7...Makeup water, 8... Cooling tower, 4'... Heat pipe, 10... Water jacket, 12... Cooling air blowing section, 13... Cooling water pipe, 14... Movable flange, 18... Reactor inner wall, 19... Reactor window foil, 21... Beam diameter, 2
3... Pre-reactor window foil, 25... Water pipe.

Claims (1)

[Scope of Claims] 1. A reaction including a mechanism in which a particle beam irradiated externally from a window foil of a particle beam accelerator is irradiated into the inside of a reactor through a reactor window foil facing the window foil across a certain intervening space. During operation of the apparatus, the particle beam is placed in the intervening space at a position that blocks the particle beam of substantial intensity that is irradiated from the accelerator and advances toward the portion other than the reactor window foil. By arranging a cooling body capable of trapping particles, heat generation due to direct particle beam absorption at the reactor window foil attachment part is prevented, and the temperature of the window foil is prevented from increasing by cooling the intervening space with the cooling body. A method for preventing temperature rise of a window foil in a particle beam irradiation device. 2. The method according to claim 1, wherein the cooling body is a cooling water pipe through which cooling water flows. 3. The cooling body is a heat pipe having a heat absorption part in a space sandwiched between an accelerator window foil and a reactor window foil, and a heat radiation part outside the heat pipe. The method described in Section 1. 4. The side wall covering the intervening space in a hood shape or the cooling body always keeps at least a part of its surface wet with water in the part sandwiched between the accelerator window foil and the reactor window foil, and from that part 2. The method according to claim 1, wherein cooling of the intervening space is promoted by the heat of vaporization of the evaporating water. 5. When operating a reaction apparatus including a mechanism for irradiating a particle beam externally from a window foil of a particle beam accelerator into the reactor through a reactor window foil facing the window foil across a certain intervening space, Cooling that can substantially trap the particle beam in the intervening space at a position that intercepts the particle beam of substantial intensity that advances toward the part other than the reactor window foil of the particle beam irradiated from the accelerator. By arranging the cooling body, heat generation due to direct particle beam absorption at the reactor window foil attachment part is prevented, and the temperature of the window foil is prevented from increasing by cooling the intervening space with the cooling body. A method for preventing temperature rise of a window foil in a particle beam irradiation device, which is characterized by sending cooling air to an intervening space sandwiched between an accelerator window foil and a reactor window foil to accelerate heat dissipation in the intervening space. 6. The method according to claim 5, wherein the cooling body is a cooling water pipe through which cooling water flows. 7. Claim 7, characterized in that the cooling body is a heat pipe having a heat absorption part in a space sandwiched between an accelerator window foil and a reactor window foil, and a heat radiation part outside thereof. The method described in Section 5. 8. The side wall covering the intervening space in a hood-like manner or the cooling body always keeps at least a part of its surface wet with water in the part sandwiched between the accelerator window foil and the reactor window foil, and from that part 6. The method according to claim 5, wherein cooling of the intervening space is promoted by the heat of vaporization of the evaporating water. 9. The intervening space is a semi-enclosed space surrounded by a side wall that covers it like a hood from the top or side, the accelerator window foil, and the reactor window foil, and the interior is 6. The method according to claim 5, characterized in that cooling air is blown in, the blown cooling air is swirled inside, and then discharged to the outside from an exhaust port provided in a portion different from the blowing port. 10 Claim 9, characterized in that fins are attached to the hood-shaped side wall to promote heat radiation.
The method described in section. 11 A small amount of water is continuously supplied to the fin surface from a water pipe placed in contact with the fins of the finned side wall, and the water is continuously vaporized to promote heat radiation. 11. The method of claim 10. 12 (a) A reactor with an irradiation window on the ceiling or vertical side wall; (b) A particle beam accelerator arranged so that the particle beam is irradiated vertically downward or horizontally on the top or side of the reactor; (c) A side wall that covers a space surrounded by the accelerator window foil and the reactor window foil in a hood shape; (d) is fixed to the reactor window foil and slides horizontally on the top surface of the reactor together with the reactor window foil; (e) In a particle beam irradiation device comprising a spacer to prevent a gap from forming between the side wall and the movable flange, the space surrounded by (a) to (e) above; The space surrounded by (a) to (e) is a semi-enclosed space having a cooling air inlet and a cooling air outlet, and the cooling water pipe is , a position that does not obstruct the progress of the main part of the particle beam irradiated from the accelerator window foil and prevents scattered particle beams generated when the particle beam collides with the accelerator window foil from reaching the reactor window foil attachment part. A window foil temperature rise prevention device in a particle beam irradiation device, characterized in that the device is disposed in a particle beam irradiation device. 13 The scattering angle of scattering due to collision with the accelerator window foil is
13. The apparatus according to claim 12, wherein a cooling water pipe is disposed at a position where a scattered particle beam having an angle larger than 15° is captured.