JP2004258011A - Mounting method of irradiation window unit and storing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable one test leak in the same state as actual mounting before mounting the irradiation window unit to a vacuum vessel of an electron beam accelerator and prevent occurrence of subsequent another trash biting. <P>SOLUTION: Process for forming the irradiation window unit 20a, process for attaching flanges 42, 52 with valve 40, 50 in the vacuum side 30 and the air side 32 of the irradiation window unit, and process for confirming vacuum exhaust and degree of vacuum in the vacuum side of the irradiation window unit having passed the valve 40 are provided. Process for introducing detection gas 58 into the air side of the irradiation window unit having passed the valve 50 and testing leak of the irradiation window unit, process for maintaining the air side to positive pressure by introducing pressurized inert gas into the air side of the irradiation window unit, process for detaching the flange 42 with valve from the irradiation window unit, process for mounting the irradiation window unit and exhausting, and process for detaching the flange 52 with valve from the irradiation window unit are provided. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention irradiates an object with an electron beam, and cross-links, modifies, cures, sterilizes, and irradiates the object an electron beam extraction unit of an electron beam accelerator that constitutes an electron beam irradiation apparatus used for surface treatment. The present invention relates to a method of attaching (mounting) an irradiation window unit for separating a vacuum side and an atmosphere side, and a method of storing the irradiation window unit before the attachment.
[0002]
[Prior art]
FIG. 4 shows an example of the electron beam irradiation apparatus. An electron beam irradiation apparatus similar to this is described in, for example, Patent Document 1.
[0003]
[Patent Document 1]
JP-A-2002-243899 (paragraphs 0002 to 0011, FIGS. 6 and 9)
[0004]
This electron beam irradiation apparatus generates an electron beam 16 having a planar shape (for example, a rectangular shape) relatively short in the X direction and relatively long in the Y direction orthogonal to the X direction without scanning the electron beam 16. The electron beam accelerator 2 is called a non-scanning type or an area type. However, the technology described in this application can also be applied to a scanning type that scans an electron beam.
[0005]
The electron beam accelerator 2 has a cylindrical vacuum container 4 long in the Y direction. The inside of the vacuum container 4 is evacuated.
[0006]
Inside the vacuum vessel 4, an electron beam source 8 that generates the flat-shaped electron beam 16 that is long in the Y direction is housed. In this example, the electron beam source 8 has a plurality of filaments 10 juxtaposed in the Y direction, an extraction electrode 12 for extracting an electron beam 16 therefrom, and a cylindrical shield electrode 14 for accommodating them. are doing.
[0007]
In the electron beam take-out part of the vacuum vessel 4 of the electron beam accelerator 2, more specifically, in the flange 6 of the electron beam take-out part, the vacuum side 30 inside the vacuum vessel 4 and the atmosphere outside the vacuum vessel 4 are provided. An irradiation window 20 separating the side 32 is provided. The atmosphere side 32 may be literally the atmosphere or an inert gas atmosphere close to the atmospheric pressure, but in this specification, the atmosphere side is referred to as the atmosphere side. The atmosphere side 32 can also be called an irradiation atmosphere side.
[0008]
The irradiation window 20 includes a window foil 26 for separating the atmosphere inside and outside the vacuum vessel 4 and transmitting the electron beam 16, a window frame 22 supporting the window foil 26, and a peripheral edge of the window foil 26 with respect to the window frame 22. And a holding frame 28 for holding the portion. With the window foil 26 as a boundary, the inside of the vacuum vessel 4 is on the vacuum side 30 and the outside of the vacuum vessel 4 is on the atmosphere side 32. The space between the window frame 22 and the window foil 26 is vacuum-sealed by packing (see packing 36 in FIG. 5).
[0009]
In this example, the irradiation window 20 has a planar shape that is long in the Y direction, and the window frame 22 is juxtaposed in the Y direction on the window frame 22 with reference to FIG. A plurality of bars 24 are provided. However, when the area of the window foil 26 is small or when the window foil 26 is the scanning type, the bar 24 may not be provided.
[0010]
The irradiation window 20 and the vacuum vessel 4 have the same potential (usually ground potential), and a DC acceleration between the irradiation window 20 and the electron beam source 8 for accelerating the electron beam 16 drawn from the electron beam source 8. A voltage is applied. The accelerated electron beam 16 is taken out to the atmosphere side 32 through the irradiation window 20 and irradiated on the irradiation object 34. Thereby, the irradiation object 34 can be subjected to processing such as crosslinking, modification, curing, and sterilization. The irradiated object 34 is transported, for example, in the direction along the X direction (the direction of arrow A in FIG. 4).
[0011]
By the way, the window foil 26 is a very thin (for example, about 10 to 50 μm thick) metal (for example, titanium or aluminum) foil, and is consumed due to heat generation due to transmission loss of the electron beam 16. They need to be replaced (eg, periodically).
[0012]
In the conventional window foil attaching method, the window foil 26 is stuck on the holding frame 28, and the holding frame 28 stuck with the window foil 26 is formed using a large number of tens of bolts (see bolts 38 in FIG. 5). It was a method of attaching to the window frame 22. The window frame 22 was previously attached to the vacuum container 4 (more specifically, the flange 6 thereof).
[0013]
In such a method, since a large number of bolts need to be removed and re-tightened, there is a problem that it takes a long time to replace the window foil 26.
[0014]
As means for solving such a problem, Patent Literature 2 discloses a technique in which the irradiation window 20 is formed into a unit type.
[0015]
[Patent Document 2]
JP-A-11-38196 (paragraphs 0008 to 0015, FIG. 2)
[0016]
Referring to FIG. 5, the irradiation window 20 is formed as a unit type by attaching the window foil 26 and the holding frame 28 to the window frame 22 separately from the vacuum container 4 of the electron beam accelerator 2 as described above. The irradiation window unit 20a is formed, and the irradiation window unit 20a is replaced not for the window foil 26 alone. That is, the irradiation window unit 20a is attached to or detached from the vacuum vessel 4 (more specifically, the flange 6) of the electron beam accelerator 2. According to this, the number of bolts (for example, bolts 60 in FIG. 3) for mounting the irradiation window unit 20a is far smaller (for example, several tens) than the number of bolts 38 (for example, several tens) for mounting the holding frame 28. (Approximately 4 to 6 pieces), so that the replacement work time can be greatly reduced.
[0017]
[Problems to be solved by the invention]
However, even if the irradiation window unit 20a as described above is adopted, the following problem still exists.
[0018]
(1) Before attaching the irradiation window unit 20a to the vacuum container 4, since the vacuum side 30 and the atmosphere side 32 of the irradiation window unit 20a are in an atmospheric pressure state and there is no pressure difference, the window foil 26 is shown in FIG. As shown by the dashed line, the tension is not applied and the state is loose. At this time, dust may be caught in the gap 62 between the peripheral portion of the window foil 26 and the window frame 22 or the gap 64 between the window foil 26 and the crosspiece 24 (this is called dust biting). .
[0019]
On the other hand, when the irradiation window unit 20a is attached to the vacuum container 4 of the electron beam accelerator 2 and the inside thereof is evacuated, as shown by the solid line in FIG. 5, the window foil 26 is located between the vacuum side 30 and the atmosphere side 32. Due to the pressure difference (approximately atmospheric pressure), the swelling state is pressed against the vacuum side 30 (in other words, pulled and the same applies hereinafter). At this time, if the dust is bitten, since the window foil 26 is very thin as described above, a hole is formed in the window foil 26, and a vacuum leak may be caused there. Although the possibility of dust biting is higher when the bar 24 is provided, even when the bar 24 is not provided, the possibility of dust biting in the gap 62 still exists.
[0020]
The necessity and the method of performing such a check of the leak due to the bite of the dust before the attachment of the irradiation window unit 20a have not been studied in the past. Neither is described nor suggested in Patent Document 2.
[0021]
(2) Since the window foil 26 is a metal foil as described above, if the irradiation window unit 20a is stored in the air after the irradiation window unit 20a is formed, the irradiation window unit 20a may be exposed to oxygen or moisture in the air. The window foil 26 may be corroded. Conventionally, in order to prevent this corrosion, the irradiation window unit 20a was stored in an inert atmosphere by putting it in a dedicated container, but a dedicated container is required for that purpose, and the cost increases accordingly. There's a problem.
[0022]
Therefore, the present invention enables a leak test to be performed in the same state as at the time of mounting before mounting the irradiation window unit to the vacuum vessel of the electron beam accelerator, and to prevent new dust from being bitten after the leak test. It is an object of the present invention to provide a method of mounting an irradiation window unit.
[0023]
In addition, before mounting the irradiation window unit on the vacuum container of the electron beam accelerator, a leak test can be performed in the same state as when mounting, and after the leak test, the window foil is placed in an inert atmosphere without using a dedicated container. Another object of the present invention is to provide a method of storing an irradiation window unit, which can be stored in a storage unit.
[0024]
[Means for Solving the Problems]
The method of mounting the irradiation window unit according to the present invention includes an irradiation window unit that separates a vacuum side inside the vacuum vessel and an atmosphere side outside the vacuum vessel, in an electron beam extraction unit of a vacuum vessel of an electron beam accelerator. In the attaching method, (a) a step of attaching a window foil for transmitting an electron beam and a holding frame for holding the window foil to a window frame to form the irradiation window unit; and (b) subsequently, the vacuum side of the irradiation window unit. Attaching a first flange with a first valve to a surface located at the position, and attaching a second flange with a second valve to a surface of the irradiation window unit located on the atmosphere side; c) then, with the first and second valves open, performing a vacuum evacuation of the irradiation window unit via the first valve to check the degree of vacuum; d) a step of introducing a detection gas into the atmosphere side of the irradiation window unit via the second valve to perform a leak test of the irradiation window unit; and (e) subsequently performing a leak test on the irradiation window unit. Introducing a pressurized inert gas into the atmosphere side of the irradiation window unit via a valve, closing the valve, and keeping the atmosphere side of the irradiation window unit at a positive pressure; Removing the first flange with the first valve from the irradiation window unit; (g) then attaching the irradiation window unit to a vacuum vessel of the electron beam accelerator; (h) A step of evacuating the vacuum container of the electron beam accelerator and (i) removing the second flange with the second valve from the irradiation window unit (claim 1). Correspondence).
[0025]
According to this mounting method, in the step (c), since the vacuum side of the irradiation window unit is evacuated, the window foil is pressed against the vacuum side by the pressure difference between the vacuum side and the atmosphere side. This is the same state as when mounting. In this state, the leak test is performed in the step (d), so that the leak test can be performed in the same state as at the time of mounting before mounting the irradiation window unit on the vacuum vessel of the electron beam accelerator. Therefore, before mounting the irradiation window unit, it is possible to check for a leak due to the dust bite.
[0026]
Moreover, after the leak test, the atmosphere side of the irradiation window unit is maintained at a positive pressure in the step (e). Therefore, in the step (f), the first flange with the first valve is removed and the irradiation window is removed. Even if the vacuum side of the unit is opened to the atmosphere, the window foil remains pressed against the vacuum side by the positive pressure. That is, since the state is almost the same as when the leak test is performed in the above step (d), the tension of the window foil is not loosened, and thus no new dust is caught.
[0027]
Further, after the irradiation window unit is attached to the vacuum vessel of the electron beam accelerator in the step (g), the inside of the vacuum vessel is evacuated in the step (h). Is pressed against the vacuum side due to the pressure difference. Therefore, after that, even if the second flange with the second valve is removed in the step (i), the tension of the window foil is not loosened. Absent.
[0028]
The storage method according to the present invention, the irradiation window unit is attached to the electron beam extraction unit of the vacuum vessel of the electron beam accelerator, and separates the vacuum side inside the vacuum vessel and the atmosphere side outside the vacuum vessel, A method of storing before the attachment, (a) attaching a window foil for transmitting an electron beam and a holding frame for holding the window foil to the window frame to form the irradiation window unit; and (b) subsequently, the irradiation window. A first flange with a first valve is attached to the surface of the unit located on the vacuum side, and a second flange with a second valve is attached to the surface of the irradiation window unit located on the atmosphere side. Attachment step; (c) Then, with the first and second valves opened, evacuating the irradiation window unit to the vacuum side via the first valve to check the degree of vacuum. (D) introducing a detection gas into the atmosphere side of the irradiation window unit via the second valve to perform a leak test of the irradiation window unit; and (e) Closing the first valve to maintain the vacuum side of the irradiation window unit in a vacuum state; and (f) then injecting an inert gas into the atmosphere side of the irradiation window unit via the second valve. Closing the valve after the introduction and keeping the atmosphere side of the irradiation window unit in an inert gas atmosphere (corresponding to claim 2).
[0029]
According to this storage method, the steps (a) to (d) are the same as the steps (a) to (d) of the mounting method. Before mounting in a vacuum vessel of the accelerator, a leak test can be performed in the same state as at the time of mounting. Therefore, before mounting or storing the irradiation window unit, it is possible to check for a leak due to the bite of dust.
[0030]
Moreover, after the leak test, the vacuum side of the window foil can be kept in a vacuum state by closing the first valve in the step (e). The vacuum state is an inert atmosphere for the window foil. In the step (f), by closing the second valve after introducing the inert gas, the atmosphere side of the window foil can be kept in the inert gas atmosphere. As described above, the irradiation window unit can be stored by placing the window foil in an inert atmosphere without using a dedicated container. That is, it is possible to prevent corrosion of the window foil without using a dedicated container and to prevent dust from entering and causing the dust to bite.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
In the following, parts that are the same as or correspond to those in the conventional example shown in FIGS. 4 and 5 are denoted by the same reference numerals, and differences from the conventional example will be mainly described.
[0032]
(1) First, an embodiment of a method of attaching the irradiation window unit will be described in the order of steps constituting the attaching method.
[0033]
(A) First, as shown in FIG. 1, the window foil 26 for transmitting an electron beam and the holding frame 28 for holding the window foil are attached to the window frame 22 to form the irradiation window unit 20a. This is performed before attaching (mounting) the irradiation window unit 20a to the vacuum container 4 of the electron beam accelerator 2. The packing 36 and the bolt 38 are as described above. In this example, a packing groove 39 for accommodating a packing 44 described later (see FIG. 2) is provided on a surface on the vacuum side 30 of the window frame 22.
[0034]
(B) Next, as shown in FIG. 2, a first flange 42 with a first bulb 40 is attached to the surface of the irradiation window unit 20a located on the vacuum side 30, and the irradiation window unit 20a is A second flange 52 with a second valve 50 is attached to a surface located on the atmosphere side 32. In this example, the attachment of the flanges 42 and 52 is performed using bolts 46 and 56. The space between the flange 42 and the window frame 22 is vacuum-sealed by a packing 44, and the space between the flange 52 and the holding frame 28 is sealed by a packing 54. The packings 36, 44, 54 are, for example, O-rings. The bolts 38, 46, 56 and a bolt 60 described later (see FIG. 3) are provided at positions where they do not interfere with each other.
[0035]
(C) Then, an appropriate evacuation device and a vacuum gauge are connected to the first valve 40, and the first and second valves 40 and 50 are opened, and the first and second valves 40 and 50 are opened. As shown by arrow B, the vacuum side 30 of the irradiation window unit 20a (more specifically, the vacuum side 30 from the window foil 26) is evacuated to check the degree of vacuum. At this time, the window foil 26 is pressed against the vacuum side 30 by the pressure difference between the vacuum side 30 and the atmosphere side 32 (see FIG. 5). This is the same state as when mounting.
[0036]
(D) Next, a detection gas (for example, helium gas or the like) is supplied as the gas 58 to the atmosphere side 32 of the irradiation window unit 20a (more specifically, the atmosphere side 32 of the window foil 26) via the second valve 50. ) Is introduced to perform a leak test of the irradiation window unit 20a. This confirms that there is no leak. The leak test is for detecting a leak (leak) of the detection gas to the vacuum side 30, and for this detection, for example, a partial pressure gauge is used. By this leak test, before mounting the irradiation window unit 20a on the vacuum vessel 4 of the electron beam accelerator 2, a leak test can be performed in the same state as when mounting. Therefore, before mounting the irradiation window unit 20a, it is possible to check for a leak due to the bite of dust.
[0037]
(E) Then, after introducing a pressurized inert gas (for example, nitrogen gas, helium gas, etc.) as the gas 58 into the atmosphere side 32 of the irradiation window unit 20a via the second valve 50, the valve By closing 50, the atmospheric side 32 of the irradiation window unit 20a is maintained at a positive pressure. Due to this positive pressure, the window foil 26 of the irradiation window unit 20a is pressed against the vacuum side 30.
[0038]
(F) Next, the first flange 42 with the first bulb 40 is removed from the irradiation window unit 20a. This is to prepare for attaching the irradiation window unit 20a to the vacuum container 4 of the electron beam accelerator 2 (see FIG. 3). At this time, the vacuum side 30 of the irradiation window unit 20a is opened to the atmosphere by removing the first flange 42 and the like, but the atmosphere side 32 of the irradiation window unit 20a is maintained at a positive pressure in the step (e). Therefore, the window foil 26 remains pressed against the vacuum side 30. That is, since the state is almost the same as when the leak test was performed in the step (d), the tension of the window foil 26 is not loosened, and therefore, no new dust is caught.
[0039]
(G) Next, as shown in FIG. 3, the irradiation window unit 20a is attached to the vacuum vessel 4 (more specifically, its flange 6) of the electron beam accelerator 2 using, for example, bolts 60. The number of the bolts 60 is, for example, four or six.
[0040]
(H) Next, the inside of the vacuum vessel 4 of the electron beam accelerator 2 is evacuated by a vacuum exhaust device (not shown). As a result, the window foil 26 of the irradiation window unit 20a is pressed against the vacuum side 30 by the pressure difference between the vacuum side 30 and the atmosphere side 32. However, in the step (e), the vacuum side is already pressed by the positive pressure. Since it is pressed against 30, the state of the window foil 26 does not greatly change.
[0041]
(I) Next, the second flange 52 with the second valve 50 is removed from the irradiation window unit 20a. Even when these are removed, the window foil 26 is pressed against the vacuum side 30 by the pressure difference between the vacuum side 30 and the atmosphere side 32 in the step (h), so that the tension of the window foil 26 is not loosened. Therefore, in this case, no new dust is generated. By this removal, the attachment (mounting) of the irradiation window unit 20a is completed, and the state becomes the same as that shown in FIG.
[0042]
(2) Next, an embodiment of a method for storing the irradiation window unit will be described. In short, this storage method is to attach the first flange 42 with the first valve 40 and the second flange 52 with the second valve 50 used in the leak test without removing them. These are used in place of dedicated containers for storage. Hereinafter, the steps will be described in order.
[0043]
First, the same steps as the steps (a) to (d) of the mounting method are performed. The contents and effects are as described above. Thus, the process up to the leak test of the irradiation window unit 20a is completed.
[0044]
(E) Next, referring to FIG. 2, the first valve 40 is closed, and the vacuum side 30 of the irradiation window unit 20a is kept in a vacuum state. The vacuum state is an inert atmosphere for the window foil 26.
[0045]
(F) Next, after introducing an inert gas (for example, nitrogen gas, helium gas, or the like) as the gas 58 into the atmosphere side 32 of the irradiation window unit 20a via the second valve 50, the valve 50 is closed. The atmosphere side 32 of the irradiation window unit 20a is kept in an inert gas atmosphere. At this time, it is not necessary to maintain the atmosphere side 32 of the irradiation window unit 20a at a positive pressure with an inert gas, but it may be maintained at a positive pressure.
[0046]
As described above, the irradiation window unit 20a can be stored by placing the window foil 26 in an inert atmosphere without using a dedicated container. That is, the corrosion of the window foil 26 can be prevented without using a dedicated container, and the dust can be prevented from entering and causing the dust.
[0047]
When the irradiation window unit 20a is attached to the vacuum vessel 4 of the electron beam accelerator 2 after this storage, (a) when the atmospheric side 32 of the irradiation window unit 20a is maintained at a positive pressure, ) May be started, and if (a) the positive pressure is not maintained, it may be started from the step (e) of the above mounting method.
[0048]
【The invention's effect】
The present invention is configured as described above, and has the following effects.
[0049]
According to the first aspect of the present invention, the leak test is performed with the window foil pressed against the vacuum side. Therefore, before mounting the irradiation window unit on the vacuum vessel of the electron beam accelerator, the leak test is performed in the same state as when mounting. Testing can be done. Therefore, before mounting the irradiation window unit, it is possible to check for a leak due to the dust bite.
[0050]
In addition, even after the leak test, the state in which the window foil is pressed against the vacuum side can be maintained until the mounting of the irradiation window unit is completed, so that no new dust is caught.
[0051]
According to the second aspect of the present invention, the leak test is performed with the window foil pressed against the vacuum side. Therefore, before mounting the irradiation window unit on the vacuum vessel of the electron beam accelerator, the leak test is performed in the same state as when mounting. Testing can be done. Therefore, before mounting or storing the irradiation window unit, it is possible to check for a leak due to the bite of dust.
[0052]
Moreover, after the leak test, the vacuum side of the window foil is maintained in a vacuum state by closing the first valve, and the atmosphere side of the window foil is closed by the inert gas by introducing the inert gas. Since the atmosphere can be maintained, the irradiation window unit can be stored by placing the window foil in an inert atmosphere without using a dedicated container. That is, it is possible to prevent corrosion of the window foil without using a dedicated container and to prevent dust from entering and causing the dust to bite.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating an example of an irradiation window unit.
FIG. 2 is a sectional view showing a state in which first and second flanges with a valve are attached to the irradiation window unit of FIG. 1;
FIG. 3 is a cross-sectional view showing a state in which the irradiation window unit of FIG. 1 is attached to a vacuum vessel of an electron beam accelerator together with a second flange with a valve.
FIG. 4 is a sectional view showing an example of an electron beam irradiation device.
FIG. 5 is an enlarged partial sectional view of the irradiation window unit in the Y direction.
[Explanation of symbols]
2 Electron beam accelerator 4 Vacuum container 20a Irradiation window unit 22 Window frame 26 Window foil 28 Holding frame 30 Vacuum side 32 Atmospheric side 40 First valve 42 First flange 50 Second valve 52 Second flange 58 Gas

Claims (2)

In a method of attaching an irradiation window unit that separates a vacuum side inside the vacuum vessel and an atmosphere side outside the vacuum vessel into an electron beam extraction unit of a vacuum vessel of an electron beam accelerator,
(A) attaching a window foil for transmitting an electron beam and a holding frame for holding the window foil to a window frame to form the irradiation window unit;
(B) Next, a first flange with a first valve is attached to a surface of the irradiation window unit located on the vacuum side, and a second flange of the irradiation window unit is attached to a surface located on the atmosphere side of the irradiation window unit. Attaching a second flange with a valve;
(C) then, with the first and second valves open, performing a vacuum evacuation of the irradiation window unit via the first valve to check the degree of vacuum;
(D) introducing a detection gas into the atmosphere side of the irradiation window unit via the second valve to perform a leak test of the irradiation window unit;
(E) Then, after introducing a pressurized inert gas into the atmosphere side of the irradiation window unit via the second valve, the valve is closed and the atmosphere side of the irradiation window unit is set to a positive pressure. And the process to keep
(F) removing the first flange with the first bulb from the irradiation window unit;
(G) attaching the irradiation window unit to a vacuum container of the electron beam accelerator;
(H) evacuation of the vacuum vessel of the electron beam accelerator;
(I) Then, a step of removing the second flange with the second valve from the irradiation window unit is provided. A method of storing an irradiation window unit attached to an electron beam take-out part of a vacuum vessel of an electron beam accelerator to separate a vacuum side inside the vacuum vessel and an atmosphere side outside the vacuum vessel before the attachment. ,
(A) attaching a window foil for transmitting an electron beam and a holding frame for holding the window foil to a window frame to form the irradiation window unit;
(B) Next, a first flange with a first valve is attached to a surface of the irradiation window unit located on the vacuum side, and a second flange of the irradiation window unit is attached to a surface located on the atmosphere side of the irradiation window unit. Attaching a second flange with a valve;
(C) then, with the first and second valves open, performing a vacuum evacuation of the irradiation window unit via the first valve to check the degree of vacuum;
(D) introducing a detection gas into the atmosphere side of the irradiation window unit via the second valve to perform a leak test of the irradiation window unit;
(E) closing the first valve and keeping the vacuum side of the irradiation window unit in a vacuum state;
(F) Next, after introducing an inert gas into the atmosphere side of the irradiation window unit via the second valve, the valve is closed and the atmosphere side of the irradiation window unit is maintained in an inert gas atmosphere. And storing the irradiation window unit.

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