JP2004226335A - Cooling structure for irradiation window section for electron beam irradiation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid the occurrence of a hydrogen fluoride (HF) system corrosive product when a sheet-like material processed with polytetrafluoroethylene is subjected to electron beam treatment using a scan type electron beam irradiation equipment, the probability of the corrosion of a window foil by deposition of the corrosive product onto a widow foil corner part to which the wind cannot be delivered, and the deposition of the corrosive product onto the window foil corner part. <P>SOLUTION: Notches are formed at both ends of a nozzle blow-off port of a cooling duct of an irradiation window foil of the electron beam irradiation equipment. The cooling wind, since going out of the notches toward the lateral direction, blows also on both the end corner parts of the window foil. A reaction product comprising a mixture of gas and liquid, is blown away if the cooling wind is strong. The device is configured such that the cooling wind blows also on the corner parts of the window foil, thereby preventing the corrosive deterioration by a deposition material with window foil corrosively-deteriorating effect, which is to deposited onto the corner parts. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００５２】
切欠きのある場合（Ｂ）を表２に示し図１１に同じもののグラフを示す。
【００５３】
【表２】

【００５４】
表における数値は風速（ｍ／ｓｅｃ）である。同じ測定点において下へ行くに従って風速が増えるのはモータの回転数が増えるからである。
【００５５】
切欠きのない場合（Ａ）では、端近くａ、ｂ点での風速が、中央近くのｆ、ｇ、ｈ、ｉ点の風速よりも低い。例えばインバータ周波数が４０Ｈｚの時、ａで３．６ｍ／ｓｅｃ、ｂで５ｍ／ｓｅｃであるが、ｇ点で６．８ｍ／ｓｅｃ、ｈ点で６．７ｍ／ｓｅｃである。窓箔の端ａ、ｂで風速が低いことがわかる。それはノズルの吹き出し方向に切欠きがないからである。
【００５６】
切欠きのある場合（Ｂ）では、図１１のように端近くの測定点ａ、ｂ、ｃでの風速が、中央部近くの測定点ｇ、ｈ、ｉの風速とほとんど同じである。
【００５７】
たとえばインバータ周波数が１０Ｈｚのとき、ａ点で風速２．３ｍ／ｓｅｃであり、ｇ点で風速１．９ｍ／ｓｅｃ、ｈ点で風速２．１ｍ／ｓｅｃである。ａ点で風速が小さいということはない。たとえばインバータ周波数が４０Ｈｚのとき、ｂ点での風速は７ｍ／ｓｅｃであり、ｈ点で６．５ｍ／ｓｅｃ、ｉ点で６ｍ／ｓｅｃである。端点ｂ点での風速が遅いということはないのである。
【００５８】
それはノズルの両側面に切欠きを付けたからである。切欠きから冷却風が側方へと広がるからノズル端と向き合わない窓箔の端も冷却風が充分の強さで吹きすさぶようになる。そのためフッ素系の生成物が窓箔に付着しない。窓箔の腐食を防ぐことができる。
【００５９】
【発明の効果】
本発明は冷却ダクト先のノズルの側面に切欠きを設け側方へも冷却風が吹き出すようにして窓箔の裏面の全体に冷却風が行き渡るようにした。フッ素を含むポリテトラフルオロエチレンコーティングシート材などを電子線処理したときにフッ化水素ＨＦを含む生成物が発生しＴｉ、Ａｌなどの窓箔に付着するとこれを腐食するのであるが、本発明の場合は冷却風が清掃風としても働き窓箔にフッ化水素が付かないようになる。そのために窓箔の端での腐食を防ぐことができる。
【００６０】
電子線は窓箔の端を通らないから窓箔端は冷却する必要はないのであるが清掃の必要はある。
【００６１】
本発明は冷却風を清掃風として利用して窓箔に腐食性の生成物が付着するのを有効に防止することができる。フッ化水素系の滞留物が付着しなくなるので窓箔の腐食を防止できる。窓箔の寿命を延長することができる。
【００６２】
窓箔が腐食する兆しが見られると処理工程を止めて電子線照射装置の真空を破り内部を掃除して窓箔を張り替えて立ち上げの試運転をして、というような余分の時間と手間が必要になるのであるが、本発明はそのような問題がおこらない。
【図面の簡単な説明】
【図１】走査型電子線照射装置の熱電子放出部、加速管、走査管、走査管下部にある照射窓部を冷却する冷却ダクトなどの構造を示す正面図。
【図２】走査型電子線照射装置の熱電子放出部、加速管、走査管、走査管下部にある照射窓部を冷却する冷却ダクトなどの構造を示す側面図。
【図３】走査管下部の照射窓と、照射窓の窓箔を冷却するために設けた冷却ダクトの縦断面図。
【図４】走査管フランジ、窓箔、冷却ダクト、ノズルなどの底面図。
【図５】切欠きのない場合の、冷却ダクトとノズルと吹き出し口の部分の側面図。
【図６】切欠きのある場合の、冷却ダクトとノズルと吹き出し口の部分の側面図。
【図７】切欠きのある場合の、冷却ダクトとノズルと吹き出し口の部分の斜視図。
【図８】照射窓に設けられた窓箔へ切欠きなしのノズルから冷却風を吹き付ける部分の縦断面図。風速測定点ａ〜ｉを黒丸によって示した。
【図９】照射窓に設けられた窓箔へ切欠きのあるノズルから冷却風を吹き付ける部分の縦断面図。風速測定点ａ〜ｉを黒丸によって示した。
【図１０】冷却機構のモータのインバータ周波数を１０Ｈｚ、２０Ｈｚ、３０Ｈｚ、４０Ｈｚと変化させ、切欠きなしノズル（Ａ）から冷却風を窓箔へ吹き付ける場合、窓箔の近傍に取った９つの測定点ａ〜ｉにおける風速の測定結果を示すグラフ。
【図１１】冷却機構のモータのインバータ周波数を１０Ｈｚ、２０Ｈｚ、３０Ｈｚ、４０Ｈｚと変化させ、切欠きありノズル（Ｂ）から冷却風を窓箔へ吹き付ける場合、窓箔の近傍に取った９つの測定点ａ〜ｉにおける風速の測定結果を示すグラフ。
【符号の説明】
２ 加速管
３ 走査機構部
４ 走査管
５ 冷却ダクト
６ 走査管フランジ
７ フランジ
８ ノズル
９ 窓箔
１０ 照射窓
２０ 蛇腹
２２ フランジ
２４ 窓箔押さえ枠
２５ 吹き出し口
２６ 冷却風
３０ 切欠き[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement in a cooling mechanism of a window foil in an electron beam irradiation apparatus. In particular, the present invention relates to a cooling mechanism having a nozzle capable of cooling the entire window foil. An electron beam irradiator heats a filament in a vacuum to generate thermoelectrons, accelerates the electrons by applying a high voltage with an accelerating tube, produces a high-speed electron beam, and takes it out to the atmosphere through the window foil of the irradiation window. This is an apparatus that applies an electron beam to an object to be processed to perform processes such as polymer crosslinking, coating film hardening, and sterilization. It is a large-scale device including a high-voltage power supply, an acceleration tube, a filament, an irradiation window, a transport mechanism, a metal housing, a cooling mechanism, and the like.
[0002]
Electron beam irradiation apparatuses are roughly classified into a scanning type and a non-scanning type. It depends on the acceleration energy. When the acceleration energy is as high as 5 MeV to 500 keV, a tall and large scanning type is used. When the acceleration energy is as low as several tens keV to 500 keV, a non-scanning type (area type) is used.
[0003]
In the case of the scanning type, a scanning coil is provided at the end of the accelerating tube, followed by a triangularly extending scanning tube. An electron beam is scanned left and right by passing an alternating current through the scanning coil to generate an alternating magnetic field. A thin electron beam accelerated to high energy is scanned vertically and horizontally to irradiate an object to be processed. Since it has high energy, it has a large penetration depth into the workpiece. It requires a high-voltage power supply circuit, a tall accelerating tube, a wide scanning tube, and the like, resulting in a larger device.
[0004]
In the case of the non-scanning type, a large number of parallel filaments are used to increase the area of the filament region from which electrons are emitted, and this is accelerated as it is in the direction of the irradiation window. Since a large area electron flow is generated, a large area of the object to be processed is irradiated with the electron beam at a stroke without scanning. It is suitable for processes that do not require much penetration depth.
[0005]
The irradiation window is a window for separating a vacuum region having a filament and an atmospheric pressure region where an object to be processed is present, and is covered with a window foil of Ti or Al. The window foil is located below the scanning tube in the case of a scanning type, and the atmospheric pressure is below the window foil, and the object to be processed is carried. Above it is a vacuum. When an electron beam passes through the window foil, the window foil is heated because energy is lost there. As it is, it melts quickly and breaks. In order to prevent this, the window foil is provided with a cooling mechanism. There are water-cooled and air-cooled types. In the water-cooled type, a crosspiece is provided above the window foil, and a cooling water passage is provided in the crosspiece so that the window foil is water-cooled from above. The heat of the window foil is transmitted to the crosspiece and carried by the cooling water.
[0006]
Since the air-cooled type cannot be installed in a vacuum, it is provided in the atmosphere immediately below the window foil. A duct with a wide nozzle is installed on the side of the irradiation window to cool the entire window foil, and cooling air is blown from the nozzle to cool the window foil. In the case of the scanning type, both are provided, and the window foil is cooled by cooling water from above and by cooling air from below. The present invention relates to such an air cooling mechanism.
[0007]
The electron beam that has passed through the window foil hits the object in the atmosphere. Various effects such as polymer crosslinking, coating film hardening, and sterilization are performed on the object. However, when an electron beam having a high energy hits the object to be processed, X-rays are emitted. X-rays are scattered and reflected. In order to shield harmful X-rays, the transport mechanism, the object to be processed, and the irradiation window are covered with a thick metal casing. Since the processing section is thickly covered by the housing, the transfer of the object to be processed is automatically performed mechanically. For this reason, a transport mechanism such as an endless orbiting conveyor travels through the metal housing, and carries the object to be processed from the entrance to the area immediately below the irradiation window (processing position) to the exit. In order to prevent the X-rays from leaking to the outside, it is designed to meander vertically.
[0008]
The accelerating power source converts a commercial power source into an appropriate voltage using a transformer, and converts the voltage to a desired high voltage using a voltage multiplier circuit that combines a number of capacitors and rectifiers. The capacitors and rectifiers that handle these high voltages are mounted on a high-voltage stand and are insulated from the ground. In the case of the scanning type with a high voltage, the power supply circuit is complicated and has a large volume. In the case of the non-scan type having a low voltage, the power supply circuit is more simplified. The above is the common structure of the electron beam irradiation device. The present invention focuses on the part of the air cooling mechanism that cools the window foil.
[0009]
[Prior art]
FIG. 1 is a front view of a part of the scanning electron beam irradiation apparatus, and FIG. 2 is a side view thereof.
In addition, there are a power supply circuit, a housing, a transport mechanism, and the like, which are not directly related to cooling, and thus are omitted here.
[0010]
The accelerating tube 2 protrudes upward, and is formed by alternately laminating insulating portions and electrode plates with holes. The inside is evacuated. An accelerating power supply voltage is divided and distributed to the electrode plate by a resistor. Since the electrons are accelerated, the voltage at the top of the accelerating tube is a negative high voltage. At the top of the accelerating tube is a filament, through which a filament current flows and is heated, causing thermions to exit from the filament.
[0011]
A negative electrode of a high voltage power supply is connected to the filament so that an acceleration voltage is applied. The thermoelectrons are accelerated by the voltage of the accelerating tube and gradually gain speed to become a high-speed electron beam and descend the accelerating tube. Below that is a scanning mechanism 3 and further a scanning tube 4. The scanning tube 4 is a triangular-shaped vacuum container.
[0012]
The scanning mechanism is a magnet that scans the electron beam right and left. An alternating current is passed through the coil to generate an alternating magnetic flux density, and the electron beam is swung right and left. The scanning tube 4 has a shape that spreads downward because the beam spreads by scanning. Below the scanning tube 4 is a scanning tube flange 6 on which a window foil 9 is stretched and held by a window foil holding frame 24 (FIG. 3).
[0013]
The mechanism for air cooling can be seen below FIGS. A horizontal cooling duct 5 is provided along the long side of the irradiation window from the upward flange 7 through the curved portion. Above the flange 7, there is a bellows 20, and a pipe (not shown) from a blower (not shown) is connected to the flange 22 thereabove. The cooling air may use dry air from which water has been removed, but in the case of air, ozone is emitted by X-rays. In a case where ozone generation is not preferable, nitrogen or argon is used instead of air.
[0014]
Here, for convenience of explanation, it is assumed that the z-axis is taken downward, the y-axis is taken along the long side of the scanning tube, and the x-axis is taken along the short side of the scanning tube. The cooling air is conveyed by a pipe from the blower, advances the bellows 20 in the z direction, changes the flow in the curved portion in the y direction, and fills the inside of the cooling duct 5. A beak-shaped nozzle 8 extends in front of the cooling duct 5. Therefore, the cooling air is further bent in the x direction in the cooling duct 5, exits from the outlet 25 of the nozzle 8, and blows on the lower surface of the window foil 9. Since the lower part of the window foil 9 is under atmospheric pressure and the upper part is under vacuum, the window foil 9 is slightly curved upward. Actually, there is a metal bar on the window foil, but the portion not in contact with the bar is curved upward.
[0015]
Since the beak-shaped nozzle 8 is located at the tip of the cooling duct 5, it exists along the long side of the scanning tube similarly to the cooling duct. That is, the nozzle is long in the y direction. However, it is short in the x direction. In addition, the height (z direction) is small, and the gap is gradually narrowed to increase the wind speed. From the nozzle 8, a sheet-like cooling air is blown out.
[0016]
FIG. 5 is an enlarged side view of the nozzle portion. The reason why the outlet 25 is slightly curved upward is to make it easier to hit the window foil surface.
[0017]
The window cooling duct 5 blows cooling air from below onto the window foil 9 of the irradiation window below the electron beam irradiation device scanning tube 4 to cool the window. The cooling duct 5 blows air from a wide and thin nozzle in a horizontal direction (y direction) to a wide range.
[0018]
However, the conventional cooling duct is still insufficient in width and insufficient, and cooling is insufficient on both sides of the window foil. This is because the lateral length D of the cooling duct is shorter than the overall lateral length L of the window foil (D <L).
[0019]
FIG. 4 is a bottom view of the scanning tube flange, window foil, and nozzle portion. The bottom surface of the rectangular scanning tube flange 6 can be seen. The window foil 9 is stuck under it and is held down by the window foil holding frame 24. The window foil holding frame 24 is fastened to the back surface of the scanning tube flange 6 by bolts. The opening of the scanning tube flange 6 has a curved edge such as Irohanihohetillinyl.
[0020]
On the other hand, the nozzle spreads only to the part of Chilinur. The cooling air 26 blown out from the nozzle 8 blows on a rectangular area including Chilinur-Nihaloy, but does not reach the window foil portion surrounded by the end of Tithehoni.
[0021]
Conventionally, the cooling wind was not blown to both ends of the irradiation window.
[0022]
[Problems to be solved by the invention]
In the cooling air blowing mechanism of the conventional example, as shown in FIG. 4, a dead space is formed in the nihohetchi portion, and a portion that is not air-cooled by the cooling air remains.
[0023]
The window foil must be cooled because the scanned electron beam passes through the window foil. When an electron beam passes through the window foil, it loses power due to the passage. The power becomes heat and heats the window foil. Since the window foil is a metal, it melts and breaks when heated. Therefore, the portion of the window foil through which the electron beam passes must be cooled.
[0024]
Conventionally, the beam scanning range is always blown by the cooling air, which is sufficient. The scanning of the electron beam was at most as little as Nichi, and it was only necessary to cool down to Lunuri and Iroha.
[0025]
However, it is not only the Joule heat of the electron beam that shortens the life of the window foil. Corrosive gas liquid and the like coming out of the object to be treated also erode the window foil and shorten the life of the window foil. This is a problem that has arisen only when treatment of products that generate corrosive products is started. This is due to the expanded use of processing.
[0026]
A case in which an electron beam is applied while conveying a sheet member coated with polytetrafluoroethylene (PTFE) in the x direction in FIG. 4 will be described. It is assumed that the width of the object to be processed falls within Nichi, and that the electron beam scanning is performed only within Nichi.
[0027]
In that case, when an electron beam is applied to the polytetrafluoroethylene material, not only X-rays are emitted, but also gas and powder containing fluorine are generated. A portion of polytetrafluoroethylene was destroyed by an electron beam. The main component of the gas is hydrogen fluoride HF. In addition, corrosive powder may come out and scatter and a part of the powder may adhere to the window foil. Since it contains fluorine, the deposits are highly corrosive. Even the window foil of Ti is corroded by the deposit. If left as it is, the window foil will corrode and make holes.
[0028]
In the part of Irohani-chinillinul where the cooling air is constantly blown, fluorine-based deposits do not adhere to the window foil due to the wind. However, the portion of the nihohetchi to which the cooling air does not reach is gradually corroded with deposits containing fluorine. If the window foil breaks, the electron beam irradiation device will break down.
[0029]
A special rotating brush with soft bristles implanted on the nihochet can be used to softly rub the nihohetchi portion of the window foil with a brush to prevent the deposition of corrosive products. However, the irradiation window portion of the electron beam irradiation device no longer has an extra space, and it is impossible to newly provide a rotating brush or a rotating mechanism.
[0030]
[Means for Solving the Problems]
It is an object of the present invention to allow cooling air to be blown to the edge of the window foil so that a corrosive substance peculiar to the fluorine-containing workpiece is not attached to a corner of the window foil when processing such a fluorine-containing workpiece. . The width of the cooling duct and the width D of the nozzle are set so as to cover the width of electron beam scanning. The cooling air does not blow beyond the scanning width. By changing the cooling duct to a large one, the wind can be sent to the corner of the window foil.
[0031]
However, doing so requires extensive remodeling and space constraints for cooling duct storage. It is difficult to increase the size of the cooling duct in terms of cost. The present invention allows the cooling air to be blown to the edge of the window foil without making the cooling duct nozzle larger, so that the window foil is not corroded by corrosive deposits. By preventing window foil corrosion, it is possible to prevent a vacuum leak due to window foil perforation in advance.
[0032]
The window foil cooling mechanism of the present invention has a cooling duct that extends in the width direction of the window foil and allows cooling air to pass therethrough, and a nozzle that is located at the tip of the cooling duct and guides the cooling air toward the window foil. Notches are provided. Cooling air blows out obliquely from the notch on the side. Since the cooling air flows out of the notch in the oblique direction, the cooling air can be blown to the corners of the window foil. Thereby, even when the polytetrafluoroethylene coating sheet is being treated, it is possible to prevent the fluorine-based product from adhering and depositing at the corners of the window foil. It is a novel idea of the present invention to provide a notch on the side of the nozzle to spread the cooling air obliquely forward.
[0033]
Although it is called cooling air, to blow off deposits and prevent corrosion is no longer cooling but cleaning. In other words, the present invention utilizes the cooling air as the cleaning air.
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
By notching both ends of the outlet of the cooling duct, cooling air is also applied to both ends of the window foil to blow off corrosive substances by the cooling air so that corrosive products do not adhere to and accumulate on the window foil. Thereby, corrosion and perforation of the window foil can be prevented. The cooling air is effectively used for cleaning and cleaning.
[0035]
An electron beam irradiation device having such a device will be described. The vertically-vertical structure shown in FIGS. 1 and 2 does not change. There is a thermoelectron generation chamber by a filament in order from the top, and the accelerating tube 2 continues below. The electrons are accelerated to a desired energy by the acceleration tube 2. The scanning mechanism 3 has a scanning magnet, and scans the beam in the y direction by passing an alternating current (for example, 200 Hz) of an appropriate frequency to the scanning coil (the scanning may be performed simultaneously in the x direction). An opening (irradiation window) is provided below the scanning tube 4 extending in the y direction.
[0036]
A window foil 9 is stretched on the back surface of the scanning tube flange 6 and is held by a window foil holding frame 24. A cooling duct 5 having a circular cross section is provided along the width of the window foil 9 so as to extend in the y direction. As described above, the bellows pipe 20 is provided at the flange 7 at the tip of the curved portion of the cooling duct, and a cooling air pipe (not shown) is connected to the flange 22.
[0037]
As can be seen from the bottom of FIG. 2, a thin nozzle 8 has a width from the cooling duct 5 but extends in the height direction (z direction). As shown in FIGS. 1 and 3, the nozzle 8 extends long in the window foil width direction (y direction), and blows a thin sheet-shaped cooling air in the -x direction in the z direction extending in the y direction. . The outlet 25 is slightly bent upward. This is in order to blow the cooling air to the rear surface of the window foil. As shown in FIG. 7, the cooling duct 5 is curved in an L shape, and the nozzle 8 extends forward from the horizontal portion. The length of the cooling duct 5 in the horizontal direction depends on the width of the irradiation window, but is about 1 m to 2 m.
[0038]
Up to that point, it is the same as the conventional example, but different from now. As shown in FIGS. 7, 9, and 6, a notch 30 parallel to the blowing direction is provided on the side surface of the tip of the nozzle 8, which is a novel feature.
[0039]
In FIG. 3, a notch 30 is visible on the other side of the nozzle. FIG. 5 shows a nozzle without a notch, and FIG. 6 shows a nozzle with a notch 30. By comparing the two, it is clear what the notch 30 is.
[0040]
FIG. 8 shows a cross section of a nozzle without a notch. FIG. 9 shows a cross section of a nozzle having a notch 30. The notch 30 is also found by comparing them.
[0041]
The outlet 25 for creating a flat flow is composed of a long upper side, a long lower side, a short right side, and a short left side, but the short right left side is notched inward from the blowing end. . The length of the notch is about 5 cm to 15 cm, and the thickness of the notch is about 5 mm to 20 mm. It is on both sides. Such processing is easy. Even with an existing nozzle, the duct can be removed and the side of the nozzle can be cut out.
[0042]
As shown in FIG. 3, the cooling air is blown from below onto the window foil curved upward. Since there is the notch 30, it spreads horizontally on the left and right. Since the cooling air has a left-right spread from the nozzle, the cooling air hits the entire surface of the window foil. In FIG. 4, the wind also flows to the nihohetchi area at the end. As a result, even when the fluorine-containing workpiece is irradiated with an electron beam, corrosive products including HF do not deposit on the corners of the window foil. The life of the window foil when a polytetrafluoroethylene-coated sheet or the like is treated is extended.
[0043]
【Example】
In order to examine the effect of the notch at the nozzle end, nine measurement points were taken immediately below the window foil, and the wind speed was measured in the case where there was no notch (A) and in the case where there was a notch (B).
[0044]
In that example, the scanning width is 1800 mm. The width of the irradiation window is 1900 mm (y direction: 1800 mm + 2R), and the length in the transport direction (x direction) is 100 mm. FIG. 4 thus shows that the radius of curvature of the semicircular arc at the end of the window at the portion of the curved nihohetchi is R = 50 mm.
[0045]
The notch is 10 mm long. In the case of B, a notch of 10 mm is formed at the nozzle tip on both sides. In the case of A, there is no notch.
[0046]
A straight line that includes the center of curvature and is parallel to the transport direction is drawn. That is not the nozzle blowing range. The distance from Asa to the edge of the semicircular arc is 50 mm. Nine measurement points are taken from the edge as a, b, c,..., H, i. a is 15 mm from the edge. A measurement point is taken every time the probe advances 10 mm inward (y direction). Here, a straight line is set as a reference point, and the coordinates are determined so that the left side is positive and the right side is negative.
[0047]
Therefore, point e is +5 mm, point f is +15 mm, point g is +25 mm, point h is +35 mm, and point i is +45 mm. Point d on the opposite side is −5 mm, point c is −15 mm, point b is −25 mm, and point a is −35 mm.
[0048]
The measurement point is not at the window foil itself but at a position 20 mm below the window foil as shown in FIGS. I want to measure the temperature on the window foil, but the probe of the anemometer cannot contact the window foil.
[0049]
The parameters include not only the measurement points but also the motor speed for blowing the cooling air. In order to increase or decrease the motor speed, the frequency of the inverter is changed to 10 Hz, 20 Hz, 30 Hz or 40 Hz. The frequency of the inverter is proportional to the motor speed. That defines the wind speed.
[0050]
Table 1 shows the case (A) having no notch, and FIG. 10 shows a graph of the same.
[0051]
[Table 1]

[0052]
Table 2 shows the case with the notch (B), and FIG. 11 shows a graph of the same.
[0053]
[Table 2]

[0054]
The numerical values in the table are wind speeds (m / sec). The reason why the wind speed increases as going downward at the same measurement point is because the rotation speed of the motor increases.
[0055]
In the case where there is no notch (A), the wind speeds at points a and b near the ends are lower than the wind speeds at points f, g, h, and i near the center. For example, when the inverter frequency is 40 Hz, it is 3.6 m / sec at a and 5 m / sec at b, but 6.8 m / sec at point g and 6.7 m / sec at point h. It can be seen that the wind speed is low at the edges a and b of the window foil. This is because there is no notch in the blowing direction of the nozzle.
[0056]
In the case of the notch (B), the wind speeds at the measurement points a, b, and c near the edges are almost the same as the wind speeds at the measurement points g, h, and i near the center as shown in FIG.
[0057]
For example, when the inverter frequency is 10 Hz, the wind speed is 2.3 m / sec at point a, 1.9 m / sec at point g, and 2.1 m / sec at point h. The wind speed is not small at the point a. For example, when the inverter frequency is 40 Hz, the wind speed at point b is 7 m / sec, at point h is 6.5 m / sec, and at point i is 6 m / sec. The wind speed at the end point b is not slow.
[0058]
This is because notches are provided on both sides of the nozzle. Since the cooling air spreads laterally from the notch, the edge of the window foil not facing the nozzle end also blows the cooling air with sufficient strength. Therefore, the fluorine-based product does not adhere to the window foil. Corrosion of window foil can be prevented.
[0059]
【The invention's effect】
In the present invention, a notch is provided on the side surface of the nozzle at the tip of the cooling duct so that the cooling air blows out to the side so that the cooling air can be spread over the entire back surface of the window foil. When a polytetrafluoroethylene coating sheet material containing fluorine is subjected to an electron beam treatment, a product containing hydrogen fluoride HF is generated and corrodes when it adheres to a window foil such as Ti and Al. In this case, the cooling air also acts as a cleaning air, so that hydrogen fluoride does not adhere to the window foil. Therefore, corrosion at the edge of the window foil can be prevented.
[0060]
Since the electron beam does not pass through the edge of the window foil, the edge of the window foil does not need to be cooled, but needs to be cleaned.
[0061]
The present invention can effectively prevent the corrosive products from adhering to the window foil by using the cooling air as the cleaning air. Since the hydrogen fluoride-based residue does not adhere, corrosion of the window foil can be prevented. The life of the window foil can be extended.
[0062]
When there are signs that the window foil is corroded, the processing process is stopped, the vacuum of the electron beam irradiation device is broken, the inside is cleaned, the window foil is replaced, and the commissioning is performed, and extra time and labor are required. Although necessary, the present invention does not have such a problem.
[Brief description of the drawings]
FIG. 1 is a front view showing a structure of a scanning electron beam irradiation apparatus, such as a thermoelectron emission unit, an acceleration tube, a scanning tube, and a cooling duct for cooling an irradiation window provided below the scanning tube.
FIG. 2 is a side view showing a structure of a scanning electron beam irradiation apparatus, such as a thermionic emission unit, an acceleration tube, a scanning tube, and a cooling duct for cooling an irradiation window below the scanning tube.
FIG. 3 is a longitudinal sectional view of an irradiation window below a scanning tube and a cooling duct provided for cooling a window foil of the irradiation window.
FIG. 4 is a bottom view of a scanning tube flange, a window foil, a cooling duct, a nozzle, and the like.
FIG. 5 is a side view of a portion of a cooling duct, a nozzle, and an outlet in a case where there is no notch.
FIG. 6 is a side view of a portion of a cooling duct, a nozzle, and a blowout port when there is a notch.
FIG. 7 is a perspective view of a portion of a cooling duct, a nozzle, and an outlet in a case where there is a notch;
FIG. 8 is a longitudinal sectional view of a portion where cooling air is blown from a nozzle without a notch to a window foil provided in an irradiation window. Wind speed measurement points a to i are indicated by black circles.
FIG. 9 is a vertical cross-sectional view of a portion where cooling air is blown from a notched nozzle to a window foil provided in an irradiation window. Wind speed measurement points a to i are indicated by black circles.
FIG. 10 shows nine measurements taken near the window foil when changing the inverter frequency of the motor of the cooling mechanism to 10 Hz, 20 Hz, 30 Hz, and 40 Hz and blowing the cooling air from the nozzle (A) having no notch onto the window foil. 9 is a graph showing measurement results of wind speeds at points a to i.
FIG. 11 shows nine measurements taken near the window foil when changing the inverter frequency of the motor of the cooling mechanism to 10 Hz, 20 Hz, 30 Hz, and 40 Hz and blowing the cooling air from the notched nozzle (B) onto the window foil. 9 is a graph showing measurement results of wind speeds at points a to i.
[Explanation of symbols]
2 Acceleration tube 3 Scanning mechanism 4 Scanning tube 5 Cooling duct 6 Scanning tube flange 7 Flange 8 Nozzle 9 Window foil 10 Irradiation window 20 Bellows 22 Flange 24 Window foil holding frame 25 Outlet 26 Cooling air 30 Notch

Claims (1)

An electron beam that generates thermoelectrons in a vacuum, accelerates with an accelerating tube, scans left and right with a scanning tube, passes through the window foil of the irradiation window, exits into the atmosphere, and hits the object to be processed with an electron beam. In the irradiation device, a notch is provided on both sides of a nozzle of a cooling duct that cools an irradiation window window foil, and a cooling wind is blown to the side from the notch. Cooling structure.

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