JP5363721B2 - Cooling device for charged particle beam equipment - Google Patents

Description

  The present invention relates to a cooling device for a charged particle beam device.

  In the charged particle beam apparatus, for example, an electromagnetic lens for converging or imaging charged particle beams such as electrons and ions is used. Such an electromagnetic lens includes an electromagnetic coil for generating a magnetic field and a magnetic path for concentrating the magnetic field.

  Of these coils, a current close to 20 A may be constantly applied, and heat generation due to Joule heat is accompanied. In order to cool this heat generation, a cooling device is provided in the vicinity of each electromagnetic coil, and the coil wire itself disclosed in Patent Document 1 is devised for cooling.

  In addition, an oil diffusion pump that is generally used to obtain a high vacuum in a charged particle beam apparatus heats and evaporates vacuum oil and evacuates it by the movement of the oil vapor. Therefore, a heater that heats the vacuum oil to a high temperature is provided. I have.

Thus, the charged particle beam device has a plurality of heat sources, and a plurality of cooling devices are installed for them. The most common of these cooling devices is a water-cooled cooling plate type in which a cooling plate for flowing 1 to 2 liters of cooling water per minute is brought into close contact with the heat source and heat exchange is performed between the cooling water and the heat source. Of the mechanism.
Japanese Patent No. 2967966 Japanese Patent No. 3231342

  When cooling the heat source by flowing the cooling medium as described above, the turbulent flow (turbulent flow) occurs when the cooling medium flows in the cooling device, or when the cooling medium flows into or out of the cooling device, causing a stirring action inside the flow path. ) To give vibration to the entire charged particle beam device.

  Charged particle beam devices, which are considered to play a leading role in nanotechnology processing and measurement devices, are devices that are extremely hated from vibration, as represented by electron microscopes. However, since the cooling medium is indispensable for the apparatus as described above, there is an increasing demand for countermeasures.

  In particular, in a transmission electron microscope, at the time of observing an atomic level crystal lattice image (high resolution image), the vibration caused by the flow of the cooling medium has reached a level that is recognized as a hindrance to the observation.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a charged particle beam that can efficiently perform cooling while suppressing generation of vibration due to turbulent flow of a cooling medium or reducing generated vibration. It is to provide a cooling device for the device.

In order to achieve the above object, a cooling device for a charged particle beam device according to an aspect of the present invention has a circumferential coolant flow path, is perpendicular to a circumferential surface, and is a radial direction of the circumference. The size of the channel in the direction perpendicular to the center (hereinafter referred to as the “depth” of the channel) is continuously and uniformly large (deeply) according to the radial distance from the center of the circumference. ). In this structure, when the pressure (water pressure) applied to the cooling medium (running water) is constant, the cross-sectional area of the flow path is such that a constant amount of water flows in any part regardless of the position in the radial direction in the flow path. It is the result of examining the flow path length (that is, flowing water resistance). In addition, although fluids other than water can be used as a cooling medium, below, water is demonstrated to an example.

  Furthermore, when forming a plurality of circumferential coolant flow paths with the same center and different radii, the depth of all the flow paths depends on the radial distance from the center of the circumference. It is characterized by a uniform deep structure. This also examined the cross-sectional area of the flow path and the flow path length (that is, the flow resistance) so that a constant flow rate could be obtained regardless of the position in the radial direction in the flow path and regardless of the flow path. It is a result.

  Cooling water is flowed at such a constant water pressure, and a constant amount of water flow according to the water pressure is obtained, so that the water flow conditions (flow rate, flow rate, etc.) for suppressing vibration are satisfied and sufficient cooling is performed. An effect can be secured.

  Also, in the case of a configuration having a plurality of flow paths as described above, the direction of the cooling medium flows in a circumferential flow path with a larger radius with a longer flow path on the assumption that the amount of flowing water per unit time is constant. By increasing the cross-sectional area of the vertical flow path (hereinafter simply referred to as “the cross-sectional area of the flow path”), a flow path configuration that takes into account the suppression of vibration associated with the occurrence of turbulent flow from a hydrodynamic point of view is realized. be able to. This condition that the amount of flowing water per unit time is constant does not conflict with the cooling effect, and vibration suppression and securing of the cooling effect are compatible.

  In cooling by flowing water, the temperature of the cooling water increases as it flows through the cooling plate for a long time. That is, a temperature difference occurs between the incoming water temperature and the outgoing water temperature. Generally, this temperature difference is about 20 ° C., although it depends on the amount of heat generated by the heating element and the amount of flowing water. Therefore, a temperature gradient is generated in the cooling plate. This temperature gradient can cause distortion in the charged particle beam device itself, and it can be observed through changes in the cooling water temperature and the ambient temperature of the device itself or the surrounding environment. It has an adverse effect as image drift.

  Therefore, providing a plurality of flow paths as described above and reversing the flow direction of the cooling medium flowing through each flow path for each flow path eliminates the temperature gradient of the cooling plate, thereby eliminating the beam or image drift. Expected to be effective. Furthermore, since the temperature distribution is uniform even if the temperature of the cooling water changes, it is expected that the influence of the device distortion will hardly appear.

  In the case of a cooling plate configuration having a plurality of flow paths, if a sufficient cross-sectional area is secured in each flow path, the cross-sectional shape of each flow path is a vertically flat shape (short in the radial direction of the circumference, Long in the vertical direction of the cooling plate) is desirable. This reduces the difference in flow path length due to the difference in radial position in the flow path, suppresses the generation of turbulent flow that causes vibration, and increases the surface area of the flow path compared to a circular pipe. This is because heat exchange between the cooling plate and the cooling medium is facilitated and good cooling efficiency is expected.

  The cooling plate having such a cooling medium flow path is constituted by a main body having a groove part and a cover part covering the groove part, and the above-mentioned flow path can be defined by the groove part and the cover part. At this time, the depth of each channel is made constant by changing the depth of the groove part uniformly and changing the thickness of the lid part according to the radial distance from the center of the circumference of the circumferential channel. It can be set as the structure which adjusts thickness.

Thus, it is effective to adjust the depth of the flow path according to the thickness of the lid when the heating element is located on the main body side. In the case of this configuration, the thickness of the cooling plate main body between the cooling medium and the heating element can be made constant regardless of the position, and the cooling efficiency can be made constant regardless of the position. Further, when the lid portion is easier to process than the cooling plate main body, the manufacturing process is facilitated.

  Conversely, the thickness of the lid is made constant, and the depth of the groove of the cooling plate body is changed uniformly according to the radial distance from the center of the circumference of the circumferential channel. Thus, the depth of each flow path can be adjusted.

  The configuration in which the thickness of the lid is constant and the groove depth of the main body side channel is adjusted in this way is effective when the heating element is located on the lid side. With this configuration, the thickness of the cooling plate lid between the cooling medium and the heating element can be made constant regardless of the position, and as a result, the cooling efficiency can be made constant regardless of the position. Further, when the processing of the cooling plate main body is easier than the lid portion, the manufacturing process is facilitated.

  Thus, if the lid part and the main body part can be processed separately, not only the distance to the heating element but also the thickness of each part can be adjusted, which is necessary for each part. Only a sufficient thickness can be ensured and a sufficient mechanical strength can be obtained.

  In the above description, “the size of the flow path in the direction perpendicular to the circumferential surface and perpendicular to the radial direction of the circumference” is called the “depth” of the flow path. This is for convenience of explanation, and this expression does not limit the method of arranging the cooling device according to the present invention. That is, in addition to the configuration in which the circumferential surface of the flow path is equal to the horizontal plane, a configuration in which the circumferential surface is a vertical surface or other configurations may be employed.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the cooling device for charged particle beam apparatuses which can cool efficiently, reducing the vibration by a turbulent flow.

  Exemplary embodiments of the present invention will be described in detail below with reference to the drawings.

  In the present embodiment, the transmission electron microscope that is most sensitive to vibration is taken into consideration, and the cooling device will be described focusing on the electromagnetic coil of the mirror body. Therefore, it is assumed that the electromagnetic coil has a shape in which the winding axis of the conductive wire is in the vertical direction and the cooling plate is in close contact with the winding surface and is disposed horizontally. Therefore, in the following description, terms based on the vertical direction such as vertical, horizontal, and depth will be used for convenience, but the orientation and direction are based on the above arrangement. However, this terminology and usage are for convenience only, and the essence of the present invention does not involve any spatial orientation such as up and down, left and right.

(First embodiment)
FIG. 1 shows a configuration of an electromagnetic coil according to this embodiment.

[Overall configuration]
An electromagnetic coil is obtained by wrapping a conductive wire material with a wire material that is electrically coated and insulated. Usually, copper, which is an electrically good conductor, is used. As described above, in the case of an electron microscope, a current of 20 A may flow through an electromagnetic coil. Heat generation due to Joule heat is inevitable, and cooling of the coil is an indispensable technical item.

In FIG. 1, a part of an electronic lens composed of an electromagnetic coil 2 and a cooling device (cooling plate) 11 above and below the coil is shown. In order to function as an electron lens, a magnetic circuit is required in addition to the portion shown in the figure, but since it is not related to the present invention, it is not drawn in FIG. As described above, the electromagnetic coil 2 generates heat due to Joule heat, and corresponds to a heat generating portion of the charged particle beam apparatus according to the present invention. Then, two cooling plates 11 are arranged in contact with the upper and lower surfaces of the electromagnetic coil 2. The electromagnetic coil 2 is cooled by exchanging heat between the cooling plate 11 and the electromagnetic coil 2.

  In the present invention, a single cooling plate is considered as a single cooling device, and if the electromagnetic coil is replaced with a heater, the above-described oil diffusion pump is immediately illustrated. Further, FIG. 1 shows an example in which the cooling plate is installed horizontally, but this is an example, and the spatial direction is arbitrary depending on the generation direction of the magnetic field of the electromagnetic coil.

  Further, FIG. 1 shows a state in which the cooling plate 11 includes a cooling plate main body portion 11 a including the cooling medium flow path 15 and a lid portion 12 that defines a cross-sectional shape of the cooling medium flow path. The cooling plate body 11 a and the lid 12 are fixed by an O-ring 13 and a bolt 14. Moreover, although the epoxy resin molding material 9 for fixing the coil 2 wound by the conductive wire material is drawn, the molding material 9 is not an essential component for the electromagnetic coil.

  The groove portion serving as the cooling medium flow path 15 communicates with the cooling medium inlet port 16 into which the cooling medium flows and the outlet port 17 through which the cooling medium flows out, which are provided on the outer peripheral surface of the cooling plate body 11a. In FIG. 1, it is made of an electromagnetic lens or an electrically insulative material that does not need to consider the circulating current in the cooling plate body due to the induced electromotive force or the lid portion generated when the magnetic field generated by the electromagnetic coil is changed. Since the cooling plate body 11a and the lid 12 are assumed, the insulating slit for suppressing the circulating current due to the induced electromotive force disclosed in Patent Document 2 is not necessary, and the cooling medium flow path is the cooling plate. It can be arbitrarily configured in a circular shape that circulates. If an insulating slit for suppressing the circulating current due to the induced electromotive force is required, the insulating slit is provided between the cooling water inlet 16 and the cooling medium outlet 17 to thereby provide a cooling medium flow path. Can be circumferential.

  In this embodiment, the cooling plate main body 11a is provided with a groove portion to form a cooling medium flow path, but other configurations may be adopted. For example, a cooling plate may be created from a cooling plate body and a flow path plate that is thermally connected to the cooling plate body, and a cooling medium flow path may be provided on the flow path plate.

  Next, the cooling water flow path system in the cooling device according to the present embodiment will be described. FIG. 11 shows a cooling water flow path system diagram. The cooling water flowing from the cooling water circulation device 26 flows into the cooling plate 11 from the cooling water inlet 16 through the pipe 25. A flow rate adjusting valve 23 and a flow meter 24 are provided on the downstream side of the cooling plate 11. By adjusting the flow rate adjusting valve 23, the flow rate of the circulating water can be adjusted. The valve 22 is a valve for turning on / off circulation of running water.

  In the flow rate adjusting valve 23, the flow rate is adjusted by adjusting the opening of the valve. However, since the cross section of the flow path in the flow rate adjusting valve 23 changes, turbulent flow is likely to occur here. By positioning the flow rate adjusting valve 23 on the downstream side of the cooling plate 11, even when turbulent flow is generated in the flow rate adjusting valve 23, the turbulent flow can be prevented from flowing into the cooling plate 11. . Therefore, it is possible to prevent the cooling plate 11 from vibrating.

[Flow channel shape]
FIG. 2 shows only the cooling device alone (one cooling plate) 11 so that the shape of the flow path through which the cooling medium flows can be easily seen. As shown in FIG. 2, the groove 15 serving as a flow path is a circumferential flow path, and the depth thereof is configured to increase as the radial distance from the center of the circumference increases. ing. By adopting such a configuration, it becomes possible to make the flow rate of the cooling medium substantially uniform at any position in the cooling flow path that forms a circumferential shape in the cooling plate 11 under a constant pressure,
Uniform cooling efficiency can be achieved. Further, as will be described later, it is possible to adopt a flow path configuration that can suppress the occurrence of turbulence (turbulent flow) in the flow of the cooling medium serving as the vibration source. In addition, in the figure explaining the shape of the cooling medium flow path including FIGS. 1 and 2, the center of the circumference formed by the flow path is drawn so that the center of the cooling plate where the flow path exists coincides. This is for the convenience of drawing, and the configuration in the implementation of the present invention is not limited to this.

  In the following, the relationship between the flow rate of water flowing through the flow path, the water pressure, the cross-sectional shape of the flow path, etc. will be examined using current, voltage, and electrical resistance as models.

  First, it is assumed that the water flow resistance R (r) is expressed as shown in Expression (1) in the same manner as the electric resistance. Here, S is the inner cross-sectional area of the pipe, l (r) is the flow path length, ρ is a coefficient that should also be called water flow resistivity, the viscosity of the cooling medium, the surface condition of the inner wall of the pipe (water repellency, etc.), It is a constant related to shape and structure.

  When the water pressure P is applied to this flow path, a relationship similar to Ohm's law of the electric system (formula (2)) is established between the flow rate I per unit time and the flow resistance R. I can assume.

  In general, cooling water is taken from one or several main pipes from a water source such as a cooling water tank, branched, and then sent to each cooling plate of the apparatus. After performing heat exchange (cooling of the apparatus) on the cooling plate, it is collected again into one or several pipes and returned to a cooling water tank or the like for drainage or circulation. Therefore, the water pressure applied to the piping of each cooling plate may be considered constant. Rather, a separate device is required to control the water pressure of each cooling pipe individually. Therefore, in the present embodiment, the description will be made on the assumption that the water pressure P applied to the flow path is constant at each position of the flow path, or in the case of a plurality of flow paths.

As shown in FIG. 3, the flow path length l (r) when the cooling flow path is configured to circulate along a circumference having a radius r around a certain point in the cooling plate is expressed by the equation It is represented by (3). Here, the circumference circuit is insufficient in the circumference by an angle θ due to the arrangement of the water inlet / outlet water channel. Note that r _ex is a radius outside the cooling plate.

In order to prevent vibration due to the cooling water flow, stirring (turbulent flow) should not occur in the cooling water flowing in the flow path. Under this condition, equivalent cooling efficiency is required in each part of the flow path. As shown in FIGS. 1 and 2, the flow path of the cooling plate according to the present embodiment is a single wide flow path. However, when this is divided into virtual narrow tubes, the above requirement is satisfied. Therefore, it is desirable that the water flow rate per unit time in each virtual capillary is equal.

  Here, assuming that the virtual thin tube is a rectangle having a depth h (r), the water flow resistance R per unit distance in the radial direction is represented by the following equation (4) as in the equation (1).

Then, in order to make the water flow rate per unit time equal in each virtual capillary as described above, the flow path depth h (r)) is set so that the water flow resistance R in each virtual capillary is constant. The shape may be changed. That is, the water flow resistance is a constant (R ₀ = const) that does not depend on the radius r in the radial direction, and the relational expression about the flow path depth h (r) is obtained from Expression (3) and Expression (4), Expression (5) Get.

  That is, it can be seen that the depth of the flow path only needs to be monotonously increased in accordance with the radial distance. FIG. 4 illustrates the relationship between the cross section of the flow path and the equation (5).

It should be noted that the specific flow path shape cannot be designed unless the constants A and B in Equation (5) are determined, but this is determined to match the water flow resistance of the pipe connecting the cooling plate and the cooling water circulation device, for example. Just do it. For example, assuming that the radius of the joint pipe is r _p and the flow path length is l _p , the water flow resistance is expressed by equation (6) as in equation (1). What should be determined.

  In any case, in the cooling device having one flow path as shown in FIGS. 1 and 2, monotonous with respect to the radial radius r from the center of the circumference forming the flow path under a constant pressure. If the flow path depth h (r) is determined to increase, the water flow rate can be made constant at any position in the flow path, and the cooling efficiency can be made uniform. As will be described later, this makes it possible to further adopt a flow path configuration capable of suppressing the generation of turbulent flow that becomes a vibration source due to water flow.

(Second Embodiment)
FIG. 5 shows the configuration of the cooling device according to the second embodiment. In the present embodiment, a plurality of short flow paths 18 to 21 are provided. Each of the plurality of flow paths 18 to 21 has a structure that circulates along the circumference of a circle having the same center and different radii.

  In FIG. 5, unlike the first embodiment, the thickness of the cover 12 is constant, and the depth of the channel is changed by changing the depth of the groove of the cooling plate body 11a. However, also in the present embodiment including a plurality of flow paths, the depth of the flow path may be adjusted by changing the thickness of the lid part while keeping the depth of the groove part constant as in the first embodiment. .

  Also in the present embodiment, as in the first embodiment, the flow rate of water at each position of each flow path is made constant so that flow turbulence such as vortices at the branching / merging points of the water distribution pipes and flow The occurrence of stagnation can be suppressed and the occurrence of vibration due to turbulent flow can be prevented. Therefore, in this embodiment as well, as described above, the depth of the flow path is configured to be continuously and uniformly deep for all the flow paths according to the radial distance from the center of the circumference formed by the flow paths. Yes. In FIG. 6, the cross-sectional shape of the flow path in this embodiment is shown. Also with this configuration, the water flow rate at each position can be made equal for the same reason as described in the first embodiment.

  By using a plurality of cooling medium flow paths in this manner, the area where the cooling plate and the cooling medium are in contact with each other is increased, and thus the heat exchange efficiency can be promoted.

(Third embodiment)
The third embodiment also includes a plurality of channels as in the second embodiment. FIG. 7 shows a cross-sectional shape of each flow path in the present embodiment. As shown in FIG. 7, the cross-sectional shape of each flow path is a rectangle, the width in the radial direction is constant, the depth is also constant within one flow path, and each flow path is at a position in the radial direction. On the other hand, it is configured to increase monotonously. That is, the cross-sectional area of each flow path is formed so as to increase uniformly according to the radial distance from the center of the circumference formed by the flow path to the flow path. The distance between each channel and the center of the circumference formed by the channels may be defined as the center position in the radial direction of each channel from the center of the circumference formed by the channels.

The water flow resistance R in each channel can be expressed as shown in Equation (1). Here, on the assumption that the water pressure P is constant, the water flow resistance R is a constant value R ₀ regardless of the radial distance r from the center of the circumference formed by the flow path so that the water flow rate in each flow path is constant. Find the conditions for Equation (1) and Equation (3
Therefore, the condition for this can be expressed as follows with respect to the cross-sectional area S (r) perpendicular to the flow direction of the water flow in the channel.

  That is, the water flow rate in each flow path can be made constant by monotonically increasing the cross-sectional area S (r) of each flow path relative to the radial distance r from the center of the circumference formed by the flow paths. it can.

  In addition, although the cross-sectional shape of each flow path is made into the rectangle in FIG. 7, this is an example and it is a shape where the cross-sectional area increases monotonously with respect to the radial direction distance r from the center of the circumference formed by the flow path. If present, the cross-sectional shape may be a circle or other shapes. The channel shape (FIG. 6) in which the depth of the channel shown in the second embodiment is monotonously deeper with respect to the radial distance r from the center of the circumference formed by the channel is also expressed by the equation (8). ) Is an example of a shape in which the cross sectional area monotonously increases with respect to the radial distance r.

  Also in this embodiment, the same effect as the second embodiment can be obtained. However, unlike the second embodiment, the water flow rate in each flow path is equal, but the water flow rate in one flow path is out of consideration, so the water flow rate may vary depending on the cross-sectional shape. It may be different depending on the radial position.

  Therefore, as shown in FIG. 8, it is preferable to provide a plurality of channels whose cross-sectional shape is vertically flat. Here, “vertically flat” means that the depth h (r) of the flow path is larger than the radial width Δr of the cross-sectional shape.

  By reducing the radial width in this way, the influence of the change in the water flow rate due to the radial position is reduced. Therefore, it can suppress that a turbulent flow arises because a water flow rate differs in the position of a radial direction. Moreover, by setting it as a flat shape, the area where the cooling water with respect to a cross-sectional area contacts a cooling plate can be enlarged. Therefore, the cooling efficiency can be improved.

  As shown in FIG. 9, if the cross-sectional shape is vertically flattened while the depth of the flow path monotonously increases with respect to the radial distance r from the center of the circumference formed by the flow path, The difference in water flow rate depending on the position in one cooling channel can be reduced, and the efficiency of cooling is improved while eliminating the influence of turbulent flow caused by the difference in water flow rate depending on the position in one cooling channel. Can be achieved.

(Fourth embodiment)
In the second and third embodiments having a plurality of flow paths, the fourth embodiment is configured such that the direction in which the cooling water flows is different depending on the flow paths as shown in FIG. As the cooling water flows, the temperature of the cooling water rises due to heat exchange with the cooling plate. Therefore, the temperature of the cooling water is low in the upstream of the flow path, but the temperature rises as it goes downstream, and the cooling efficiency decreases. In addition, a temperature gradient is generated in the cooling plate due to the temperature difference between the upstream side and the downstream side of the cooling water flow. This temperature difference in the cooling plate becomes a partial temperature difference of the charged particle beam device itself, and the charged particles Causes beam drift of the wire.

Therefore, by changing the direction of the cooling water flowing through each flow path, the temperature of the cooling plate can be kept substantially uniform regardless of the position of the cooling plate. Therefore, the influence on the temperature drift of the charged particle beam due to the temperature difference can be reduced, and when this embodiment is used for the electron lens of an electron microscope, favorable conditions are ensured for higher resolution observation. be able to.

  In addition, although it is suitable to flow a cooling water in the opposite direction for every adjacent flow path, it is good also as a structure which changes the direction which flows a cooling water for every several flow paths.

(Examination of laminar flow conditions)
In the above description, the flow channel shape for keeping the water flow rate in each flow channel constant has been described. However, although the constant water flow rate is a preferable condition for preventing the occurrence of turbulent flow, it is not a necessary and sufficient condition for preventing turbulent flow. For example, if the water flow rate is excessively increased, turbulent flow will occur even if the flow path shape is as described above. Therefore, the conditions for a laminar flow without generating a turbulent flow in the cooling water will be considered.

One of the dimensionless indicators of the flow state is the Reynolds number. The definition of the Reynolds number is given by

  Here, U is the representative velocity of the fluid, L is the representative length in the flow, ν is the kinematic viscosity coefficient of the fluid, μ is the viscosity of the fluid, and η is the density of the fluid. There are various ways of determining what is the “representative” in the flow, but it is usually determined in relation to the phenomenon of interest. For example, in the Reynolds number of a circular pipe, U is the cross-sectional average flow velocity, and L is the pipe diameter (tube inner diameter).

  A Reynolds number of 0 to 2000 is generally regarded as laminar flow and 3000 or more is regarded as turbulent flow. In general, Re = 2300 is often used as a boundary value between laminar flow and turbulent flow, but there is actually no clear threshold value for separating laminar flow and turbulent flow. However, in any case, laminar flow can be realized by reducing the Reynolds number, so studies using the Reynolds number are performed.

  When the flow rate I is increased by increasing the pressure without changing the inner diameter of the pipe, the fluid flow rate U increases. In other words, L does not change and U increases, so the Reynolds number increases, generating turbulence and increasing the vibration of the cooling pipe. On the other hand, when the amount of flowing water is adjusted so that the inner diameter of the pipe is increased but the flow velocity is not reduced, the Reynolds number increases because U is constant and L increases. That is, when the flow velocity flowing through the pipe is large or when the inner diameter of the pipe is large, the Reynolds number increases, and it can be seen that turbulent flow is likely to occur. However, in the case of general water flow cooling, this model is not used, and even when the inner diameter of the pipe is increased, the flow rate does not increase so much and the flow velocity often decreases. Regarding the increase and decrease of the Reynolds number, it is necessary to consider including the water flow rate.

  Between the flow velocity U and the flowing water amount I per unit time, the following relationship is established using the cross-sectional area S of the pipe.

  In the case of a circular pipe, the following relationship is established between the pipe inner diameter L and the cross-sectional area S.

  The Reynolds number in the case of a circular pipe is expressed as follows using equations (10) and (11).

  That is, when the amount of flowing water I per unit time is constant, the Reynolds number decreases when the cross-sectional area S of the pipe is increased, and the vibration of the pipe is also suppressed. Further, the expression (12) means that reducing the amount of flowing water has a first-order effect in reducing the Reynolds number, and an increase in the cross-sectional area of the pipe has a half-order effect. In other words, reducing the amount of running water is more effective. Therefore, in order to suppress vibration, it is preferable to reduce the amount of flowing water within the range allowed by the heat resistance performance of the apparatus.

  Now, looking at equation (12), if the water flow rate I is constant and the cross-sectional area S of the pipe is also constant, the Reynolds number is constant. That is, if the predetermined water flow rate I and the cross-sectional area S are determined, the cross-sectional area of the flow path needs to be increased as the radius increases when a plurality of flow paths are provided as in the second and third embodiments. Looks like there is no.

  However, the Reynolds number is an index representing the nature of the fluid flowing through the cross section of the tube, as is clear from its definition, and does not indicate anything about the direction of fluid flow. When the flow path length increases with an increase in the radial distance from the center of the circumference of the flow path as in the present invention, the chance of generating turbulence increases. Therefore, it is reasonable to increase the cross-sectional area and decrease the Reynolds number in advance for a tube having a longer flow path. Also from this viewpoint, the configurations of the second and third embodiments (for example, FIGS. 6, 7, 8, and 9) are effective.

  When the cross-sectional shape of the tube is not circular, the effect of friction with the inner wall of the tube and friction between the fluids decreases the Reynolds number, depending on the shape. Considering this, in the case of a tube having the same cross-sectional area, the Reynolds number is smaller in the flat shape. At this time, the representative length L of the flow is the smaller tube width.

  As shown in FIGS. 8 and 9, the tube width Δr (constant) and the depth h (r), the depth h increases monotonically according to r, and is flattened vertically so as to satisfy h (r)> Δr. Consider the case of arranging multiple rectangular tubes. At this time, the representative length L of the tube cross section is the tube width Δr (L = Δr). Since the relational expression (11) between the flow velocity U and the flowing water amount I per unit time is established, the Reynolds number can be expressed as follows.

As already described, the cross-sectional shape of a vertically flat tube has a small difference in flow path length (ie, Δr) between the inner side r _in and the outer side r _{out in} the tube. Regardless of this, the structure easily satisfies the condition that the water flow resistance R is constant. Also, if enough compared to the tube width Δr depth h (r) smaller, the depth of each pipe is sufficient regarded as representative depth h _r of the tube.

  The flat cooling pipe has a large surface area relative to the volume per unit length of the pipe. That is, since the area where the fluid contacts the cooling plate is large, the heat exchange efficiency is good, and a sufficient function as a cooling pipe can be realized. However, if the effect of friction between the fluid and the inner wall of the pipe becomes significant over the entire pipe if the pipe width is made excessively small, the relationship of formula (3) does not hold. It is necessary to make it sufficiently larger than the distance affected by the friction.

  From the above results, it can be seen that the cross-sectional shape of the cooling pipe should satisfy the formula (8) and be a plurality of pipes having a small cross-sectional area. That is, it can be seen that the configuration shown in FIGS. 8 and 9 is preferable. The number of pipes is designed so that the capacity of the whole cooling water filled in the cooling plate is sufficiently large and the flow rate per unit time is large, but the cross-sectional flow rate is slow (slowly flows). It is desirable.

It is a figure which shows the structure of the electromagnetic coil and cooling device which concern on 1st Embodiment. It is a figure which shows the structure of the cooling plate in 1st Embodiment. It is a figure explaining the shape of a cooling channel. It is a figure which shows the cross-sectional shape of the cooling flow path in 1st Embodiment. It is a figure which shows the structure of the cooling device in 2nd Embodiment. It is a figure which shows the cross-sectional shape of the cooling flow path in 2nd Embodiment. It is a figure which shows the cross-sectional shape of the cooling flow path in 3rd Embodiment. It is a figure which shows another example of the cross-sectional shape of the cooling flow path in 3rd Embodiment. It is a figure which shows another example of the cross-sectional shape of the cooling flow path in 3rd Embodiment. It is a figure which shows the structure of the cooling device in 4th Embodiment. It is a figure which shows the cooling water flow path system of the cooling device in this embodiment.

Explanation of symbols

2 Electromagnetic coil 9 Epoxy resin molding material 11 Cooling plate 11a Cooling plate main body 12 Lid 13 O-ring 14 Bolt 15 Cooling medium flow path (groove)
DESCRIPTION OF SYMBOLS 16 Cooling medium inflow port 17 Cooling medium outflow port 18-21 Several cooling flow path 22 Valve for turning on / off circulation of flowing water 23 Flow control valve 24 Flowmeter 25 Piping 26 Cooling water circulation apparatus

Claims (14)

A cooling device in a charged particle beam device , comprising: a cooling plate disposed in contact with a heat generating portion of the charged particle beam device; and a cooling water circulation device for supplying and recovering cooling water to the cooling plate ,
The cooling plate is provided with a circumferential flow path for flowing a cooling medium, and the flow path of the flow path in a direction perpendicular to the circumferential surface and perpendicular to the radial direction of the circumference is provided. The size of the joint pipe that uniformly increases in accordance with the radial distance from the center of the circumference and that connects the water flow resistance of the flow path and the cooling water circulation device connected to the flow path. cooling device in the charged particle beam apparatus characterized by being constructed such that the water flow resistance match.   The flow path of the cooling medium provided in the cooling plate has a plurality of circumferential configurations with the same center and different radii, perpendicular to the circumferential surface and moving around the circumference. The size of each flow path in the direction perpendicular to the radial direction is configured to be continuously and uniformly increased according to the radial direction distance from the center for all flow paths. The cooling device in the charged particle beam apparatus according to claim 1.   The cooling device for a charged particle beam apparatus according to claim 2, wherein the flow direction of the cooling medium in the plurality of flow paths is different for each flow path. A cooling device in a charged particle beam device , comprising: a cooling plate disposed in contact with a heat generating portion of the charged particle beam device; and a cooling water circulation device for supplying and recovering cooling water to the cooling plate ,
The cooling plate is provided with a plurality of circumferential flow paths having a single center for flowing the cooling medium and different radii, and a cross-sectional area of the flow path perpendicular to the flow direction of the cooling medium is provided. Each joint that increases uniformly according to the radial distance from the center of the circumference and connects between the water flow resistance of each of the flow paths and the cooling water circulation device connected to each of the flow paths. cooling device in the charged particle beam apparatus characterized by the flow resistance of the pipe is constructed such that match.   The cross-sectional shape of each of the flow paths is a flat shape that is large in a direction perpendicular to the circumferential surface and perpendicular to the radial direction of the circumference and short in the radial direction of the circumference. The cooling device in the charged particle beam apparatus according to claim 4, wherein the cooling apparatus is a charged particle beam apparatus.   The cooling device in the charged particle beam apparatus according to claim 4 or 5, wherein a flow direction of the cooling medium in the plurality of flow paths is different for each flow path.   The cooling plate includes a main body having a groove and a lid that covers the groove, and the circumferential channel is defined by the groove and the lid, and is perpendicular to the circumferential surface of the groove. And the thickness in the direction perpendicular to the radial direction of the circumference is constant, and the thickness of the lid portion in the circumferential surface depends on the radial direction distance from the center of the circumference. It changes, The cooling device in the charged particle beam apparatus in any one of Claims 1-6 characterized by the above-mentioned.   The cooling plate is composed of a main body having a groove portion and a lid portion covering the groove portion, and the circumferential flow path is defined by the groove portion and the lid portion, and within the circumferential surface of the lid portion. The thickness of the groove portion is perpendicular to the circumferential surface of the groove and the size in the direction perpendicular to the radial direction of the circumference depends on the radial distance from the center of the circumference. It changes, The cooling device in the charged particle beam apparatus in any one of Claims 1-6 characterized by the above-mentioned. A cooling device in a charged particle beam device , comprising: a cooling plate disposed in contact with a heat generating portion of the charged particle beam device; and a cooling water circulation device for supplying and recovering cooling water to the cooling plate ,
The cooling plate is provided with a circumferential flow path for flowing a cooling medium, and the flow path of the flow path in a direction perpendicular to the circumferential surface and perpendicular to the radial direction of the circumference is provided. The size increases uniformly according to the radial direction distance from the center of the circumference,
The radial radius from the center of the circumference is r,
The depth of the flow path of the position of the radius r with a h (r),
Pi is π,
The angle at which the flow path is insufficient to orbiting theta,
The radius of the outside of the cooling plate r _ex,
The radius of the joint pipe connecting the cooling water circulation device is r _p ,
When the flow path length between the cooling water circulation device is l _p ,
Cooling device in the charged particle beam apparatus characterized by the flow channel depth h (r) is configured so as to satisfy the following equation (14).

  The flow path of the cooling medium provided in the cooling plate has a plurality of circumferential configurations with the same center and different radii, perpendicular to the circumferential surface and moving around the circumference. The size of each flow path in the direction perpendicular to the radial direction is configured to be continuously and uniformly increased according to the radial direction distance from the center for all flow paths. The cooling device in the charged particle beam device according to claim 9. The cooling device in the charged particle beam device according to claim 10, wherein the flow direction of the cooling medium in the plurality of flow paths is different for each of the flow paths. A cooling device in a charged particle beam device , comprising: a cooling plate disposed in contact with a heat generating portion of the charged particle beam device; and a cooling water circulation device for supplying and recovering cooling water to the cooling plate ,
The cooling plate is provided with a plurality of circumferential flow paths having a single center for flowing the cooling medium and different radii, and a cross-sectional area of the flow path perpendicular to the flow direction of the cooling medium is provided. While uniformly increasing according to the radial distance from the center of the circumference,
The radial radius from the center of the circumference is r,
The depth of the flow path of the position of the radius r with a h (r),
Pi is π,
The angle at which the flow path is insufficient to orbiting theta,
The radius of the outside of the cooling plate r _ex,
The radius of the joint pipe connecting the cooling water circulation device is r _p ,
When the flow path length between the cooling water circulation device is l _p ,
A cooling device in a charged particle beam device, wherein the flow path depth h (r) satisfies the following mathematical formula (14).

  The cross-sectional shape of each of the flow paths is a flat shape that is large in a direction perpendicular to the circumferential surface and perpendicular to the radial direction of the circumference and short in the radial direction of the circumference. The cooling device in the charged particle beam apparatus according to claim 12, wherein the cooling apparatus is a charged particle beam apparatus. The cooling device in the charged particle beam apparatus according to claim 12 or 13, wherein a flow direction of the cooling medium in the plurality of flow paths is different for each of the flow paths.

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