JPH09245999A - Heat receiving apparatus with high thermal load - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the cooling performance and improve the economy by introducing a cooling method such that the beam transmissive, diffusive and absorptive phenomena in a substance are converted into an undulation phenomenon, in addition to a conventional heat removing method for a high thermal load heat-receiving apparatus. SOLUTION: The heat absorbed by a target material layer 2 is carried through thermal conduction to a heat-removing cooling layer 5 as the outermost layer in tight attachment with the side face, moved to a cooling water 6 through heat transfer, and carried to the outside. Thus heat removal is made. The energy of the diffused X-rays emitted into the inter-layer gap 3 reduces with collision made thereafter, and the rays are captured and absorbed by/in an absorptive material layer 4 having a good thermal conductivity, and conversion into heat is achieved. The absorbed heat is carried by thermal conduction to the cooling layer 5 in tight attachment to the periphery of the absorptive material layer 4, and heat removal is made by the cooling water 6. In case a large quantity of diffused X-rays intrudes into the layer 4, a porous heat-resistant substance is selected so as to promote the volume heat emission within the target material layer 2, and the cooling effect of this region is heightened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high heat load heat-receiving device, and more particularly, to generate and utilize high-energy photons and particle beams, for example, accelerator, nuclear fusion, nuclear power, medical equipment, industrial application, basic research fields. The present invention relates to a high heat load heat receiving device suitable for.

[0002]

2. Description of the Related Art The conventional heat removal technology for a high heat load heat-receiving device is to irradiate a target substance attached to the tip of the heat-receiving device with a high-energy photon / particle beam, etc. It is configured so that it is absorbed / heated and transferred to the cooling flow path by heat conduction, and its energy is carried to the outside by a cooling medium such as water, gas, liquid metal, liquid nitrogen.

Further, in order to improve the heat removal technique for high heat load, improved techniques such as expansion of the irradiation area of the target substance (oblique incidence of the beam), movement / rotation of the target substance, and vibration of the beam have been added. The basics of the heat removal method are the same as the above-mentioned configuration.

[0004]

In recent years, with the increase in size of accelerators, synchrotron radiation generators, etc., the equipment to be irradiated with the high-energy, high-intensity photons / particle beams generated has a heat removal limit by the conventional method. More often than not, it is exposed to high-intensity beams that exceed the range. Therefore, development of heat resistant materials and development of heat removal technology are energetically carried out in many research institutions.

However, the development of heat removal technology by the conventional method has already reached a sophisticated area, and an approach to greatly improve the heat removal performance as an extension of the conventional method involves considerable difficulty.

The present invention has been made in view of the above points,
The purpose is to use an optical method that considers the heat removal cooling of the target substance under irradiation of high-intensity photon / particle beam by replacing the transmission, scattering, and absorption phenomena of the beam with the wave phenomenon (hereinafter, The introduction of the optical cooling method) provides a high-heat-load heat-receiving device that can significantly improve heat removal performance.

[0007]

In the present invention, in order to make the heat-receiving structure under the irradiation of high-intensity photon / particle beam optically function, the target substance layer has a multi-layer structure and the following three kinds of solving means are adopted. did. (1) Each target substance layer is composed of a thin transmissive / scattering substance having a thickness of 1 mfp (mean free path) or less.

(2) A vacuum layer or a void layer of a dilute gas is provided between the target substance layers.

(3) The final target substance layer and the outer peripheral layer attached outside the photon / particle beam irradiation region are made of an absorptive substance and a heat removal cooling substance having good thermal conductivity.

First, the basic idea of the optical cooling method for the heat-receiving device under irradiation of the photon / particle beam, which is the origin of the present invention, will be described below by taking X-rays as a typical example of the photon / particle beam.

When the X-ray beam passes through the target material layer,
It is well known that X-ray absorption, scattering and transmission phenomena are caused by collision with a target substance. The phenomena associated with the passage of these substances can be considered by replacing the particle image on the left side with the optical image on the right side, as shown below.

Collisionless transmitted X-ray energy flux ⇔ Straight transmitted light Forward scattered X-ray energy flux ⇔ Refractive transmitted light Backscattered X-ray energy flux ⇔ Reflected light True absorbed X-ray energy flux ⇔ Absorbed light On the basis of this optical analogy It was the origin of the present invention that we first noticed that heat removal cooling design of high heat load heat receiving equipment was possible.

Prior to the explanation of the optical cooling method, the target substances are classified into the following three types according to their properties.

Permeable substance: ・ X-ray absorption and scattering are small, Scattering substance: ・ X-ray forward and backward scattering is large, Absorbing substance: True X-ray Those that absorb a lot.

Here, in order to effectively function the optical cooling method, it is important to select the target substance having the above-mentioned three kinds of properties. First, the transmissive substance is selected from the target substances suitable for the purpose of use, and the thickness of the substance layer is thinned to 1 mfp or less of the typical design X-ray energy (eg incident X-ray energy). To adopt.

It is one of the main points of the present invention to control the amount of X-ray absorption in the material layer by changing the thickness of the permeable material layer. Therefore, depending on the progress of material technology development in the future, It is expected that the upper limit of the layer thickness may exceed 1 mfp.

Next, regarding the selection of the scattering and absorbing substances, the selection can be made according to the basic principle of the scattering / absorption phenomenon accompanying the passage of the X-ray beam through the substance. For example,
X used in a synchrotron radiation device to which the present invention is applied
The line energy is several keV to several hundred keV, and the main cause of the scattering / absorption phenomenon in this region is the Compton effect. Therefore, the relation between the true scattering and absorption ratio of the target substance and the X-ray energy is calculated. be able to.

As a specific example, carbon (C) exhibits a property as a scattering substance when the X-ray energy is at least 10 and several keV, and exhibits a property as an absorptive substance when the energy is less than that. Further, it is understood that iron (Fe) behaves as a scattering substance in the energy region of about 100 keV or more, and acts as an absorbing substance in the energy region of less than that. By understanding these properties, it is possible to select a scattering material and an absorbing material that are suitable for the target device. It should be noted that the classification of the scattering substance and the absorbing substance is not a property peculiar to the element.

The optical cooling method is a basis of optical analogy in the heat removal cooling of the multilayer heat-receiving structure, in addition to the conventional heat removal method by thermalization / absorption, by newly utilizing the transmission / scattering phenomenon of X-rays. It is a method of improving the heat removal cooling performance of the heat receiving structure by adding a mechanism for carrying out heat transfer by using electromagnetic wave energy as a medium to remove heat, and the function of the means described in each claim will be described below. .

In the heat-receiving structure having a multi-layer structure of the target substance according to claim 1, each target substance layer under X-ray irradiation is a thin transmission / scattering substance having a thickness of 1 mfp or less, The absorbed energy per each material layer can be reduced to about several% of the incident amount or less, and furthermore, since the conversion into heat energy in the thin target material layer is volumetric heat generation, the heat generation distribution in the material layer can be reduced. It works to prevent localization. Moreover, since the transmission, scattering, and absorption of the X-ray beam can be controlled by selecting the type and layer structure of each target substance, the heat load absorbed by the target substance can be removed by the conventional method by heat conduction. The range of choices to reduce the area is expanded.

In the multilayer heat-receiving structure according to claim 2, by providing a vacuum layer or a void layer of a dilute gas between each target substance, each target substance layer is thermally insulated and the scattering X emitted to the outside of the substance layer. It serves to carry the linear beam energy out of the illuminated area at the speed of light (or particle velocity in the case of particle beams). Further, by using the scattering substance as the target substance layer material, the reflection characteristic of the X-ray beam can be improved.

With respect to the functions of the absorptive substance having good thermal conductivity and the heat removal cooling substance which form the outermost layer of the multilayer heat receiving structure according to claim 3, the X-ray beam is reduced in energy by multiple collisions with the target substance. Capture, absorb and heat,
It serves to receive the absorption heat generated in the target substance layer by heat conduction.

Further, the amount of heat received is carried to the outside of the heat receiving structure by a heat transfer phenomenon by a cooling medium such as water passing through a cooling flow path incorporated in the outermost layer constituent material, and the heat is removed. Since most of the outermost layer constituent material is attached to the outside of the X-ray beam irradiation region, the heat exchange cross-sectional area can be made sufficiently large, so that heat removal cooling by the conventional method becomes possible.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a basic working structure of an optical cooling method for a heat-receiving structure having a multi-layer structure under irradiation with high-intensity X-rays, and the function thereof will be described together.

First, the high-intensity X-ray beam 1 is incident on the target material layer 2 having a multi-layer structure, and when it collides with the target material, scattering, transmission, and absorption phenomena occur. Each target substance layer 2
Reduces the layer thickness to less than 1 mfp
The transparency of the line beam 1 is improved and the amount of absorbed heat is kept low. Further, a substance having a high X-ray scattering efficiency is selected as the type of the target substance to increase the X-ray dose emitted to the interlayer void 3. The amount of heat absorbed by each target substance layer 2 is transferred by heat conduction to the outermost heat removal cooling layer 5 (with a built-in cooling flow path) that is in close contact with the side surface, and the amount of heat is transferred to the cooling water 6 by heat transfer to the outside. It is carried and removed from heat. Since the amount of absorbed heat in the target substance layer 2 is small and is insulated by the interlayer gap 3,
It is possible to remove heat by the conventional method.

Next, the scattered X-rays emitted to the interlayer void 3 are trapped and absorbed in the absorptive material layer 4 of a good heat conductor while being reduced in energy by the subsequent collision, and then heat-treated. The absorbed heat amount is transferred by heat conduction to the heat removal cooling layer 5 that is in close contact with the periphery of the absorbent substance layer 4, and is removed by the cooling water 6. When the amount of scattered X-rays entering the absorptive material layer 4 is large,
By selecting a porous heat-resistant substance such as porous tungsten (W) as the material of the absorptive substance layer 4, the X-ray scattering effect of the interlayer void 3 is also used to promote volumetric heat generation in the target substance layer 2. A device that enhances the cooling effect in this region is also within the scope of the present invention.

FIG. 2 shows an example in which the optical cooling method of the present invention is applied to cooling an X-ray optical element used in a synchrotron radiation device that generates and utilizes X-rays of high energy and high intensity.

As shown in the figure, a high intensity X-ray beam 1
Is incident on the front side surface of the target substance layer 2 of the multilayer heat receiving structure. The functions of the target substance layer 2, the interlayer gap 3, the absorptive substance layer 4, the cooling water 6, and the heat removal cooling layer 5 arranged on both sides are the same as those described above with reference to FIG.

Here, in order to show the effectiveness of the optical cooling method,
The results of designing the multilayer heat receiving structure shown in the bird's-eye view of the X-ray optical element in FIG. 2 as a specific example will be described.

As the basic design conditions, the parameters of the region which is regarded as important in the advanced synchrotron radiation research and development field were taken up and the following conditions were set.

First, the design conditions for incident X-rays are:
(1) Incident X-ray energy: 50 keV, (2) Total inflow X
Linear energy amount: 20 kW, (3) Irradiated area: Vertical 2 cm x
Horizontal 1 cm = 2 cm ² , (4) Irradiated X-ray energy flux: 10 k
W / cm ² = 100 MW / m ² , (5) Direction of X-ray incidence on first layer of target substance: vertical incidence was assumed.

Next, as materials for the target substance layer 2 and the heat removal cooling layer 5, a carbon fiber reinforced carbon composite material (C / C material), which is a heat-resistant and scattering substance, and copper, which has good thermal conductivity, are used. (Cu) material was selected. The dimensions of each target substance layer 2 made of C / C material are 2 cm in length, 1 cm in width, and 0.5 cm in thickness (up to 0.2 cm).
mfp) was assumed.

The amount of X-ray energy absorbed in each C / C target substance layer 2 calculated under these conditions is 700 W at maximum.
Becomes Since the thickness of each target substance layer 2 is thinner than the mean free path, the X-ray energy absorbed in the target substance layer 2 is evenly distributed in the thickness direction, resulting in volumetric heat generation. The amount of heat absorbed / heated by each C / C target substance layer 2 is 350 W / cm ² of heat flux from both ends (cross sectional area 2 cm × 0.5 cm) in the lateral direction of the target substance layer 2 to the Cu heat removal cooling layer 5. Flows in. The heat flux of this degree can be removed by forced convection heat transfer of water flowing through the cooling flow path in the Cu heat removal cooling layer 5.

Here, the heat calculation of the multi-layer heat-receiving structure was performed assuming that the thickness of the Cu layer up to the cooling channel is 0.5 cm and heat is removed using a smooth tube with a cooling water flow rate of about 10 m / s. As a result, the temperature difference between the central portion of the target substance layer having the highest temperature and the cooling water temperature was slightly less than 200K. This result shows that the target substance layer 2 made of C / C material has a high strength X of 100 MW / m ^2.
It shows that it can withstand a certain amount of radiation even if it receives steady irradiation of a line.

As a result of the above design examination, the multilayer heat-receiving structure using the optical cooling method of the present invention has a high X-ray absorption energy of X-ray absorption energy against local steady irradiation of high intensity X-rays exceeding 100 MW / m ² . It can be concluded that heat removal cooling is possible.

In recent years, many research institutes in the fields of nuclear fusion and synchrotron radiation have developed high-heat-load heat removal technology by conventional methods. However, short-term rating is several tens of MW / m ² , long-term rating is few. Considering that it is pointed out that it is difficult to develop high heat load heat removal materials / equipment exceeding MW / m ² , adoption of the optical cooling method of the present invention significantly improves heat removal cooling performance of high heat load heat receiving equipment. Can be expected.

FIG. 3 shows an example in which an optical cooling method is applied to the cooling of a beam stopper of an apparatus for generating and utilizing high energy and high intensity X-rays and particle beams.

As shown in the figure, the high-intensity X-ray / particle beam 1 is incident on the umbrella-shaped target substance layer 2 having a multilayer structure. Each target material layer 2 is composed of an umbrella-shaped transparent / scattering material with good thermal conductivity, and by obliquely incident an incident X-ray beam or the like, the absorbed heat load per unit area can be reduced by expanding the irradiation area. , The dispersion efficiency of scattered X-rays to the periphery is improved. The outer periphery of the target substance layer 2 is cooled by the cooling water 6.

The target substance layer 2 is supported by a support rod 8 placed outside the irradiation area. The inter-layer voids 3 are present not only between the layers but also around the target substance layer 2 and have a function of reducing the absorbed heat load per unit area due to scattered X-rays flowing into the absorptive substance layer 4 in the outer peripheral portion. . This is effective when the amount of scattered X-ray energy is large.
The scattering material layer 7 near the entrance serves to reflect the primary scattered X-rays having a relatively high energy and lower the energy. It should be noted that an attempt to increase the scattering efficiency of X-rays by making the surface of the material layer uneven is also within the scope of the present invention.
The structure and function of the outermost heat removal cooling layer 5 are the same as those in the above-described example.

[0040]

According to the high heat load heat-receiving device of the present invention described above, in addition to the conventional heat removal method by thermalization / absorption, the transmission, scattering, and absorption phenomena of the beam in the substance are changed to the wave phenomenon. Since the cooling method based on the optical method that was considered as a replacement was introduced, it is expected that the adoption of this optical cooling method will improve the heat removal cooling performance over the conventional method, and the type and arrangement of the heat receiving equipment materials As the range of choices is expanded, it is possible to expect improved economic efficiency.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a basic configuration of a multilayer heat receiving structure in a high heat load heat receiving device of the present invention.

FIG. 2 is a partial perspective view showing an X-ray optical element adopting the optical cooling multilayer heat receiving structure of the present invention.

FIG. 3 is a cross-sectional view showing an X-ray / particle beam stopper that employs the optically cooled multilayer heat receiving structure of the present invention.

[Explanation of symbols]

1 ... X-ray beam, 2 ... Target substance layer, 3 ... Interlayer void, 4 ...
Absorbent substance layer, 5 ... Heat removal cooling layer, 6 ... Cooling water, 7 ... Scattering substance layer, 8 ... Support rod.

Claims (3)

[Claims] 1. A high-intensity photon / particle beam is applied to a target substance attached to the tip of a heat-receiving device, and the beam energy at that time is absorbed / heated inside the target substance, and heat conduction leads to a cooling channel. In a high heat load heat-receiving device configured to carry the beam energy to the outside by a carrying cooling medium, the target substance is a multi-layer heat-receiving structure, and each target substance layer has a thickness of 1 mfp (mean free path) or less A high heat load heat-receiving device characterized by being composed of a scattering material. 2. The high heat load heat-receiving device according to claim 1, wherein a vacuum or gas void layer is provided between the target substance layers. 3. The final layer of the multi-layered target substance layer, and the outer peripheral layer attached outside the irradiation region of the photon / particle beam are composed of an absorptive substance having good thermal conductivity and a heat removal cooling substance. The high heat load heat-receiving device according to claim 1 or 2.