JPH11133199A - Solid target and solid target system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid target capable of lengthening a life, excellent in cost effectiveness, and capable of reducing capacity of a cooling installation. SOLUTION: In a solid target 20 generating neutron by being irradiated with high-energy proton ray 10, a plurality of flat plate-shaped targets 25 made of heavy metal are disposed leaving a fixed gap between them in the incoming direction of the proton ray 10, the fixed gap forms a coolant passage 14 permitting coolant to flow therein for cooling the flat plate-shaped targets 25, and center temperature of each of the flat plate-shaped targets 25 is caused to fall within a fixed temperature range by making the thickness of the flat plate- shaped targets 25 greater as the distance from an incoming position of the proton ray 10 gets larger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid target for generating high-density neutrons by blasting a heavy metal by irradiating a heavy metal with a high energy proton beam or the like, and a solid target system provided with a cooling system for the solid target.

[0002]

2. Description of the Related Art A target system that irradiates a heavy metal with a high-energy proton beam to generate high-density neutrons by spallation can generate the largest amount of neutrons with respect to incident energy. And the facilities are simple. Therefore, for the purpose of various uses such as life science using neutrons, material / materials research, nuclear physics, medical treatment, etc.
The construction of high-power target systems in Europe, the United States, and Japan is planned. The target includes a solid target such as tantalum or tungsten, and a liquid metal target such as mercury. The solid target has been used conventionally. However, at present, the output of the target system which is planned is 10 times or more that of the conventional system, and the heat generation density of the target is 3 kW / cm ³ or more. Therefore, the cooling, reliability and life of the target are important issues. I have.

[0003] As a conventional technique of a solid target, for example, 13th Meeting of the International Collaboratio
n on Advanced Neutron Sources, October 11-14, pp.51
8-521 (1995). The target is 2.
It is composed of 55 flat tantalums of 6 to 30 mm arranged side by side, and has a structure in which cooling water is supplied to gaps between the respective targets to cool them. The heat density is high at the proton beam entrance,
Since the heat generation density decreases as the distance from the incident position increases, the target thickness decreases at the incident portion and increases as the distance from the incident position increases. The thickness distribution of such a flat target is determined so that the calorific value of each target and the heat flux on the surface are substantially constant.

[0004]

However, the above prior art has the following problems. Since the heat value Q of each target is proportional to the product qδ of the heat density q and the thickness δ, making the heat value Q substantially constant seems at first glance from the viewpoint of cooling. However, since the heat inside the target is transferred to the surface by heat conduction, the temperature difference ΔTcs between the center and the surface is proportional to qδ ^2.
Tcs is proportional to the thickness δ, and the center temperature of a thick target increases. This significantly reduces the life of the target, necessitates frequent replacement, and reduces economics.

As described above, in the prior art, from the viewpoint of cooling performance, emphasis is placed on making the amount of heat generated by each target substantially constant, and the center temperature that most affects the life is not considered. As a result, there is a problem that the center temperature of a thick target is increased and the life is shortened.

[0006] A first object of the present invention is to provide a solid target which can extend the life and is excellent in economy.

A second object of the present invention is to provide a solid target capable of reducing the capacity of a cooling facility.

[0008]

A first aspect of the present invention for achieving the first object is a solid target for generating neutrons by irradiating a high energy proton beam or the like with a plurality of flat plates made of heavy metal. The target is arranged with a predetermined gap in the incident direction of a proton beam or the like, and the predetermined gap forms a coolant flow path through which a coolant for cooling the flat target flows. The thickness of the flat target is increased as the distance from the position increases, so that the center temperature of each flat target is within a predetermined temperature range.

According to a second aspect of the present invention, in the first aspect, when the central temperature of the flat target is Tc and the maximum use temperature depending on the target material is Tmax, Center temperature Tc of flat target
Is distributed such that the following relationship is satisfied: 0.8 Tmax ≦ Tc ≦ Tmax.

According to a third aspect of the present invention, in the first or second aspect, the thermal conductivity of the flat target is λ, the heat capacity is ρCp, and the heat transfer coefficient on the surface is h. , The maximum operating temperature that depends on the target material is Tmax
When the temperature of the coolant is Tw, the interval of pulse irradiation of proton beams or the like is tp, and the heat generation density of each flat target is q, the thickness δ of the flat target is δ ≦ [{1.0+ ( 2h ² / λ) (a ₁ −b)} 0.5 ^{· 1.0} ] (2
λ / h) δ ≧ [{ 1.0+ (2h 2 / λ) (a 2 -b)} 0 · 5 -1.0] (2
_{λ / h) a 1 = (} Tmax-Tw) / q a 2 = (0.8Tmax-Tw) / q b = configured to meet 0.5Tp / a (ρCp).

According to a fourth aspect of the present invention for achieving the second object, in any one of the first to third aspects, the flow path area of the throttle provided at the outlet of each coolant flow path is distributed. Alternatively, by distributing the gap of each coolant flow path, coolant is supplied to each coolant flow path at a flow rate proportional to the heat generation amount Q proportional to the product qδ of the heat generation density q and the thickness δ of each flat target. It is constituted so that.

According to the first to third aspects of the present invention, the central temperature of each flat target is set to a predetermined temperature range irrespective of the calorific value of each flat target. Since the temperature can be lower than the dependent maximum use temperature, the life of the target can be extended and a solid target with excellent economy can be realized.

According to the fourth aspect of the present invention, the total flow rate of the coolant is reduced by supplying the coolant with a flow rate proportional to the calorific value of each flat target to each of the coolant flow paths. Since the capacity of the supply coolant circulation pump can be minimized, the capacity of the cooling equipment can be reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a solid target and a solid target system according to the present invention will be described below with reference to FIGS. FIG. 1 is a schematic configuration diagram of a first embodiment of a solid target, (a) is a longitudinal sectional view, and (b) is A in (a).
FIG. 3A is a cross-sectional view of FIG. FIG.
FIG. 2 is a schematic configuration diagram of a first embodiment of a solid target system including the solid target of FIG. 1 and its cooling equipment.

FIG. 1 shows a configuration including a target container 12, a window 11 attached to the tip of the target container 12, and a solid target 20 inserted into the target container 12. The solid target 20 includes a plurality of flat targets 25, a target support 21, and the like. The plurality of flat targets 25 are easily installed on the target support 21 by being inserted into the grooves of the target support 21 from above.

A coolant channel 14 is formed in a gap between adjacent flat targets 25. By inserting the solid target 20 configured by mounting the plurality of flat targets 25 on the target support 21 into the target container 12 in this manner, the space between the solid target 20 and the target container 12 is filled with cooling water. An inlet channel 13 and an outlet channel 15 are formed. For the target container 12, the window 11, and the target support 21, a material having good corrosion resistance such as stainless steel is used. Flat target 25
, Heavy metals such as tantalum, tungsten, and depleted uranium are used. The thickness δ of the flat target 25 increases as the distance from the incident position of the proton beam 10 increases. More specifically, since the heat generation density q in the flat target 25 decreases as the distance from the incident position of the proton beam 10 decreases, the center temperature Tc of each flat target 25 becomes 0.8 Tmax ≦ Tc ≦ Tmax.
The thickness δ of each plate-like target 25 is distributed so as to satisfy the following relationship. Tmax is the maximum service temperature depending on the target material.

A throttle portion 17 is provided at the outlet of each coolant flow path 14, and a heat generation amount Q of each flat target 25 is provided.
(Proportional to qδ), the coolant flow rate is proportional to each coolant flow path 1
4 so as to be supplied to each of the coolant passages 14.
Are distributed. Further, a curvature is provided at a lower end portion of the target support 21 located at the inflow portion 16 of the coolant flow passage 14 to reduce pressure loss of the cooling water.

The proton beam 10 accelerated to 1 GeV or more by the accelerator is irradiated on a plurality of flat targets 25 through the window 11, and a large amount of neutrons are generated by spallation of the flat targets 25. At this time, the flat target 25 generates heat with a high heat generation density of ³ kW / cm ³ or more. Since the heat of the flat target 25 becomes high due to this heat generation, it is cooled by cooling water. The cooling water flowing into the inlet channel 13 is
After cooling the flat target 25 through the coolant channel 14, it flows out of the outlet channel 15.

As shown in FIG. 2, the cooling facility 40 includes a coolant tank 41, a coolant circulation pump 42, a cooler 43, a coolant purification device 44, and the like. The cooling water is supplied from the coolant tank 41 to the solid target 20 by the coolant circulation pump 42. The cooling water whose temperature has been raised by cooling the flat target 25 in the solid target 20 is cooled by the cooler 43, the impurities are removed by the coolant purifier 44, and then returns to the coolant tank 41. Coolant tank 41
A pressurized gas 46 is sealed in the upper part of the pressurized gas 4.
By pressurizing the cooling system at 6, the cooling water is prevented from boiling in the coolant channel 14.

As the cooler 43, a small plate type heat exchanger, a shell and tube type heat exchanger, or the like can be used. The secondary cooling water supplied from the secondary cooling water inlet 51 to the cooler 43 and heated is discharged from the secondary cooling water outlet 52 and cooled by a cooling tower or the like, and heat is finally released to the atmosphere or the like. As the coolant purification device 44, a device in which a filtration device such as a filter and a desalination device for ion exchange are separately provided, a filtration desalination device having a filtration function and a desalination function, or the like can be used. The use of the filtration and desalination apparatus can reduce the size of the cooling facility 40. The reason why the coolant purifier 44 is provided downstream of the cooler 43 is that filters and ion exchange resins cannot be used at high temperatures in general.

In the embodiment shown in FIG. 1, an example is shown in which the projection 17 is provided at the upper end of the target support 21 to form the narrowed portion 17, and the flat target 25 is formed in a simple flat shape. As shown in FIG. 4 and FIG. 4, the projection 17 may be provided on the upper end of the target element 27 without forming the projection on the target support 21 of the solid target 20 to form the narrowed portion 17. FIG. 3 is a view showing a modification of the solid target shown in FIG. 1. FIG. 3 (a) is shown in FIG. 1 (b), and FIG.
(C) respectively. FIG. 4 is a detailed view of the target element 27 of FIG. 3, (a) showing a front view, and (b) showing a side view.

In this modification, the same effects as those of the embodiment shown in FIG. 1 can be obtained, but the processing of the target support 21 becomes easy, but the production of the target element 27 becomes complicated. In particular, since heavy metals such as tantalum and tungsten, which are target materials, are expensive and difficult to machine in many cases, the flat target 26 made of heavy metals such as tantalum and tungsten is provided only at the center (in FIG. ), And it is reasonable that the remaining portion of the target element 27 is made of stainless steel or the like.

Hereinafter, the principle and effects of the features applied to the above-described embodiment will be specifically described. ΔTp is the adiabatic temperature rise of the flat target 25 (or 26) due to one pulse irradiation of the proton beam 10, ΔTcs is the time average temperature difference between the center and the surface of the flat target 25 due to the irradiation of the proton beam 10, and the surface of the flat target Assuming that the time-average temperature difference between the coolant and the coolant is ΔTsw and the coolant temperature is Tw, the center temperature Tc of the flat target immediately after the irradiation of the proton beam 10 with a pulse can be expressed by the following equation.

[0024]

Tc = 0.5ΔTp + ΔTcs + ΔTsw + Tw ΔTp = (Tc−T ₀ ) = qtp / (ρCp) ΔTcs = (T ₀ −Ts) = qδ ² / (8λ) ΔTsw = (Ts−Tw) = qδ / (2h Where T ₀ and T s are the time average temperature at the center of the plate target and the time average temperature at the surface, δ is the thickness of the plate target, λ is the thermal conductivity, and ρCp is the heat capacity. , H is the heat transfer coefficient on the surface, tp is the interval between pulse irradiations of the proton beam 10, and q is the heat generation density. Rearranging Equation 1 results in the following equation.

[0025]

Tc = 0.5qtp / (ρCp) + qδ2 / (8λ) + qδ / (2h) + Tw (Equation 2) The sum of the second to fourth terms on the right side of Equation ² is the time average at the center of the flat target. At the temperature T ₀ , the center temperature Tc of the flat target immediately after the pulse irradiation of the proton beam 10 is the first temperature on the right side.
The temperature rises from the time average temperature T ₀ by the term. Center temperature Tc
Is too high, the target material is damaged and the life of the flat target is shortened.

In order to lower the center temperature Tc, the following equation 1 is used.
What is necessary is just to reduce the thickness δ of the flat target. But,
When the thickness δ is reduced, it is necessary to increase the number of flat targets, which not only deteriorates economical efficiency but also increases the number of coolant channels 14 and the amount of cooling water. Problem arises. Therefore, it is necessary to select the thickness δ so as to be under the optimum condition.

In this embodiment, as described above, when the maximum operating temperature determined by the material of the flat target is Tmax, the thickness δ is adjusted so that the center temperature Tc of the flat target falls within the range of the following equation. Set.

[0028]

0.8 Tmax ≦ Tc ≦ Tmax (Equation 3) In Equation 3, the lower limit is set to 0.8 times the maximum use temperature Tmax because, for example, the optimum use temperature range of tantalum is 200 to 250. ° C and width, the maximum operating temperature Tmax =
This is because 250 ° C. and 0.8 Tmax = 200 ° C.
When the center temperature Tc exceeds 250 ° C., the life of the flat target decreases sharply. If the center temperature Tc is less than 200 ° C., the thickness δ of the flat target becomes too thin, so that not only the strength is reduced, but also the required number of sheets is increased and the economic efficiency is deteriorated.

However, since the maximum operating temperature Tmax depends not only on the target material but also on the required life,
It does not have to be 0 ° C. What is important is that the most reasonable and economical target system can be realized by setting the center temperature Tc of each flat target within the range of Equation 3 to make the life of each flat target uniform. From the equations (2) and (3), the optimum range of the thickness δ of the flat target can be expressed by the following equation.

[0030]

Equation 4] ^{δ ≦ [{1.0+ (2h 2} / λ) (a 1 -b)} 0 · 5 -1.0] (2λ / h) δ ≧ [{1.0+ (2h 2 / λ) ^{_{(a 2 -b)} 0 ·}} 5 -1.0] (2λ / h) a 1 = (Tmax-Tw) / q a 2 = (0.8Tmax-Tw) / q b = 0.5tp / (ρCp (Equation 4) When the distance from the incident position of the proton beam 10 increases, the heat generation density q in the flat target sharply decreases. However, if the thickness δ is distributed in the range of Equation 4, the central temperature Tc Is in the range of Equation 3, so that all the flat targets can be used under optimal conditions and the life can be extended.

Hereinafter, the operation of the present embodiment will be described more specifically with reference to FIG. FIG. 5 is a diagram showing the distribution of the heat generation density and the center temperature of the flat targets of the present embodiment and the conventional example. The horizontal axis in FIG.
The vertical axis represents the heat generation density q and the center temperature Tc. However, the width of the coolant channel 14 is not included in the distance on the horizontal axis.

Since the proton beam 10 is absorbed by the flat target, the heat generation density q sharply decreases as the distance increases. At this time, if the heat value Q proportional to the product qδ of the heat density q and the target thickness δ is made constant, as in the conventional example, as shown in FIG. Increases, the center temperature Tc rapidly increases.

On the other hand, in the case of the present embodiment, as shown in FIG. 5, by distributing the thickness δ of the flat target in the range of Expression 4, the center temperature Tc becomes the range of Expression 3 regardless of the distance. All flat targets can be used under optimal conditions to extend their life. In the present embodiment having such a configuration, the calorific value Q and the surface heat flux q _S in each flat target is not constant with respect to distance as in the prior art,
As shown in FIG. 6, it decreases as the distance increases. Therefore,
In the present embodiment, the cooling water flow rate W supplied to each coolant flow path 14 is determined by the heat value Q and the surface heat flux q at each flat target.
It is more reasonable to decrease the value as the distance increases, as shown in FIG. 6, in accordance with the change in _S.

Further, as is apparent from the integration regarding the distance of the cooling water flow rate W in FIG. 6, the present embodiment can reduce the total flow rate of the cooling water as compared with the conventional example. Thereby, the capacity of the coolant circulation pump 42 and the capacity of the coolant purification device 44 can be reduced, and the diameter of these pipes can be reduced, so that a more economical cooling facility 40 can be realized.

The means for realizing the distribution of the cooling water flow rate W shown in FIG. 6 will be specifically described below. The pressure loss ΔP and the cooling water flow rate W in each coolant flow path 14 can be expressed by the following equations.

[0036]

ΔP = 0.5 (ζ _in + 1.0 + fL / d + ζ _out ) ρ _W V ² W = Vbδ _W (Equation 5) In Equation 5, ρ _W is the density of the cooling water, V is the flow velocity, b is the width of the coolant channel 14, δ _W is the gap of the coolant channel 14,
Bideruta _W is flow area, zeta _in the coolant channel 14 inlet pressure loss coefficient of the coolant flow path 14, 1.0 acceleration loss factor, fL
/ D is a coefficient of friction loss in the coolant passage 14, and ζ _out is a pressure loss coefficient of the throttle 17 in the coolant passage 14.

Since the pressure losses ΔP in the respective coolant passages 14 are equal to each other, the cooling water flow rate W
And the flow velocity V so that the distribution shown in FIG.
The pressure loss coefficient ζ _out of the throttle section 17 of No. 4, that is, the flow path area may be determined. In Equation 5, the pressure loss coefficient ζ _out (flow path area) of the throttle portion 17 of the coolant flow path 14 is fixed, and the gap δ _W of the coolant flow path 14 is changed for each coolant flow path 14. The distribution of the cooling water flow rate W shown in FIG. 6 may be realized.

Next, the reason why the throttle portion 17 of the coolant flow path 14 is provided on the outlet side will be described. Since the high heat generation portion in the flat target is extremely local, the coolant flow path 14
When boiling occurs, there are problems such as a decrease in the flow rate of the cooling water in the high heat generating portion requiring cooling, and an increase in the flow resistance and a variation in the flow rate of the cooling water in each coolant flow path 14. Occurs. Therefore, it is necessary to prevent boiling in the coolant flow path 14. For this purpose, the surface temperature Tsv of the flat target immediately after the irradiation of the proton beam 10 may satisfy the following expression.

[0039]

Tsv = 0.5qtp / (ρCp) + Ts <Tst (Pw) + ΔTsh (Equation 6) In Equation 6, Ts is the time average temperature on the surface of the flat target, ρCp is the heat capacity of the flat target, tp Is the pulse irradiation interval of the proton beam 10, q is the heat generation density, ΔTsh is the degree of superheating for boiling, and Tst (Pw) is the coolant flow path 1.
4 is the saturation temperature for the pressure Pw.

From equation (6), to avoid boiling, the saturation temperature T
st, that is, the pressure Pw in the coolant channel 14 may be increased.
The pressure Pw in the coolant flow path 14 is increased to about 20 atm by the pressurized gas 46 in the coolant tank 41. However, if the pressure is increased, the design pressure of the cooling equipment 40 needs to be increased, and the economy is reduced. It is better to reduce the pressure as much as possible because it will worsen.

When the throttle portion 17 of the coolant flow path 14 is provided on the inlet side, the pressure Pw and the saturation temperature Tst in the high heat generating portion of the flat target are obtained by the pressure loss coefficient ζ _{out in} Equation (5).
Will decrease. In order to avoid this, it is necessary to provide the throttle section 17 on the outlet side of the coolant flow path 14. Also,
In this embodiment, by providing a curvature at the lower end of the target support 21 located at the inflow portion 16 of the coolant flow path 14, the pressure loss coefficient ζ _in at the inlet in Equation 5 is almost zero (when there is no curvature, ζ _in = 0.5) to prevent the pressure Pw and the saturation temperature Tst from lowering in the high heat generating portion of the flat target. As described above, in the embodiment of the present invention shown in FIGS. 1 to 4, as the distance from the incident position of the proton beam 10 increases, the thickness δ of the plate-shaped target satisfies Equation 4.
Is made thicker, so that the center temperature Tc expressed by the equation (2) satisfies the equation (3). That is, the central temperature Tc is set to be between 0.8 and 1.0 times the maximum use temperature Tmax. As a result, the center temperature Tc of the flat target can be reliably kept below the maximum use temperature Tmax, so that the life can be extended and the economy can be improved.

In this case, the calorific value Q of the flat target
Is proportional to qδ, and q and δ are distributed as shown in FIG. Therefore, the throttle portion 17 is provided on the outlet side of each coolant flow passage 14 to adjust the flow passage area, or the gap of the coolant flow passage 14 is adjusted, so that the heat value Q in each flat target is adjusted.
By supplying the cooling water flow rate to each coolant flow path 14 in proportion to the total flow rate of the cooling water, the total flow rate of the cooling water can be reduced,
A more economical cooling facility 40 can be provided.

Next, a second embodiment of the solid target according to the present invention will be described with reference to FIG. 7A and 7B are schematic configuration diagrams of the second embodiment, in which FIG. 7A is a longitudinal sectional view, FIG. 7B is a sectional view taken along line AA of FIG. 7A, and FIG. 7C is a sectional view taken along line BB of FIG. . Also in this embodiment, the cooling equipment 40 shown in FIG. 2 can be applied. This embodiment is characterized in that cooling water flows in from two inlets 30a and 30b provided in the target container 12, cools the flat target 25 respectively, and flows out from outlets 35a and 35b. Also, the coolant flow path 14
Is not provided with a throttle. Other configurations are the same as those of the first embodiment.

The cooling water flowing from the inlet 30a is supplied to the inlet channel 31a, the coolant channel 14, the connecting channel 32a, the coolant channel 14, the connecting channel 33a, the coolant channel 14, and the outlet channel 3.
It flows out of the outlet 35a through 4a. The cooling water flowing from the inlet 30b flows into the inlet passage 31b, the coolant passage 14,
The fluid flows out of the outlet 35b through the connecting channel 32b, the coolant channel 14, the connecting channel 33b, the coolant channel 14, and the outlet channel 34b. Thus, each cooling water cools the flat target 25 three times (passes through the coolant passage 14 three times).

In this embodiment, as in the first embodiment,
As the distance from the incident position of the proton beam 10 increases, the thickness δ of the flat target 25 increases, and the center temperature Tc of the flat target 25 expressed by Expression 2 becomes
, The relationship 0.8Tmax ≦ Tc ≦ Tmax is satisfied. Further, the gap δ _W of the coolant flow path 14
Is adjusted so that the flow rate of the cooling water to each coolant flow path 14 is supplied in proportion to the heat value Q of the flat target 25.

Therefore, in this embodiment, the same effects as in the first embodiment can be obtained. Further, in the case of the present embodiment, since the cooling water passes through the coolant channel 14 three times,
The total flow rate of the cooling water can be reduced as compared with the first embodiment, and a more economical cooling facility 40 can be realized.

On the other hand, the coolant temperature T in Equations 2 to 4
Since w gradually rises in the process in which the cooling water passes through the coolant passage three times, the thickness δ of the flat target 25 needs to be relatively thinner toward the downstream side as compared with the first embodiment.
In the coolant channel 14 on the downstream side, the pressure P
In order to prevent w and Tst from lowering, the throttle section 17 of the first embodiment is not provided. Therefore, the pressure loss coefficient ζ _out of Equation 5 is 0.

[0048]

According to the first to third aspects of the present invention, since the center temperature of each flat target can be made equal to or lower than the maximum use temperature which depends on the target material, the life of the target can be extended and the solid-state material having excellent economy can be obtained. The target can be realized.

According to the fourth aspect, the total flow rate of the coolant supplied to the solid target can be reduced, so that the capacity of the cooling equipment can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of a solid target according to the present invention, wherein (a) is a longitudinal sectional view, (b) is an AA sectional view of (a), and (c) is a sectional view of (a). It is BB sectional drawing.

FIG. 2 is a schematic configuration diagram of a first embodiment of a solid target system according to the present invention.

FIG. 3 is a view showing a modification of the solid target of FIG. 1;
1A is a cross-sectional view taken along line AA of FIG. 1A, and FIG.
It is B sectional drawing.

4 is a detailed view of the target element of FIG. 3, (a) is a front view, and (b) is a side view.

FIG. 5 is a diagram showing a distribution of heat generation density and center temperature of a flat target.

FIG. 6 is a diagram showing distributions of a surface heat flow rate and a cooling water flow rate of a flat target.

FIG. 7 is a schematic configuration diagram of a second embodiment of the solid target according to the present invention, wherein (a) is a longitudinal sectional view, (b) is an AA sectional view of (a), and (c) is a sectional view of (a). It is BB sectional drawing.

[Explanation of symbols]

11 ... window, 12 ... target container, 13, 31
a, 31b: inlet channel, 14: coolant channel, 15, 34
a, 34b: outlet flow path, 16: inflow section, 17: throttle section,
20: solid target, 21: target support, 2
5, 26: flat target, 27: target element,
28 Projection, 30a, 30b Inlet, 32a, 32b, 33
a, 33b ... connecting flow path, 35a, 35b ... outlet, 40 ...
Cooling equipment, 41: coolant tank, 42: coolant circulation pump, 43: cooler, 44: coolant purification device, 46: pressurized gas.

Claims (5)

[Claims] 1. A solid target for generating neutrons by irradiating a high energy proton beam or the like, wherein a plurality of plate-like targets made of heavy metal are arranged at a predetermined gap in a direction of incidence of the proton beam or the like. The predetermined gap forms a coolant flow path through which a coolant for cooling the flat target flows, and the thickness of the flat target increases as the distance from the incident position of a proton beam or the like increases. A solid target, wherein the center temperature of the flat target is configured to be within a predetermined temperature range. 2. The method according to claim 1, wherein the central temperature Tc of each flat target is 0.8 Tmax ≦ Tc ≦, where Tc is the central temperature of the flat target and Tmax is the maximum operating temperature depending on the target material. A solid target, wherein the thicknesses of the respective flat targets are distributed so as to fall within the range of Tmax. 3. The method according to claim 1 or 2, wherein the thermal conductivity of the plate-like target is λ, the heat capacity is ρCp, the heat transfer coefficient at the surface is h, the maximum use temperature depending on the target material is Tmax, and the cooling is Tmax. Assuming that the material temperature is Tw, the interval of pulse irradiation of proton beam or the like is tp, and the heat generation density of each flat target is q, the thickness δ of the flat target is δ ≦ [{1.0+ (2h ² / Λ) (a ₁ -b)} 0.5 ^{· 1.0} ] (2
λ / h) δ ≧ [{ 1.0+ (2h 2 / λ) (a 2 -b)} 0 · 5 -1.0] (2
λ / h) a solid target characterized in that it satisfies a ₁ = (Tmax−Tw) / qa ₂ = (0.8Tmax−Tw) /qb=0.5 tp / (ρCp). 4. The method according to claim 1, wherein
By distributing the flow path area of the throttle portion provided at the outlet of each coolant flow path or distributing the gap of each coolant flow path, the product qδ of the heat generation density q and the thickness δ of each flat target is obtained. A solid target characterized in that a coolant having a flow rate proportional to a proportional heat value Q is supplied to each coolant channel. 5. A solid target system comprising: a solid target for generating neutrons by irradiating a high energy proton beam or the like; and cooling equipment for supplying a coolant for cooling the target to the solid target. The solid target has a plurality of flat targets arranged at predetermined intervals in the incident direction of proton beams or the like, and a plurality of flat targets formed as the predetermined gaps for flowing a coolant for cooling the flat targets. A coolant tank including a coolant and a pressurized gas, a coolant circulation pump for supplying coolant from the coolant tank to the solid target, and the solid target. A cooling device that cools the coolant discharged from the cooling device, and a coolant purification device that purifies the coolant cooled by the cooler and returns the coolant to the coolant tank. Wherein the solid target is solid target system characterized by having the features according to any one of claims 1 to 4.