Activating and collecting device for laser inertial confinement fusion

Abstract

The invention discloses an activating and collecting device for laser inertial confinement fusion, which comprises a fixing ring, a foil supporting plate, a collecting foil, an activating medium, a background foil, a collector supporting plate and a collector shell, and is characterized in that a vanadium foil is arranged in the collecting foil, graphite paper is arranged in the collecting foil, and the activating medium is arranged in the collecting foil. An aluminum foil and a titanium foil are arranged in the collecting foil, the collecting foil comprises a vanadium foil, graphite paper, the aluminum foil and the titanium foil, the thickness of the collecting foil is micron dimension, the diameter of the collecting foil is smaller than 150mm, the surface of the collecting foil needs to be polished until the surface roughness is smaller than or equal to 1mu m rms, and by activating a medium and reducing the consumption of DIM, the medium can be activated while neutrons are activated, and the surface roughness of the collecting foil is smaller than or equal to 1mu m rms. The reliability of different collected materials and the collection efficiency of different products of the four materials in an ICF extreme environment can be measured in one time through the vanadium foil, the graphite paper, the aluminum foil and the titanium foil of the collection foil, and the experiment efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ICF neutron yield diagnosis and solid radioactive product collection, and specifically relates to an activation collection device for laser inertial confinement fusion. Background Technique

[0002] Laser inertial confinement fusion is a technology that drives the fusion reaction of fuel through lasers or other particle beams. In this process, the laser beam is focused on a fuel target, usually a solid or gas spherical target composed of deuterium and tritium, generating huge temperature and pressure, thereby triggering the fusion reaction. Currently, there are relatively few collection devices for solid radioactive products on ICF devices internationally. Using the solid radioactive product collection technology, on the one hand, for the collection of implosion neutron activation fragments, various diagnostic parameters of the implosion target pellet can be determined (such as the areal density ρR of the fuel and the ablation condition of the laser and the fuel, etc.), and on the other hand, for the collection of solid radioactive products generated by the reaction, it can meet the cross-section measurements of certain nuclear reactions in the ICF environment, such as 3He(α,γ)7Be and 7Be(α, γ)11C.

[0003] However, in practical applications, the diagnostic technology of offline activation measurement is an important field in the research of laser inertial confinement fusion (ICF). Due to the extremely short duration of laser inertial confinement fusion (picosecond level), for online measurement technology, the neutron signals, gamma signals directly generated by the implosion, and gamma signals indirectly generated by neutron inelasticity will all respond inside the detector, thus affecting the complexity of the waveform signal analysis obtained in the oscilloscope, and further affecting the measurement accuracy and background interference problems. Summary of the Invention

[0004] To solve the above technical problems, an activation collection device for laser inertial confinement fusion is provided. This technical solution solves the problem that the diagnostic technology of offline activation measurement is an important field in the research of laser inertial confinement fusion (ICF). Due to the extremely short duration of laser inertial confinement fusion (picosecond level), for online measurement technology, the neutron signals, gamma signals directly generated by the implosion, and gamma signals indirectly generated by neutron inelasticity will all respond inside the detector, thus affecting the complexity of the waveform signal analysis obtained in the oscilloscope, and further affecting the measurement accuracy and background interference problems.

[0005] To achieve the above objectives, the objectives of the present invention can be achieved through the following technical solutions: The device is composed of a radioactive product collection foil (hereinafter referred to as the collection foil), a radioactive product background foil (hereinafter referred to as the background foil), a neutron activation medium (hereinafter referred to as the activation medium), and some necessary mechanical fixing structures. At the same time, the mechanical structure at the bottom needs to reserve an interface for connection with DIM.

[0006] An activation collection device for laser inertial confinement fusion, Preferably, the device comprises a fixing ring, a foil support plate, a collecting foil, an activation medium, a background foil, a collector support plate and a collector housing, and is characterized in that: a vanadium foil is arranged inside the collecting foil, a graphite paper is arranged inside the collecting foil, an aluminum foil and a titanium foil are arranged inside the collecting foil, the vanadium foil, graphite paper, aluminum foil and titanium foil of the collecting foil have a thickness of micrometer order and a diameter of less than 150mm, and the metal foil needs to be surface polished to a surface roughness of ≤1umrms.

[0007] Preferably, the lower end of the collecting foil is attached to the upper end of the activation medium, and the activation medium is made of indium metal or In-enriched indium metal using metallic indium as the material for neutron activation.

[0008] Preferably, the lower end of the activation medium is attached to the upper end of the background foil, and the configuration of the background foil is completely consistent with that of the collecting foil.

[0009] Preferably, a foil support plate is provided at the upper end of the collecting foil, and a fixing ring is provided at the upper end of the foil support plate.

[0010] Preferably, the lower end of the background foil is arranged on the upper end of the collector support plate.

[0011] Preferably, the lower end of the collector support plate is arranged inside the collector shell.

[0012] Preferably, after the background foil is in close contact with the collector support plate, it is butted against by screws at the rear end of the collector housing, and at the same time, the screws are tightened by the fixing ring to ensure that the collecting foil and the background foil are stressed and flat without wrinkles.

[0013] Compared with the prior art, the present invention provides an activation collection device for laser inertial confinement fusion, which has the following beneficial effects: (1) The present invention reduces the consumption of DIM by activating the medium, and can collect radioactive products while neutron activating the medium.

[0014] (2) The present invention uses vanadium foil, graphite paper, aluminum foil and titanium foil as collector foils to measure the reliability of different collector materials and the collection efficiency of different products of four materials in the extreme environment of ICF in one test, thereby improving the experimental efficiency.

[0015] (3) The present invention adopts a graphite collection scheme to increase the collection foil area while reducing the sample volume during measurement by means of incineration, thereby minimizing the possibility of self-absorption and improving the accuracy of the measurement results.

[0016] (4) The present invention uses a background foil to deduct the neutron activation background in the collection foil, thereby improving the reliability of the measurement results.

[0017] (5) The present invention ensures the stable and flat installation of all components through the foil support plate, the collector support plate, the collector housing, and the fixing ring, avoiding wrinkles or misalignments, improving the collection efficiency, reducing any interference or blockage that may affect the performance, and ensuring that the contact surface between the collection foil and the foil support plate is flat without wrinkles or irregular bends. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic diagram of the overall structure of the present invention; Figure 2 is a schematic diagram of the collection foil structure of the present invention; Figure 3 is a schematic diagram of the overall process of the present invention; The reference numerals in the figures are: 1, fixing ring; 2, foil support plate; 3, collection foil; 31, vanadium foil; 32, graphite paper; 33, aluminum foil; 34, titanium foil; 4, activation medium; 5, background foil; 6, collector support plate; 7, collector housing. DETAILED DESCRIPTION OF THE INVENTION

[0019] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations.

[0020] Please refer to Figure 1-2 As shown, an activation collection device for laser inertial confinement fusion includes a fixing ring 1, a foil support plate 2, a collection foil 3, an activation medium 4, a background foil 5, a collector support plate 6, and a collector housing 7. Inside the collection foil 3, there is a vanadium foil 31, a graphite paper 32, an aluminum foil 33, and a titanium foil 34. The vanadium foil 31, graphite paper 32, aluminum foil 33, and titanium foil 34 in the collection foil 3 have a thickness in the micron range and a diameter less than 150 mm. For metal foils, the surface needs to be polished to a surface roughness ≤ 1 um rms.

[0021] In this solution, the fixed ring 1 of the collection foil 3 is the end facing the TCC, and its machining should ensure flatness. The foil support plate 2 of the collection foil 3 is made of tantalum material, and its width should be as small as possible. While increasing the solid angle of the collection foil 3, it should have sufficient strength to resist the impact of the implosion shock wave. The materials selected for the collection foil 3 are vanadium foil 31 with a thickness of 50 μm, graphite paper 32 with a thickness of 50 μm, aluminum foil 33 with a thickness of 100 μm, and titanium foil 34 with a thickness of 100 μm. Among them, the vanadium foil 31 has a certain impact resistance and can be made thinner under the same implosion conditions to reduce the volume and thus reduce the self-absorption effect during off-line gamma measurement. The advantage of the graphite paper 32 is that it can be incinerated after the implosion, making the subsequent measurement work more convenient. The aluminum foil 33 and the titanium foil 34 are relatively common materials on the market. By using four different materials, while collecting radioactive products, it is also possible to test the adsorption capacity of different materials for different radioactive products and neutron activation fragments, so as to specifically obtain the selection of the best material. For the metal collection foil 3, it needs to be polished to ensure the smoothness of the surface and avoid local ablation, which reduces the collection efficiency. The high-energy neutrons, particles, and radiation generated by the fusion reaction interact with these foil layers when the laser beam irradiates the collection foil 3 through the targeting device. The vanadium foil 31 and the titanium foil 34 can absorb part of the neutrons and radiation, reducing the radiation damage to other components and protecting the structure of the reactor. The graphite paper 32 and the aluminum foil 33 further absorb neutrons and energy. The activation medium 4 serves as a storage and conversion medium for neutrons and energy, ensuring that these energies can be effectively managed and used for subsequent thermoelectric conversion processes. The background foil 5 and the collector housing 7 mainly play a protective role, avoiding damage to the internal structure by external radiation and high temperature.

[0022] Please refer to Figure 1 As shown, the lower end of the collection foil 3 is attached to the upper end of the activation medium 4. The activation medium 4 is prepared using indium metal as the material for neutron activation or indium metal enriched with 115In. The lower end of the activation medium 4 is attached to the upper end of the background foil 5. The configuration of the background foil 5 is exactly the same as that of the collection foil 3. The space between the collection foil 3 and the background foil 5 is filled with the activation medium 4, and its thickness does not exceed 10 cm.

[0023] In this solution, the activation medium 4 uses indium metal as the material for neutron activation, and its thickness should be as small as possible. For the DD reaction, neutrons with an energy of 2.45 MeV will undergo an inelastic reaction with 155In, i.e., 155In + n → 155mIn + n' (the cross-section is about 326 mb). The half-life of 155mIn is 4.49 h, which is suitable for activation measurement. The characteristic γ energy released by the activation reaction is 336.24 keV, and the detection efficiency for high-purity germanium detectors is also relatively high. The activation medium 4 absorbs neutrons from the collection foil 3 and generates a nuclear reaction through neutron activation. Indium material has good neutron absorption ability, especially the 115In isotope, which enables it to effectively absorb neutrons and undergo a nuclear reaction after absorption, generating radioactive isotopes with specific characteristics. The configuration of the background foil 5 must be the same as that of the collection foil 3. Its role is to evaluate the impact of neutrons generated by the implosion on different types of collection foils 3. For example, 27Al + n → 24Na + α, where 24Na has a certain radioactivity, thus affecting the measurement of radioactive products on the collection foil 3. The background foil 5 has the same structure and function as the collection foil 3 and can cooperate closely with the activation medium 4. Its main role is to provide a stable underlying structure for neutrons or other particles, support the activation medium, and ensure the stability of the system.

[0024] Please refer to Figure 1 As shown, a foil support plate 2 is provided at the upper end of the collection foil 3, a fixing ring 1 is provided at the upper end of the foil support plate 2, the lower end of the background foil 5 is provided at the upper end of the collector support plate 6, and the lower end of the collector support plate 6 is provided inside the collector housing 7. After the background foil 5 is in close contact with the collector support plate 6, it is resisted by the screws at the rear end of the collector housing 7. At the same time, the fixing ring 1 tightens the screws to ensure that the collection foil 3 and the background foil 5 are stressed and flat without wrinkles.

[0025] In this solution, place the collection foil 3 on the foil support plate 2, ensuring that the lower end of the collection foil 3 is butted against the upper end of the foil support plate 2. The contact surface between the collection foil 3 and the foil support plate 2 is flat without wrinkles or irregular bends. If unevenness is found, fine-tuning is required to ensure uniform stress on the collection foil 3. Check the screw holes and structural alignment of the fixing ring 1 to ensure that the fixing ring 1 can be smoothly installed. Place the fixing ring 1 on the upper end of the collection foil 3, ensuring that it is butted against the edge of the collection foil 3, and tighten the fixing ring 1 with screws. Special attention should be paid to the tightening force to ensure that the fixing ring 1 applies uniform pressure to the collection foil 3, so that the collection foil 3 is flat and wrinkle-free, avoiding any excessive or insufficient local pressure. Butt the lower end of the background foil 5 against the upper end of the collector support plate 6, ensuring close contact between the background foil 5 and the collector support plate 6 without gaps. After the background foil 5 and the collector support plate 6 are in close contact, ensure that their fixing relationship is stable without looseness or misalignment. Fix the collector support plate 6 to the collector housing 7 with the screws at the rear end of the collector housing 7 to ensure that the collector support plate 6 is stably and closely attached to the background foil 5. There should be only the target pellets in front of the entire collection device's field of view, without any obstruction, to avoid forming an ablation field and reducing the collection efficiency.

[0026] Please refer to Figure 3 As shown, during the subsequent processing flow, after the implosion test is completed, take out the collection device, put the background foil 5, the collection foil 3, and the activation medium 4 into a low-background high-purity germanium detector to obtain different energy spectrum data, and reverse-infer the yields of radioactive products / activation fragments and the yield of neutrons based on the calibration results of the detector.

[0027] Principle and usage process of this device: First, the fixed ring 1 of the collection foil 3 is the end facing the TCC, and its processing should ensure flatness. The foil support plate 2 of the collection foil 3 is made of tantalum material, and its width should be as small as possible. While increasing the solid angle of the collection foil 3, it should also have sufficient strength to resist the impact of the implosion shock wave. The materials selected for the collection foil 3 are vanadium foil 31 with a thickness of 50 μm, graphite paper 32 with a thickness of 50 μm, aluminum foil 33 with a thickness of 100 μm, and titanium foil 34 with a thickness of 100 μm. Among them, the vanadium foil 31 has a certain impact resistance and can be made thinner under the same implosion conditions to reduce the volume and thus reduce the self-absorption effect during off-line gamma measurement. The advantage of the graphite paper 32 is that it can be incinerated after the implosion, making the subsequent measurement work more convenient. The aluminum foil 33 and titanium foil 34 are relatively common materials on the market. By using four different materials, while collecting radioactive products, it is also possible to test the adsorption ability of different materials for different radioactive products and neutron activation fragments, so as to specifically obtain the selection of the best material. For the metal collection foil 3, it needs to be polished to ensure the smoothness of the surface and avoid local ablation, which reduces the collection efficiency. The high-energy neutrons, particles, and radiation generated by the fusion reaction interact with these foil layers when the laser beam irradiates the collection foil 3 through the targeting device. The vanadium foil 31 and titanium foil 34 can absorb some neutrons and radiation, reducing the radiation damage to other components and protecting the structure of the reactor. The graphite paper 32 and aluminum foil 33 further absorb neutrons and energy. The activation medium 4 serves as a storage and conversion medium for neutrons and energy, ensuring that these energies can be effectively managed and used for subsequent thermoelectric conversion processes. The background foil 5 and the collector housing 7 mainly play a protective role, avoiding external radiation and high temperature from damaging the internal structure. The activation medium 4 uses indium metal as the material for neutron activation, and its thickness should be as small as possible. For the DD reaction, 2.45 MeV neutrons will have an inelastic reaction with 155In: 155In + n → 155mIn + n’ (cross section about 326 mb). The half-life of 155mIn is 4.49 h, which is suitable for activation measurement. The characteristic γ energy released by the activation reaction is 336.24 keV, and the detection efficiency for high-purity germanium detectors is also relatively high. The activation medium 4 absorbs neutrons from the collection foil 3 and generates nuclear reactions through neutron activation.Indium materials have good neutron absorption capabilities, especially the 115In isotope, which enables it to effectively absorb neutrons and undergo a nuclear reaction after absorption, generating radioactive isotopes with specific characteristics. The configuration of the background foil 5 must be consistent with that of the collection foil 3. Its role is to evaluate the impact of neutrons generated by the implosion on different types of collection foils 3. For example, 27Al + n → 24Na + α, where 24Na has a certain radioactivity, thus affecting the measurement of radioactive products on the collection foil 3. The background foil 5 has the same structure and function as the collection foil 3 and can cooperate closely with the activation medium 4. Its main role is to provide a stable underlying structure for neutrons or other particles, support the activation medium, and ensure the stability of the system. During the subsequent processing flow, after the implosion test is completed, the collection device is taken out, and the background foil 5, the collection foil 3, and the activation medium 4 are placed in a low-background high-purity germanium detector to obtain different energy spectrum data. According to the calibration results of the detector, the yields of radioactive products / activation fragments and the neutron yield are deduced inversely.

[0028] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification is only the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection required by the present invention is defined by the appended claims and their equivalents.

Claims

1. An activation collection device for laser inertial confinement fusion, comprising a fixing ring (1), a foil support plate (2), a collection foil (3), an activation medium (4), a background foil (5), a collector support plate (6) and a collector housing (7), characterized in that: A vanadium foil (31) is arranged inside the collecting foil (3), a graphite paper (32) is arranged inside the collecting foil (3), and an aluminum foil (33) and a titanium foil (34) are arranged inside the collecting foil (3). The vanadium foil (31), graphite paper (32), aluminum foil (33) and titanium foil (34) of the collecting foil (3) have a thickness of micrometer order and a diameter of less than 150 mm. The metal foil needs to be surface polished to a surface roughness of ≤1 μm rms.

2. The activation collection device for laser inertial confinement fusion according to claim 1, wherein: The lower end of the collecting foil (3) is attached to the upper end of the activation medium (4), and the activation medium (4) is made of indium metal or 115In-enriched indium metal using metallic indium as the material for neutron activation.

3. The activation collection device for laser inertial confinement fusion according to claim 1, wherein: The lower end of the activation medium (4) is attached to the upper end of the background foil (5), and the configuration of the background foil (5) is completely consistent with that of the collecting foil (3).

4. The activation collection device for laser inertial confinement fusion according to claim 3, wherein: The space between the collecting foil (3) and the background foil (5) is filled with an activation medium (4), the thickness of which does not exceed 10 cm.

5. The activation collection device for laser inertial confinement fusion according to claim 3, characterized in that: A foil support plate (2) is provided at the upper end of the collecting foil (3), and a fixing ring (1) is provided at the upper end of the foil support plate (2).

6. The activation collection device for laser inertial confinement fusion according to claim 5, characterized in that: The lower end of the background foil (5) is arranged on the upper end of the collector support plate (6).

7. The activation collection device for laser inertial confinement fusion according to claim 6, characterized in that: The lower end of the collector support plate (6) is arranged inside the collector housing (7).

8. The activation collection device for laser inertial confinement fusion according to claim 6, wherein: After the background foil (5) and the collector support plate (6) are tightly attached, they are butted against each other by screws at the rear end of the collector housing (7), and at the same time, the fixing ring (1) tightens the screws to ensure that the collector foil (3) and the background foil (5) are stressed and flat without wrinkles.

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