Laser Fusion Target

Abstract

This invention provides a laser fusion target pellet, which is spherical and includes, from the outside in, an ablation layer, a radiation confinement layer, a room-temperature solid main fuel layer, and a fuze region. The fuze region contains an ignition trigger material. The radiation confinement layer is made of a gradient alloy of a first metal element and a second metal element, where the first metal element is a high-Z element and the second metal element is a low-Z or medium-Z element. This invention solves the problems of hydrodynamic instability, radiation energy leakage, and difficulty in preparing cryogenic fuel in existing target pellets.

Description

Technical Field

[0001] This invention belongs to the field of controlled nuclear fusion, specifically, it relates to a laser fusion target pellet. Background Technology

[0002] Laser-driven inertial confinement fusion (ICF) is one of the important pathways to achieving controlled nuclear fusion. In recent years, significant progress has been made in international inertial confinement fusion research. The National Ignition Facility (NIF) in the United States has achieved fusion ignition and obtained a scientific energy gain greater than 1 (i.e., the energy produced by fusion exceeds the energy of the incident laser). This progress scientifically verifies the feasibility of achieving net energy output in laser-driven inertial confinement fusion. In indirect inertial confinement fusion, a high-energy laser is injected into a black cavity from both ends. The laser interacts with the cavity walls and is efficiently converted into a uniform X-ray radiation field. Under uniform X-ray irradiation, the surface material of the target pellet located at the center of the black cavity is rapidly ejected outward, simultaneously generating enormous inward recoil pressure, driving the target pellet to implode inward. In the final stage of the implosion, the fuel is compressed to extremely high density and temperature, triggering a deuterium-tritium fusion reaction and releasing a large amount of energy. When the energy produced by fusion exceeds the energy input to drive the laser, ignition and energy gain are achieved.

[0003] The target pellet is the core component containing deuterium-tritium fuel, and its design directly determines the success or failure of implosion and ignition. Currently, the mainstream target pellets used in inertial confinement fusion employ cryogenic targets. This configuration requires the formation of a uniformly thick, solid deuterium-tritium ice layer on the inner wall of the target shell through a "beta layering" process, maintaining a temperature near the triple point (approximately 18.3 K). Although this configuration physically provides a lower entropy value, it has certain limitations in engineering implementation and large-scale applications.

[0004] First, the unique ice homogenization process of cryogenic targets presents a challenge in matching with the high-frequency requirements of continuous operation. Fusion power plant engineering typically requires the drive system to continuously deliver target pellets at frequencies of 0.1–10 Hz. However, cryogenic targets must rely on the self-heating effect of tritium decay to achieve "beta stratification" to eliminate defects on the surface of the solid ice layer. This phase change crystallization process requires precise temperature control and typically lasts for more than ten hours. This thermodynamic homogenization process, with its stringent temperature requirements, increases the complexity of large-scale system integration and makes it difficult to adapt to the high-throughput, pipeline-style preparation and turnover cycles required by commercial power plants. Second, cryogenic systems present energy consumption issues. Maintaining large-scale target preparation and turnover facilities in the cryogenic zone requires corresponding thermodynamic refrigeration power consumption. In the closed-loop energy system of a fusion power plant, the operation of large-scale cryogenic systems consumes a portion of the plant's self-consumption electricity, thereby reducing the reactor's net energy gain and limiting the overall energy efficiency of the system.

[0005] Therefore, there is an urgent need to develop a stable target configuration based on room-temperature solid fuel in order to overcome the technical bottlenecks of fusion targets in terms of low temperature and environmental adaptability. Summary of the Invention

[0006] The purpose of this invention is to provide a laser fusion target pellet to solve the problems of difficulty in preparing existing cryogenic fuels and leakage of radiation energy from room-temperature deuterium-tritium fuel targets.

[0007] To achieve the above objectives, the present invention provides a laser fusion target pellet, which is spherical and includes, from the outside to the inside, an ablation layer, a radiation confinement layer, a room-temperature solid main fuel layer, and a fuze region; the fuze region contains an ignition triggering material, and the radiation confinement layer is made of a gradient alloy material formed by a first metal element and a second metal element, wherein the first metal element is a high-Z element and the second metal element is a low-Z element or a medium-Z element.

[0008] Preferably, the ablation layer is made of a hydrocarbon polymer (CH), and the thickness of the ablation layer is 100 mm. 200 μm; or, The ablation layer is made of high-density carbon (HDC) and has a thickness of 40 mm. 100 μm.

[0009] Preferably, along the radial inward direction of the target pellet, the radiation confinement layer sequentially includes an outer region, a middle region, and an inner region, wherein the atomic percentage of the first metal element in the outer region and the inner region is lower than that in the middle region. The thickness of the radiation confinement layer is 20. 55 μm.

[0010] Preferably, along the radial inward direction of the target pellet, the atomic percentage of the first metal element in the radiation confinement layer smoothly increases to a maximum value and then smoothly decreases.

[0011] The first metallic element is gold, tungsten, or tantalum, and the second metallic element is beryllium, aluminum, titanium, or copper.

[0012] Preferably, the first metallic element is tungsten, and the second metallic element is titanium; the density of the outer region ranges from 4.5 to 7.0 g / cm³. 3 The density range of the intermediate region is 17.0~19.3 g / cm³. 3 The density range of the inner region is 4.5~7.0 g / cm³. 3 .

[0013] Preferably, the material of the room-temperature solid main fuel layer is deuterated tritium polystyrene with an initial material density of 1.0~1.2 g / cm³. 3 ;or

[0014] The room-temperature solid main fuel layer is made of lithium deuterium tritide, with an initial material density of 0.78 ~ 0.82 g / cm³. 3 .

[0015] Preferably, the thickness of the room-temperature solid main fuel layer is 50 mm. 150 μm.

[0016] Preferably, the ignition zone is located at the center of the target pellet, and the ignition triggering material is deuterium-tritium gas with an initial gas density of 0.2~0.22 mg / cm³. 3 .

[0017] Preferably, the fuse area is spherical with a radius of 1000. 1500 μm.

[0018] The beneficial effects of this invention are as follows: Addressing the difficulties in preparing cryogenic fuels and the leakage of radiation energy from room-temperature deuterium-tritium fuel targets, the laser fusion target of this invention introduces a radiation confinement layer of gradient alloy material. This layer suppresses the fluid mixing of high-Z elements into the core fuel region caused by hydrodynamic instability, as well as the radiation energy loss caused by carbon or lithium in the solid fuel layer. Furthermore, this dense metallic boundary simultaneously serves as a physical shell encapsulating the internal room-temperature fuel. This invention utilizes a room-temperature solid main fuel layer to replace cryogenically frozen deuterium-tritium ice that relies on long-term homogenization processes, eliminating the need for complex cryogenic maintenance and ice layer homogenization processes.

[0019] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0020] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0021] Figure 1 A schematic structural diagram of a laser fusion target pellet according to an embodiment of the present invention is shown.

[0022] Explanation of reference numerals in the attached figures: 1. Ablation layer; 2. Radiation confinement layer; 3. Room temperature solid main fuel layer; 4. Fuze zone. Detailed Implementation

[0023] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0024] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] In the field of ICF and in the context of this invention, the following definition is made based on the atomic number Z of the element: Low Z elements: These are elements with atomic number Z ≤ 10, such as hydrogen isotopes, lithium, beryllium, carbon, etc. Z elements: These are elements with atomic numbers 11 ≤ Z ≤ 40, such as silicon, aluminum, titanium, and copper. High Z elements: These are metallic elements with atomic number Z > 70, such as gold, tungsten, and tantalum.

[0027] This invention proposes a laser fusion target pellet, which is spherical and includes an ablation layer, a radiation confinement layer, a room-temperature solid main fuel layer, and a fuze region arranged sequentially from the outside to the inside. An ignition trigger source is provided in the fuze region. The radiation confinement layer is made of a gradient alloy material formed by a first metal element and a second metal element, wherein the first metal element is a high-Z element and the second metal element is a low-Z element or a medium-Z element.

[0028] The ablation layer is the outermost layer of the target pellet, serving as the initial energy absorption and driving layer; the room-temperature solid main fuel layer is the combustion core for energy gain; an ignition trigger source is located within the fuze zone to ignite the outer room-temperature solid main fuel layer. The target pellet of this invention incorporates a radiation confinement layer formed of a gradient alloy material between the ablation layer and the room-temperature solid main fuel layer, used to confine the radiated energy of the fuel layer within the target pellet. The gradient alloy material creates a smooth impedance transition, effectively reducing the Atwood number at the fluid interface during the implosion deceleration phase, thereby suppressing the mixing of high-Z elements into the core fuel region caused by hydrodynamic instabilities (such as Rayleigh-Taylor instability). The laser fusion target pellet of this invention uses room-temperature solid main fuel, avoiding the dependence of traditional target pellets on maintaining a solid ice layer through an ultra-low temperature (approximately 18K) cryogenic system, thus alleviating related engineering and mass production limitations.

[0029] As a preferred embodiment, the ablation layer is composed of a hydrocarbon polymer, and the thickness of the ablation layer is 100 mm. 200 μm, material density is 1.0 g / cm³ 3 Up to 1.2 g / cm 3 Alternatively, the ablation layer may be made of high-density carbon with a thickness of 40 mm. 100 μm, material density is 3.2 g / cm³ 3 Up to 3.5 g / cm 3 .

[0030] As the initial energy absorption and driving layer, the ablation layer matrix is ​​made of hydrocarbon polymers or high-density carbon with high mechanical strength. In the field of ICF, high-density carbon specifically refers to diamond used as the ablation layer material. Under direct laser beam irradiation, the ablation layer material ablates and generates an outwardly expanding plasma flow. According to the principle of momentum conservation, the ablation pressure generated by this process drives the internal radiation confinement layer and fusion fuel to undergo a centripetal implosion towards the center.

[0031] As a preferred option, the radiation confinement layer is made of a gradient alloy material with an overall thickness of 20 mm. 55 μm. Gradient alloy materials refer to alloy materials in which the composition of each metal material exhibits a continuous and smooth gradient in space. Along the radial direction inward from the target pellet, the radiation confinement layer successively includes an outer region, a middle region, and an inner region. The atomic percentage of the first metal element in the outer and inner regions is lower than that in the middle region. To achieve the dual physical functions of impedance matching and radiation trapping, the first metal element is gold, tungsten, or tantalum, and the second metal element is beryllium, aluminum, titanium, or copper. That is, the material of the radiation confinement layer can be a tungsten-titanium alloy, a tantalum-titanium alloy, a tungsten-beryllium alloy, a gold-copper alloy, or a gold-aluminum alloy.

[0032] As a preferred embodiment, along the radial direction inward from the target pellet, the atomic percentage of the first metal element in the radiation confinement layer smoothly increases to a maximum value and then smoothly decreases. Taking tungsten as the first metal and titanium as the second metal element as an example, the outer region is a titanium-rich region with a relatively low material density, which helps to reduce the difference in hydrodynamic impedance with the outer carbon-based ablation layer; the tungsten content increases in the middle region, and due to tungsten's high surface density and high atomic number, it can form a radiation blocking layer, reducing the preheating of the internal fuel by X-rays and superheated electrons; the inner region again uses a titanium-rich region to construct a smoother impedance transition between the high Z element confinement layer and the internal low-density solid fuel. Preferably, the density range of the outer region is 4.5~7.0 g / cm³. 3 The density range in the intermediate region is 17.0~19.3 g / cm³. 3 The density range of the inner region is 4.5~7.0 g / cm³. 3 .

[0033] This spatial composition gradient alloy material can effectively reduce the Atwood number at the fluid interface during the implosion deceleration phase, thereby suppressing the mixing of high-Z elements into the core fuel region caused by hydrodynamic instabilities (such as Rayleigh-Taylor instability). Furthermore, the dense metallic boundary simultaneously serves as a physical shell encapsulating the internal ambient-temperature fuel (solid main fuel and gas within the fuze zone).

[0034] As a preferred option, the room-temperature solid main fuel layer uses a hydrogen isotope solid material that is physically and chemically stable at room temperature, such as deuterated tritium polystyrene or lithium deuterated tritium. The chemical formula of deuterated tritium polystyrene is [C8D]. x T y [n], where x and y represent the stoichiometric coefficients of deuterium and tritium atoms in the monomer, x + y = 8. The initial material density of deuterated tritium polystyrene is 1.0 ~ 1.2 g / cm³. 3 The chemical formula for lithium deuterium tritide is LiD. 1-x T x Where x is the atomic percentage of tritium in the hydrogen isotope, 0 < x < 1. The atomic percentage of lithium deuterium-tritide is 0.78 ~ 0.82 g / cm³. 3 The thickness of the solid primary fuel layer at room temperature is 50 mm. 150 μm.

[0035] As the combustion medium providing the main fusion energy gain, the room-temperature solid main fuel layer replaces the cryogenically frozen deuterium-tritium ice that relies on long-term homogenization, eliminating the need for complex cryogenic maintenance and ice homogenization processes. After ignition in the fuze region, the room-temperature solid main fuel layer absorbs the outwardly radiated thermal energy and particle kinetic energy, supporting the radial self-sustaining propagation of the combustion wave in the solid medium, thereby achieving fusion energy output.

[0036] The ignition zone is located at the center of the target pellet and is a miniature cavity filled with high-purity deuterium-tritium gas at room temperature. The initial material density of the ignition trigger material is 0.2 ~ 0.22 mg / cm³. 3 The fuse region is spherical with a radius of 1000. 1500 μm. The main function of the fuze region is to serve as the initial ignition trigger source. During the implosion stagnation stage, the gas core of the fuze region forms a central hot spot, generating and releasing a high flux of 3.5 MeV α particles and 14.1 MeV neutrons, thereby igniting the outer solid main fuel layer, which is in a high-density, low-temperature state.

[0037] The following describes the physical process of fusion occurring in the laser fusion target pellet according to the present invention under the action of an external driving source: Phase 1: Energy Deposition and Ablation Acceleration. External driving energy (laser) irradiates the outermost ablation layer of the target pellet. The surface material absorbs the energy and ionizes, forming an outwardly expanding plasma corona region. The reaction force of the outward ejection of plasma generates an ablation pressure on the ablation surface in the hundreds of megabars. This ablation pressure drives the shock wave to propagate inward, accelerating the entire target pellet shell inward. During this acceleration process, the high-Z elements in the middle region of the radiation confinement layer absorb transmitted X-rays and superheated electrons, reducing the preheating rate of the inner solid main fuel layer and causing its compression process to approach the low-entropy isentropic line.

[0038] The second stage: Shock wave propagation and fluid compression. The shock wave penetrates each layer sequentially inward. At the interface between the carbon-based ablation layer and the radiation confinement layer, the medium- or low-Z elements in the outer region of the alloy layer reduce the hydrodynamic density span between the high-Z elements and the ablation layer interface, decreasing the Atwood number of the interface, thereby reducing the shock wave reflectivity and suppressing the growth of Rayleigh-Taylor instability (RTI). The shock wave penetrates the heavy metal confinement layer and enters the solid main fuel layer, increasing its density. Simultaneously, the central atmospheric pressure deuterium-tritium (DT) gas is compressed in volume due to the centripetal push of the outer dense shell, and the gas density and temperature begin to rise.

[0039] The third stage: deceleration and hotspot formation. When the implosion shell converges near the geometric center of the target, the central deuterium-tritium gas is compressed, increasing in pressure. The high internal gas pressure does negative work on the inwardly moving dense shell, causing it to decelerate. During this deceleration stage, the medium- or low-Z elements in the interface region inside the radiation confinement layer reduce the Atwood number at the interface between the outer high-Z region and the internal fuel region, inhibiting the hydrodynamic mixing of high-Z element materials into the central gas region. When the macroscopic inward velocity of the plasma drops to zero, the system reaches the stagnation point, and the central gas temperature reaches the fusion ignition condition (approximately 5 keV), forming a hotspot.

[0040] Phase Four: Central Ignition and Combustion Wave Propagation. In the hotspot region, deuterium-tritium ions undergo a fusion reaction, producing 14.1 MeV neutrons and 3.5 MeV alpha particles. Due to their longer mean free path, most neutrons penetrate the target pellet and escape; alpha particles, with their shorter mean free path, have their kinetic energy primarily deposited at the inner boundary of the high-density solid main fuel layer surrounding the hotspot. The combustion wave propagates through the main fuel layer before the target pellet shell undergoes hydrodynamic disintegration, achieving fusion energy output.

[0041] Example 1

[0042] Figure 1 A schematic structural diagram of a laser fusion target pellet according to this embodiment is shown. Figure 1 As shown, the laser fusion target is spherical and includes, from the outside in, an ablation layer 1, a radiation confinement layer 2, a room-temperature solid main fuel layer 3, and a fuze region 4. The ablation layer 1 is made of HDC. The radiation confinement layer 2 is made of a tungsten-titanium gradient alloy; along the radial direction of the target, the proportion of tungsten atoms in the radiation confinement layer smoothly increases to a maximum value and then smoothly decreases. The room-temperature solid main fuel layer 3 is made of deuterated-tritium polystyrene. The fuze region 4 contains deuterated-tritium gas.

[0043] The following details the regulatory function of the laser fusion target radiation confinement layer in this embodiment at different stages of the implosion physical evolution: blocking external preheating sources inward during the acceleration stage and trapping fuel radiation energy outward during the retardation stage. Quantitative and qualitative evaluations are then performed on the above two functions and boundary conditions.

[0044] During the acceleration phase, the radiation confinement layer possesses the function of absorbing superthermal electrons and X-rays. If these high-energy carriers penetrate the outer layer and enter the main fuel region, they will trigger fuel preheating, leading to an increase in the entropy of the fuel layer in the initial stage of compression, thus deviating from the isentropic compression trajectory. The middle region of the tungsten-titanium alloy layer of this invention is rich in high atomic number tungsten (Z = 74). For X-ray radiation, the photoelectric absorption cross section of a material is highly positively correlated with its atomic number. The high mass absorption coefficient of tungsten gives it the physical property of attenuating the transmitted X-ray flux. Furthermore, for superthermal electrons generated in the coronal region, the strong Coulomb field of high-Z elements increases the collision energy loss rate of electrons in the medium. The penetration depth of superthermal electrons in high-Z media decreases with the increase of the effective charge number of the material. Through the high atomic number and high-density barrier provided by the tungsten-titanium alloy layer, the proportion of high-energy carrier energy generated in the plasma coronal region that is deposited inside the radiation confinement layer is increased. This physical mechanism maintains the low-entropy state of the inner solid fuel during the implosion compression process.

[0045] During the impingement and hot spot ignition stages, the target pellet constructs a radiation boundary based on optical thickness. In this stage, the solid main fuel layer, due to its high temperature, generates bremsstrahlung radiation, and the tungsten-titanium alloy radiation confinement layer covering the outer surface constitutes the radiation trapping boundary. The macroscopic transport of radiation energy in the medium is controlled by opacity. Under the approximation of local thermodynamic equilibrium, the absorption capacity of high-Z element plasma for X-ray radiation is determined by the Rossland average opacity (κ). R Characterization. Tungsten in the main region of the radiation confinement layer has a large number of bound electrons outside its nucleus, and its κ... R Significantly higher than low Z elements. Assuming the system reaches its stagnation point and the central hot spot is at the ignition threshold (T ≈ 5 keV), the tungsten dense confinement layer is compressed to a density ρ. W ≈ 500g / cm 3 According to the standard opacity model, under a radiation temperature environment of approximately 5 keV, the κ of tungsten plasma in this state... R The order of magnitude is approximately 10 3 cm 2 / g. The areal density of the compressed tungsten layer is set to (ρΔR). W ≈ 0.5 g / cm 2 The effective optical thickness τ of this layer against thermal radiation X-rays W The calculation is as follows: τ W = κ R · (ρΔR) W ≈ 10 3 × 0.5 = 500 Calculations show that τ W 1. The tungsten-titanium alloy layer is located in the optically thick region. Under these conditions, outwardly propagating X-ray photons undergo multiple absorption and re-emission processes before penetrating the alloy layer, making the dense metal layer a spatially radiatively closed boundary.

[0046] The following describes the relationship between the radiation wall albedo and net radiative cooling of the target pellet during the combustion wave propagation phase. When the radiative energy flow emitted from the internal fuel layer strikes the inner surface of the optically thick tungsten layer, the energy is conducted into the interior of the metal layer in the form of radiative thermal waves. The ratio of the energy flow absorbed by the metal wall and re-emitted back to the fuel region to the incident energy flow is defined as the radiation wall albedo R. albedo For high-Z material boundaries, the albedo R albedo Controlled by the radiative heat conduction equation. For quantitative evaluation, it is assumed that the albedo R of the high-Z element tungsten wall surface is [value missing] at a typical implosion delay timescale (approximately 100 ps) and an ignition threshold temperature of T ≈ 5 keV. albedo ≈ 0.85.

[0047] Let P be the initial volumetric cooling power of the solid main fuel layer due to electron-ion bremsstrahlung radiation. rad_initial After introducing the boundary effect of the tungsten-titanium alloy radiation confinement layer, due to the radiation reabsorption and reemission mechanism of the wall surface, the net radiative cooling power P lost outward from the solid main fuel layer is significantly reduced. rad_net Expressed as: P rad_net = P rad_initial × (1 - R albedo ) Substitute the aforementioned assumed value R albedo Calculate ≈ 0.85: P rad_net ≈ P rad_initial × (1 - 0.85) = 0.15P rad_initial Calculations show that, under the physical boundary intervention of the tungsten-titanium alloy radiation confinement layer, the net radiation energy loss of the inner solid main fuel layer is reduced to 15% of that in the state without high Z element boundary conditions. This analysis indicates that this radiation confinement mechanism can reduce the radiation cooling rate of fuels containing non-hydrogen isotopes.

[0048] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A laser fusion target pellet, characterized in that, The target pellet is spherical and includes, from the outside to the inside, an ablation layer, a radiation confinement layer, a room-temperature solid main fuel layer, and a fuze region. The fuze region contains an ignition triggering material. The radiation confinement layer is made of a gradient alloy material formed by a first metal element and a second metal element, wherein the first metal element is a high-Z element and the second metal element is a low-Z or medium-Z element.

2. The laser fusion target pellet according to claim 1, characterized in that, The ablation layer is made of a hydrocarbon polymer (CH) and has a thickness of 100. 200 μm; or, The ablation layer is made of high-density carbon (HDC) and has a thickness of 40 mm. 100 μm.

3. The laser fusion target pellet according to claim 1, characterized in that, Along the radial inward direction of the target pellet, the radiation confinement layer sequentially includes an outer region, a middle region, and an inner region, wherein the atomic percentage of the first metal element in the outer region and the inner region is lower than that in the middle region. The thickness of the radiation confinement layer is 20. 55 μm.

4. The laser fusion target according to claim 3, characterized in that, Along the radial inward direction of the target pellet, the atomic percentage of the first metal element in the radiation confinement layer smoothly increases to a maximum value and then smoothly decreases.

5. The laser fusion target pellet according to claim 3, characterized in that, The first metallic element is gold, tungsten, or tantalum, and the second metallic element is beryllium, aluminum, titanium, or copper.

6. The laser fusion target pellet according to claim 5, characterized in that, The first metallic element is tungsten, and the second metallic element is titanium; the density of the outer region ranges from 4.5 to 7.0 g / cm³. 3 The density range of the intermediate region is 17.0~19.3 g / cm³. 3 The density range of the inner region is 4.5~7.0 g / cm³. 3 .

7. The laser fusion target pellet according to claim 1, characterized in that, The material of the room-temperature solid main fuel layer is deuterated tritium polystyrene, with an initial material density of 1.0~1.2 g / cm³. 3 ;or The room-temperature solid main fuel layer is made of lithium deuterium tritide, with an initial material density of 0.78 ~ 0.82 g / cm³. 3 .

8. The laser fusion target pellet according to claim 1, characterized in that, The thickness of the room-temperature solid main fuel layer is 50 mm. 150 μm.

9. The laser fusion target according to claim 1, characterized in that, The ignition zone is located at the center of the target pellet, and the ignition triggering material is deuterium-tritium gas with an initial gas density of 0.2 ~ 0.22 mg / cm³. 3 .

10. The laser fusion target pellet according to claim 1, characterized in that, The fuse area is spherical with a radius of 1000. 1500 μm.

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