Quasi-isentropic compression device and method indirectly driven by laser

Abstract

The invention provides a quasi-isentropic compression device and method indirectly driven by laser, and the device comprises a column cavity, a film and a sample platform, the cylindrical cavity is provided with a laser injection hole and a loading hole, and the film covers the loading hole; a vacuum gap is formed between the thin film and the sample platform; the sample platform is used for placing a to-be-loaded sample; according to the device and the method, the compression state that the peak pressure intensity reaches million barometric pressure, the strain rate is higher than 107 / s and the interface temperature rise is about 1500K can be realized, and the condition that the interface Rayleigh-Taylor instability growth of a high-density sample is promoted by a low-density medium is met, so that an experimental technical basis is provided for material physical property research under extreme conditions.

Description

Technical Field

[0001] This invention relates to the field of high-pressure physics technology, and more specifically, to a laser-indirectly driven quasi-isentropic compression device and method. Background Technology

[0002] Studying the physical properties of materials under extreme high pressure conditions is an important direction in the field of high pressure physics. In particular, it is necessary to effectively separate the pressure and temperature effects during the loading process in order to obtain the equation of state data close to the room temperature compression line under the off-hugoniot loading path, the high pressure constitutive relationship of solid metals, and to carry out experimental research on interface Rayleigh-Taylor instability.

[0003] In the study of equations of state, impact compression is the primary method for achieving extreme high pressure, high density, and high temperature states in the laboratory. However, the steep impact loading path, accompanied by a significant temperature rise, leads to a strong coupling between pressure and temperature effects, resulting in the measured Hugoniot equation of state being only an "incomplete equation of state." To more accurately describe the physical behavior of materials under high pressure, it is necessary to develop quasi-isentropic compression techniques with high compression and low temperature rise to achieve a loading process that more closely approximates an isothermal or isentropic path.

[0004] In the study of material strength, to obtain the constitutive behavior of solid metals under high pressure, it is essential to ensure that they remain solid throughout the loading process without melting to reflect their strength characteristics. Practical engineering problems often involve high strain rates, high pressures, and strong shear deformations. Research indicates that experimental methods based on interfacial Rayleigh-Taylor instability growth are effective means of obtaining material strength under high strain rates and high pressures. Therefore, there is an urgent need to develop a quasi-isentropic loading technique that can simultaneously achieve high peak pressure, high strain rate, and satisfy the Rayleigh-Taylor instability growth condition.

[0005] Quasi-isentropic compression, through a relatively gentle loading path, allows materials to achieve high compression with minimal temperature rise, more closely resembling a reversible compression process, making it an ideal experimental method for conducting the aforementioned research. Currently commonly used quasi-isentropic compression techniques mainly include two-stage light gas gun impedance gradient flyplate loading, vacuum cavity detonation loading, and magnetically driven loading. However, existing methods still have the following main limitations: 1) It is difficult to maintain a strain rate above 10 while achieving a peak pressure of over 100 GPa. 7 The pressure is quasi-isentropic compression at / s. The typical pressure of a second-stage light gas gun is tens of GPa, and the strain rate is approximately 10. 5 / s~10 6 / s; the pressure level of vacuum chamber detonation loading is comparable, but the strain rate is typically below 10. 5 / s; Although magnetically driven loading can reach pressures on the order of 100 GPa, its strain rate is generally still below 10.7 / s.

[0006] 2) It is difficult to effectively construct interface conditions suitable for Rayleigh-Taylor instability experiments. These experiments require achieving an interface configuration where a low-density medium drives a high-density metal sample under high pressure to induce instability growth. Traditional loading methods have significant limitations in this regard, restricting the development of related experiments.

[0007] Currently, laser-driven technology has the capability to generate pressures exceeding 100 GPa and strain rates exceeding 10. 7 The laser loading capacity of / s is highly promising. However, conventional laser loading typically exhibits strong impact characteristics, with steep paths and significant temperature rises, easily leading to sample melting and failing to meet the quasi-isentropic requirements. Furthermore, the preheating effect of high-energy rays accompanying the laser-driven process preheats the sample before the arrival of the main loading wave, further exacerbating the risk of melting and thus disrupting the experimental conditions where the metallic sample remains in a solid state.

[0008] Therefore, there is an urgent need to develop a new laser-driven loading technology that can achieve higher peak pressure and higher strain rate while maintaining good quasi-isentropic compression characteristics and meeting the requirements of Rayleigh-Taylor instability experiments on solid-state metal interfaces for interface state, so as to support more in-depth research on high-pressure properties and material strength. Summary of the Invention

[0009] To overcome the shortcomings of existing laser loading techniques, which suffer from excessively high sample temperature rise and easy melting due to their inherent impact loading characteristics, and whose accompanying X-ray preheating further disrupts the low temperature rise and solid-state conditions required for quasi-isentropic compression, this invention provides a laser-indirectly driven quasi-isentropic compression device and method, capable of achieving peak pressures up to one million atmospheres (100 GPa) and strain rates higher than 10. 7 The compression state with an interface temperature rise of about 1500K and the conditions for the growth of Rayleigh-Taylor instability of the interface of the low-density medium driving the high-density sample are met, thus providing an experimental technical basis for the study of material properties under extreme conditions.

[0010] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: In a first aspect, the present invention provides a laser-indirectly driven quasi-isentropic compression device, comprising: a cylindrical cavity, a thin film, and a sample platform; The cylindrical cavity is provided with a laser injection hole and a loading hole, and the thin film covers the loading hole; A vacuum gap is provided between the thin film and the sample platform; the sample platform is used to place the sample to be loaded.

[0011] Preferably, the column cavity is a single-end injection structure or a double-end injection structure; When the cylindrical cavity is a single-end injection structure, there is one laser injection hole, which is located at one end of the cylindrical cavity; there is one loading hole, which is located at the other end of the cylindrical cavity. When the cylindrical cavity is a double-ended injection structure, there are two laser injection holes, which are respectively opened at both ends of the cylindrical cavity; there is one loading hole, which is opened on the side wall of the cylindrical cavity.

[0012] Preferably, the material of the column cavity is gold or uranium.

[0013] Preferably, the material of the film is a halogen-doped hydrocarbon polymer film.

[0014] Preferably, the halogen is bromine.

[0015] Preferably, the sample to be loaded is a composite sample of a metal thin film and a lithium fluoride crystal impedance matching.

[0016] Preferably, the apparatus further includes a measuring device for measuring the interface particle velocity of the sample to be loaded.

[0017] Preferably, the measuring device is a VISAR (Velocity Interferometer with Arbitrary Reflecting Surface).

[0018] Secondly, the present invention also provides a laser-indirectly driven quasi-isentropic compression method, which, using the above-mentioned apparatus, includes the following steps: A laser is injected into the cylindrical cavity through the laser injection hole, and an X-ray radiation field is generated through the loading hole; The thin film is ablated using the X-ray radiation field to generate plasma jets. The plasma jet is made to fly across the vacuum gap, thus undergoing momentum broadening; Quasi-isentropic compression is achieved by impacting the sample to be loaded with a plasma jet that has undergone momentum broadening.

[0019] Preferably, the method further includes: The interface particle velocities of the sample to be loaded are measured using an arbitrary reflective surface velocity interferometer (VISAR) to invert the historical loading path of the quasi-isentropic compression.

[0020] Compared with the prior art, the beneficial effects of the technical solution of the present invention are: This invention provides a laser-indirectly driven quasi-isentropic compression device and method, wherein the device includes: a column cavity, a thin film, and a sample platform; the column cavity is provided with a laser injection hole and a loading hole, and the thin film covers the loading hole; a vacuum gap is provided between the thin film and the sample platform; the sample platform is used to place the sample to be loaded.

[0021] The beneficial effects of this invention are as follows: 1) Achieving a breakthrough in compressive performance: This invention significantly improves energy conversion efficiency by optimizing the energy coupling path between the laser and the target, enabling the peak pressure acting on the metal sample to stably exceed 100 GPa, while the strain rate remains consistently above 10. 7 / s. This technical indicator not only far exceeds the capabilities of traditional loading methods (such as two-stage light gas guns, detonation loading, etc.), but also surpasses existing laser direct-drive schemes. It solves the core bottleneck in the field of quasi-isentropic compression where peak pressure and high strain rate are difficult to balance, and provides an unprecedented experimental platform for studying the dynamic behavior of materials under extreme conditions.

[0022] 2) Comprehensive optimization of compression quality ensures high fidelity and high controllability of the process. The core contribution of this invention lies in the systematic elimination of the preheating effect, guaranteeing pure solid-state loading. Specifically, it adopts an indirect driving path of "laser-X-ray-ablation plasma," firstly avoiding the preheating of the sample by high-energy particles such as superthermal electrons in direct driving; furthermore, by doping the thin film with halogen elements, it effectively shields the sample from the preheating of the sample by M-band high-energy photons in soft X-rays. These two shielding mechanisms work together to successfully suppress the sample interface temperature rise to below approximately 1500K, ensuring that the metal sample remains solid under high pressure, avoiding strength failure and entropy increase caused by melting, thereby significantly improving the isentropic nature of the compression path. In addition, the laser energy undergoes multiple absorptions and re-emissions within the cylinder cavity, naturally forming a highly uniform X-ray radiation field, overcoming the problem of uneven laser focal spot energy distribution in direct driving, achieving high spatial uniformity of pressure on the sample loading surface, and laying a solid foundation for obtaining reliable one-dimensional strain loading data.

[0023] 3) The invention possesses fundamental innovation and broad applicability in its technical approach and structural design. The proposed "thin film / vacuum gap / sample to be loaded" tandem target structure is key to achieving the aforementioned high-performance indicators. This structure broadens the momentum of the ablation plasma through the vacuum gap, cleverly shaping the initial impact loading into a smooth, continuously rising quasi-isentropic pressure wave. This design differs from all existing technologies in principle; it is not only the core of obtaining high pressure and high strain rate but also actively creates a specific interface state of "low-density medium driving a high-density sample," thereby satisfying the physical conditions for Rayleigh-Taylor instability growth. This allows the invention to transcend the scope of simple state equation measurement, enabling direct application to experimental research on higher-order scientific problems such as the evolution of solid-state metal interface instability and the constitutive strength of materials, providing crucial, multi-parameter experimental data support for verifying and constructing advanced constitutive models. Attached Figure Description

[0024] Figure 1This is a structural diagram of a laser-indirectly driven quasi-isentropic compression device provided in Example 1.

[0025] Figure 2 This is a structural diagram of the quasi-isentropic compression device with a single-end injection structure cylinder provided in Example 2.

[0026] Figure 3 This is a structural diagram of the quasi-isentropic compression device with a double-ended injection structure cylinder provided in Example 2.

[0027] Figure 4 This is a flowchart of a laser-driven quasi-isentropic compression method provided in Example 3.

[0028] Figure 5 The figure shows the experimental results of a laser-driven quasi-isentropic compression method provided in Example 3.

[0029] Figure 6 The diagram shows the experimental results of the prior art provided in Example 3. Detailed Implementation

[0030] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this application. To better illustrate this embodiment, some parts in the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions; It will be understood by those skilled in the art that certain well-known structures and their descriptions may be omitted in the accompanying drawings.

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] Example 1 like Figure 1 As shown, this embodiment provides a laser-indirectly driven quasi-isentropic compression device, including: a cylindrical cavity, a thin film, and a sample platform; The cylindrical cavity is provided with a laser injection hole and a loading hole, and the thin film covers the loading hole; A vacuum gap is provided between the thin film and the sample platform; the sample platform is used to place the sample to be loaded.

[0033] In the specific implementation process, the laser is first injected into the column cavity through the laser injection hole, and an X-ray radiation field is generated through the loading hole; Using X-ray radiation to ablate thin films and generate plasma jets; To cause the plasma jet to fly across the vacuum gap and undergo momentum broadening; Finally, the plasma jet, after momentum broadening, impacts the sample to be loaded to achieve quasi-isentropic compression.

[0034] Example 2 This embodiment provides a laser-indirectly driven quasi-isentropic compression device, including: a cylindrical cavity, a thin film, and a sample platform; The cylindrical cavity is provided with a laser injection hole and a loading hole, and the thin film covers the loading hole; A vacuum gap is provided between the thin film and the sample platform; the sample platform is used to place the sample to be loaded. In this embodiment, the column cavity is a single-end injection structure or a double-end injection structure; like Figure 2 As shown, when the cylindrical cavity is a single-end injection structure, there is one laser injection hole, which is located at one end of the cylindrical cavity; and there is one loading hole, which is located at the other end of the cylindrical cavity. like Figure 3 As shown, when the cylindrical cavity is a double-ended injection structure, there are two laser injection holes, which are respectively opened at both ends of the cylindrical cavity; there is one loading hole, which is opened on the side wall of the cylindrical cavity. In this embodiment, the material of the column cavity is specifically gold; In this embodiment, the material of the thin film is specifically a halogen-doped hydrocarbon polymer thin film; In this embodiment, the halogen is specifically bromine; In this embodiment, the sample to be loaded is specifically a composite sample of metal thin film and lithium fluoride crystal impedance matching. In this embodiment, the device further includes: a measuring device for measuring the interface particle velocity of the sample to be loaded; In this embodiment, the measuring device is specifically a VISAR (Velocity Interferometer with Arbitrary Reflecting Surface).

[0035] In practical implementation, the device (target structure) of this embodiment includes: 1) Gold column cavity: A pure gold column cavity with a wall thickness of 50~80μm is used. For single-end injection, such as... Figure 2 As shown, the upper end of the gold column cavity has a circular laser injection hole, and the lower end has a rectangular loading hole; during double-end injection, as... Figure 3 As shown, circular laser injection holes are opened at the upper and lower ends of the gold column cavity, and rectangular loading holes are opened on the side wall; 2) A bromine-doped hydrocarbon thin film, approximately 200 μm thick; 3) Vacuum gap, approximately 400 μm wide; 4) Metal thin film / lithium fluoride crystal impedance matching composite sample; 5) Arbitrary reflector velocity interferometer (VISAR) is used to measure the particle velocity at the interface of composite samples, thereby measuring the loading history of the quasi-isentropic driving source; First, the laser is injected into the column cavity through the laser injection hole, and an X-ray radiation field is generated through the loading hole; Using X-ray radiation to ablate thin films and generate plasma jets; To cause the plasma jet to fly across the vacuum gap and undergo momentum broadening; Quasi-isentropic compression is achieved by impacting the sample to be loaded with a plasma jet after momentum broadening. Finally, the interface particle velocities of the sample to be loaded are measured using an arbitrary reflective surface velocity interferometer (VISAR) to invert the historical loading path of the quasi-isentropic compression.

[0036] Example 3 like Figure 4 As shown, this embodiment provides a laser-indirectly driven quasi-isentropic compression method, using the apparatus in Embodiment 2, and includes the following steps: S1: Injecting laser light into the cylindrical cavity from the laser injection hole and generating an X-ray radiation field through the loading hole; S2: The thin film is ablated using the X-ray radiation field to generate plasma jets; S3: The plasma jet is made to fly across the vacuum gap, and its momentum is broadened; S4: Quasi-isentropic compression is achieved by impacting the sample to be loaded with the plasma jet after momentum broadening; S5: Measure the interface particle velocity of the sample to be loaded using an arbitrary reflective surface velocity interferometer (VISAR) to invert the historical loading path of the quasi-isentropic compression.

[0037] In its specific implementation, this embodiment provides an advanced laser-driven quasi-isentropic compression technology. Its core lies in constructing a complete and controllable technical path from laser energy injection to the generation of a high-quality quasi-isentropic compression state through a series of synergistic technical steps, ultimately achieving a peak pressure greater than 100 GPa and a strain rate greater than 102. 7 A quasi-isentropic compression process of / s.

[0038] This method is based on indirect laser driving. First, multiple high-energy laser beams are injected into a cylindrical cavity made of a high atomic number material (such as gold). The laser is absorbed by the inner wall of the cavity and converted into a soft X-ray radiation field with a peak radiation temperature of over 130 eV. This process transforms the non-uniform laser energy into a spatially uniform X-ray source, laying the foundation for subsequent uniform loading.

[0039] Next comes the crucial steps of radiation ablation and preheating shielding. The cylinder surface has loading holes and is covered with a hydrocarbon film hundreds of micrometers thick, intentionally doped with high atomic number elements such as bromine. When a uniform X-ray radiation field ablates this film, it unloads at the downstream interface, forming a low-density plasma jet. The doped bromine plays a key role, effectively shielding high-energy rays (such as M-band X-rays) generated during laser-driven processes, preventing them from penetrating the film and preheating the subsequent sample. This avoids melting the sample due to preheating, ensuring the metal sample remains solid during the experiment.

[0040] To achieve a smooth transition from shock wave to quasi-isentropic compressive wave, this method also introduces a momentum broadening mechanism for the vacuum gap. A vacuum gap with a width of several hundred micrometers is set behind the doped hydrocarbon film, the distance of which is maintained by a precision support frame, and the entire system is kept below 10... -2 In a vacuum environment of Pa, as the low-density plasma jet passes through this vacuum gap, the momentum distribution of its internal matter is fully broadened longitudinally, and the originally steep velocity and density profiles are naturally smoothed, forming a gently sloping mechanical driving source.

[0041] The plasma, after momentum broadening, then achieves quasi-isentropic compression of the sample. It impacts the sample to be loaded (e.g., a composite sample consisting of an aluminum thin film and a lithium fluoride crystal window) placed behind the vacuum gap, efficiently converting kinetic energy into the sample's internal energy. This loading process causes the pressure at the sample's front interface to rise along a smooth, uninterrupted path, effectively avoiding impact jumps and achieving near-isentropic compression. During this process, the sample interface temperature rise is successfully suppressed to approximately 1500 K, consistently below the melting temperature of aluminum under high pressure, ensuring the material's solid-state properties. To ensure the quality of experimental data, the surface roughness of the metal thin film needs to be controlled to the tens of nanometers level, and there should be no bubbles or pores at the window interface; this can be achieved through advanced processes such as magnetron sputtering.

[0042] Finally, to accurately characterize the properties of this quasi-isentropic driving source, this method employs in-situ measurement techniques. An arbitrary reflector velocity interferometer (VISAR) is deployed behind the sample to be loaded. As the compression wave propagates within the sample, VISAR precisely measures the particle velocity history at the sample's rear interface or the sample / window interface. Through inversion analysis of this velocity history data, the loading path (pressure-time relationship) of the driving source can be accurately obtained, providing a direct and reliable basis for verifying the quality of quasi-isentropic compression and optimizing experimental parameters.

[0043] To verify the effectiveness of this method, this embodiment also provides a verification experiment. Specifically, 41 laser beams with a total energy of 32.8 kJ (or within the range of 32.8 kJ to 41 kJ) and a pulse width of 1 ns are injected into a gold column cavity (this experiment uses...). Figure 3 Taking the double-ended injection structure as an example, a uniform X-ray radiation field is formed to ablate the bromine-doped hydrocarbon film. The resulting low-density plasma flies across the vacuum gap, shaping the loading process on the aluminum film / lithium fluoride crystal composite sample into a smoothly rising pressure curve. This quasi-isentropic compression wave ultimately acts on the metal film sample, compressing it within a time frame on the order of tens of nanoseconds.

[0044] By setting an arbitrary reflective surface velocity interferometer (VISAR) behind a lithium fluoride crystal, the particle velocity at the aluminum thin film / lithium fluoride crystal interface was measured using VISAR. The quasi-isentropic compressed raw measurement data are as follows: Figure 5 As shown in (a); subsequently, the pressure data of the aluminum film front interface (loading surface) is obtained by inversion, thereby realizing in-situ measurement of the quasi-isentropic driving source loading path, as shown in (a). Figure 5 As shown in (b) and (c), Figure 5 In the middle (b), the experimental data (solid line) and the calculation results (dashed line) of the particle velocity at the aluminum thin film / lithium fluoride crystal interface are presented. Figure 5 In the middle (c), the experimental data (solid line) and the calculation results (dashed line) of the front interface pressure of the aluminum film are shown. Figure 5 Both (b) and (c) show that this method achieves quasi-isentropic loading (from 20 ns to 55 ns) for a duration of up to 35 ns. The peak pressure generated in the sample by this method can reach 130 GPa, and no impact is formed during the compression process, indicating that it is a high-quality quasi-isentropic compression.

[0045] Meanwhile, this embodiment uses a laser-driven hydrocarbon thin film disclosed in the prior art as a comparison, such as... Figure 6 As shown in (a) and (b), these are the original VISAR measurement images and schematic diagrams of the pressure on the loading surface of the aluminum thin film sample, respectively. Figure 6 It can be seen that by directly irradiating brominated polystyrene films with two 3ns pulse width lasers, the peak loading pressure on aluminum film samples is only 70GPa, and the quasi-isentropic loading duration reaches 12ns (from 22ns to 34ns). By comparing with existing technologies, the significant advantages of this method in peak pressure, waveform smoothness (representing the degree of quasi-isentropic loading), and isentropic compression duration can be verified.

[0046] The same or similar labels correspond to the same or similar parts; The terms used to describe positional relationships in the accompanying drawings are for illustrative purposes only and should not be construed as limiting this application. Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A laser-indirectly driven quasi-isentropic compression device, characterized in that, include: Column cavity, thin film, and sample platform; The cylindrical cavity is provided with a laser injection hole and a loading hole, and the thin film covers the loading hole; A vacuum gap is provided between the thin film and the sample platform; the sample platform is used to place the sample to be loaded.

2. The laser-indirectly driven quasi-isentropic compression device according to claim 1, characterized in that, The column cavity can be a single-end injection structure or a double-end injection structure; When the cylindrical cavity is a single-end injection structure, there is one laser injection hole, which is located at one end of the cylindrical cavity; there is one loading hole, which is located at the other end of the cylindrical cavity. When the cylindrical cavity is a double-ended injection structure, there are two laser injection holes, which are respectively opened at both ends of the cylindrical cavity; there is one loading hole, which is opened on the side wall of the cylindrical cavity.

3. The laser-indirectly driven quasi-isentropic compression device according to claim 1, characterized in that, The material of the column cavity is specifically gold or uranium.

4. The laser-indirectly driven quasi-isentropic compression device according to claim 1, characterized in that, The material of the film is specifically a halogen-doped hydrocarbon polymer film.

5. The laser-indirectly driven quasi-isentropic compression device according to claim 4, characterized in that, The halogen is specifically bromine.

6. The laser-indirectly driven quasi-isentropic compression device according to claim 1, characterized in that, The sample to be loaded is specifically a composite sample of a metal thin film and a lithium fluoride crystal impedance matching.

7. A laser-indirectly driven quasi-isentropic compression device according to any one of claims 1 to 6, characterized in that, The apparatus further includes a measuring device for measuring the interface particle velocity of the sample to be loaded.

8. The laser-indirectly driven quasi-isentropic compression device according to claim 7, characterized in that, The measuring device is specifically a VISAR (Velocity Interferometer with Arbitrary Reflecting Surface).

9. A laser-indirectly driven quasi-isentropic compression method, using the apparatus described in any one of claims 1 to 8, characterized in that, Includes the following steps: A laser is injected into the cylindrical cavity through the laser injection hole, and an X-ray radiation field is generated through the loading hole; The thin film is ablated using the X-ray radiation field to generate plasma jets. The plasma jet is made to fly across the vacuum gap, thus undergoing momentum broadening; Quasi-isentropic compression is achieved by impacting the sample to be loaded with a plasma jet that has undergone momentum broadening.

10. A laser-indirectly driven quasi-isentropic compression method according to claim 9, characterized in that, The method further includes: The interface particle velocities of the sample to be loaded are measured using an arbitrary reflective surface velocity interferometer (VISAR) to invert the historical loading path of the quasi-isentropic compression.

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