Laser-driven projectile launch structure and method

Abstract

The application provides a laser-driven projectile launching structure and method. The laser-driven projectile launching structure comprises a pulsed laser, a shock wave-induced medium, a film and a projectile. The pulsed laser irradiates the shock wave-induced medium from one end of the shock wave-induced medium. The film is arranged on the other end of the shock wave-induced medium, and the projectile is installed on the side of the film away from the shock wave-induced medium. The application can confine the laser-induced plasma in the glass, avoid the direct contact of the plasma with the film and the projectile, prevent the direct damage of the plasma to the film and the projectile, and effectively avoid the fragment pollution in the projectile test. The application can realize the 4 times sound speed launching of the ten-micron projectile and the supersonic launching of the sub-millimeter projectile through the shock wave effect. The launcher adopted by the application removes the metal layer, and the structure is simpler, and is more suitable for the projectile impact test under complex working conditions such as high temperature and vacuum.

Description

Technical Field

[0001] This invention relates to the field of impact dynamics, specifically to a laser-driven projectile launching structure, and more particularly to a structure and method for high-speed laser-driven micro-projectile launching. Background Technology

[0002] High strain rate (>10⁴ s⁻¹) impacts are ubiquitous in industry, including extreme protection requirements such as space debris impacts and bullet penetration, as well as manufacturing processes like cold spraying and shot peening. The mechanical behavior of materials exhibits a strong dependence on strain rate. For example, as the strain rate transitions from low (<10⁴ s⁻¹) to high (>10⁴ s⁻¹), the strain rate sensitivity of metal flow stress increases significantly, and may be accompanied by thermohardening. Therefore, studying the mechanical properties of materials under high strain rates is essential. Macroscopic high strain rate mechanical property testing methods, such as pendulum impact (GB / T 3808-1818), drop hammer impact (GB / T14152-1816), and plate impact tests, are limited by acceleration energy and can only evaluate the mechanical properties of macroscopic materials with strain rates less than 10⁴ s⁻¹, thus unsuitable for simulating testing requirements at higher strain rates. Laser-induced projectile impact testing (LIPIT) is a desktop testing method used to test the properties of materials when the strain rate exceeds 10⁴ s⁻¹.

[0003] Previous LIPIT emitters utilized plasma generated by laser ablation to accelerate micro-projectiles (Veysset D, Sun Y, Kooi SE, et al. International Journal of Impact Engineering, 2020, 137:103465.). The emitter structure consisted of a transparent glass substrate, an ablation layer, and an elastomer. The ablation layer, typically a submicron-thick metal film, was attached to the transparent glass substrate (typically 200 μm thick). A uniform elastomer layer (20-80 μm thick) was applied to the rear surface of the sacrificial ablation layer. Before testing, the micro-projectile was placed on the free surface of the elastomer. The ablation of the sacrificial ablation layer resulted in plasma generation, causing the elastomer layer to deform rapidly, thereby propelling and accelerating the projectile to high speed. The elastomer layer acted as a thermal insulation material, effectively isolating the plasma generated by thermal ablation from the projectile, thus preventing impact from ablation-generated fragments. However, previous limitations of the LIPIT structure restricted its application to materials or phenomena at high strain rates; at high launch velocities (>400 m / s), the size of the projectile was limited to the range of a few micrometers to tens of micrometers, which restricted the feasible thickness of the penetration test sample to the submicrometer level. Launching larger submillimeter-sized projectiles is necessary to enable penetration testing of thin films in the micrometer range and to achieve impact indentation testing over a wider strain rate range.

[0004] Previous studies have focused on optimizing the polymer film material to improve LIPIT launch performance. Veysset et al. (D. Veysset, J. Lee, M. Hassani, et al. Applied Physics Reviews, 8(2021)011319.) replaced the PDMS polymer film with a more robust polyurea to achieve faster launch velocities. However, the maximum launch velocity of micron-sized projectiles remains limited to below approximately 1.3 km / s, and drops below the supersonic threshold when the diameter of the silica projectile exceeds 50 μm. This is attributed to the polyurea film's inability to withstand stronger plasma pressures. Another LIPIT projectile launcher (Veysset D, Sun Y, Kooi SE, et al. International journal of impactengineering, 2020, 137:103465.) removes the elastomer layer to directly accelerate the projectile and has been used to achieve projectile velocities up to 2 km / s. However, this comes at the cost of projectile integrity and fragmentation effects. Akio Yonezu et al. (M. Kajihara, K. Nagaami, T. Miyagaawa, T. Kondo, A. Yonezu. Acta Materialia, 262(2024)119467.) used a 30-micrometer-thick black tape instead of traditional metal and polymer layers for the dual purpose of absorbing laser light and propelling projectiles. This method simplifies the launcher preparation process and maintains a launch velocity similar to the previous LIPIT. However, this method remains susceptible to fragmentation when the tape is subjected to strong plasma impacts. Although recent studies have optimized the launcher configuration, the fundamental principles of direct plasma-driven thin-film expansion or projectile launchers remain unchanged. The fragility of the elastomeric film under strong plasma impacts continues to limit the size and velocity of projectiles that can be launched without fragmentation.

[0005] In summary, existing technologies suffer from challenges such as the difficulty in achieving high-speed launch of submicron projectiles and the risk of film breakage and contamination under high-pressure plasma. Therefore, there is an urgent need to develop a laser-driven device and method for high-speed launch of submicron projectiles while avoiding film breakage and contamination. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a laser-driven projectile launching structure and method.

[0007] A laser-driven projectile launching structure according to the present invention includes a pulsed laser, a shock wave inducing medium, a thin film, and a projectile;

[0008] A pulsed laser is directed from one end of a shock wave-induced medium to the shock wave-induced medium.

[0009] The thin film is disposed on the other end of the shock wave inducing medium, and the projectile is mounted on the side of the thin film away from the shock wave inducing medium.

[0010] Preferably, the film is a single-layer opaque polymer film.

[0011] Preferably, the film is fixed to the shock wave inducing medium by an adhesive layer, the thickness of which is more than ten times the thickness of the film.

[0012] Preferably, the projectile is a rigid glass or ceramic ball with a stiffness coefficient that is more than ten times that of the film stiffness coefficient.

[0013] Preferably, the shock wave inducing medium is glass, and the glass thickness is more than five times the size of the breakdown spot.

[0014] Preferably, the shock wave inducing medium is a closed structure, including a top cover, side walls and a bottom, wherein the top cover, side walls and bottom are made of glass and are integrally connected.

[0015] Preferably, the film is a black polyimide film with a thickness ranging from 15 μm to 30 μm;

[0016] The thickness of the glass is 5mm-10mm.

[0017] Preferably, the projectile is a SiO2 sphere with a diameter of 7-20 μm, an Al2O3 sphere with a diameter of 25-35 μm, a soda-lime glass sphere with a diameter of 30-300 μm, or a ZrO2 sphere with a diameter of 55-65 μm.

[0018] Preferably, the adhesive layer is a UV adhesive layer with a thickness of less than 1 μm.

[0019] According to the laser-driven projectile launching method provided by the present invention, which employs the aforementioned laser-driven projectile launching structure, the method further includes the following steps:

[0020] A pulsed laser is focused inside the shock wave induction medium, inducing plasma, which acts on the surrounding medium to generate a shock wave. The shock wave drives a thin film on one side of the shock wave induction medium, causing the film to peel off and expand, thus launching a projectile from the surface of the film.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. By designing the shock wave induction medium as a closed structure, this invention can confine the laser-induced plasma inside the glass, avoiding direct contact between the plasma and the thin film and the projectile, preventing direct damage to the thin film and the projectile by the plasma, and effectively avoiding fragment contamination during projectile testing.

[0023] 2. This invention launches projectiles using shock waves, enabling the launch of ten-micrometer-level projectiles at four times the speed of sound, as well as the supersonic launch of submillimeter-level projectiles. It is suitable for penetration testing of films with wider thicknesses and impact indentation testing with wider strain rates.

[0024] 3. Compared with existing technologies, the launcher used in this invention has removed the metal layer, making its structure simpler and more suitable for projectile impact testing under complex conditions such as high temperature and vacuum. Attached Figure Description

[0025] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0026] Figure 1 This is a schematic diagram of the structure of the present invention;

[0027] Figure 2 This is a comparison of the velocity-laser energy relationship of a 10-micron SiO2 projectile launched by the present invention and by conventional launching methods;

[0028] Figure 3 This is a comparison of the maximum projectile velocity-projectile mass relationship between the present invention and conventional launching methods.

[0029] The diagram shows:

[0030] Detailed Implementation

[0031] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0032] Example 1: Example 1 is a basic example of the present invention:

[0033] The present invention provides a laser-driven projectile launching structure, comprising a pulsed laser (1), a shock wave inducing medium (2), a thin film (5), and a projectile 6; in a preferred embodiment, the projectile 6 is a micro-projectile.

[0034] A pulsed laser 1 irradiates the shock wave induction medium 2 from one end of the shock wave induction medium 2; the thin film 5 is disposed on the other end of the shock wave induction medium 2, and the projectile 6 is mounted on the side of the thin film 5 away from the shock wave induction medium 2. In a preferred embodiment, since the projectile 6 has a very small volume, it can be adsorbed onto the bottom surface of the thin film 5 by its own self-adsorption.

[0035] Specifically, the pulsed laser 1 irradiates the shock wave inducing medium 2 from above; the thin film 5 is arranged at the bottom of the shock wave inducing medium 2, and the projectile 6 is mounted on the bottom surface of the thin film 5.

[0036] The film 5 is a single-layer opaque polymer film that does not break during projectile launch. The film 5 is fixed to the lower surface of the shock wave inducing medium 2 by an adhesive layer, the thickness of which is more than ten times the thickness of the film 5.

[0037] The projectile 6 is a rigid glass or ceramic sphere with a stiffness coefficient more than ten times that of the film 5. This is to prevent excessive deformation of the projectile during its launch by the film and to prevent energy loss from the shock wave due to an excessively thick adhesive layer. In a preferred embodiment, the film 5 is a black polyimide film with a thickness ranging from 15 μm to 30 μm. In another preferred embodiment, the stiffness coefficient of the projectile 6 is 50 GPa.

[0038] The shock wave inducing medium 2 is glass. Preferably, the shock wave inducing medium 2 is a closed structure, including a top cover, side walls, and a bottom. The top cover, side walls, and bottom are all made of glass and are integrally connected. The glass thickness is more than five times the size of the breakdown spot to ensure the necessary conditions for shock wave formation and prevent plasma leakage. Specifically, the size of the breakdown spot is the spot size when the pulsed laser 1 breaks down the shock wave inducing medium 2. In a preferred embodiment, the thickness of the glass is 5mm-10mm.

[0039] The present invention also provides a laser-driven projectile launching method, which, using the aforementioned laser-driven projectile launching structure, further includes the following steps:

[0040] A pulsed laser 1 is focused inside the shock wave induction medium 2, inducing high-pressure plasma 3, which acts on the surrounding medium to generate a shock wave 4. The shock wave 4 drives the thin film 5 beneath the shock wave induction medium 2 to peel off and expand, launching projectiles 6 from the surface of the thin film 5. The surrounding medium refers to the portion of the shock wave induction medium 2 that is not irradiated by the laser, or in other words, the portion of the shock wave induction medium 2 that is not interacted with by the laser.

[0041] Example 2: Example 2 is a specific embodiment of the present invention:

[0042] like Figure 1As shown, 8mm thick quartz glass is used as the shock wave inducing medium 2, and a 25μm thick black polyimide film is used as the film 5. The polyimide film 5 is bonded to the quartz glass with a UV adhesive less than 1μm thick. The projectile 6 is made of SiO2 spheres with a diameter of 7-20μm, Al2O3 spheres with a diameter of 25-35μm, soda-lime glass spheres with a diameter of 30-300μm, and ZrO2 spheres with a diameter of 55-65μm, etc., for backup launch.

[0043] Then, high-speed projectiles are launched by focusing a pulsed laser 1 inside the quartz glass, inducing high-pressure plasma 3, which acts on the surrounding medium to generate a shock wave 4. The shock wave 4 drives the polyimide film 5 under the quartz glass to peel off and expand, launching the projectile 6 on the surface of the polyimide film 5 at a certain speed.

[0044] like Figure 2 As shown, the projectile launched using the technical solution of this invention can reach a maximum speed of four times the speed of sound, which is about twice that of traditional methods. Figure 3 As shown, the present invention enables supersonic launch of submillimeter projectiles, achieving faster launch speeds for larger projectiles compared to traditional methods.

[0045] The working principle of this invention is as follows:

[0046] A pulsed laser is focused inside the shock wave-induced medium to induce high-pressure plasma. The plasma acts on the surrounding medium to generate a spherical shock wave. The shock wave drives the thin film beneath the shock wave-induced medium to peel off and expand, launching a projectile from the surface of the thin film at a certain speed.

[0047] In summary, this invention isolates the thin film and the projectile from direct damage by plasma, avoids the breakage of the thin film during high-speed projectile launch, has a simple structure, is suitable for complex working conditions such as high temperature and vacuum, can be used for high strain rate ballistic testing of materials, and effectively avoids debris contamination during testing.

[0048] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and 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 application.

[0049] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A laser-driven projectile launching structure, characterized in that, It includes a pulsed laser (1), a shock wave induced medium (2), a thin film (5), and a projectile (6); A pulsed laser (1) is irradiated from one end of a shock wave induced medium (2) into the shock wave induced medium (2); The thin film (5) is arranged on the other end of the shock wave inducing medium (2), and the projectile (6) is installed on the side of the thin film (5) away from the shock wave inducing medium (2); The film (5) is a single-layer opaque polymer film; The film (5) is fixed to the shock wave inducing medium (2) by an adhesive layer, the thickness of which is less than ten times the thickness of the film (5); The shock wave inducing medium (2) is glass, and the thickness of the glass is more than five times the size of the breakdown spot. The shock wave inducing medium (2) is a closed structure, including a top cover, side walls and bottom. The top cover, side walls and bottom are all made of glass, and the top cover, side walls and bottom are integrally connected. The film (5) is a black polyimide film with a thickness ranging from 15μm to 30μm; The thickness of the glass is 5mm-10mm.

2. The laser-driven projectile launching structure according to claim 1, characterized in that, The projectile (6) is a rigid glass or ceramic ball with a stiffness coefficient that is more than ten times that of the film (5).

3. The laser-driven projectile launching structure according to claim 1, characterized in that, The projectile (6) is a SiO2 ball with a diameter of 7~20 μm, an Al2O3 ball with a diameter of 25~35 μm, a sodium-calcium glass ball with a diameter of 30~300 μm, or a ZrO2 ball with a diameter of 55~65 μm.

4. The laser-driven projectile launching structure according to claim 1, characterized in that, The adhesive layer is a UV adhesive layer with a thickness of less than 1 μm.

5. A laser-driven projectile launching method, characterized in that, The laser-driven projectile launching structure according to any one of claims 1 to 4 further includes the following steps: A pulsed laser (1) is focused inside the shock wave induction medium (2) to induce plasma (3), which acts on the surrounding medium to generate a shock wave (4). The shock wave (4) drives the thin film (5) on one side of the shock wave induction medium (2), causing the thin film (5) to peel off and expand, and to launch the projectile (6) on the surface of the thin film (5).

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