Laser-driven projectile launching structure and method

Abstract

The invention provides a laser-driven projectile launching structure and method. The laser-driven projectile launching structure comprises pulse laser, a shock wave inducing medium, a film and a projectile; the pulse laser irradiates the shock wave inducing medium from one end of the shock wave inducing medium; the thin film is arranged at the other end of the shock wave inducing medium, and the projectile is installed on the side, away from the shock wave inducing medium, of the thin film. According to the invention, the laser-induced plasma can be limited in the glass, so that direct contact between the plasma and a film and a projectile is avoided, direct damage of the plasma to the film and the projectile is prevented, and fragment pollution in a projectile test is effectively avoided. The projectiles are launched under the action of shock waves, and four-time sonic speed launching of ten-micron projectiles and supersonic speed launching of submillimeter projectiles can be achieved. Compared with the prior art, the launcher has the advantages that a metal layer is removed, the structure is simpler, and the launcher is more suitable for bullet impact tests under complex working conditions such as high temperature and vacuum.

Description

Technical Field

[0001] The present invention relates to the field of impact dynamics, and in particular, to a laser-driven projectile launching structure, and in particular, to a laser-driven micro-projectile high-speed launching structure and method. Background Art

[0002] Impacts at high strain rates (>104s-1) are ubiquitous in industry, including extreme protection requirements such as space debris impact and bullet penetration, as well as manufacturing processes such as cold spraying and shot peening. The mechanical behavior of materials shows a strong dependence on strain rate. For example, as the strain rate changes from low (<104s-1) to high (>104s-1), the strain rate sensitivity of metal flow stress increases significantly, and may be accompanied by temperature hardening. Therefore, it is very necessary to study the mechanical properties of materials at high strain rates. High strain rate mechanical property test methods on the macro scale, such as pendulum impact (GB / T 3808-1818), drop hammer impact (GB / T14152-1816) and flat plate impact test, are limited by the acceleration energy and only allow the evaluation of the mechanical properties of macroscopic materials at strain rates less than 104s-1, so they are not suitable for testing requirements that simulate higher strain rate conditions. Laser induced pellet impact testing (LIPIT) is a desktop testing method used to measure the properties of materials at strain rates exceeding 104s-1.

[0003] Previous LIPIT launchers used plasma generated by laser ablation to accelerate microprojectiles (Veysset D, Sun Y, Kooi SE, et al. International journal of impact engineering, 2020, 137: 103465.). The launcher structure includes a transparent glass substrate, an ablation layer and an elastomer. The ablation layer, usually a metal film (sub-micron thick), is attached to a transparent glass substrate (typically 200μm thick). A uniform layer of elastomer (20-80μm thick) is applied to the rear surface of the sacrificial ablation layer. Before testing, the microprojectile is placed on the free surface of the elastomer. The ablation of the sacrificial ablation layer causes the generation of plasma, which rapidly deforms the elastomer layer, thereby propelling and accelerating the projectile to a high speed. The elastomer layer acts as a thermal insulation material, effectively separating the plasma generated by thermal ablation from the projectile, thereby preventing the impact of fragments generated by ablation. However, the defects of the previous LIPIT structure have limited its application to materials or phenomena under high strain rates; at high launch speeds (>400m / s), the size of the projectile is limited to a few microns to tens of microns, which limits the feasible thickness of the penetration test sample to the submicron level. It is necessary to launch larger submillimeter projectiles to achieve penetration testing of films with thickness in the micron range and to achieve impact indentation testing over a wider strain rate range.

[0004] In previous studies, improving the launch performance of LIPIT depends on optimizing the materials of the polymer film. Veysset et al. (D. Veysset, J. Lee, M. Hassani, et al. Applied Physics Reviews, 8 (2021) 011319.) replaced the polymer film of PDMS with a tougher polyurea to achieve a faster launch speed. However, the maximum launch speed of micron-sized projectiles is still limited to about 1.3 km / s, and when the diameter of the silica projectile exceeds 50 μm, the maximum speed drops below the supersonic threshold. These are attributed to the inability of the polyurea film to withstand stronger plasma pressure. Another LIPIT projectile launcher (Veysset D, Sun Y, Kooi SE, et al. International journal of impact engineering, 2020, 137: 103465.) removes the elastomer layer to directly accelerate the projectile, and has been used to achieve projectile speeds of up to 2 km / s. However, this comes at the expense of projectile integrity and fragmentation effects. Akio Yonezu et al. (M. Kajihara, K. Nagaami, T. Miyagawa, T. Kondo, A. Yonezu. Acta Materialia, 262 (2024) 119467.) used 30-micron-thick black tape instead of traditional metal and polymer layers, which has the dual purpose of absorbing laser light and propelling projectile launch. This method simplifies the preparation process of the launcher and maintains a launch speed similar to the previous LIPIT. However, this method is still susceptible to fragmentation effects when the tape is strongly impacted by plasma. Although recent studies have optimized the configuration of the launcher, the basic principle of the launcher for direct plasma-driven film expansion or projectile launch remains unchanged. When impacted by strong plasma, the fragility of elastomeric films continues to limit the size and speed of projectiles that can be launched without fragmentation.

[0005] In summary, the existing technology has technical problems such as difficulty in high-speed launch of submicron projectiles and film breakage pollution under the action of high-voltage plasma. Therefore, it is urgent to develop a laser-driven micro-projectile high-speed launch device and method that can launch submicron projectiles at high speed and avoid film breakage pollution. Summary of the invention

[0006] In view of the defects in the prior art, the object of the present invention is to provide a laser driven projectile launching structure and method.

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

[0008] The pulse laser is irradiated from one end of the shock wave inducing medium to the shock wave inducing medium;

[0009] The film is arranged on the other end of the shock wave inducing medium, and the projectile is installed on the side of the 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 via an adhesive layer, and the thickness of the adhesive layer is less than ten times the thickness of the film.

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

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

[0014] Preferably, the shock wave inducing medium is a closed structure, including an upper cover, side walls and a bottom, the upper cover, side walls and bottom are made of glass, and the upper cover, side walls and bottom 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 pellets are SiO2 balls with a diameter of 7 to 20 μm, Al2O3 balls with a diameter of 25 to 35 μm, soda-lime glass balls with a diameter of 30 to 300 μm, or ZrO2 balls with a diameter of 55 to 65 μm.

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

[0019] According to a laser-driven projectile launching method provided by the present invention, the laser-driven projectile launching structure is adopted, and the method further comprises the following steps:

[0020] The pulsed laser is focused inside the shock wave inducing medium, inducing plasma, which acts on the surrounding medium to generate shock waves. The shock waves drive the film on one side of the shock wave inducing medium, causing the film to peel off and expand, and the projectiles on the surface of the film are launched.

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

[0022] 1. The present invention designs the shock wave inducing medium as a closed structure, which can confine the laser-induced plasma inside the glass, avoid direct contact between the plasma and the film and the projectile, prevent direct damage to the film and the projectile by the plasma, and effectively avoid debris contamination in the projectile test.

[0023] 2. The present invention launches projectiles through the action of shock waves, which can achieve the launch of ten-micron projectiles at four times the speed of sound and the supersonic launch of sub-millimeter projectiles. It is suitable for film penetration tests with wider thicknesses and impact indentation tests with wider strain rates.

[0024] 3. Compared with the prior art, the launcher used in the present invention removes the metal layer, has a simpler structure, and is more suitable for projectile impact testing under complex working conditions such as high temperature and vacuum. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0026] Figure 1 It is a structural schematic diagram of the present invention;

[0027] Figure 2 Comparison of the relationship between the launch speed and laser energy of 10 micron SiO2 pellets of the present invention and the traditional launch method;

[0028] Figure 3 The figure is a comparison of the maximum projectile velocity-projectile mass relationship between the present invention and the traditional launching method.

[0029] The figure shows:

[0030] DETAILED DESCRIPTION

[0031] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0032] Embodiment 1: Embodiment 1 is the basic embodiment 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 film (5) and a projectile 6; in a preferred embodiment, the projectile 6 is a micro-projectile.

[0034] The pulse laser 1 is irradiated from one end of the shock wave inducing medium 2 to the shock wave inducing medium 2; the film 5 is arranged on the other end of the shock wave inducing medium 2, and the pellet 6 is installed on the side of the film 5 away from the shock wave inducing medium 2. In a preferred example, since the volume of the pellet 6 is very small, the pellet 6 can be adsorbed on the bottom surface of the film 5 by its own self-adsorption;

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

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

[0037] The projectile 6 is a rigid glass ball or ceramic ball, and its stiffness coefficient is more than ten times that of the film 5, so as to prevent excessive deformation of the projectile during the film-driven projectile launch and prevent the loss of shock wave energy due to excessive thickness of the adhesion layer. In a preferred embodiment, the film 5 is a black polyimide film with a thickness range of 15 μm-30 μm. In a 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 an upper cover, side walls and a bottom. The upper cover, side walls and bottom are made of glass, and the upper cover, side walls and bottom are connected as one piece. The thickness of the glass is more than five times the size of the breakdown light spot to ensure the necessary conditions for the formation of shock waves and prevent the leakage of plasma. Specifically, the breakdown light spot size is the spot size when the pulsed laser 1 breaks through the shock wave inducing medium 2. In a preferred example, the thickness of the glass is 5mm-10mm.

[0039] The present invention also provides a laser-driven projectile launching method, which adopts the laser-driven projectile launching structure and further comprises the following steps:

[0040] The pulse laser 1 is focused inside the shock wave inducing medium 2, inducing high pressure plasma 3, acting on the surrounding medium to generate shock waves 4, and the shock waves 4 drive the film 5 below the shock wave inducing medium 2 to peel off and expand, and launch the projectile 6 on the surface of the film 5. The surrounding medium is the part of the shock wave inducing medium 2 that is not irradiated by the laser, and can also be understood as the part of the shock wave inducing medium 2 that is not acted upon by the laser.

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

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

[0043] Then, high-speed projectiles are launched by the following method: pulse laser 1 is focused inside the quartz glass, inducing high-pressure plasma 3, acting on the surrounding medium to generate shock waves 4, and shock waves 4 drive the polyimide film 5 under the quartz glass to peel off and expand, and the projectiles 6 on the surface of the polyimide film 5 are launched at a certain speed.

[0044] like Figure 2 As shown, the launch speed of the ten-micron projectile using the technical solution of the present invention can reach up to 4 times the speed of sound, which is about twice as fast as the traditional method. Figure 3 As shown, the technical solution of the present invention is used to achieve supersonic launch of submillimeter projectiles, which can achieve faster launch of larger projectiles compared to traditional methods.

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

[0046] The pulsed laser is focused inside the shock wave inducing medium, inducing high-pressure plasma. The plasma acts on the surrounding medium to generate a spherical shock wave. The shock wave drives the film below the shock wave inducing medium to peel off and expand, and the projectile on the surface of the film is launched at a certain speed.

[0047] In summary, the present invention isolates the direct damage of plasma to the film and the projectile, avoids the breakage of the film when the projectile is fired at high speed, 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 the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0049] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A laser driven projectile launching structure, characterized in that: It comprises a pulse laser (1), a shock wave inducing medium (2), a film (5) and a projectile (6); A pulse laser (1) is irradiated onto the shock wave inducing medium (2) from one end of the shock wave inducing medium (2); The 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 film (5) away from the shock wave inducing medium (2).

2. The laser driven projectile launching structure according to claim 1, characterized in that: The film (5) is a single-layer opaque polymer film.

3. The laser driven projectile launching structure according to claim 1, characterized in that: The film (5) is fixed on the shock wave inducing medium (2) via an adhesive layer, and the thickness of the adhesive layer is less than ten times the thickness of the film (5).

4. The laser driven projectile launching structure according to claim 1, characterized in that: The projectile (6) is a rigid glass ball or a ceramic ball, and its rigidity coefficient is more than ten times the rigidity coefficient of the film (5).

5. The laser driven projectile launching structure according to claim 1, characterized in that: The shock wave inducing medium (2) is glass, and the thickness of the glass is more than five times the size of the breakdown light spot.

6. The laser driven projectile launching structure according to claim 5, characterized in that: The shock wave inducing medium (2) is a closed structure, comprising an upper cover, side walls and a bottom, wherein the upper cover, side walls and bottom are made of glass material, and the upper cover, side walls and bottom are integrally connected.

7. The laser driven projectile launching structure according to claim 5, characterized in that: The film (5) is a black polyimide film with a thickness ranging from 15 μm to 30 μm; The thickness of the glass is 5mm-10mm.

8. The laser driven projectile launching structure according to claim 1, characterized in that: The pellets (6) are SiO2 balls with a diameter of 7 to 20 μm, Al2O3 balls with a diameter of 25 to 35 μm, soda-lime glass balls with a diameter of 30 to 300 μm, or ZrO2 balls with a diameter of 55 to 65 μm.

9. The laser driven projectile launching structure according to claim 3, characterized in that: The adhesive layer is a UV adhesive layer, and the thickness of the adhesive layer is less than 1 μm.

10. A laser-driven projectile launching method, characterized in that: The laser driven projectile launching structure according to any one of claims 1 to 9 further comprises the following steps: A pulsed laser (1) is focused inside a shock wave inducing medium (2), inducing plasma (3), which acts on the surrounding medium to generate a shock wave (4). The shock wave (4) drives a film (5) on one side of the shock wave inducing medium (2), causing the film (5) to peel off and expand, and launching a projectile (6) on the surface of the film (5).

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