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As the space environment has deteriorated, it is necessary to monitor the impact events of space debris on orbiting spacecraft. The PVDF piezoelectric film release charge by the impact and its response is fast. The rest of the PVDF film can be re-measured. It can be used to detect space debris impacting spacecraft events, which has obvious advantages in real-time space detection and sensing. In this paper, penetration and cratering experiments of the target were carried out. The projectile directly high-speed impacted the target with PVDF piezoelectric film by the light gas gun loading. The results show that the relationship between damage mode and response characteristics is obtained. Based on the time-of-flight method, the velocity of the projectile and the time of action in the target are analyzed. The response signals of the penetration and cratering experiments are compared and analyzed, which can be used to identify the damage mode of the target plate.

Aluminum honeycomb framework reinforced Al/PTFE material is a kind of high inert energetic material, which has higher strength and structure advantages than that of pure Al/PTFE material. In order to meet the requirements of special penetration/blasting performance, this paper adds aluminum honeycomb framework with arm length of 1.5 mm into the traditional formula Al/PTFE (mass percentage of Al and PTFE is 26.5% and 73.5%). The energetic material reinforced by aluminum honeycomb framework (20.5% Al/73.5% PTFE/6% aluminum honeycomb) is obtained by cold pressing sintering，and the experimental evaluation of release energy generated by high velocity impact in vacuum was performed by using two-stage light gas gun loading system, transient optical fiber pyrometer measurement system, overpressure measurement system and infrared thermal imager measurement system. Experimental results show that the impact reaction temperature is about 700 °C in vacuum in the velocity range of 0.96–1.5 km/s, and the energy release of the specimen increases with the increase of impact velocity. When the impact velocity is greater than 1.5 km/s, the specimen fully reacts, and the energy released by the complete reaction of the specimen does not exceed 8.3 kJ/g.

To profoundly reveal the protective performance of CFRP/aluminum foam sandwich structure, the high-speed impact simulation models of CFRP, aluminum foam and their sandwich structures are built by ABAQUS/Explicit module. The VUMAT user material subroutine is written for CFRP panel, and Hashin damage criterion is introduced. The elastic constitutive model and macro modeling method for the aluminum foam are chosen. The impact process under different working conditions is numerically simulated and the reliability of the model is verified by one-stage light gas gun loading experiment at the corresponding simulation conditions. At the same time, the protective performance of CFRP/ aluminum foam sandwich structure under different steel projectile shapes, impact velocities and impact angles (the angle between the ballistic and the target normal line) are simulated. The results show that the Mises stress nephogram of CFRP panel is peanut-like with obvious directivity. The stress wave propagates fastest in the direction perpendicular to the fiber. In the impact velocity range of 172−450 m/s, with the increase of impact velocities, the loss of kinetic energy will increase, but the increase of kinetic energy loss will decrease with the increase of impact velocities, and the contact force between the projectile and the sandwich structure will also increase. Thus the sandwich structure will have more serious delamination and fiber breakage, which will consume more kinetic energy. When the velocity of the projectile is greater than 300 m/s, the impact capability of the sandwich structure tends to the upper limit of impact capacity. In the impact velocity range of 170∼300m/s, the sandwich structure has stronger protective performance than ball-nosed projectile when the flat-nosed projectile impact, and the difference of the residual velocity between the two kinds of projectiles is larger. The shape of the projectile has a great influence on the protective performance of the CFRP/ aluminum foam sandwich structure. When the impact velocity is greater than 300m/s, the residual velocities of the two kinds of projectiles are almost the same, and the shapes of the projectile have a gradual effect on the performances of the CFRP/ aluminum foam sandwich structure. The anti-shock performance of sandwich structure under oblique impact is stronger than that of vertical impact. With the increase of impact angles, the transverse deformation of sandwich structure increases, and the anti-shock performance of sandwich structure also increases.

In view of the objective reality that it takes a long time for debris to locate the impact point when debris impacts the spacecraft bulkhead, timely and accurate determination of the location of the impact source is the premise and basis for damage repair, which is of great significance to the safety of astronauts. In this paper, the experiments of 2A12 aluminium plate impacted by 2A12 aluminium projectile under different impact parameters have been performed by using the self-built acoustic emission testing system and two-stage light gas gun loading system. The calculated coordinates are compared with the experimental coordinates by using triangular positioning method, quadrilateral positioning method and acoustic emission (AE) signal processing method based on Wavelet transform. The experimental results show that the positioning accuracy of quadrilateral positioning method is better than that of triangular positioning method, and the acoustic emission signal processing method based on wavelet transform is obviously better than that of quadrilateral positioning method.

In order to deeply reveal the microscopic damage mode and microscopic damage mechanism of Carbon Fiber Reinforced Plastic laminates (CFRP laminates) impacted vertically by the ice projectile at high velocity. In this paper, the loading system of the one-stage light gas gun, the liquid nitrogen circulating cooling system, the impact pressure measuring system and the high speed camera acquisition system are used, and the experiments of the spherical ice projectile (simulated hail ice, SHI) with diameter of 11 mm impacting CFRP laminates vertically at the velocity of 50-200 m/s were carried out. The impact pressure of the SHI impacting the target, the strain of X-Y in the two main directions at the impact point were measured, and the deflection/ time history curve at the impact point during the impact process was obtained. By using ABAQUS/Explicit finite element software, the numerical simulation of high-velocity vertical impact of SHI on CFRP laminates was compared with the image acquisition results of the high speed camera at different moments during the impact process, and the failure morphology and process of SHI was analyzed. At the same time, the delamination of the target obtained by numerical simulation is compared with the cracking of the CFRP fiber reinforcement and the delamination of the epoxy resin interface obtained by microscopic SEM observation, the correctness of using cohesion model to describe the micro-damage of CFRP laminates induced by SHI impacting vertically at high speed was verified. The damage failure threshold of CFRP laminates under the impact load of SHI under given experimental conditions was obtained. By establishing a three-point simply supported physical model, the ultimate deflection of laminated plates subjected to delamination failure was analyzed. Based on the measurement of strain and deflection at impact point, the valuable reference for the prediction of delamination failure in CFRP laminates can be provided, then the detection of the micro-damage to the surface composite part of the aircraft will be realized by the control of the sensor. Keywords: CFRP laminates, Cohesion model of ice projectiles, Microscopic damage model, Microscopic damage mechanism, Delamination failure prediction

Aluminum/Polytetrafluoroethylene (Al/PTFE) reactive material occurs chemical reaction and release a large amount of energy under the impact load, which has the dual characteristics of strength and energy release, so it can be applied to the attack of confined space targets to enhance the damage effect on the target. In order to study the dynamic strength of enhanced Al/PTFE and the real-time impact release energy, based on the traditional formula Al/PTFE (26.5%/73.5%), enhanced Al/PTFE reactive material specimens were prepared by cold pressing and rapid cooling processes, and the dynamic mechanical properties of the specimens were tested by the Split Hopkinson Pressure Bar (SHPB) testing system. The experiments have been conducted by using two-stage light gas gun loading system combining with the impact release energy related testing system under vacuum condition. Meanwhile, the evolutionary process of reaction product was numerically simulated by ANSYS/Fluent, and the boundary conditions of the numerical simulation were defined by self-programmed UDF subroutine. Experiments, theoretical analysis and numerical simulation were adopted to obtain the real time energy release of Al/PTFE reactive materials at different impact velocities. The results show that the maximum dynamic failure strength of the enhanced Al/PTFE reactive projectile is 126 MPa, and the strain rate hardening phenomenon and viscoelastic effect are exhibited when the strain rate is in the range of 1500 ∼ 3000 s−1. When the strain rate is in the range of 3000 ∼ 4000 s−1, the specimen is insensitive to strain rate. When the impact velocities are 2.30 km/s and 2.54 km/s, the energies that the reactive projectiles release are 8.36 kJ/g and 8.38 kJ/g, respectively, and the reactive material reacts completely. When the impact velocities are 1.64 km/s, 1.80 km/s and 1.94 km/s, the projectiles have not fully reacted. The reactive degree of the reactive projectile increases with the increase of the impact velocity. For the complete reaction of Al/PTFE reactive projectile, the critical impact velocity of the enhanced reactive material is between 1.94 km/s and 2.30 km/s.

In view of the wide demands of sandwich structure with porous material as core layer in many important fields such as protection engineering, aerospace, automobile manufacturing and ship, etc. In order to reveal the energy absorption and damage characteristics of high velocity impact aluminum foam core and CFRP/aluminum foam core structure, the quasi-static loading system, one-stage light gas gun loading system, the impact pressure testing system and the high-speed camera acquisition system were used to perform the quasi-static compression experiments of aluminum foam and the projectiles with different materials impacting on the aluminum foam core and CFRP/aluminum foam sandwich structure at the speeds of 100–300 m/s. The influences of impact velocity and projectile’ density on the damage characteristics of CFRP/aluminum foam sandwich structure and the attenuation effect of shock wave in sandwich structure have been studied. The experimental results showed that the curve of stress and strain has three typical zones similar to porous materials: elastic zone, yield platform zone and compaction zone under quasi-static compression loading. Due to its brittle and low tensile strength of aluminum foam material, the single aluminum foam plate has poor ballistic performance under the high-speed impact of projectiles with different materials. Therefore, closed cell aluminum foam needs to be combined with high strength panels to form sandwich structure to improve its ballistic performance. Keywords: High velocity impact, Aluminum foam core, CFRP/aluminum foam sandwich structure, Energy dissipation, Damage characteristics

With pancake-coil electromagnetic launcher as a research object, the experimental platform of the pancake-coil electromagnetic launch intercepting system with 50-kV pulse capacitors as energy storage was built and tested for discharge to study the electromagnetic launch intercepting system. The oscillation problem of the current flowing through freewheeling loop was solved by connecting the reverse-cut diode stack in series with trigger vacuum switch (TVS). However, due to limiting power component, the experimental system can work normally at 9.4-kV capacitor voltage. A proportional 3-D model of the pancake-coil electromagnetic launcher and an external excitation circuit model were established based on the structural and circuit parameters of the experimental system to perform simulation. The accuracy of the simulation model was proved by comparing the simulated and measured currents obtained under same capacitor parameters. Based on the established finite element model, maximum launching capacity and energy efficiency of the experimental system platform were estimated through simulation, and the space–time distribution characteristics of the magnetic field were analyzed during the launching process. In addition, the electromagnetic-structure coupling simulation was carried out to study the deformation problems of components of launcher by sequential coupling. All the work done in this paper provides guidance for a detail research, and we want to try to improve our electromagnetic launch experimental system.

Aiming at the reality of different potential differences on the surface of a spacecraft, it is very difficult to obtain a potential difference in the laboratory. In order to disclose the influence of potential difference on discharge, we have segmented a spacecraft surface into different parts with reserved gaps, in which gaps reserved in two adjacent surfaces are added resistances to create a multi-surface with different potential differences, and the low-potential surface as a, impact target in the split targets. In order to disclose the discharge characteristics, it is very vital to establish the charging and discharge systems. Therefore, a circuit system with different potential differences, discharge testing system, and ultra-high speed camera acquisition system are established by ourselves, and combining with a two-stage light gas gun loading system, nine sets of experiments have been conducted about hypervelocity impact on a 2A12 aluminum target with different potential differences. In experiments, gaps of a 2A12 aluminum target are the same among different potential parts in every experiments the gaps are 2 mm, 5 mm and 10 mm and applied voltages are 300 V, 200 V, and 100 V in every group experiment, respectively. The experiments have been performed at the impact velocity of about 3 km/s and the incidence angle of $$60^{\circ }$$ (between projectile flying trajectory and target plane). Voltage and current probes are adopted to acquire discharge voltage and current during the process of impact. The experimental results show that the discharge induced by impact plasma is produced among high- and low-potential targets, the gaps with 2 mm, 5 mm, and 10 mm can evoke a primary discharge among different split targets, and a primary discharge current peak and discharge duration increase with the increase of the applied voltage at the same gap of split targets. Meanwhile, a secondary discharge is induced at the conditions of the gap for 2 mm and corresponding applied voltage of 200 V as well as 5 mm and 300 V, respectively.

In order to determine the positions of debris collision spacecraft accurately, the experiments have been performed to impact orthogonal stacking two-dimensional Polyvinylidene fluoride (PVDF) piezoelectric film at different collision speeds based on the piezoelectric effects of the PVDF film by using two-stage light gas gun loading system and the self-constructed positioning system. The debris source was positioned accurately by PVDF strips sensor and testing system, which has been established to extract piezoelectric signals of the PVDF film during the process of impacting. The visualization of the position for debris impacting spacecraft was achieved through the LABview language programme and signal processing acquired by the signal acquisition system in the experiments. The experimental results show that the positions of the debris impacting source can be realized accurately by the piezoelectric effects of the orthogonal stacking two-dimensional PVDF film, the flight velocity and the incidence angle of the debris can be determined by installing the double-set PVDF film as the targets with a certain spacing.

To disclose the electrical output characteristics of PZT-5H piezoelectric ceramic with 50 ohm resistor as a electrical output load at the condition of different projectile’ ratios of length to diam...

Stacked piezoelectric ceramics (PZT-5H) are often used as sensors and pulsed power sources in moving objects. They will be subjected to a larger overload force when the moving objects collide with the target. In order to study the influence of the connection mode (parallel/series) of ceramic chips on the electrical output characteristics of stacked PZT-5H during overload, many experiments were performed using a nylon projectile to impact the stacked piezoelectric ceramic with different impact velocities by using a one-stage light gas gun as the loading device. The influence of a full bridge rectifier circuit on electrical output characteristics of the stacked PZT-5H was analyzed.

The spherical ice projectile impacting vertically on Carbon Fiber Reinforced Plastic laminates (CFRP laminates) with different curvatures was developed by using the one-stage light gas gun loading system. The numerical simulation results of the vertical impact of the arched CFRP laminates with different curvatures by SHI were compared with the experimental test results, Scanning Electron Microscopy micro failure mode and the image acquisition of the high speed camera by using ABAQUS/Explicit finite element software. The deformation process and failure mode of arched CFRP laminates with different curvatures and simulated hail ice (SHI)were analyzed, and the reliability of the numerical simulation was verified. By establishing a two-hinged simply supported mechanical physical model of arched laminates, the principal stresses of each layer along the direction of 0° and 90° of fibers in arched laminates were obtained. It would provide technical support for the prediction of fiber failure and delamination damage in the process of impacting on laminates at high velocity.

In order to study the charge characteristics of monocrystalline silicon irradiated by femtosecond pulsed laser, measurement systems of charge and infrared temperature induced by femtosecond pulse laser irradiation monocrystalline silicon are established by using oscilloscope and infrared thermal imager. The monocrystalline silicon (circle disc) irradiated by femtosecond pulse laser are carried out along the thickness direction of monocrystalline silicon. The experimental results show that the thermo-mechanical coupling effect of femtosecond pulsed laser irradiated on monocrystalline silicon will produce polarization in the target. At the initial stage of laser irradiation, the laser damage threshold of the interface between crystal surface and air is low and the charge mainly transfers along the surface of monocrystalline silicon, resulting in a high polarization. With the continuation of laser irradiation, it proves that the charge transfers in monocrystalline silicon gradually, and the polarization degree decreases with the modification of the material internal structure. After laser irradiation for a certain time, the charge transfers tend to be stable. Because the target lies in front of the laser focus, its energy density is insufficient to destroy the macrostructure of the target due to laser-pressure and temperature gradient, the polarization effect tends to be stable, resulting in a stable periodic change of charge transfer and recovery.

CFRP/Al HC SPs (Carbon Fiber Reinforced Plastic/Aluminum Honeycomb Sandwich Panels)composite structures are widely used in the aerospace and many other fields due to their excellent performances. In order to reveal profoundly the dynamic response characteristics of CFRP/Al HC SPs composite structure under high-velocity impact loading, the experiments about aluminum honeycomb core and CFRP/Al HC SPs composite structure impacted by high-velocity projectiles have been performed by using a one-stage light gas gun loading and a high-speed camera systems, respectively. The whole physical process of collision is analyzed by using TEMA software which is provided by high-speed camera's manufacturer, and the pictures and related physical parameters of the projectile passing through the different layers at the key moments are extracted based on the set frame rate of the video. Meanwhile, the ABAQUS/Explicit module was used to conduct numerical simulation under the same conditions as the experiments, and extracting the pictures and related physical parameters during the projectile penetrating through aluminum honeycomb core and the sandwich panels at the different key moments. The results show that the durations of action for the projectile impacting the Al HC core and the CFRP/Al HC SPs at the velocity about 280 m/s were 86 μs and 240 μs in experiments, respectively, and the durations of action were 90.7 μs and 236.2 μs at the same experimental conditions in numerical simulation, which were basically consistent comparing the experimental to simulated results. Moreover, more than 70% for the kinetic energy of the projectile consumed by the sandwich panels was attributed to the front panel and the aluminum honeycomb core during the entire impact process, and all these have verified the reliability of the numerical simulation. Keywords: CFRP/Al HC SPs, ABAQUS/Explicit, Duration of action between projectile and target, Energy absorption

The infrared thermal imaging system was used in order to investigate the temperature field distributions for optical glass lenses irradiated by femtosecond pulsed laser. The experimental research of the temperature field distributions on the surface of the H-K9L optical glass lenses with anti-reflection film and film free have been accomplished by this system combining with the irradiation at different frequencies and actuation duration by the femtosecond pulsed laser. The angle between the normal direction of the mirror surface and the laser output was 45 degrees. Experimental results showed that the coating of the lens on surface increases the distortion of the heat-affected zone and the temperature field, the penetration time increases as well as the temperature gradient decreases at the same time, which was caused by the reflection reducing coating on the surface of the lenses and this kind of coating has a certain protective effect to the optical lenses. The output frequencies of the laser presented a positive correlation linearly to the maximum surface temperatures of the lens in a certain range when the output energy of single laser pulse was constant. The spectral of temperature field was dominated by low frequency signals, the higher the laser output frequency was, the larger the amplitude of the spectrum signals was. The evolutionary processes of temperature for feature points at the edge of heat-affected zone were basically the same, therefore the laser irradiation in a small angle less than 45 degrees had little influence on the distributions and the evolutionary processes of the surface temperature fields in the heat-affected zone for thin targets.

In order to reveal influence of external capacitance on the voltage input and input energy provided by the PZT-5H piezoelectric ceramic composite structure under high-speed impact loading, experiments have been performed by using one-stage light gas gun loading system combining with a power supplier circuit and power output testing system, which the aspect ratio of 1:1 column projectile impact monolithic and multi-piece piezoelectric ceramic composite structure at the near impact velocity and different storage capacity. The experimental results show that the more larger storage capacitance is, the smaller the piezoelectric ceramic output voltage is. However, the smaller of the capacitor voltage is, the smaller the value of energy storage is; with the energy storage capacitance increasing, the piezoelectric capacitance ratio and the energy conversion rate of piezoelectric ceramics decreases; In addition, the storage energy capacitor increases with the increasing of the piezoelectric ceramic layers; the relationships of storage energy capacitor and piezoelectric ceramic capacitor has a great influence on the input voltage and storage energy for storage energy capacitor.

Solar array is one of the core components of spacecraft exposed to space environment; it is vulnerable to the impact from space debris. Discharge of solar array induced by ultrahigh-speed collision will produce a serious threat to the power supply system of spacecraft in orbit. In order to mitigate discharge effect and simulate working state of solar array effectively during debris impacting on solar array, realizing charging through sunlight irradiance on the ground simulating experiments is very difficult. Therefore, the inverse process of solar energy generation is adopted by applied power supply to solar array. In addition, loading and measurement systems of discharge have been established in a laboratory. A two-stage light gas gun was used to launch the projectile to impact on solar array at the applied power supply voltage of 100 V, and the spacings among the cells of solar array were 0.6, 3, and 5 mm, respectively. The applied power supply system, the diagnostic system of plasma characteristic parameters, and the measuring system of discharge current and voltage were constructed to provide voltage for solar array, diagnosing characteristic parameters of plasma and measuring discharge parameters, respectively. Six sets of experiments have been performed to measure discharge current and voltage induced by plasma during 2A12 aluminum projectile impacting on the solar array with carbon fiber reinforced plastics Al honeycomb sandwich and 2A12 aluminum substrates, respectively. The experimental results showed that the discharge did happen during 2A12 aluminum projectile impacting on solar array, and the discharge current among the cells increased with the increase of the impact velocity under the given experimental conditions. Also, increasing spacings among the cells of solar array could indeed mitigate or inhibit plasma discharge effects created by hypervelocity impact on solar array at the same projectile incident angles and applied power supply.

To introduce the application background the self-powered technology for Fuze bridge fire, high overload microthermal battery activation, rocket ignition, and the aircraft escape actual condition lifesaving system ignition power supply, which intends to use the high-speed impact of piezoelectric ceramic in the process of missile launching high overload pressure or missile and target intersection in the process of high overload stress wave of piezoelectric ceramics and the transformation of power, for closer to confession technology for Fuze bridge ignition, high overload microthermal battery activation, rocket ignition, and aircraft escape system engineering problems. The stress wave propagation in the PZT-5H piezoelectric ceramic composite target and load resistance effect to the electrical output characteristics is investigated under the strong shock loading; the experiments have been performed about cylindrical steel projectiles normal impact on PZT-5H piezoelectric ceramic composite target by using polyvinylidene fluoride stress test system and electrical output test system combining with one-stage light gas gun loading system. The experimental results show that the stress duration and peak stress are about $9~\mu \text{s}$ and 232 MPa, respectively, when the cylindrical projectile impacts on piezoelectric ceramic composite target at the impact velocity of 345 m/s. The outputs of current pulse peak, voltage pulse peak, and energy peak are 20 A, 734 V, and 11 mJ under the stress interactions of 200–300 MPa. At the near-impact stress conditions, the electrical output characteristics of piezoelectric ceramics are greatly affected by the load resistance. The output voltage pulse increases with the increasing of load resistance value, and the values of the load resistance have a significant effect on output energy; output energy conversion rate is up to 82% when the load resistance is $50~\Omega $ .

In order to study the temperature distribution and thermal stress of femtosecond pulsed laser interacting with energetic materials, in this paper, a femtosecond pulse laser loading system combined with an infrared thermal imager was used to experimentally study the temperature of the material when the femtosecond pulse laser irradiated Al/PTFE reactive material. Scanning electron microscope (SEM) was used to analyze the ablation morphology of laser ablated Al/PTFE. The theoretical model of the interaction between laser and Al/PTFE reactive material was established and the numerical calculation was carried out. The thermal stress was calculated and analyzed by using the material temperature measured by the experiment according to the thermoelastic theory. The following conclusions are obtained. The material is melted and vaporized under laser irradiation and ablation marks appear. The material temperature and ablation depth in the experiment and numerical simulation have a certain consistency. The heat released by the exothermic reaction in the laser irradiation area of the material has little effect on the surrounding materials. The radial thermal stress generated during laser irradiation is compressive stress, and the circular stress along the radius of the light spot changes from compressive stress to tensile stress. The greater the laser repetition frequency and the longer the laser action time are, the greater the thermal stress is. The maximum radial compression stresses are 2.54 MPa and 4.52 MPa when the laser repetition frequencies are 500 Hz and 1000 Hz, respectively.

Based on the objective reality of gradient potential existence in spacecraft surface caused by charging particles in space-plasma environment or solar wind activities, electrostatic discharge of spacecraft with surface charging or deep dielectric charging would be induced by debris or meteoroids impact. To simulate the gradient potential on the spacecraft surface in the laboratory, spacecraft surface was segmented into different parts, which different spacing reserved in two adjacent surfaces was added resistance to create different potential surfaces, and the highest potential surface as a target in the segmented surface. Circuit system realizing different gradient potential, discharge test system, as well as ultrahigh-speed camera acquired system was built by ourselves; combining with two-stage light gas gun loading system, four set experiments have been performed about hypervelocity impact on 2A12 aluminum target with gradient potential. In the experiments, spacings of 2A12 aluminum target were the same among different potential parts in every experiment, and the spacings of four set experiments were 2, 5, 10, and 15 mm, and high-potential 2A12 aluminum as the target, respectively. The experiments were performed at the impact velocity of about 3 km/s and the incidence angles of 60° (between projectile flying trajectory and target plane). Voltage probes and current probes were used to acquire discharge voltages and currents during the process of the impact. The experimental results showed that the discharge induced by impact plasma was generated between high- and low-potential targets by forming a plasma discharge channel, the gaps with 2–15 mm can evoke discharge among different targets, and the variations of the discharge current along the high- and low-potential targets did not obviously. However, the discharge duration decreased with an increasing of distance between high- and low-potential targets at the near collision velocities and the same incidence angle of the projectile. The whole physical process of discharge had experienced four stages in general, which created by hypervelocity impact 2A12 aluminum targets with gradient potential. The first stage was plasma generated by hypervelocity impact, the second stage was complex mixed plasma including plasma generated by hypervelocity impact and discharge plasma induced by split targets with gradient potential, the third stage was discharge plasma induced by hypervelocity impact, and the fourth stage was the discharge between charging particles due to the reciprocating motion of charging particles in the electromagnetic field.

In order to reveal the temperature evolutionary characteristics of typical ferroelectric RAM (Random Access Memory) irradiated by femtosecond pulsed laser, a physical model of a typical ferroelectric RAM is established. The idea of using a continuous laser instead of a high-energy pulsed laser of the same energy on the laser transmission path was theoretically derived. The physical expression and thermal conduction model of the laser at different positions on the transmission path were simulated by Comsol Multiphysics simulation software. The melting and heat conduction process of the pulsed laser irradiating ferroelectric RAM are simulated, and the laser with different irradiation time is obtained. The temperature field distribution, melting and thermal conduction simulation parameters of the multi-layer target of the ferroelectric RAM are simulated by the femtosecond pulsed laser under the simulation conditions. The results show that the COMSOL Multiphysics simulation can accurately simulate the temperature field evolution of femtosecond pulsed laser irradiating ferroelectric RAM in the simulation experiment of single event effects. Heat radiation of the periphery of the ferroelectric RAM and the bottom of the heat transfer dominates. Thermal radiation transfers less energy to the pins and the periphery. After 5 s under the laser interaction, the temperature distribution of the ferroelectric RAM is stable. The heat conductivity, melting and convection characteristics of the ferroelectric RAM are basically consistent with the experimental results.

In view of the key problems of the discharge phenomenon caused by the impact of small space debris on the satellite's charged surface and the electromagnetic field induced entering the interior of the satellite after coupling through the aperture. In this paper, the characteristics of the coupling plasma, the plasma induced discharge and the propagation of the electromagnetic field induced by discharge through the aperture are studied by using the two-stage light gas gun loading system, the discharge charge monitoring system, the plasma diagnosis system and the electromagnetic testing system; Combined with the characteristic parameters of plasma inside and outside the Simulated satellite, the curves of discharge current and voltage, and the spectrum characteristics of electromagnetic radiation inside and outside the simulated satellite, the characteristics of electromagnetic field propagating into the Simulated satellite through the aperture under different potential on the surface of the simulated satellite are analyzed. The experimental results show that the characteristic parameters of the ionized plasma produced by the ionization of the target and the projectile splash increase with the increase of the surface potential of the target, and the ionized plasma determines the discharge characteristics and electromagnetic field characteristics; After the electromagnetic field generated by the impact side propagates through the aperture into the inner of the simulated satellite, the electromagnetic field in the simulated satellite appears signal attenuation in most frequency bands, but signal enhancement occurs in a few frequency bands; The main reason of electromagnetic signal attenuation is that the electromagnetic field directions at the edge of the aperture and the back of the target are opposite to that at the impact side; The enhancement of electromagnetic signals in some frequency bands is caused by the plasma entering the simulated satellite.

In order to reveal the influence of sintered and unsintered aluminum/polytetrafluoroethylene (Al/PTFE) reactive material on heat conduction, ignition and deflagration characteristics under the condition of thermal loading, the sintered and unsintered samples prepared by molding process are heated by acetylene flame as heat source. The heat conduction and deflagration behaviors of samples are measured synchronously by infrared thermal imager and high-speed camera before and after ignition. Meanwhile, combining with the three-dimensional differential equation of heat conduction in cylindrical coordinate system, the temperature gradient, heat flux and ignition moments during the process of heat conduction are solved by numerical simulation. The results show that the two kinds of samples both undergo the evolutions of temperature gradient and thermal shock wave induced by temperature gradient. The instantaneous energy accumulation caused by thermal shock wave promotes the samples to deflagrate, and the heat conduction durations before ignition, ignition temperature of sintered sample are both smaller than that of unsintered sample. The micro-morphologies before ignition indicate that the unsintered sample needs to accumulate more energy to achieve deflagration. The deflagration reaction extent of unsintered sample is more intense than that of sintered sample, however, the deflagration durations of sintered sample lasts longer. The maximum flame area of unsintered sample is 30.6% larger than that of the sintered sample, and the maximum temperatures of the flame core of sintered and unsintered sample are 1284 K and 1425 K, respectively.

In order to study the cook-off characteristics of traditionally formulated Al/PTFE (Al/PTFE mass percentage was 26.5%/73.5%) reactive materials in air environment and the effect of aluminum honeycomb skeleton (4% of the total mass of the sample, which means that mass percentage of Al/PTFE was 22.5%/73.5%) on the release energy of traditional Al/PTFE reactive materials, Al/PTFE samples with and without aluminum honeycomb skeleton were prepared on the basis of traditional preparation process. The infrared (wavelength range 1.7–5.1 μm) and visible light (wavelength range 400–700 nm) radiation temperature and the evolutionary process of ignition and deflagration of the two reactive materials during the cook-off process were measured in real time by using the self-built cook-off equipment by combining with infrared thermal imager, transient fiber pyrometer and high speed camera. The experiment results show that the ignition temperature threshold of the reactive materials with aluminum honeycomb skeleton is 27 K lower than that of the traditionally formulated reactive materials. Meanwhile reaction release energy and the radiation temperature of the sample with the aluminum honeycomb skeleton are higher, but the deflagration duration is shorter. The reaction of the materials with aluminum honeycomb skeleton is more severe than that of the traditionally formulated reactive materials, which further demonstrates that the reaction release energy of the Al/PTFE reactive materials containing the aluminum honeycomb skeleton is significantly enhanced.

The theories of impact dynamics and adiabatic temperature change were adopted to investigate the ionization degree of the plasma generated by the 2A12 aluminum target during 2A12 aluminum projectile hypervelocity impact, and the radiant temperature was also estimated during hypervelocity impact. A two-stage light gas gun combined with the plasma characteristic parameters measured by a triple Langmuir probe was applied, and then the fitting relationship between the plasma ionization degree and the theoretical impact temperature as well as the fitting relationship between the maximum electron density and impact velocity were obtained with the aid of the theoretical derivation of the plasma ionization degree and the electron temperature and electron density extracted from experiments.

To researching the damage characteristics of typical logical chip modules in spacecraft due to plasma generated by hypervelocity impacts, we have established a triple Langmuir probe diagnostic system and a logical chips measurement system, which were used to diagnose plasma characteristic parameters and the logical chip module's logical state changes due to the plasma created by a 7075 aluminum projectile hypervelocity impact on the 2A12 aluminum target. Three sets of experiments were performed with the collision speeds of 2.85 km/s, 3.1 km/s and 2.20 km/s, at the same incident angles of 30 degrees and logical chip module's positions by using a two-stage light gas gun loading system, a plasma characteristic parameters diagnostic system and a logical chip module's logical state measurement system, respectively. Electron temperature and density were measured at given position and azimuth, and damage estimation was performed for the logical chip module by using the data acquisition system. Experimental results showed that temporary damage could be induced on logical chip modules in spacecraft by plasma generated by hypervelocity impacts under the given experimental conditions and the sensors' position and azimuth.

In order to study the ignition performance of self-powered overload igniter based on Lead Zirconate Titanate (PZT), shock simulation tests for different electro-explosive devices (EED) were carried out by using separated Hopkinson pressure bar to simulate overload environment. The output energy of PZT, temperature rise process of bridge wire in EED, initiation temperature of the detonator, ignition energy, and initiation delay of igniter are experimentally analyzed. The experimental results show that: 1) the matching degree between the resistance of EED and PZT plays a key role in the sensitivity of the igniter; 2) Whether the igniter can detonate successfully depends not only on the maximum overload but also on the overload action time; 3) During the ignition process, the initiating explosive starts to react before the bridge wire fuses; 4) There is a delay time from the output energy to the reaction temperature of the initiating explosive to the complete reaction of the initiating explosive, which is the main reason for the delay of the igniter.

Aiming at the evaluation model of Aluminum/Polytetrafluoroethylene (Al/PTFE) impact reaction energy release established by Ames R G, the factors that have great influence on reaction energy release, such as vessel wall energy absorption and ejected gas energy, are ignored in the model. In fact, the sum of the initial kinetic energy and the impact reaction energy release should include the increase of target internal energy, the enthalpy of gas products, the thermal radiation energy, the kinetic energy of gas products and the energy absorbed by the vessel wall. The evolutionary rules of each part energy are quantitatively evaluated by quasi-closed vessel experiments at different impact velocities combining with various measured methods such as overpressure sensor, high speed camera, instantaneous optical pyrometer and infrared thermal imager. The Ames R G model is modified based on the results of reaction energy release at different impact velocities, and a modified model of reaction energy release considering temperature is established. The results show that with the increase of impact velocity, the enthalpy of gas products and the energy absorbed by the vessel wall increase greatly. The energy absorbed by the vessel wall accounts for most of the projectile impact energy release. The impact reaction energy release of unit mass projectile increases with the increase of impact velocities. When the impact velocities are in the range of 389–509 m/s, the increase of reaction release energy is significantly lower than that of 509–596 m/s. The modified model considering energy loss can be used to quickly evaluate and characterize the reaction energy release characteristics of active materials under impact load.

The insufficient dynamic compressive strength of the Al/PTFE energetic material with traditional ingredients has seriously restricted its application in the field of national defence. However, the improvement of strength must be at the expense of activity. In view of the contradiction, this paper pioneers aluminum honeycomb skeleton reinforcement method to achieve both strength and activity. On the basis of traditional ingredients Al/PTFE (mass percentage of 26.5%/73.5%), three types of energetic materials were prepared by cold pressing sintering process by adding different aluminum honeycomb skeletons with arm lengths of 1 mm, 1.5 mm and 2 mm, respectively. The dynamic compressive strengths of the specimen are obtained by using self-built Split Hopkinson Pressure Bar (SHPB) loading system and high-speed camera acquisition system. Meanwhile, the impact reaction release energies are also evaluated experimentally by using the one-stage light gas gun loading system combined with the transient optical fiber pyrometer measurement system, the overpressure measurement system and the infrared thermal imager measurement system. In term of dynamic compressive strength and impact reaction release energy, the performances of three types of Aluminum honeycomb reinforced energetic material were compared with those of traditional ingredients energetic material. The experimental results show that compared with the strength (25.17 MPa) of traditional ingredients Al/PTFE energetic material, the strengths of three kinds of energetic materials reinforced by aluminum honeycomb framework with arm lengths of 1 mm, 1.5 mm and 2 mm are 1.5, 3.1 and 2.2 times that of the traditional ingredients Al/PTFE, respectively; Especially, at the impact velocity of 510 m/s, the release energy of three kinds of Al/PTFE energetic materials reinforced by aluminum honeycomb framework with arm lengths of 1 mm, 1.5 mm and 2 mm were 2.52 kJ/g, 1.94 kJ/g and 2.40 kJ/g, respectively. However, the release energy of traditional ingredients Al/PTFE energetic material was only 1.85 kJ/g. Compared with the traditional ingredients Al/PTFE, the compressive strengths and release energies of three kinds of energetic materials reinforced by different arm lengths of Aluminum honeycomb were significantly improved under the same impact conditions.

With the rapid development of material science, the original aluminum alloy shield structure of spacecraft has been gradually replaced by sandwiched structure of carbon fiber reinforced resin matrix composite structure with aluminum honeycomb. In order to reveal the damage characteristics induced by debris impacting on shield structure of spacecraft and aiming at the engineering requirements that spacecraft undergo alternately high and low temperature environment during on-orbit operation, CFRPs/aluminum honeycomb core sandwich shield structure is used as the impact object. The damage characteristics of 2A12 aluminum projectile impacting on CFRPs/aluminum honeycomb sandwich structure with different aluminum honeycomb arm lengths at different impact velocities are studied by using the high and low temperature system for the target and the loading system of two-stage light gas gun. The experimental results show that the arm lengths of aluminum honeycomb have little effect on the perforation area of front and rear surfaces of CFRPs/aluminum honeycomb sandwich structure at high temperature, but the impact speed has a great effect on the perforation areas of front and rear surfaces of rear panels. The lower the impact speed is, the smaller the perforation diameter is. The deformation and ablation areas of the front and rear surfaces of the aluminum honeycomb increase with the increasing of the arm length of the aluminum honeycomb. At the same time, the physical quantities mentioned above have similar changes in low temperature environment. The fitting formulas, such as the relationships among perforations of the front and rear surfaces of CFRP and the arm lengths of aluminum honeycomb, and ablation area of aluminum honeycomb and the arm lengths of aluminum honeycomb are given at the given experimental conditions. The micro-morphology and damage characteristics of the panels and aluminum honeycomb are analyzed at the different locations near the impact point at high temperature.

In order to obtain the elemental compositions of the projectile and target materials during 2A12 aluminum projectile shot on a natural dolomite plate, three kinds of experiments have been conducted using a spectral acquirement system established on a two-stage light gas gun for impact velocities ranging from 2.20 km/s to 4.20 km/s, at the same projectile incidence angle of 30°. Experimental results show that the elemental compositions of the projectile and target materials in the strong shock experiments have a good agreement with the original elemental compositions of the projectile and target. In addition, the relations between spectral radiant intensity and elemental compositions of the projectile and target materials have been obtained for different impact velocities, in which the spectral radiant intensity of the main elements in the material increases with increasing impact velocity, and more elements appear with increasing impact velocity since more energy would result from a higher velocity impact.

To investigate the relationship between stress wave propagation and the plasma discharge generated by a projectile high-velocity impact on solar array with 2A12 aluminum substrate structures at the incidence angle of 60°. Three sets of experiments about stress wave propagating and plasma discharge in composite structure of solar array have been performed by taking advantage of PVDF (polyvinylidene fluoride) film sensor, plasma characteristic parameter diagnostic system, discharge measurement system and two-stage light gas gun loading system established by ourselves. Experimental results showed that the duration of stress wave was about 30±5μs, and maximum stresses are about 1400±200MPa in experiments. Furthermore, the discharge phenomenon did happen and the duration of discharge current was also different in solar array at the different impact velocities. The basic consistency between stress wave propagation and discharge duration is also confirmed by experiments.

Damages by a laser to materials are mainly caused by thermal and dynamic effects; such effects are referable for evaluating damage by a laser to the optical lens and the design of a laser system. We have designed several independent laser–material interaction measurement systems and carried out experimental research based on them. The results show that the laser plasma oscillation frequency is 500 Hz and accompanied by discharge phenomena. The average pressure stress on the material is 1.1 GPa; then it attenuates to the Lamb wave; and the surface coating of the lens reduces the radius of the heat-affected zone to one third of that without film.

Plasma-induced discharge is an important effect on the solar array of orbiting space vehicles subjected to hypervelocity impact, which will pose a serious threat to the power supply system of spacecraft. The paper investigates experimentally the process that the projectile in various impact velocities and incidence angles impact on solar array with sandwich structure comprising of a coverglass, a silica gel and a 2A12 aluminum liner at the different positions. The electron temperature and density of the plasma were diagnosed by applying in independent-constructed Triple Langmuir Probe diagnostic system, meanwhile, the charging and discharge test system were also constructed by ourselves. Three sets of experiments have been performed by two-stage light gas gun loading system and related measurement system. Especially, residual velocity was measured when projectile pierced through the solar array with composite structure. Experimental results revealed the discharge causes based on stress wave theory, and the discharge current characteristics of a primary and a secondary discharge of solar array induced by hypervelocity impact were given through hypervelocity impact experiments. Finally, it will provide a valuable benchmark for the construction of solar array against space debris.Plasma-induced discharge is an important effect on the solar array of orbiting space vehicles subjected to hypervelocity impact, which will pose a serious threat to the power supply system of spacecraft. The paper investigates experimentally the process that the projectile in various impact velocities and incidence angles impact on solar array with sandwich structure comprising of a coverglass, a silica gel and a 2A12 aluminum liner at the different positions. The electron temperature and density of the plasma were diagnosed by applying in independent-constructed Triple Langmuir Probe diagnostic system, meanwhile, the charging and discharge test system were also constructed by ourselves. Three sets of experiments have been performed by two-stage light gas gun loading system and related measurement system. Especially, residual velocity was measured when projectile pierced through the solar array with composite structure. Experimental results revealed the discharge causes based on stress wave theory, and th...