Light Gas Gun Loading System Research Articles

Dynamic Constitutive Model of Tungsten‐Whisker‐Reinforced Aluminum/Polytetrafluoroethylene Composite Material and Quantitative Determination of Impact Reaction Release Energy in Vacuum Environment

To meet the strength requirements of aluminum/polytetrafluoroethylene (Al/PTFE) in practical applications, tungsten (W) whisker is added into the traditional formula Al/PTFE (26.5%/73.5%) to improve the dynamic compressive strength of the reactive material. Mechanical properties of reactive material specimens prepared by sintering are tested. In the results, it is shown that the dynamic compressive strength of Al/PTFE‐reactive material reinforced by tungsten whisker with volume fraction of 13.1% can reach 141 MPa at strain rate of 1800 s−1. The constitutive model of dynamic compression for tungsten‐whisker‐enhanced Al/PTFE‐reactive material is constructed, and the results are basically consistent with the experimental results. The quantitative impact energy release of reactive material specimens under vacuum environment are performed by using the two‐stage light gas gun loading system, and the quantitative impact release energies of Al/PTFE‐reactive material reinforced by tungsten whisker under different whisker percentage content and diameter are obtained.

Plasma and Light Flash Radiant Features Generated by Al/PTFE Projectile High-Velocity Impact Thin Aluminum Target

To reveal the characteristic parameters and the evolutionary rules of plasma and light flash radiation produced by aluminum powder/polytetrafluoroethylene (Al/PTFE) projectile hypervelocity impacting on 2A12 thin aluminum plate, the Al/PTFE projectile was obtained by the improved sintering process of the sample, which is based on the process of the traditional Al/PTFE (mass percentage ratio of aluminum powder and PTFE is 26.5%/73.5%). The dynamic compressive strength of the sample was characterized by the self-constructed split Hopkinson pressure bar (SHPB) system. Meanwhile, the experiments, enhanced Al/PTFE projectile (mass 0.22 g, size <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5\times5$ </tex-math></inline-formula> mm) impacting on 2A12 aluminum targets with the thicknesses of 2 and 3 mm at different impact speeds (1.95–2.45 km/s), have been performed using a two-stage light gas gun loading system combining with a high-speed camera acquisition system, a transient fiber pyrometer measurement system, and a plasma characteristic parameter diagnostic system. The electron temperature, electron density of plasma, and the radiant temperature (in the range of visible light wavelength) of light flash have been experimentally studied. The results show that the dynamic compressive strength of the Al/PTFE specimen with rapid cooling was significantly improved at the strain rate of 4000 s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> comparing with the traditional Al/PTFE projectile (the dynamic compressive strength was 32–44 MPa), which can reach more than 100 MPa. The maximum electron temperature, electron density, and visible light radiant temperature produced by the hypervelocity impact increase with an increase in impact velocities and target thicknesses, respectively.

Dynamic response of slender body passing through ice and water mixture at high velocity

ABSTRACT In the process of underwater motion, the trajectory of the projectile will be greatly disturbed due to the complicated underwater environment and cavitation effect. In order to study the effect of the ice water mixture on projectile motion, the experiments of a titanium alloy slender body with a truncated conical and plat warhead passing through ice and water mixture have been performed by using a one-stage light gas gun loading system, an overpressure sensor measurement system and a high-speed camera acquisition system in this paper. The experimental results show that the volume of the cavity generated by the slender body with a small length-to-diameter ratio is larger, and the slender body deflects in the process of movement. For a slender body with a large length-to-diameter ratio, the cavity formed is closer to the central axis and the maximum radial size of the cavity. No matter the warhead shapes are truncated conical or plat warhead, the diameter and lasting time of the cavity increase with the increase of the slender body's velocities. Under the condition that the length-to-diameter ratio and the velocity of the slender bodies are similar, the overall evolutionary trend of the overpressure generated by two kinds of slender bodies is similar. But the fluctuation range of the overpressure amplitude of the plat warhead is small, the curve oscillation amplitude of the adjacent time is large and the peak value of the overpressure for the truncated conical warhead is large. Under the same ratio of length to diameter, the velocity has no obvious influence on the trajectory of the slender body after hitting the ice particles. When the slender body collides with ice particles, the deflection angle of its trajectory is larger than that of impacting on the edge of ice particles. When the slender body collides with the ice particles, the interaction between the ice particles and the slender body is large, and the deflection angle of the slender body is larger after impact.

Dynamic characteristics of enhanced Al/PTFE and real-time quantitative evaluation of impact release energy under vacuum environment

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.

Damage mechanism of CFRP laminates with different curvatures impacted by ice projectile at high velocity

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.

Energy release of Al/PTFE materials enhanced by aluminum honeycomb framework subjected to high speed impact under vacuum environment

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.

Research on the electromagnetic propagating characteristics of hypervelocity impact on the target with aperture and different potential conditions

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.

Characterization of dynamic compressive strength and impact release energy of Al/PTFE energetic materials reinforced by aluminum honeycomb skeleton

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.

Experimental investigation on location of debris impact source based on acoustic emission

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.

Experimental research on damage characteristics of CFRP/aluminum foam sandwich structure subjected to high velocity impact

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.

Experimental research on discharge characteristics induced by hypervelocity impact on split targets with potential gradient

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.

Relationships between shock stress and electrical output characteristics for PZT-5H under high-velocity impact loading

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 diameter and high-speed impact loading. The one-stage light gas gun loading system, shock stress testing system and the electrical output testing system were constructed by ourselves in laboratory. Experiments have been performed to research cylindrical 2A12aluminum projectile (different ratios of length to diameter) vertically impacting on PZT-5H piezoelectric ceramic composite targets at the different impact velocities. The experimental results showed that the duration of the stress wave on the piezoelectric ceramic increased with the increasing of ratio of length to diameter for the projectile, however the piezoelectric ceramics could continue to supply power with the increasing of ratio of length to diameter for the projectile after the stress wave was unloaded. The phenomenon of charge leakage did exist during the the process of interaction between the projectile with a large ratio of length to diameter and the piezoelectric ceramic composite targets, and the duration of voltage output pulse became shorter due to the influence of leakage current. The shock stress peaks of PZT-5H piezoelectric ceramic composite targets reaches several hundred MPa in pulse width of 30 μs, and part of the piezoelectric ceramic was completely depolarized, and the peak of voltage pulse generated was 580 V across a load resistor of 50 ohms, meanwhile energy output up to 30mJ within 10 μs.

Experimental investigation on characteristics of stress wave propagation and plasma discharge induced by high-velocity impact solar array

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.

Space debris positioning based on two-dimensional PVDF piezoelectric film sensor

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.

Research on discharge effect of solar array with power supply subjected to hypervelocity impact

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.

Influence of the Storage Energy Capacitance on Their Electrical Output Characteristics of Piezoelectric Ceramic during the Process of High-Velocity Impact

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.

Influence of different gaps among the split targets with gradient potential to the discharge effects generated by hypervelocity impact

Due to the actual situation of spacecraft surface’ charging, such as convex corners, weld line, whalebone and a multiple-interfaces with different materials, all these are main factors leading to uneven charging of spacecraft surface, even creating gradient potential. If the charging spacecraft surface is impacted by debris or micrometeor, discharge effect induced by impacting will pose a serious threat to spacecraft in orbit. So realizing spacecraft charging surface with different potential differences and grasping discharge characteristics are a decisive importance at the different experimental conditions in laboratory. To simulate the spacecraft surface with a gradient potential in laboratory, spacecraft surface is split into different parts, which different gaps reserved in 2 adjacent surface is added resistance to create different potential surfaces, and the high potential surface as a impact target in the split targets. Charging circuit system realizing different gradient potential and discharge test system are built by ourselves, combining with two-stage light gas gun loading system, six sets of experiments have been performed about hypervelocity impact on 2A12 aluminum split targets with gradient potentials. In the experiments, gaps of 2A12 aluminum target are the same among different parts in every experiments, the gaps of the split targets are 2mm, 3mm, 5mm, 7mm and 10mm in the experiments, respectively. And the applied voltage is 300V in all the experiments and high-potential 2A12 aluminum plate as the impact target. The experiments have been performed at the impact velocity of about 3km/s and the incidence angles of 60o and 90o (between projectile flying trajectory and target plane), respectively. Voltage probe and current probes are used for acquiring discharge voltages and currents during the process of the impact. The experimental results showed that the discharge induced by impact plasma were generated among high and low-potential target by forming a plasma discharge channel. With the increasing of the gaps among the high and low-potential targets, the peak values of the discharge current decreased first then increased. When the gaps of split targets reached a certain value, the peak values of the discharge current decreased again. Meanwhile, the gaps among high and low-potential targets was 5mm, the peak value of the discharge current was the smallest. With the increasing of the gaps among the split targets, a primary discharge duration also increased. However, when the gaps among the split targets were greater than 5mm, increasing trend of discharge duration would slow down. When the gaps among the split targets were greater than 7mm, there was a secondary discharge phenomenon, and the physical explanations were given about the influence of different gaps among the split targets on the discharge effects created by hypervelocity impact.

The Propagation of Stress Wave in the PZT-5H Composite Target and the Influence of Load Resistance on the Electrical Output Under the Strong Shock Loading

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 $ .

Electrostatic Discharge of Plasma Created by Hypervelocity Impact 2A12 Aluminum Targets With Gradient Potential

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.

Experimental study on plasma discharge induced by high-velocity impact solar array associated with projectile incidence angles

The purpose of the paper is to investigate the discharge characteristics of plasma generated by a projectile high-velocity impact solar array with 2A12 aluminum substrate structures at the incidence angles of 30°, 45° and 60°, respectively. Three sets of experiments were performed to impact solar a rray by taking advantage of discharge measurement system established and two-stage light gas gun loading system. Experimental results showed that the second discharge phenomenon did happen in the solar array at the given experimental conditions, and the discharge current peak and time interval between the primary discharge and the second discharge are the biggest at the projectile incidence angle of 45° in the conditions of the near impact velocity and the different projectile incidence angles.