Projectile Energy Research Articles

Electron-impact ionization of water molecules at low impact energies.

The electron-impact ionization of water molecules at low impact energies is investigated using a theoretical approach named M3CWZ. In this model, which considers exchange effects and post-collision interaction, the continuum electrons (incident, scattered, and ejected) are all described by a Coulomb wave that corresponds to distance-dependent charges generated from the molecular target properties. Triple differential cross-sections for low impact energy ionization of either the 1b1 or 3a1 orbitals are calculated for several geometrical and kinematical configurations, all in the dipole regime. The M3CWZ model is thoroughly tested with an extensive comparison with available theoretical results and COLTRIMS measurements performed at projectile energies of Ei = 81eV [Ren et al., Phys. Rev. A 95, 022701 (2017)] and Ei = 65eV [Zhou et al., Phys. Rev. A 104, 012817 (2021)]. Similar to other theoretical models, an overall good agreement with both sets of measured data is observed for the angular distributions. Our calculated cross-sections' magnitudes are also satisfactory when compared to the other theoretical results, as well as to the cross-normalized relative scale data at 81eV impact energy. The 65eV set of data, measured on an absolute scale, offers a further challenging task for theoretical descriptions, and globally the M3CWZ performs fairly well and comparably to other theories. The proposed approach with variable charges somehow allows to capture the main multicenter distortion effects while avoiding high computational costs.

Study on the attenuation pattern of stress wave in granite impacted by 30CrMnSiA alloy steel projectiles at 1.5–5.5 km/s

The damage ability of hypervelocity kinetic energy projectile penetrating ground has become a hotspot in modern military research. In this study, a hypervelocity impact test on a granite target subjected to projectiles using a two-stage light gas gun is conducted to study the stress wave evolution in granite under hypervelocity penetrations. The parameters of the *MAT_JOHNSON_HOLMQUIST_CERAMICS(JH-2) constitutive equation are calibrated using the results of the splinter impact test and the static test, and numerical simulations are performed using the smoothed particle hydrodynamics method coupled with finite element method (SPH-FEM coupled method) to extend the resulting data. A formula for calculating the stress wave peak attenuation is established, indicating that the maximum impact pressure produced by the hypervelocity impact decreases exponentially with scaling distance, and the attenuation coefficient is related to the degree of rock damage. Additionally, the attenuation of the speed of sound is used to characterize rock damage, and the damage deterioration law of granite under hypervelocity impact is analyzed based on the damage factor.

State-selective electron capture in Ar16++H(1s) collisions for charge-exchange recombination spectroscopy

Abstract State-selective electron capture in collisions of Ar16+ ions with ground-state hydrogen atoms has been modeled using the two-center wave-packet convergent close-coupling approach. The partially stripped He-like projectile ion is represented using a model potential. Experimental measurements are not available for this collision system and to date, only the classical trajectory Monte Carlo (CTMC) method has been applied to calculate cross sections. The calculated total electron-capture cross section (TECS) is in good agreement with the previous CTMC results at the low energies but slightly larger at higher energies. This is likely because, in this work, we account for capture into highly excited states, which contribute significantly to the TECS at the intermediate energies. The n-resolved electron-capture cross sections have also been presented for capture into states with n = 6 − 19 , where n is the final-state principal quantum number. The most important of these are the cross sections for capture into the n = 14 − 17 states, which are used in charge-exchange recombination spectroscopy techniques. For these cross sections, a significant difference is observed between the present and previously published data. The cross sections differ by an order of magnitude in the 10−60 keV u−1 energy range. The agreement between the calculations is observed at the energies above 70 keV u−1. The n ℓ -resolved electron-capture cross sections have also been presented at 15, 60, 100 and 200 keV u−1 projectile energies, where ℓ is the final-state angular momentum quantum number.

Charge Transfer in He+ - He → He(1s4l, l ≥ 2) - He+ Collisions in Intermediate Energy Range.

The anticrossing spectra of the helium line λ1s4l D3,F-1s2p P3=447.2 nm emitted after electron capture by He+ ions in He+-He collisions were measured for projectile energies of 10-29 keV. Furthermore, considering the excited states' time evolution, the theoretical intensity functions were calculated. The electric field and density distributions of the target He atoms in the collision volume were taken into account, and by fitting the theoretical intensities to the measured ones, the post-collisional states of the charge-transferred He atoms were determined. The results indicate that for the intermediate projectile energy range, the electronic charge distributions were asymmetric, but the electric dipole moments did not change, as in the case of the target atoms excited directly in the collisions. This result shows that the Paul trap mechanism may play an important role in the charge transfer excitation in this energy range.

Cracking of submerged beds

We investigate the phenomena of crater formation and gas release caused by projectile impact on underwater beds, which occurs in many natural, geophysical and industrial applications. The bed in our experiment is constructed of hydrophobic particles, which trap a substantial amount of air in the pores of the bed. In contrast to dry beds, the air–water interface in a submerged bed generates a granular skin that provides rigidity to the medium by producing skin over the bulk. The projectile's energy is used to reorganize the grains, which causes the skin to crack, allowing the trapped air to escape. The morphology of the craters as a function of impact energy in submerged beds exhibits different scaling laws than what is known for dry beds. This phenomenon is attributed to the contact line motion on the hydrophobic fractal-like surface of submerged grains. The volume of the gas released is a function of multiple factors, chiefly the velocity of the projectile, depth of the bed and depth of the water column.

NEBOAS: A Neutron yiElds Based On AcceleratorS application

The web-based application NEBOAS was developed to calculate the neutron yield of the accelerator-based neutron source MONNET (MONo-energetic NEutron Tower) at JRC-Geel. Neutrons are produced with p and d-induced reactions on particular targets. NEBOAS provides double differential neutron yields, as a function of the angle of neutron emission and energy. It provides also integrated neutron yields, and neutron energy spectra. Any projectile energy may be utilized, as long as it is covered by the nuclear data available on thin targets (that just degrade the projectiles' energy) or thick targets (that stop the projectiles). The calculation employs reaction cross-section evaluations from Evaluated Nuclear Data File (ENDF) or compilations of experimental measurements from the Experimental Nuclear Reaction Data (EXFOR), and stopping powers as recommended in the National Institute of Standards and Technology (NIST) or the Stopping and Range of Ions in Matter (SRIM-2013) databases.

Development of a cylindrical mirror analyser electron spectrometer and associated data acquisition system to study inner shell electron emission following ion-atom collision

In this paper we report on the development and performance of a cylindrical mirror analyser electron spectrometer for ion atom collision experiments. A low cost data acquisition system using Arduino microcontroller has also been developed and tested. We have measured the Auger emission spectra for various gaseous targets in collision with 1 MeV proton beams. Relative total Auger emission cross sections have also been measured for N2 molecular target as a function of incident proton energy. The projectile energy dependence agrees well with earlier reported measurements.

Research on mass loss and nose shape evolution of kinetic energy projectiles penetrating concrete at high velocity

Research on mass loss and nose shape evolution of kinetic energy projectiles penetrating concrete at high velocity

Assessment and litigation of ocular injuries by less-lethal weapons.

The main cause of serious ophthalmological injuries, includingviolent eye amputations in the context of so-called less lethalweapons, is the use of blunt objects, such as batons or extendablesticks and the use of kinetic energy projectiles (rubber bullets,pellets, foam projectiles or others). Such injuries in the contextof population control have been considered to constitute cruel,inhuman or degrading treatment or even torture when they arecarried out, intentionally or unintentionally, by State officials(or with their acquiescence or protection) and involve any of thepurposes contemplated in the Convention against Torture. Dueto their special characteristics, they constitute rights violationsthat entail unique difficulties and complexity from both a legaland forensic point of view. This paper addresses some of thesedifficulties with practical legal and forensic recommendations.It is structured in two parts: First, legal, where we considerlegal difficulties and provide suggestions on elements for obtainingevidence are given. Second, medico-psychological andforensic where we review the elements to be considered in theinterview, the medical and ophthalmological evaluation, andthe psychometric, psychological and psychiatric evaluation.

Stop Rubber Bullets. The use of kinetic energy projectiles and torture in the Spanish State.

Rubber bullets are projectiles whose use is potentially lethal. Between 1976 and 2017, they have caused at least 23 deaths and dozens of injuries in Spain, many of them serious, with loss of sight being the main type. In the period 2000 - 2020 alone, more than 40 people have been affected. We review the legal framework, human impacts that go far beyond statistics and medical and psychosocial approaches. The paper focuses on key learnings in survivors' organisation, the process towards the prohibition of these weapons and strategic litigation, forensic documenta-tion and political advocacy.

Energy and Z dependence of low velocity Nq+ ion induced M X-ray relative intensities for some heavy elements

The intensity ratios, IMk/IMn (exp)(k = ξ, γ, m1; n = total, αβ), for some heavy elements, 70Yb, 79Au, 81Tl, 82Pb and 83Bi induced by 1000 keV−1750 keV Nq+ (q = 4, 5) ions have been measured in order to investigate their dependence on the projectile energy and atomic number of the respective target elements. The measured intensity ratios have been compared with two sets of values calculated using the Mj (j = 1–5) sub-shell ionization cross sections based on the ECPSSR-UA model, the X-ray emission rates based on the Dirac-Hartree Slater (DHS) model, two sets of the fluorescence and Coster-Kronig yields based on the DHS model and those evaluated by McGuire employing non-relativistic Hartree-Slater model. Significant differences have been observed between the present measured IMk/IMαβ (exp) (k = ξ, γ, m1) intensity ratios and those calculated using independent particle approximation (IPA) models based single atomic vacancy state physical parameters.

Dynamic failure behavior of 7B52 laminated aluminum alloy subjected to deformable projectile impact

The ballistic response and failure mechanisms during the impact of a 304 steel-core projectile on a 7B52 laminated aluminum alloy plate were investigated. The impact resistance of the target plate was obtained through ballistic testing, and a detailed analysis of the fracture mechanism was conducted using microstructure characterization. Furthermore, an enhanced Gurson-Tvergaard-Needleman (GTN) model was employed to simulate the ballistic impact process, as well as the initiation and propagation of fractures. The results revealed significant deformation following the impact of the 304 steel-core projectile on the 7B52-T6 laminated plate. The target plate exhibited spalling failure, shear failure, and ductile hole expansion, with spalling failure being caused by intergranular fracture mechanisms. In the high stress triaxiality regions of the 7A62 alloy, intergranular cracks are prone to occur, and shear stress influences the expansion of the cracks. Fragments following layer cracking adhere to the 7A52 layer, thereby increasing the ballistic resistance surface area. The 7A52 layer on the rear side of the target plate effectively absorbed the projectile's energy through bending and stretching deformation, thereby offering enhanced protection. Furthermore, the spall resistance of the 7B52 laminated plate eliminate secondary damage caused by spall fragments.

First investigation on the isomeric ratio in multinucleon transfer reactions: Entrance channel effects on the spin distribution

The multinucleon transfer (MNT) reaction approach was successfully employed for the first time to measure the isomeric ratios (IRs) of 211Po isomer (25/2+) and its ground state (9/2+) at the IGISOL facility using a 945 MeV 136Xe beam impinged on 209Bi and natPb targets. The dominant production of isomers compared to the corresponding ground states was consistently revealed in the α-decay spectra. Deduced IR of 211Po populated through the 136Xe+natPb reaction was found to have an enhancement of ≈1.8-times than that observed for the 136Xe+209Bi. State-of-the-art Langevin-type model calculations have been utilized to estimate the spin distribution of an MNT residue. The computations qualitatively corroborate with the considerable increase in the IRs of 211Po produced from 136Xe+natPb compared to 136Xe+209Bi. Theoretical investigations indicate a weak dependence of target spin on the IRs. The enhancement of the 211Po isomer in the 136Xe+natPb over 136Xe+209Bi can be attributed to the different proton (p)-transfer production routes. Estimations demonstrate an increment in the angular momentum transfer, favorable for isomer production, with increasing projectile energy. Comparative analysis reveals the two entrance channel parameters, projectile mass and p-transfer channels, strongly influencing the population of the high-spin isomer of 211Po (25/2+). This letter reports the first experimental and theoretical study on the IRs of nuclei formed from two different p-transfer channels via two independent MNT reactions.

Stacking effects on dynamic mechanical behavior of bilayer hexagonal boron nitride under impact

Hexagonal boron nitride (h-BN) is a promising material for ballistic armor due to its excellent mechanical properties, enriched by different bilayer stacking arrangements. Molecular dynamics methods are used to study the stacking effects on the static and dynamic mechanical properties of bilayer h-BN. The AB (nitrogen) stacked bilayer structure attracts our attention because of its superior interlayer synergistic ability to resist projectile indentation up to a maximum force of 152.89 nN, which is about 22.9 % higher than the average value of other stacked bilayers. The impact response of bilayer h-BN with AB (nitrogen) stacking arrangement is then investigated at velocities of 2–4 km/s, which has the highest critical perforation velocity of 3.075 km/s, increased by 36.7 % compared to monolayer h-BN. At a low impact velocity of 2.5 km/s, the AB (nitrogen) stacked h-BN bilayer spends the shortest time to dissipate the impact energy of projectile and remains intact, while the top layers of other stacked bilayers are penetrated. At high impact velocities, a perforation event occurs, accompanied by multiple deflections of crack tips from zigzag to armchair to zigzag again, which intrinsically enhances the toughness of material. This study provides more understanding of the dynamic mechanical behavior of bilayer h-BN, as well as the design of armor structures based on stacking arrangements of 2D materials.

Design of an add-on ceramic composite armour against 14.5 × 114 mm API/B32 projectile for the armoured vehicles and investigation of the ballistic performance of the armour

Abstract A ceramic/composite add-on armour system with innovative ceramic geometry (cylindrical) against 14.5 × 114 mm API/B32 projectile was developed and ballistic performance of the armour was investigated both experimentally and numerically. Numerical analysis was used to calculate exit velocities of the projectile after passing through the ceramic/composite layer (before penetrating the Armox 500T which simulates hull structure of an armoured vehicle) and also contributed to the selection of optimum ceramic thickness. The calculated projectile velocity-time curves (from numerical analysis) for three different ceramic thicknesses are given comparatively in the study. The curve characteristics are the same for three different analyses. The duration of the total absorption of the projectile energy is about 0.2 microseconds (ms). There were differences in the transmission of the stress wave and the delamination in the Ultra-High-Molecular-Weight Polyethylene (UHMWPE) layers differed as ceramic thickness increases. The separation between the layers varied with the change in projectile energy. As a result of the ballistic test, the armour prevented 14.5 × 114 mm API/B32 ammunition with desired damage mechanisms. In the x-ray image taken after the shootings, it was seen that the ceramic damage was local which enhanced multi-hit resistance capability and the geometry of the cylindrical alumina played an important role in the localization of the ceramic zone damage during the projectile penetration process. Due to this cylindrical ceramic geometry, the projectile moving on after the moment of impact constantly encounters a curved and new surface, and thus it is deflected and exposed to more wear. The areal density of the armour was also reduced by using the UHMWPE (which is one of the composite material whose fibres have the lowest density and good mechanical properties) composite plate as the backing plate.

Protection mechanism of B4C–TiB2–SiC composite ceramic under ultra-high velocity impact

As the penetration technology develops and the projectile velocity increases, it becomes imperative to investigate the protection mechanism of high-performance ceramic under hypervelocity impact. The impact process of tungsten alloy projectile penetrated into B4C–TiB2–SiC composite ceramic target using ballistic test and finite element simulation at an ultra-high velocity of 2154 m/s was researched in the present study. Additionally, the protection mechanisms were described in terms of the morphology of target damage, the behavior of projectile kinetic energy dissipation, and the temperature field cloud. The findings from the ballistic experiments highlighted that the formation of macro-damage areas (concentrated damage, cone crack, circumferential crack, and radial crack areas) and micro-fragmentation zones could consume a significant amount of impact energy. The mixed fracture mode and the typical inelastic deformation characteristics (dislocations and micro-twinning) contributed to the energy dissipation. Simulation results indicated that the surface dwell effect of the projectile exhibited the highest rate of energy consumption. Furthermore, the temperature field results indicated that the maximum temperature on composite ceramic surface could reach 2310 K, which was below the melting point of B4C ceramic (2723 K). However, this temperature could cause the melting of the majority of metal materials. Therefore, ceramic materials exhibited a significant advantage under conditions of ultra-high impact velocities.

Research on the high-speed impact of projectiles on reinforced concrete equivalent targets

Due to the prolonged production cycle of reinforced concrete target plates and the need for a series of preparations and tests before use, it is essential to study the equivalent relationship between reinforced concrete target plates and steel target plates. Numerical simulations of the process of projectiles vertically penetrating reinforced concrete target plates were conducted using LS-DYNA software. Models for both reinforced concrete and steel targets were established, and the equivalent thickness conversion relationship between the two was obtained. Simulation results indicated an inverse proportional relationship between projectile residual kinetic energy and target thickness. Curve fitting using Origin software was performed to obtain the conversion relationship between the thicknesses of reinforced concrete target plates and steel targets. The simulation results were validated, showing an error in concrete target plate thickness conversion of less than 10%. The research results provide theoretical support and data references for the equivalent study of reinforced concrete target plates and steel target plates.

Approximate theory of armour perforation by ductile hole expansion

The present study suggests a complete analytical model for armour perforation by ductile hole enlargement process. The new approximate model is applicable for entry, tunnelling and exit phases of a rigid nose-pointed projectile with an arbitrary nose-shape. The theory is based on dividing the target into infinitesimal thin layers, in which a cylindrical hole expansion is assumed. The elastoplastic work that is consumed by the target for infinitesimal projectile advancement is based on the specific cavitation energy and leads to reduction of the projectile kinetic energy. Several equivalent formulae for ballistic limit velocity, and a formula for the ballistic limit thickness are found to be independent of projectile nose-shape and nose length. The approximate model is compared with numerical simulations for AA6061-T651 targets that are impacted by two different ogive nose-shape projectiles at several striking velocities. A small nose-shape effect on the ballistic limit velocity is observed in the numerical simulations and is attributed mainly to the target axial effect and the bulge formation at the target rear surface, which are not considered in the approximate model.

ERCS24: An updated version of the ERCS08 program for calculations of the cross sections for atomic electron removal based on the ECPSSR theory and its variants

ERCS24: An updated version of the ERCS08 program for calculations of the cross sections for atomic electron removal based on the ECPSSR theory and its variants

Experimental and numerical investigation on Multiwalled carbon nanotubes (MWCNTs) dispersed CFRP laminate subjected to spherical and conical impacts

ABSTRACT As lightweight and load-bearing efficiency needs have grown, conventional metal has steadily given way to carbon fibre-reinforced polymer (CFRP) laminates. Also, CFRP laminates are more prone to localised damage due to impact loads like tool drop, runway debris and hail stone. This paper, investigated the penetration and perforation behaviour of CFRP laminate reinforced with 0.2 and 0.5 wt% MWCNTs. The projectile impact experiment was conducted using spherical and conical projectiles and the impact resistance was evaluated. The results revealed that 0.5 wt% MWCNTs embedded in CFRP laminate provided better impact resistance to both projectiles. The ballistic limit velocity was enhanced by 14.2% and 17.9% for spherical and conical projectiles, respectively, in the case of 0.5 wt% MWCNTs. Furthermore, numerical simulations were performed using an orthotropic model with Chang-Chang composite failure criteria. The results from numerical findings were consistent. It was concluded that MWCNTs reinforcement improves the projectile impact resistance and energy absorption.