Gun Discharge Research Articles

Contextual Factors Influencing Firearm Deaths Occurring Among Children.

Contextual factors that contribute to firearm injuries among children aged 0 to 10 are not well understood. A retrospective review of the National Fatality Review-Case Reporting System was conducted for firearm deaths of children aged 0 to 10 from 2004 to 2020. Descriptive analyses characterized child and parent demographics, incident details, firearm characteristics, and firearm use. Cluster analysis identified key clustering of contextual variables to inform prevention efforts. Within the study timeframe, 1167 child firearm deaths were reported (Mage = 4.9; 63.2% male; 39.4% urban). At the time of the incident, 52.4% of firearms were reported unlocked and 38.5% loaded. Firearm deaths occurred primarily at the child's home (69.0%) or a friend or relative's home (15.9%), with most involving a handgun (80.6%). Children were supervised in 74.6% of incidents, and 38.4% of child supervisors were impaired during the incident. Cluster analysis identified incident contextual factors clustering in distinct groups, including unsupervised firearm play, long gun discharge while cleaning, hunting, or target shooting, supervised discharge within the child's home, murder-suicide events, deaths occurring in the context of intimate partner violence, and community violence firearm deaths. Data highlight the importance of primary prevention through secure firearm storage to prevent child firearm deaths. Efforts focused on identifying and reducing intimate partner violence, addressing community violence (eg, community greening), and implementing policy that limit firearm access (eg, domestic violence restraining orders, background checks), may reduce child firearm deaths.

Effects of discharge parameters on plasma acceleration and transmission characteristics of a coaxial gun operated in gas-prefilled mode

The effects of discharge parameters on the discharge process and plasma transport characteristics of a coaxial gun in the gas-prefilled mode are studied. The plasma optical intensity and ejection velocity are measured by photodiodes, the optical emission spectrum is taken by a spectroscopic system, and the plasma evolution in the transport process is captured by a high-speed camera. The plasma acceleration characteristics under different discharge parameters show that the velocity and electron density of the ejection plasma are mainly determined by the pre-filled pressure and discharge current, which is consistent with the snowplow model. The kinetic energy of ejection plasma can be significantly increased by reducing the outer loop inductance, which is conducive to increasing the energy utilization efficiency. The time-varying images of plasma radiation and the plasma density at different transport locations illuminate the transmission characteristics of coaxial gun discharge plasma. The results show that the snowplow effect continues to play a role in the plasma transport process, and the plasma accumulation is induced by the combination of shock wave compression. The current-driven magneto hydrodynamics instability occurs during the transport process, and the luminous signal of the plasma current sheet oscillates periodically. In addition, the plasma impact effect is obvious and the gas retarding effect is enhanced with the increase in the gas pressure. These results give us a more comprehensive view of the coaxial gun discharge process and plasma transport and provide a certain reference for optimizing the parameters selection and physical design of coaxial gun discharge plasma characteristics.

Dynamics and impurity spectral characteristics of coaxial gun discharge plasma

<sec>The coaxial gun discharge can produce plasma jet with high velocity, high density and high energy density, and has extensive applications, such as in plasma space propulsion, simulation of the interaction between edge local mode and wall materials in ITER, fuel injection in magnetic confinement fusion devices, and laboratory astrophysics. In the pre-filled discharge mode or snowplow mode, the plasma current sheet is formed near the insulating layer surface and moves toward the end of the coaxial gun under Lorentz force. Plasma velocity, density and purity characteristics are very important research contents for the actual applications of coaxial gun. Emission spectrometry as a non-interference method can be used to diagnose a variety of plasma physical properties.</sec><sec>In this experiment, the effects of different discharge currents and gas pressures on the plasma dynamics, electron density and impurity emission spectra of coaxial gun discharge plasma are studied through the measurement of plasma photocurrent, emission spectra and the shooting of discharge images. The experimental results show that the acceleration time of the plasma in the gun decreases with current increasing in a range of 30–70 kA when the gas pressure is 10 Pa, the spectral intensity of anode and cathode impurities in plasma increase with current amplitude increasing. When the discharge current is 40 kA and the gas pressure is in a range of 10–70 Pa, the acceleration time of plasma increases with gas pressure rising, and the spectral intensity of the cathode impurity in the plasma decreases with the pressure increasing, while the spectral intensity of the anode impurity increases gradually, but its growth rate decreases continuously. The analysis indicates that the presence of metallic impurities originating from the electrode material limits the jet velocity of the plasma and is the main cause of the deviation from theoretical value. The plasma pinch effect at the nozzle of coaxial gun and the acceleration time of high-density arc in the gun are important factors affecting anode ablation. The impurity of cathode material is produced by ion bombardment sputtering, which mainly depends on the energy carried by ions. Therefore, a reasonable choice for discharge parameters is the key factor to obtain optimal plasma characteristics during the discharge of the coaxial gun.</sec>

Suicide Attempt by Successive Nail Gun Discharges to the Head and Chest: A Case Report

As firearms are frequently used in suicide attempts, there is wide recognition of this potential danger with restrictions and barriers present in many jurisdictions to limit the purchase and possession of firearms. However since nail guns were introduced in the 1950s, nail gun discharge (NGD) injuries have been an increasing phenomenon due to more widespread availability and ease of use without restrictions on possession. Although existing literature has described suicide attempts by NGD to single body sites, reports of injuries to multiple body sites are rarer. In this case report, we present the case of a patient who survived multiple, severe, self-inflicted penetrating wounds secondary to a suicide attempt by NGD. Through this case report, we aim to identify future opportunities to tailor aspects of risk assessment for patients who may have occupational access to tools such as nail guns, as this should be a consideration when screening for risk and safety planning. [ Psychiatr Ann . 2023;53(11):525–527.]

Design and Experiment of Discharge Control Methods for Three-Stage Coil Gun Experiments

The aim of this study was to design operation methods for three-stage coil gun experiments and to fabricate and compare prototypes of control systems using these methods. Two methods are proposed: (1) recognizing the position of a projectile using a photointerrupter and (2) operating a control circuit to supply power to a silicon-controlled rectifier when the projectile reaches an intended position by registering the delay time between coil gun operations. The distance between the projectile and the solenoid coil during a coil gun operation is a key design factor. For the multi-stage coil gun manufactured in this study, the discharge time must be determined according to the position of the projectile, which moves at high velocity. Therefore, the selected method should have minimal operation error and allow the circuit to be easily used according to the coil gun stage and configuration. This study compares the prototypes of coil gun discharge circuits that were fabricated based on the proposed methods by applying them to three-stage coil guns and measuring their velocities. The findings of this study could be used to suggest design methods for experimental models for coil guns with fewer stages according to the final velocity and coil gun stage to be manufactured.

Detection of organic and inorganic gunshot residues from hands using complexing agents and LC-MS/MS.

Gunshot residue (GSR) refers to a conglomerate consisting of both organic molecules (OGSR) and inorganic species (IGSR). Historically, forensic examiners have focused only on identifying the IGSR particles by their morphology and elemental composition. Nonetheless, modern ammunition formulations and challenges with the GSR transference (such as secondary and tertiary transfer) have driven research efforts for more comprehensive examinations, requiring alternative analytical techniques. This study proposes the use of LC-MS/MS for chromatographic separation and dual detection of inorganic and organic residues. The detection of both target species in the same sample increases the confidence that chemical profiles came from a gun's discharge instead of non-firearm-related sources. This strategy implements supramolecular molecules that complex with the IGSR species, allowing them to elute from the column towards the mass spectrometer while retaining isotopic ratios for quick and unambiguous identification. The macrocycle (18-crown-6-ether) complexes with lead and barium, while antimony complexes with a chelating agent (tartaric acid). The total analysis time for OGSR and IGSR in one sample is under 20 minutes. This manuscript expands from a previous proof-of-concept publication by improving figures of merit, increasing the target analytes, testing the method's feasibility through a more extensive set of authentic specimens collected from the hands of both shooters and non-shooters, and comparing performance with other analytical techniques such as ICP-MS, electrochemical methods and LIBS. The linear dynamic ranges (LDR) spread across the low ppb range for OGSR (0.3-200 ppb) and low ppm range (0.1-6.0 ppm) for IGSR. The method's accuracy increased overall when both organic and inorganic profiles were combined.

Influence of discharge parameters on pulsed discharge of coaxial gun in deflagration mode

Coaxial gun can produce high-speed and high-density plasma jet and has some potential applications in many research areas such as space thruster, space debris impact simulation, nuclear fusion, and material processing. The coaxial gun is usually composed of a pair of coaxial cylindrical and hollow electrodes. The pulsed discharge of coaxial gun has two discharge modes, i.e., deflagration mode and pre-fill mode. Compared with the pre-fill mode, deflagration discharge mode can induce a plasma jet with few impurities, high collimation, and fast speed. In this paper, the effect of gas injection mass and discharge voltage on the discharge characteristic of deflagration mode are studied with electrical and optical diagnosis including the emission spectrum, plasma velocity and discharge current measurements. The experimental results show that when the gas injection mass is relatively low, such as 1.4 mg, many plasma clusters eject from the muzzle. As the gas flowing into the coaxial gun bottom increases, the plasma density increases and the jet velocity decreases. Eventually, when the gas injection mass increases to 2.6 mg, one cluster of plasma is found and ejects from the muzzle of the gun. In the discharge process, as a small quantity of gas flows into the bottom of the coaxial gun through the electromagnetic valve continuously, new current paths will be generated at the bottom of the coaxial gun and move forward. This results in the observation of multiple plasma jet at the exit of the coaxial gun. It is noted that the plasma densities are different for different gas mass flowing into coaxial gun bottom, but the currents have little effect in the first discharge half cycle due to the small plasma inductance in discharge circuit. Meanwhile, the plasma characteristics under different voltages with the fixed gas mass of 2.6 mg flowing into the coaxial gun bottom are experimentally measured. The results show that the plasma density and speed increase with voltage increasing, which is attributed to the stronger discharge current and larger self-induced Lorentz force. More neutral particles can be ionized into plasma with discharge voltage increasing, and the transport speed becomes faster under the enhanced force. In addition, the multiple ionization phenomena are observed again when the discharge voltage increases from 5 kV to 8 kV. This study provides an insight into how to better apply the coaxial gun discharge plasma to practical engineering field. The article further verifies the phenomenon of multiple discharges at the bottom of the coaxial gun by changing the charging capacitance and analyzing the magnetic probe signals.

Motion characteristics of coaxial gun discharge plasma current sheet

The coaxial gun discharge, used as plasma jet with high density and velocity, has a wide variety of applications such as plasma space propulsion, simulation experiment of thermal transient events in the International Thermonuclear Experimental Reactor, plasma refueling for fusion reactors and a laboratory scale platform for studying astrophysical phenomena. The plasma produced in the coaxial gun can be accelerated by self-induced Lorentz force, and the ionization in the transport process can be based on " snow-plow model” in which a coaxial current sheet moves forward and sweeps a large amount of the gas between two electrodes to cause the plasma dump. Based on the measurements of discharge current, voltage, photocurrent and magnetic signal, the experimental investigation on the characteristics of plasma motion and current sheet channel distribution in the gun operated under different discharge conditions and various pressures is carried out. In this paper, it is emphasized to explore the electrical and dynamic properties about plasma in the first half-cycle of current. The results show that the plasma velocity increases with the increase of the current amplitude, and that the transport distance is proportional to the axial kinetic energy of ions when the pressure is fixed at 10 Pa and discharge current is adjusted from 35.7 kA to 69.8 kA. Moreover, in the case of high current, the plasma jet from the nozzle tends to form a new current path at the bottom of the gun. However, when the discharge current is fixed at 49.8 kA and the gas pressures range from 5 Pa to 40 Pa, the plasma motion velocity and transport distance are continuously reduced. Meanwhile, it is not found that new current paths are generated at the bottom of the coaxial gun under high pressure. The generation of the new current path is relevant to the channel impedance formed by more charged particles left at the bottom of the gun and neutral particles leaking from current sheet during discharge. Besides, a multiple discharge phenomenon is presented in experiment and the secondary discharge breakdown position occurs at the head of the electrode when the current is reversed to a positive value. Therefore, this study provides a reasonable choice of electrical parameters to obtain optimal plasma characteristics during the discharge of the coaxial gun.

Determining the ion temperature and energy distribution in a lithium-plasma interaction test stand with a retarding field energy analyzer.

The ThermoElectric-driven Liquid-metal plasma-facing Structures (TELS) experiment at the University of Illinois is a gas-puff driven, theta-pinch plasma source that is used as a test stand for off-normal plasma events incident on materials in the edge and divertor regions of a tokamak. The ion temperatures and resulting energy distributions are crucial for understanding how well a TELS pulse can simulate an extreme event in a larger, magnetic confinement device. A retarding field energy analyzer (RFEA) has been constructed for use with such a transient plasma due to its inexpensive and robust nature. The innovation surrounding the use of a control analyzer in conjunction with an actively sampling analyzer is presented and the conditions of RFEA operation are discussed, with results presented demonstrating successful performance under extreme conditions. Such extreme conditions are defined by heat fluxes on the order of 0.8 GW m-2 and on time scales of nearly 200 μs. Measurements from the RFEA indicate two primary features for a typical TELS discharge, following closely with the pre-ionizing coaxial gun discharge characteristics. For the case using the pre-ionization pulse (PiP) and the theta pinch, the measured ion signal showed an ion temperature of 23.3 ± 6.6 eV for the first peak and 17.6 ± 1.9 eV for the second peak. For the case using only the PiP, the measured signal showed an ion temperature of 7.9 ± 1.1 eV for the first peak and 6.6 ± 0.8 eV for the second peak. These differences illustrate the effectiveness of the theta pinch for imparting energy on the ions. This information also highlights the importance of TELS as being one of the few linear pulsed plasma sources whereby moderately energetic ions will strike targets without the need for sample biasing.

Measurements of plasma profiles using a fast swept Langmuir probe in the VINETA-II magnetic reconnection experiment

A fast-swept Langmuir probe capable to be biased at a high voltages has been constructed and successfully operated at the VINETA-II magnetic reconnection experiment. The presented circuit has two main features beneficial for fast transient parameter changes in laboratory experiments as, e.g., plasma guns or magnetic reconnection: the implementation simplicity and the high voltage sweep range. This work presents its design and performance for time-dependent measurements of VINETA-II plasmas. The probe is biased with a sinusoidal voltage at a fixed frequency. Current − voltage characteristics are measured along the falling and rising slopes of the probe bias. The sweep frequency is fsweep= 150 kHz. The spatiotemporal evolution of radial plasma profiles is obtained by evaluation of the probe characteristics. The plasma density measurements agree with those derived from a microwave interferometer, demonstrating the reliability of the measurements. As a model plasma system, a plasma gun discharge with typical pulse times of 60 μ s is chosen.

Experimental study on coaxial gun pulse discharge plasma density change in transport process

Coaxial gun discharge plasma with high density and velocity has a number of potential applications in fusion energy, plasma refueling, disruption mitigation in tokamaks, plasma space propulsion, acceleration of dust particles to hypervelocity etc., and thus has become an important research topic in fields of nuclear physics and aerospace engineering. In this paper, we report the experimental investigation on electrical and transport characteristics of coaxial gun discharge plasma. Based on electrical and optical diagnoses, the discharge voltage, discharge current and axial velocity of plasma transport are measured. Meanwhile, the emission spectrum technology is employed to measure the Stark broadening of H spectral line and then plasma density is calculated. The experimental results show that the discharges in the coaxial gun present a feature of multiple discharges and blow-by instability phenomena are observed by photomultiplier acquired signals. In addition, the plasma velocity and density in the transport process are not constant. It is found that the axial plasma velocity in the transport process decreases due to mass gain caused by the snowplow model and the change tendency of plasma density in the transport process is dependent on various settings. A systematic study has been carried out for exploring plasma density change in transport process, and different experimental parameters are adopted in order to further analyze the physical mechanism of plasma density change in transport process. When the air pressure in the coaxial gun is changed from 4.0 Pa to 10 Pa, for 1.08 kJ applied power energy, an obvious difference appears in transport properties of plasma density, i.e., plasma density increases gradually in 4.0 Pa air while it increases first and then decreases in 10 Pa air. However, the plasma density increases continually in air pressure of 10 Pa when the power energy is increased to 7.68 kJ. Moreover, when the working gas is replaced with argon and discharge setting is 4.0 Pa pressure and 1.08 kJ applied power energy, the plasma density decreases continually in the transport process. The distinct behaviors, as analyzed, are mainly caused by plasma energy transformation difference in the transport process. As it is known, the plasma movement at high velocity in coaxial guns can ionize neutral particles and consume its energy, which results in the increasing plasma density and the decreasing electron and ion temperatures in the transport process. Then, a maximum density is present in the transport process when the electron and ion temperatures are lower than that at which gas ionization occurs. The axial location of maximum density changes with applied power energy, working gas pressure and species, which means that plasma energy transformation and density change properties in transport process strongly rely on different external parameters. The study provides some insight into how to better apply the coaxial gun discharge plasma to practical engineering field.

Discharges of plasma induced by hypervelocity impact on the solar array with different substrate structures

The purpose of the paper is to investigate the discharge of the plasma generated by a projectile hypervelocity impact on solar array with three kinds of different substrates at the 60° incidence angle and the external applied voltage of 100 voltage. Four sets of experiments were performed to impact solar arrays with CFRP Aluminum honeycomb sandwich substrate, Aluminum honeycomb sandwich substrate and the aluminum substrate by using two-stage light gas gun loading system and discharge measurement system established. Experimental results showed that discharge voltage and discharge current of the solar array with CFRP Aluminum honeycomb sandwich substrate are the most strongest among the solar array with CFRP Aluminum honeycomb sandwich substrate, Aluminum honeycomb sandwich substrate and the aluminum substrate. This work will be helpful to improve the material and substrate' structure of the solar arrays in spacecrafts.

Penetrating Cardiac Nail Gun Injury in a Child

Nail gun injuries primarily occur in the extremities of adult males as a consequence of accidental occupational trauma. Such injury involving the thorax is much less common, and penetrating cardiac injury secondary to pneumatic nail gun discharge is rare. Although potentially lethal, most cases with cardiac trauma are survivable with expedient surgical intervention. Despite improvements in engineered safety mechanisms, the incidence of nail gun injuries has risen as use of the devices has increased. The widespread availability of these tools to nonprofessional consumers exposes a broader population to the potential hazards associated with these devices. We describe the presentation and successful management of the first reported case of penetrating cardiac nail gun injury in a young child.

Numerical and experimental study of the dynamics of a μs helium plasma gun discharge with various amounts of N2 admixture

This paper presents a combined 2D numerical and experimental study of the influence of admixture on the dynamics of a He– discharge in the 10 cm long dielectric tube of a plasma gun set-up. First, the comparison between experiments and simulations is carried out on the ionization front propagation velocity in the tube. The importance of taking into account a detailed kinetic scheme for the He– mixture in the simulations to obtain a good agreement with the experiments is put forward. For the μs driven plasma gun, the two- and three-body Penning reactions occurring in the plasma column behind the ionization front, are shown to play a key role on the discharge dynamics. In the experiments and simulations, the significant influence of the amplitude of the applied voltage on the ionization front propagation velocity is observed. As the amount of varies, simulation results show that the ionization front velocity, depends on a complex coupling between the kinetics of the discharge, the photoionization and the 2D structure of the discharge in the tube. Finally, the time evolution of axial and radial components of the electric field measured by an electro-optic probe set outside the tube are compared with simulation results. A good agreement is obtained on both components of the electric field. In the tube, simulations show that the magnitude of the axial electric field on the discharge axis depends weakly on the amount of conversely to the magnitude of the off-axis peak electric field. Both, simulations and first measurements in the tube or within the plasma plume show peak electric fields of the order of 45 kV·cm−1.

Accidental Death of Construction Worker due to Unintended Nail Gun Discharge: a Case Report

Background : In spite of being rare, intracranial nail gun injury represents one of the fatal penetrating head injuries. Case Report: Here we report a case of intracranial nail gun injury in a 28 years old well-trained construction worker who left the electric nail gun on the edge of the window to pick up one of his tools from the ground. Unfortunately, his leg got entangled in the nail gun cable and thus the nail gun dropped on the ground firing a nail that killed the worker. Conclusion: To the best of our knowledge, this first time death from nail gun injury is reported in the Arab world; although, there are previous reports of survivable nail gun cardiac injuries and cranial injuries from Saudi Arabia. Thus, it is important to raise public awareness about such cases in order to reduce the occurrence of nail gun injuries. Moreover, health and safety inspections mandated and supported by law, might be much more effective in reducing such injuries.

磁化同軸プラズマガン装置におけるCTプラズマの特性評価とパルス高熱負荷模擬試験への適用

A magnetized coaxial plasma gun (MCPG) device at Univ. of Hyogo was used as a simulation facility for pulse heat loads such as ELMs (Edge Localized Modes) onto plasma-facing materials in magnetically confined fusion devices. In the present study, characterization of the compact toroid (CT) plasmas produced by the MCPG device was performed. Dependences of the CT plasma parameters of line-averaged electron density, ion temperature and flow velocity on the gun discharge voltage and the bias magnetic flux were measured. As a result, it was observed that the pulse length, the line-averaged electron density, and the ion temperature and flow velocity were approximately 200 µs, approximately 6×1021 m-3, approximately 30 eV, and approximately 50 km s-1, respectively. The surface energy density measured with a tungsten calorimeter was approximately 0.4 MJ m-2. Thus, it was shown that the ELM-like pulsed plasma heat loads with the energy density and the pulsed length predicted in the ITER divertor can be produced using the MCPG device.

Unexpected Plasma Plume Shapes Produced by a Microsecond Plasma Gun Discharge

The plasma plume shapes produced at the outlet of a 1 mm inner diameter plasma gun capillary are investigated over an extended range of both neon flow rates and pulse repetition rate (prr). Various complex, but stable, plume shapes are observed. It appears first that for a given flow rate, the plume shape can be modulated with prr sweeping, revealing fascinating multidart shape when discharge is triggered at a fundamental frequency and up to the sixth harmonic. Second, reproducible similar plume patterns, either multidarts or conical shaped, can be obtained for given appropriate flow rate/prr parameter couples. These phenomena tend to show the effect of the force exchange between the neutral gas flow and the discharge species resulting in plume patterning.

Quasi-steady carbon plasma source for neutral beam injector

Carbon plasma is successfully sustained during 1000 s without any carrier gas in the bucket type ionization chamber with cusp magnetic field. Every several seconds, seed plasmas having ∼3 ms duration time are injected into the ionization chamber by a shunting arch plasma gun. The weakly ionized carbon plasma ejected from the shunting arch is also ionized by 2.45 GHz microwave at the electron cyclotron resonance surface and the plasma can be sustained even in the interval of gun discharges. Control of the gun discharge interval allows to keep high pressure and to sustain the plasma for long duration.

Stun gun induced myotendinous injury of the iliopsoas and gluteus minimus

We report a 57-year-old man with a complete tear of his iliopsoas tendon at the distal myotendinous junction, a near complete tear of the iliopsoas tendon at the lesser trochanter of the femur, and a high-grade tear of his gluteus minimus tendon at the greater trochanter of the femur after being struck by a stun gun in the proximal left thigh. The stun gun discharge resulted in a forced contraction of the left hip flexor muscles, which resulted in pain, weakness and difficulty with active hip flexion. Three months after the being struck with the stun gun, the patient underwent magnetic resonance imaging (MRI) of the left hip. MRI of the left hip revealed a complete tear of the left iliopsoas tendon from the lesser trochanter with 4cm of proximal retraction and a high-grade strain of the gluteus minimus tendon at the greater trochanter. The distal iliopsoas myotendinous junction and lesser trochanter tendon insertion were surgically repaired. This case illustrates that a stun gun can cause acute rupture of the iliopsoas tendon and tear of the gluteus minimus tendon, which is well visualized on MRI.

Depth of concussion in cattle shot by penetrating captive bolt

The prevalence of shallow depth of concussion following captive bolt shooting was assessed in 1608 cattle at an abattoir. Depth of concussion was determined in each animal from physical collapse, presence or absence of corneal reflex, normal rhythmic breathing, eyeball rotation, and whether the animal was re-shot. The presence of nystagmus and the absence of tongue protrusion were also monitored as potential indicators of a shallow depth of concussion, and simultaneous noise measurements assessed whether loudness of gun discharge was linked to concussion depth. The prevalence of a shallow depth of concussion was 8% for all cattle and 15% for young bulls. Nystagmus was associated with other indicators of a shallow depth of concussion. Absence of tongue protrusion was not associated with depth of concussion, but could serve as a useful indicator of jaw relaxation and insensibility following exsanguination. Soft-sounding shots (⩽111 dB) when using 4.5 gr cartridges were associated with shallow depth of concussion.