Gun Chamber Research Articles

Design and development of vacuum system for electron beam powder bed fusion process

A vacuum system is one of the crucial components of the Electron Beam-Powder Bed Fusion Process (EB-PBF). It ensures the generation of a high-intensity electron beam. This paper presents a vacuum system design for the EB-PBF process. The work chamber and EB gun chamber have been designed and verified using ANSYS workbench for stress, strain, and deformation limits and found satisfactory. The analytical calculations have been performed for all the pumps, considering the various gas loads during the process. After the design, the vacuum system has been fabricated and tested for its stability, ultimate vacuum, and leak rate. The helium leak test results show that all the joints have a leak rate better than 1 × 10−8 mbar l/s. Further, the analytical results of each pump have been compared with experimental results and found almost in line with the theoretical results. The results show that a pressure lower than 1 × 10−5 mbar and 5 × 10−6 mbar can be achieved in the work chamber and EB gun chamber in less than 23 min and 10 min respectively. The chamber was evacuated multiple times and found that the chamber could still hold pressure better than 1 × 10−2 mbar after 48 h.

‘Fabricado no Sul’: Histórias de computação sobre a insegurança da GS

Abstract Sci-fi tales of computing technologies have been carriers of an unabashed anxiety vis-à-vis the present and the future of politics. In International Relations, these tales split in two: either technology divides developed from developing, while also forging paths to development; or it helps contain unruly bodies–human’s, nature’s, otherwise. Drawing on the case of activist app Fogo Cruzado, this article proposes to shift the narrative towards the different political pathways that can be fabricated through an engagement with existing digital infrastructures. In re-enacting the trajectory of a bullet from a gun chamber to a smartphone notification, I show how the making of situated digital artifacts can illuminate how we think about Global South politics and disrupt two assumptions structured through tales of control and domination: one, that digital infrastructures are monolithic, seamless, and consistent; and two, that tales of technological innovation need to happen in the North.

Evaluation of dosimetric parameters after electron gun and ion pump replacement in linear accelerator device and comparison of results by gATE/Geant4 simulation

This study evaluates dosimetric data such as PDD, dose profile and tissue phantom rate (TPR20/10) after replacing the LINAC device's electron gun and ion chamber pump. These values obtained after the change were compared with the standard PDD protocol, British Journal of Radiology Supplement 25 (BJR 25) report, Beam Data (measured and recorded as reference values during the setup phase, BD) and simulation results. In additional, uncertainty results were obtained for absorbed doses to water using different calculation tools. The experimental setup was created in the GATE/Geant4 simulation program, and the experimentally obtained TPR20/10, beam profile and PDD values were compared with the simulation. The difference between TPR20/10 values for 6 and 18 MV photon energies was found to be below 1% for 6 MVs and 3% for 18 MV. When different calculation tools were used, uncertainties were found in the absorbed dose measurements ranging between 0.8% and 1.87%, which is compatible with the uncertainties (1.4-2.1%) specified in the IAEA report. Even though small uncertainties were observed in the results, the differences between the calculations in the measurements of absorbed doses were insignificant. Estimated uncertainties for GATE was a little smaller than those measured using experimental methods, BD and BJR 25. Although the values obtained are within the tolerance, after such significant materials are changed in the LINAC device, a water phantom should be set up, the measurements should be repeated, and the results should be confirmed to be within the limit values.

Influence of High-temperature Environment on Cook-off Characteristics of Modular Charge

In order to study the heating process of the modular charge loaded into the chamber after the continuous firing of the large caliber gun in the high-temperature environment, a 2D transient cook-off model of the modular charge retained in the chamber was established with cook-off method. When the ambient temperature is 323K and the critical temperature of the inner wall of the gun chamber is 443K, the wall temperature distribution of the gun is solved after 2 rounds/min of continuous firing. Taking this as the initial temperature condition, the cook-off process of the modular charge in the chamber is numerically simulated, and then the cook-off-odd characteristics of the modular charge in the high-temperature environment are analyzed. The results show that after 33 rounds of continuous firing at 2 rounds/min at 323K ambient temperature, the temperature of the inner wall of the gun chamber reaches 442.7K, and the modular charge would have a cook-off response after 107.5s after loading into the chamber, and the response temperature is 483.5K. The initial response position of the modular charge is located at the inner wall of the upper right corner of the module cartridge. The consistency between numerical calculation and experimental results shows that the model could analyze the cook-off problem of modular charge in bore well.

Room-Temperature-Grown amorphous Indium-Tin-Silicon-Oxide thin film as a new electron transporting layer for perovskite solar cells

We report the amorphous quaternary oxide, indium-tin-silicon-oxide (ITSO), thin film as a new electron-transport layer (ETL) for perovskite solar cells (PSCs). ITSO thin films are grown by magnetron co-sputtering indium-tin-oxide (ITO) and silicon oxide (SiO2) on commercial transparent conducting oxide (TCO) thin films at room temperature. As Si content increases (0–53.8 at%) the optical bandgap increases by approximately 1.3 eV and the electrical resistivity increases by six orders mainly because of the carrier concentration decrease. Consequently, the ITSO electronic structure depends largely on Si content. PSCs employing ITSO thin films as ETLs were fabricated to evaluate the effect of Si content on device performances. Si content influenced the shunt and series resistance. The optimized device was obtained using an ITSO film with 33.0 at% Si content, exhibiting 14.50% power-conversion efficiency. These results demonstrate that ITSO films are promising for developing efficient PSCs by optimizing the growing process and/or In/Sn/Si/O compositions. This approach can reduce PSC manufacturing process time and costs if ITO and ITSO are grown together by continuous sequential sputtering in a dual gun (ITO and SiO2) chamber.

Reduction of impurity sources in Si crystal growth system with electron gun beam heating

A new series of experiments was conducted to determine the source of impurities in the process of silicon crystal growth with electron beam heating. A gas-dynamic window was placed between the electron gun and growth chamber. Also positively-charged traps were placed along the crucible to reduce the number of electrons hitting the chamber and the crucible. Five experiments were conducted: two with the window, two with charge traps, and one with both the window and charge traps. The analysis of obtained samples showed that the gas-dynamic window decreases the content of Al, Cu, Fe, Cr and O2, and the trap, used in the experiments, decreases the content of Fe, Cr and Cu in residues of the melt. The content of all impurities, except Al, is close to the goal level. Al impurities come only from the gun, but the gas-dynamic window cannot eliminate them completely. It seems that Al impurities come either as neutral atoms carried by the gas or as positively charged ions. To reduce these impurities, a separation of the Al flow from the beam by the magnetic field is proposed.

Analytical and numerical methods for calculation the deep of penetration the welding seam formed by the electron beam generated by glow discarge electron guns

The article is devoted to the problem of defining the focal diameter of electron beam, formed by the glow discharge electron guns, as well as the necessary pressure in the gun chamber for realising the welding process. Taking into account, that glow discharge electron guns are widely used in industry for welding of different metals, and that for providing the high quality of welding joints estimation of energetic parameters in beam focus is very important, proposed methods are very important for effective elaboration and designing of the novel glow discharge electron guns constructions for specific technological operations. With known focal beam deameter and thermodinamic parameters of welding details material the deep of penetration of welding seam, as well as the necessary pressure in discharge chamber have been estimatied. Two proposed methods are generally based on the analytical solving of explite equation and on numeracal solving of sophisticated non-linear equation. Obtained simulation results with and without taking into account the spsace charge of own beam electrons are also given

A calculation method of interior ballistic two-phase flow considering the recoil of gun barrel

The theory of interior ballistic two-phase flow (IBTPF) is the primary means to study the distributions of physical quantities in gun chamber. In previous calculations, the gun breech is usually simplified as a fixed wall boundary, totally ignoring the effect of gun barrel recoil on interior ballistic processes. Thus to truly describe the interior ballistic process of the self-propelled gun (SPG), the transfer matrix method of multibody system (MSTMM) is combined with the theory of IBTPF in this paper. By simultaneously solving the generalized coordinate equations of multibody system and the conservation equations of IBTPF, the gun barrel recoil is converted to the moving boundary of the gun breech, and a more accurate calculation method of IBTPF is established. The results show that the simulated vibration characteristics, dynamic response during launch as well as interior ballistic performance of the SPG are all in good agreement with test values. Compared with no recoil, the gun barrel motion affects the growth regularity of the chamber volume behind the projectile, and eventually results in the changes of interior ballistic performance indexes such as maximum breech pressure and muzzle velocity. Overall, this study provides a more accurate prediction and simulation tool to enable better insight into such complicated interior ballistic processes, which is of great significance to the launch safety analysis and subsequent ballistic calculations.

Effects of module number and firing condition on charge thermal safety in gun chamber

Thermal safety of modular charge which is fed into and retained in the chamber after gun fires consecutively is first investigated with cook-off method. A two-dimensional cook-off model of modular charge in gun chamber is established and the cook-off process of modular charge in gun chamber is numerically simulated. Then the effects of module number and firing condition on charge thermal safety are evaluated by researching the cook-off response characteristics of modules. The results show that, under conditions of different module numbers the cook-off responses all occur on the module closest to the boundary of missile, and the single-base propellants located at the inner surface of cartridge ignite first. When the number of loaded module changes from 1 to 6, the cook-off response temperatures vary little, only in a small range of 478.1 K–482.4 K. The cook-off response times decrease logarithmically in the range of 211.2 s–166.7 s with the increasing length of residual air gap in gun chamber. The simulation results are well matched with the experimental data. Furthermore, different firing conditions have great influence on the cook-off response time, minor influence on the initial response position and little influence on the response temperature. Under the three conditions of consecutive 32 launches with 5 rounds/min, 43 launches with 1 round/min, and 41 launches with different firing frequencies, the cook-off response temperatures are 479.2 K, 481.1 K and 479.9 K respectively and the response times are 709.2 s, 211.2 s and 214.4 s respectively. The response position is near the middle area of the inner cartridge surface in the former condition and near the right area in the latter two conditions.

Secondary electron emission from reticulated cellular copper surfaces

An experimental and computational study of the secondary electron yield (SEY) of copper foam is presented. Ray-tracing Monte Carlo (MC) simulations, based on primary electron transport and interactions with the electron system in solid and foam-type copper, are also included. The 3D reticulated foam geometry is explicitly represented in the MC model. This allows the influence of the complex copper surface on the energy and angular dependence of the SEY to be determined. Experimental measurements of SEY were performed in a high-vacuum electron gun chamber. Solid copper and copper foam with 100 pores per inch and a 4.6% volume fraction were tested for energy and angular dependence of SEY. Incident angles were varied from 0° to 75° and electron beam energy ranged from 20 eV to 570 eV. The agreement between MC simulations and experiments suggests that a general reduction of the SEY by around 20% is due to the interaction and subsequent adsorption of a fraction of emitted secondary electrons on the internal surfaces of the reticulated foam. Moreover, it is found that the SEY becomes nearly independent of the incident electron energy above 200 eV for steep angles of incidence (θ>45°).

ИНТЕЛЛЕКТУАЛЬНАЯ СИСТЕМА КОНТРОЛЯ ДОСЫЛА АРТИЛЛЕРИЙСКОГО СНАРЯДА В КАМОРУ ОРУДИЯ

The aim of the study is to develop a method for controlling the sending of an artillery shell to the gun’s chamber using an acoustic portrait. The existing method for controlling the delivery of artillery ammunition to the gun’s chamber with a separate loading method is based on measur-ing the speed of one of the elements of the rammer. Such an approach to the control didn’t provideguaranteed reliability due to the impossibility of measuring speed in the final segment of the pro-jectile’s inertia motion. At present, vibroacoustic methods of analysis are widely used in various fields of science and technology and can be extended to the problem under consideration. The essence of the method proposed in the article is to excite acoustic vibrations in the "projectile - gun chamber" system and to distinguish characteristic acoustic portraits (signatures) with their subsequent analysis. To study this method, a laboratory bench has been developed that imitates the barrel of a gun with a chamber, and a shell simulator with various obturator belts. A projectile impact at the moment of jamming in the chamber cone or applied externally, for example, on the gun’s body, excites characteristic acoustic vibrations, which differ for cases of reliable and insuf-ficient sending. In the developed stand, acoustic vibrations were excited by an external impact on the resonator and were recorded for subsequent analysis. For an unambiguous classification of events of reliable jamming and insufficient submission, it is necessary to select the optimal vector of signs of an acoustic portrait of the obtained audio recordings. The usual spectral conversion makes it possible to distinguish characteristic frequencies, however, the set of such spectral com-ponents is not suitable as classification features due to the significant array of data obtained as a result of this analysis, and also due to the inability of the Fourier transform to recognize short-term low-power bursts. Therefore, as the classification features were selected mel-frequency cepstral coefficients. Based on the set of such coefficients, using the artificial neural network, the degree of jamming of the projectile simulator in the stand was classified into three categories: “sleep-row is not jammed”, “insufficient shell projectile”, “projectile jammed”. As a result of training the neural network on a significant sample of audio recordings, a classification accuracy of 90% was achieved. It is shown that the developed method of such vibroacoustic analysis can be applied in robotic artillery weapon control systems, as well as in other technical tasks, for exam-ple, in oil and gas production to control the docking of articulated main pipes.

Interaction of clustered air gun bubbles in marine prospecting

The study of air gun bubbles is significant to marine resource detection, and the use of clustered air guns is an effective way to reduce the undesirable bubble pulse in engineering applications. In this paper, an improved air gun bubble model is established based on the boundary element method. The mass and heat transfer of the gas from the air gun chamber to the bubble, and the heat transfer between the bubble and surrounding water, are taken into consideration. Using this model, motion of non-spherical clustered air gun bubbles is simulated. Through consideration of the bubble topology under coalescence and splitting, the multi-period pressure waves released from the clustered air guns are successfully calculated. The influence of the separation distance and the volume distribution of two bubbles on the far-field pressure wave are then investigated. A critical value for the distance between two bubbles, at which the bubble pulse is effectively suppressed, is found. Changing the bubble volume distribution not only reduces the bubble pulse but also decreases the primary pulse, provided the volumes of the two bubbles are not equal. Finally, the pressure waves generated by three bubbles and by two bubbles are compared. Although pressure waves from three bubbles have a long period, the bubble pulse attenuation effects are almost the same as those for two bubbles.

An Airgun Array Source Model Accounting for High-Frequency Sound Emissions During Firing—Solutions to the IAMW Source Test Cases

JASCO's Airgun Array Source Model (AASM) is a combined deterministic and stochastic model that separately treats the low-frequency and high-frequency components of signals produced by airgun arrays. The low-frequency module is based on solving the equations of motion for interacting spherical bubbles. The high-frequency module is based on a stochastic model of the airgun spectrum, which has been derived from a principal component regression analysis of the experimental data. This stochastic model determines the frequency spectrum of an airgun waveform during the rapid onset of a pressure that occurs when air is released from the gun chamber. AASM combines the output of these two modules to predict the source waveform of an airgun array over a wide frequency range (0-25 kHz). AASM was among the source models included in benchmark comparisons presented at the International Airgun Modeling Workshop (IAMW), held in Dublin, Ireland, in 2016. Results from the workshop showed that different source models agreed reasonably well at low frequencies (<;200 Hz), but they diverged substantially at high frequencies (>1 kHz). To help better understand the reasons for a mismatch between source models, this paper presents solutions to the IAMW source test cases, calculated using AASM, as well as a detailed description of AASM's theoretical underpinnings.

Сurrent Issues in Sebaceous Sweat Fingerprint Residue Visualization on Fired Cartridge Cases

This article focuses on issues concerning discovery of hands deposits on cases fred with certain models of fre weapons – 5.45 mm assault rifle АК-74М, 9 mm Makarov gun, 7,62 mm TT gun. Five persons left in turn on each of the above ammunition rounds intentionally qualitative hand traces, following which a shot was fred. After the shot the fre shot cases were collected and packed, avoiding contact between side surfaces and package material. The possibilities of discovery hand deposits on fred cases were determined by using reductive-oxidative and physical-chemical methods. The mechanism of “latent degradation” of hand deposits on cases formed before fring caused by the influence of the shot fact (high temperature, static and dynamic power contact of fred case with gun chamber walls) has been reviewed.

Studies on ballistic parameters of di-butyl phthalate-coated triple base propellant used in large caliber artillery gun ammunition

ABSTRACTTriple base propellant (TBP) containing mainly nitrocellulose, nitroglycerine, and nitroguanidine has been manufactured and coated with plasticizer in the present work. The aim was to study ballistics of di-butyl phthalate (DBP)-coated TBP. DBP solution in ethanol containing nitrocellulose dope was used for coating onto the propellant grains. DBP-deterred propellant showed inhibition to burning, resulting in lowering the values of ballistic parameters namely peak pressure (Pmax), dPmax, pressure index (α), and burning rate coefficient (β) during closed vessel firing. Increase in percentage of DBP in coating solution led to further decrease in ballistic parameters. Dynamic evaluation of the surface-moderated propellant showed comparatively lower muzzle velocity and chamber pressure for deterred propellant batches without leaving any unburnt particles in gun chamber at subzero temperatures with the lowest possible charge mass. The DBP-coated propellant can be useful in 155-mm artillery gun to achieve higher loading density as it has lower flame temperature and chamber pressure as compared to uncoated propellant which will result in increasing barrel life due to reduction in the barrel erosion.

Numerical Analysis of Ar and Ar-H2 Atmospheric Plasma Spray With a Simplified Model

To study the difference of plasma spraying process between argon and argon-hydrogen working gas, a relative simplified fan-shaped numerical model of argon/argon-hydrogen atmospheric plasma spray process was set up to analyze the multi-physic field in the spraying gun. The model took electrodes especially cathode and anode boundary layers into consideration. In other words, a two-temperature plasma model was employed. With regard of both ionization and recombination of ions and electrons, their number density distributions, which are important to determine whether the injected particles are charged, were studied. The influence of secondary gas on plasma flow was investigated. According to the results, when adding hydrogen into the pure argon plasma, the temperature and velocity of the gas flow in spray gun chamber increased. The calculated results will provide theoretical guidance for the design and optimization of gun structure.

Numerical study on motion of the air-gun bubble based on boundary integral method

To simulate the motion of the non-spherical bubble generated by air gun, boundary integral method is used in conjunction with the basic theory of the air gun. The time length of the bubble aeration τ (i.e., the close time of the air gun), the utilization efficiency of the gas inside the air gun chamber η, the heat transfer coefficient α and other key parameters of the air gun are employed to control the motion of the bubble. In the simulation of a single air gun bubble with buoyancy, the vortex ring model is used to simulate the motion of the toroidal bubble after jet impacts, and it is extended to the multiple vortex rings in the simulation of the interaction between two clustered air gun bubbles. Some new findings are summarized as follows: (i) Under the effect of the buoyancy, the shape of the bubble becomes non-spherical at later phase of bubble collapse, but the deformation seems to have little effect on the far-field pressure. (ii) For the clustered air gun bubbles, the primary-to-bubble pulse ratio will reach a maximum when the standoff distance d is about 1.6 times maximum radius of a single bubble. (iii) Primary-to-bubble pulse ratio is relative large at a small firing depth of the air gun H (the vertical distance from the bubble center to the free surface).

Practical design of the electron gun for a microfocus x-ray source

A practical electron gun including the cathode, the grid, the anode, the insulator, the joint flange, and the gun chamber was developed to build a 90 keV microfocus x-ray source with high performance. Based on the electron emission theory at metal surface, the cathode, the grid, and the anode were optimized to achieve fine crossover, high maximum brightness, and high effective brightness with 1 mA beam current. In order to improve stability of the gun, the grid, the anode, the insulator, the joint flange, and the gun chamber were designed and fabricated to eliminate discharge at the peak and the creepage along insulator. Results show that the effective brightness of this model is 1.05×105A/(cm2 sr) with 1 mA beam current, and the microfocus x-ray source has a resolution below 4 μm when the target current is 100 μA. The practical electron gun can improve the beam current quality of the microfocus x-ray source.

Nonlinear Material Behavior Analysis under High Compression Pressure in Dynamic Conditions

Gun chamber pressure is an important parameter in proofing of ammunition to ensure safety and reliability. It can be measured using copper crushers or piezoelectric sensor. Pressure calculations in copper crusher method are based on linear plastic deformation of copper after firing. However, crusher pressure deformation at high pressures deviates from the corresponding values measured by piezoelectric pressure transducers due to strain rate dependence of copper. The nonlinear deformation rate of copper at high pressure measurements causes actual readings from copper crusher gauge to deviate from true pressure values. Comparative analysis of gun chamber pressure was conducted for 7.62 × 51 mm ammunition using Electronic Pressure, Velocity, and Action Time (EPVAT) system with piezoelectric pressure transducers and conventional crusher gauge. Ammunitions of two different brands were used to measure chamber pressure, namely, NATO standard ammunition and non-NATO standard ammunition. The deformation of copper crushers has also been simulated to compare its deformation with real time firing. The results indicate erratic behavior for chamber pressure by copper crusher as per standard deviation and relative spread and thus prove piezo sensor as more reliable and consistent mode of peak pressure measurement. The results from simulation, cost benefit analysis, and accuracy clearly provide piezo sensors with an edge over conventional, inaccurate, and costly method of copper crusher for ballistic measurements due to its nonlinear behavior.

Operator splitting technique with FORCE scheme employed to simulate pressure wave motion inside gun chamber

The work is focused to study the mathematical modeling and numerical simulation of solid propellant combustion during internal ballistics cycle. Here, we have used a reduced single phase model from Baer–Nunziato two-phase flow model for gas and solid mixture of propellant. The model consists of balance equations of mass, momentum and energy with constitutive laws. First ORder CEntred (FORCE) scheme is employed to provide an insight of motion of pressure wave in gun chamber during burning of igniter and solid propellant. The study is performed with the constant emission rate of igniter gases. The burning rate of propellant is expressed as a non-linear function of pressure in terms of pressure exponent. Depending on the pressure exponent three cases are evolved: constant, linear and non-linear rate of burning of propellant. FORCE scheme captures the motion of pressure wave with time and space. The local phenomena of pressure, temperature, velocity, density and rate of burning are demonstrated from breech end to the base of the projectile at different time. The effect of discontinuous pressure on burning dimensions of grain are examined. The non-uniform burning of grain dimensions may result into grain fracture. This study helps in designing the system to avoid such situations.