The gun control system of the IFUSP microtron

A thermionic gun control system has been developed for the IFUSP microtron. The control system, which is composed of a dedicated microcomputer, A/D converter, grid pulser, filament and grid power supplies, is kept at a high voltage potential. The gun parameters are handled through a PC computer at ground potential via fiber-optic link.     

The performance of fighting vehicle hydraulic gun buffers

This paper describes research into the performance of high-energy gun recoil absorbers, usually referred to as gun buffers, for use on military fighting vehicles. A test facility, built at the University of Birmingham, to simulate the gun reaction loads imposed on the recoil absorbers is described. Tests to examine the sensitivity of the buffer performance to change in recoil mass, velocity, fluid and density are presented. A theoretical model to predict the buffer behaviour is derived which enables parameters such as fluid compressibility, aeration and elasticity of the system to be investigated. The theoretical predictions are shown to agree with data obtained from tests.     

The electromagnetic θ gun and tubular projectiles

Unlike the better known rail gun, the θ gun applies the propelling force along the length of its projectile. This is shown to allow much greater acceleration of high fineness ratio projectiles for a given barrel pressure, allowing much shorter barrels for military applications. A computer code which simulates performance of the θ gun is described and experimental results from a few simple, low energy experiments show close agreement with code predictions. Trajectories and aerodynamic heating for three candidate military projectiles are calculated for vertical and horizontal atmospheric launches where initial velocity is as high as 3 km/s. The calculations indicate that in some cases a thin layer of heatshield (ablator) will be required to control projectile heating.     

湿喷机机械臂喷枪振动特性的研究

为了提高某公司生产的CHP30型湿喷机机械臂的工作性能,运用D H坐标法对该机械臂进行运动学分析;基于刚柔耦合系统动力学理论,建立了机械臂的刚柔耦合模型,利用ADAMS分别对机械臂的刚性模型和刚柔耦合模型进行了动力学分析,得到了不同载荷情况下机械臂末端在各坐标轴方向上的位置曲线.仿真结果表明：机械臂和混凝土的重力动载荷以及喷射作用力是其产生振动的主要原因,最大振幅约为0.04 m,与实际情况相吻合;端部喷射作用力对机械臂末端振动的影响程度因喷射方位的改变而变化,喷射侧面时,振幅最大,喷射顶部时,振幅最小;橡胶输送管悬挂在2个锁扣上时对机械臂的振动影响较小.仿真结果对湿喷机机械臂的设计有一定的指导作用,同时为机械臂末端的轨迹规划和机械臂的疲劳分析提供了理论依据．     

Advanced electromagnetic gun simulation

The objectives of this simulation are to support the varlous ElectroMagnetic Gun (EMG)operability requirements, to be maintainable, to duplicate test results or simulate a theoretical system, and to be able to rapidly assess performance and conduct trade studies. This versatile simulation is capable of both performance analysis and some limited component sizing studies. The simulation will permit mixing and matching of various potential EMG components to simulate conceptual or real rapid-fire and single-shot EMG configurations. A generic preprocessor was developed to permit the handling of the large amounts of input data required to operate this simulation. The concept of input data templates is used to minimize the difficulty of specifying runs and generating input data. A simulation executive operates the simulation itself, and a postprocessor catalogs and prepares the output data for both tabular and graphic display.     

粉末喷枪应用计算方法

1 扁平型喷嘴(适用于环抱力及渗透力强的工件) (1) 有折边的平板件,或有为数不多的弯曲、凸凹工件,每支喷枪可覆盖面积约为1.0 m2/min.     

United Kingdom EM gun programme

The authors review the progress in the RARDE (Royal Armament Research and Development Establishment) electromagnetic gun (REMGUN) program. They cover research on both railgun and LIA (linear induction accelerator) technology, including work on modeling, projectile/barrel interactions armatures, switching, and instrumentation. They also describe the major research facilities. Progress is reported in the identification and development of single-shot switches, integrated switch/barrel concepts, armatures and pulse power supplies as well as the integration of railgun components. LIA research has concentrated on launcher design and projectile/barrel interactions, highlighting the problems of pulse power systems for this form of electromagnetic launcher     

Theory of magnetic reconnection in solar and astrophysical plasmas

Magnetic reconnection is a fundamental process in a plasma that facilitates the release of energy stored in the magnetic field by permitting a change in the magnetic topology. In this paper, we present a review of the current state of understanding of magnetic reconnection. We discuss theoretical results regarding the formation of current sheets in complex three-dimensional magnetic fields and describe the fundamental differences between reconnection in two and three dimensions. We go on to outline recent developments in modelling of reconnection with kinetic theory, as well as in the magnetohydrodynamic framework where a number of new three-dimensional reconnection regimes have been identified. We discuss evidence from observations and simulations of Solar System plasmas that support this theory and summarize some prominent locations in which this new reconnection theory is relevant in astrophysical plasmas.     

Development of femtosecond photocathode RF gun

Femtosecond electron bunches are essential for the observation of ultrafast reactions and phenomena in materials. To improve the time resolution of pulse radiolysis and ultrafast electron diffraction (UED), which involve the use of ultrashort electron bunches and ultrashort light, a femtosecond photocathode RF gun driven by a femtosecond laser was investigated experimentally. Bunch charge generated in the RF gun was studied based on the Schottky effect. Thermal emittance was estimated as 0.26 mm mrad at an rms laser spot size of 0.21 mm. Bunch length and longitudinal emittance were obtained as 180 fs and 0.87 deg keV, respectively, at a bunch charge of 3.5 pC and rms laser spot size of 0.38 mm.     

Shelf-life estimation of gun propellant stockpile

Gun propellant stability is an important consideration when assessing the safety of gun ammunition. In order to predict deteriorating stability of propellant stockpiles over lifetime, the master sample surveillance program has long been used by U.S. military laboratories. In this paper, we utilize the information obtained from the Navy's master sample surveillance program and employ a random effects linear model to estimate the safe shelf-life of gun propellant stockpiles. Estimation methods are discussed and applied to 5-inch 54-caliber Navy Cool (NACO) propellants. Several recommendations are made to improve the current practice of the surveillance program and subsequent data analyses.     

A compulsator driven rapid-fire EM gun

A compulsator-driven railgun is an attractive alternative to the homopolar generator-inductor-switch configuration, especially for repetitive duty. A conceptual design of a rapid-fire EM-gun system is presented. The generator is sized to accelerate a 0.08-kg projectile to 2 to 3 km/s at a 60 pulse-per-second repetition rate. Initial design parameters are discussed, and example current and velocity waveforms are given. The generator is discharged at the proper phase angle to provide a current zero just as the projectile exits the muzzle of the railgun.     

Nanoscillator and gun under temperature effect

We propose a system like motor or gun molecular with a nanotube and C60 nanosphere as a probe. The initial position of C60 is out of symmetry that permits the probe to start the system movement due to van der Waals force acting in the probe. For higher initial temperatures there are ejections of the probe like a nanogun. The simulation was made by classic molecular dynamics with standard parameterization. Thermodynamics properties were obtained like molecular motor and gun versus initial temperature. The nanotube has 360 carbon atoms with up to almost 0.7 ns of simulation.     

The rotating bed reactor as a power source for EM gun applications

Electromagnetic gun applications of the Rotating Bed Reactor (RBR) are examined. The RBR is a compact (∼ 1 m³), (up to several thousand MW(th)), high-power reactor concept, capable of producing a high-temperature (up tosim 3000degK) gas stream with a MHD generator coupled to it, the RBR can generate electric power (up to ∼ 1000 MW(e)) in the pulsed or cw modes. Three EM gun applications are investigated: a rail gun thruster for orbit transfer, a rapid-fire EM gun for point defense, and a direct ground-to-space launch. The RBR appears suitable for all applications.     

Electromagnetic gun/projectile interface considerations

Projectile/electromagnetic-gun interface design considerations for electromagnetic gun weapon system (EMGWS) area D1 projectiles, area B-guns, and area C-guns are presented. Projectile/EM gun interfaces are primary considerations in the projectile structural design and the design of the sabot obturator/bore rider, pusher plate, and armature. Acceleration profile, armature type and mass, preinjector characteristics, bore pressure, magnetic fields, and plasma temperature are all key issues in the ultimate projectile performance. Armature design is a critical technical issue for both the projectile and EM gun design because of the high masses involved. Solid armatures are heavier than plasma armatures, but operate at higher electrical efficiencies. Plasma armatures are both being considered for the B-guns and C-guns. Performance tradeoffs are presented for penetration versus peak acceleration and armature mass. Contributors to projectile dispersion such as in-bore balloting, projectile spin, and EM launcher muzzle arc effects are assessed     

Explosive gun launcher for impact studies

We have modified the design of an explosive gun launcher described at the Third Symposium on Hypervelocity Impact for use with pre-cast explosive charges and to provide performance information for steel projectiles. Other modifications include additional confinement of the detonation products, a longer barrel and longer conical transition from breech to barrel, provision for dynamic sealing of the access hole for the detonator wires, and additional buffering to prevent spall fracture of the projectile in the barrel. The modified gun launched a 12.1 gram steel projectile to a measured velocity of 3.2 km/s. Computational simulations have been performed to determine the effects of changes in the projectile density, confinement material density, and explosive type. The use of recyclable confinement material is discussed.     

Arc dynamics in the rail gun

A one-dimenslonal model is discussed which is suitable for analyzing the properties of the plasma in an arc-driven rail gun. It is pointed out that a set of twelve coupled equations can be derived, the solution of which yields the electromagnetic fields associated with the arc as well as its fluid-dynamical characteristics. The calculations are then applied to analyze the arc in a recent experiment by Rashleigh and Marshall. From a limiting-case analytic solution of the governing equations, some approximate scaling laws can be derived which determine how the arc characteristics vary with gun dimensions, projectile mass, arc mass, and accelerating current. The accuracy of the scaling relations is discussed by comparing results predicted by them for various arcs with results predicted by the more general, numerical solutions of the governing equations.     

Fast magnetic reconnection with anomalous ion heating and its application

Magnetic reconnection of two toroidal plasmas with the third field component B_x parallel to the X-lines revealed a clear dependence of sheet-current resistivity and ion heating energy on the sheet-width normalized by the ion gyroradius. Initially, the effective resistivity of sheet-current stayed constant, but it increased significantly when the sheet was compressed shorter than the ion-gyroradius. The anomalous current-sheet dissipation was followed by large increase in ion outflow velocity and ion temperature. This anomalous effect caused both the reconnection speed and the ion heating energy to increase with external compression force and inversely with the B_x component. These properties of reconnection lead us to a new controlled plasma heating for various fusion plasmas and other industrial plasmas.