Electron Beam Guns for High Energy Electron Accelerators: An Overview

Thermionic electron beam is a fundamental part of all types of linear accelerators around the world in the field of Experimental High Energy Physics. Thermionic beam is very inexpensive and simple to produce. In this work, we give an overview of generation, design and applications of the electron beam with particular reference to e-beam generation at high energy linear accelerators. Experimental data are presented in tabular form for ready reference. We also make an evaluation of these high energy sources with our in-house designed e-beam gun. Finally, a comparison has been presented in terms of characteristic parameters of all these high performance sources.

REQUIREMENTS AND DESIGN METHOD FOR MATCHING AIRCRAFT GUNS WITH THEIR SUPPORTING STRUCTURE

In aircraft structural dynamic design the matching of guns with their supporting structure is one of the most important tasks on which hinges the success or failure of the structural design. The design curves for matching guns with their supporting structure can be obtained from response calculations of the plate-spring system supporting the gun on the ground,the model structure tested on the ground and the actual structure.A set of matching curves is given for engineering application.Then,the matching design can be accomplished by means of impact load spectrograms so as to perform an optimal structural design and to make further improvements on dynamic design program.

Space Guns for the Moon and on the Moon

Space gun--a device for launching objects in space. It refers to rocket-free methods of output objects into orbit. Space gun is not able to deliver the object in stationary orbit around the planet, for this, it must be equipped with a rocket engine to adjust the course after launch the object. This makes it possible to replace the existing excessively expensive rocket systems with new methods of delivering payload （space gun）. Thus, the costs of scientific programs are decreasing at times, and many studies are becoming available, less risky and environmentally safer.

一种民用无人机反制系统的设计

本文设计了一种民用无人机反制系统,用于保护重点区域的低空空域安全。系统基于软件无线电理念设计:软件平台使用GUN Radio,硬件平台使用Hack RF。文章分析了驱离迫降民用无人机的原理,详细阐述了模拟GPS信号和产生宽带噪声信号的方法,通过理论计算推断系统的输出功率,系统理论上可对100 m范围内的民用无人机进行反制。经验证,系统可实现对无人机的驱离迫降,达到反制效果。系统方案简洁、成本低,可推广至类似的项目研究领域,具有较高的研究价值。

Construction of smart propellant with multi-morphologies

Smart materials,which exhibit shape memory behavior in response to external stimuli,have shown great potential for use in biomedical applications.In this study,an energetic composite was fabricated using a UV-assisted DIW 3D printing technique and a shape memory material(SMP)as the binder.This composite has the ability to reduce the impact of external factors and adjust gun propellant combustion behavior.The composition and 3D printing process were delineated,while the internal structure and shape memory performance of the composite material were studied.The energetic SMP composite exhibits an angle of reversal of 18 s at 70°,with a maximum elongation typically reaching up to 280% of the original length and a recovery length of approximately 105%during ten cycles.Additionally,thermal decomposition and combustion behavior were also demonstrated for the energetic SMP composite.

An internal ballistic model of electromagnetic railgun based on PFN coupled with multi-physical field and experimental validation

To accelerate the practicality of electromagnetic railguns,it is necessary to use a combination of threedimensional numerical simulation and experiments to study the mechanism of bore damage.In this paper,a three-dimensional numerical model of the augmented railgun with four parallel unconventional rails is introduced to simulate the internal ballistic process and realize the multi-physics field coupling calculation of the rail gun,and a test experiment of a medium-caliber electromagnetic launcher powered by pulse formation network(PFN)is carried out.Various test methods such as spectrometer,fiber grating and high-speed camera are used to test several parameters such as muzzle initial velocity,transient magnetic field strength and stress-strain of rail.Combining the simulation results and experimental data,the damage condition of the contact surface is analyzed.

Modelling of internal ballistics of gun systems:A review

A deep understanding of the internal ballistic process and the factors affecting it is of primary importance to efficiently design a gun system and ensure its safe management. One of the main goals of internal ballistics is to estimate the gas pressure into the combustion chamber and the projectile muzzle velocity in order to use the propellant to its higher efficiency while avoiding over-pressure phenomena. Dealing with the internal ballistic problem is a complex undertaking since it requires handling the interaction between different constituents during a transient time lapse with very steep rise of pressure and temperature. Several approaches have been proposed in the literature, based on different assumptions and techniques. Generally, depending on the used mathematical framework, they can be classified into two categories: computational fluid dynamics-based models and lumped-parameter ones. By focusing on gun systems, this paper offers a review of the main contributions in the field by mentioning their advantages and drawbacks. An insight into the limitations of the currently available modelling strategies is provided,as well as some considerations on the choice of one model over another. Lumped-parameter models, for example, are a good candidate for performing parametric analysis and optimisation processes of gun systems, given their minimum requirements of computer resources. Conversely, CFD-based models have a better capacity to address more sophisticated phenomena like pressure waves and turbulent flow effects. The performed review also reveals that too little attention has been given to small calibre guns since the majority of currently available models are conceived for medium and large calibre gun systems.Similarly, aspects like wear phenomena, bore deformations or projectile-barrel interactions still need to be adequately addressed and our suggestion is to dedicate more effort on it.

Mussel-inspired PTW@PDA composites for developing high-energy gun propellants with reduced erosion and enhanced mechanical strength

The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun propellants.To address it,novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate whisker(PTW,K_(2)Ti_(6)O_(13)),and after was incorporated into gun propellant as erosion-reducing and mechanical-reinforcing fillers.The interfacial characterizations results indicated that as-prepared PTW@PDA composites exhibits an enhanced surface compatible with propellant matrix,thereby facilitating their dispersion into propellants more effectively than raw PTW materials.Compared to original propellants,PTW@PDA-modified propellants exhibited significant less erosion,with a Ti-Kbased protective coating being detected on the eroded steel.And 0.5 wt%and 1.0 wt%addition of PTW@PDA significantly improved impact,compressive and tensile strength of propellants.Despite the inevitably reduction in relative force,PTW@PDA slightly increase propellant burning rate while exerting little adverse impact on propellant dynamic activity.This strategy can provide a promising alternative to develop high-energy gun propellant with less erosion and more mechanical strength.

Small Arms Survey 2010—GANGS,GROUPS,AND GUNS

1.Background of The Small Arms Survey The proliferation of small arms and light weapons represents a grave threat to human security. The unchecked spread of these weapons has exacerbated inter-and intra-state conflicts,contributed to

On the theory of photocathode rf guns

In this paper we give a set of analytical formulae to describe the characteristics of photocathode rf guns at any rf frequencies, such as energy, energy spread, bunch length, out going current, and emittance etc. as functions of the laser injection phase, which are useful in the design and practical operation of rf guns.

Mining, Bridges, Opium, and Guns： Chinese Investment and State Power in a Late Qing Frontier

In the last three decades of its rule, the Qing government attempted to establish Chinese-style administration in many of the empire＇s non-Hart territories, and, in conjunction with non-government actors, foster land cultivation, Han migration, Chinese education, and industries such as mining. This paper investigates these processes in Liangshan, in upland Southwest China. Here, attempts to establish Chinese administration came only in 1907, after a period of substantial private and state investment in mining, transport infrastructure, and, to a lesser extent, land cultivation. Government officials often assumed that such things would aid the political integration in China, but as this paper argues, the consequences were more complicated than that. Although better transport simplified the logistics of government military campaigns, increased commercial activity in the region also allowed its indigenes to acquire firearms for the first time.

One-step green method to prepare progressive burning gun propellant through gradient denitration strategy

Gradiently denitrated gun propellant(GDGP)prepared by a“gradient denitration”strategy is obviously superior in progressive burning performance to the traditional deterred gun propellant.Currently,the preparation of GDGP employed a tedious two-step method involving organic solvents,which hinders the large-scale preparation of GDGP.In this paper,GDGP was successfully prepared via a novelty and environmentally friendly one-step method.The obtained samples were characterized by FT-IR,Raman,SEM and XPS.The results showed that the content of nitrate groups gradiently increased from the surface to the core in the surface layer of GDGP and the surface layer of GDGP exhibited a higher compaction than that of raw gun propellant,with a well-preserved nitrocellulose structure.The denitration process enabled the propellant surface with regressive energy density and good progressive burning performance,as confirmed by oxygen bomb and closed bomb test.At the same time,the effects of different solvents on the component loss of propellant were compared.The result showed that water caused the least component loss.Finally,the stability of GDGP was confirmed by methyl-violet test.This work not only provided environmentally friendly,simple and economic preparation of GDGP,but also confirmed the stability of GDGP prepared by this method.

Development and simulation of a gridded thermionic cathode electron gun for a high-energy photon source

A gridded thermionic cathode electron gun was developed for the linear accelerator of the High Energy Photon Source(HEPS).An electron gun should provide a large maximum bunch charge with a wide adjustable range.To satisfy these requirements,the shape of the electrode was optimized using a multi-objective genetic algorithm.A large bunch charge with an adjustable range was achieved using the grid-limited gun,the flow of which was analyzed using 3-D simulations.The electron gun has been manufactured and tested,and the measured data of the grid-limited current and simulation results are compared and discussed in this study.

Design,fabrication,and testing of an X-band 9-MeV standing-wave electron linear accelerator

In this study,an X-band standing-wave biperiodic linear accelerator was developed for medical radiotherapy that can accel-erate electrons to 9 MeV using a 2.4-MW klystron.The structure works atπ/2 mode and adopts magnetic coupling between cavities,generating the appropriate adjacent mode separation of 10 MHz.The accelerator is less than 600-mm long and constitutes four bunching cells and 29 normal cells.Geometry optimizations,full-scale radiofrequency(RF)simulations,and beam dynamics calculations were performed.The accelerator was fabricated and examined using a low-power RF test.The cold test results showed a good agreement with the simulation and actual measurement results.In the high-power RF test,the output beam current,energy spectrum,capture ratio,and spot size at the accelerator exit were measured.With the input power of 2.4 MW,the pulse current was 100 mA,and the output spot root-mean-square radius was approximately 0.5 mm.The output kinetic energy was 9.04 MeV with the spectral FWHM of 3.5%,demonstrating the good performance of this accelerator.

Analysis of Corrosion Mechanisms of Low-cement or No-cement Al_(2)O_(3)-MgO Gunning Mix with Special Calcined Alumina in Rotary Slag Test

Al_(2)O_(3)-MgO and Al_(2)O_(3)-spinel low cement castables(LCC-AM and LCC-AS)have been extensively used in steel ladles as working linings.Nevertheless,the use of alumina-magnesia gunning mixes has been mainly kept for maintaining these castable linings,because of high rebound loss,poor green strength,high porosity and short life-span.Thanks to a high BET alumina(MC-G),it is now possible to develop a series of high-performance no-cement or low-cement Al_(2)O_(3)-MgO gunning mixes(NCG-AM or LCG-AM).The paper focuses on the BOF slag resistance of NCG-AM,LCG-AM,LCC-AM and LCC-AS.The corrosion mechanisms of rotary slag samples were studied by scanning electron microscopy(SEM/EDS).The results reveal different microstructures around MgO particles,depending on the four used compositions.Continuous and thicker spinel phases were formed in NCG-AM,which was proved to have the best corrosion resistance after the dynamic slag test.MC-G can provide a high diffusion flux of Al^(3+)in terms of kinetics and hence inhibits Kirkendall porosity around MgO particles.In addition,a continuous spinel phase acts like a pinning nail to reinforce the matrix and thus decreases erosion by slag.In contrast to NCG-AM,the porous spinel phase was found around unreacted MgO particles and some particles were carried away near the interface of LCC-AM and slag.The NCG-AM containing MC-G had been tested in two steel plants,and it extended the service life of the ladles up to 50%.In addition,this study suggests the potential application of NCG-AM as steel ladle linings.

RLPG点火过程中贮液室压力振荡分析

建立了 2 3 mm RLPG点火过程分析模型 ,研究了贮液室产生压力振荡的主要原因 .分析了 RLPG在点火过程中贮液室液体压力振荡现象 ,此期间压力振荡频率相对较低 ,危害较大 .分析模型考虑了高压下液体可压缩性 ,模拟计算结果表明 ,液体可压缩性是此期间压力振荡的主要原因 .经过改进 RLPG结构 ,采用合理措施 。

Book Review of Bloodbath Nation

Published in January 2023, illustrated by photographer Spencer Ostrander, Bloodbath Nation is the latest non-fiction work by Paul Auster. This paper makes a review of Bloodbath Nation, including its structure, content, author’s writing style and features of cover and illustrations, and gives a brief evaluation of this work.

中医推拿手法测力分析仪FZ－Ⅰ型的研制及法合力作用点轨迹分析

本文报导了中医推拿手法测力分析仪ＦＺ－Ⅰ型的研制，实测了摆动类法在测力仪上的作用力，分析了合力作用点的几何轨迹。结果表明摆动类法合力作用点几何轨迹形态可分成四类，并对产生不同形态的原因进行了分析并提出了定量判别指标。

摆动类法推拿作用力时域分析

依据中医推拿手法测力分析仪FZ-1型上所得(扌衮)法推拿作用力数据,对(扌衮)法作用力进行了时域分析。对垂直分力,得出了反映手法正确性的定量指标峰值离散度J_0,峰值时间F_0和总体均匀性R_0,对于教师-学生组和医生-学生组均有显著性差异(P<0.01)。同时对水平分力进行了定性分析。