非均匀磁场约束条件下的电子束空气等离子体特性

为了揭示大气环境电子束等离子体的性质,基于蒙特卡罗程序包Geant4建立了一个包含电离、激发以及轫致辐射等物理过程的计算模型,用于模拟非均匀磁场约束条件下高能强流稳态电子束的输运特性、以及大气环境等离子体的性质。结果表明：非均匀磁场可以有效控制电子束在空气中的输运轨迹,显著降低电子束的发散;随着电子束在空气中行程的增加,电子束能谱开始展宽并向低能区移动;输运装置出口能量损失比电子束射程末端高2个量级,且随着电子束输运距离的增加,等离子体密度降低;等离子体密度的高低与电子束能量直接相关。     

非均匀磁场约束条件下的电子束空气等离子体特性

为了揭示大气环境电子束等离子体的性质,基于蒙特卡罗程序包Geant4建立了一个包含电离、激发以及轫致辐射等物理过程的计算模型,用于模拟非均匀磁场约束条件下高能强流稳态电子束的输运特性、以及大气环境等离子体的性质。结果表明:非均匀磁场可以有效控制电子束在空气中的输运轨迹,显著降低电子束的发散;随着电子束在空气中行程的增加,电子束能谱开始展宽并向低能区移动;输运装置出口能量损失比电子束射程末端高2个量级,且随着电子束输运距离的增加,等离子体密度降低;等离子体密度的高低与电子束能量直接相关。     

Oblique injection of EC ordinary waves in a Tokamak plasma

Summary A detailed analysis of the propagation and damping of ordinary waves in the electron cyclotron frequency range in a Tokamak-like stratified plasma is given. The waves are supposed to be launched from the low-magnetic-field side of the machine in the meridian plane, with an angle, with respect to the perpendicular at the launching point, to the toroidal magnetic field. In this first part of the paper the emphasis, is on the WKB analysis of the process,i.e. on the study of the local-dispersion relation, first in the cold case and then taking full account of finite-Larmor-radius effects. A thorough study of the intricacies presented by both cold and hot dispersions around the Preinhaelter, and Kopecky critical angle of injection is made. This complicated behaviour has not been analysed in previous works on the subject.

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Riassunto Si presenta un’analisi molto dettagliata della propagazione e dell’assorbimento di onde ordinarie con frequenza vicina alla frequenza ciclotronica degli elettroni in un plasma stratificato che simula la geometria, del Tokamak. Si suppone che l’onda venga lanciata dalla parte esterna della macchina, nel piano meridiano, ma obliquamente rispetto alla normale alle linee di forza del campo toroidale nella posizione di lancio. In questa prima parte del lavoro si pone l’accento sull’analisi locale, di tipo WKB, del fenomeno, vale a dire sulle caratteristiche delle dispersioni e si studia prima di tutto la dispersione fredda e poi quella piú completa basata sull’equazione di Vlasov. Si studia in grande dettaglio il comportamento intricato di entrambe le dispersioni nell’intorno del valore critico di Preinhaelter e Kopecky dell’angolo d’iniezione. Questo andamento complicato della dispersione non era stato studiato nei lavori esistenti sull’argomento.

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Резюме Проводится подробный анализ распространения и затухания обыкновенных волн в области электронной циклотронной частоты в стратифицированной плазме Токамака. Прелполагается, что волны запускаются со стороны слабого магнитного поля машины в меридианной плоскости под углом к перпендикуляру в точке запуска к тороидаляному магнитному полю. В первой части статьи проводится ВКБ анализ процесса,. т.е. исследуется локальное дисперсионное соотношение, сначала в холодном случае, а затем, учитывая эффекты, связанные с конечным ларморовским радиусом. Особое внимание уделяется трудностям, связанным с холодной и горячей дисперсиями вокруг критического угла инжектирования Преннхалтера и Копецкого. Это сложное поведение не было проанализировано в предыдущих работах на эту тему.

     

磁化等离子体环境对氢原子能级结构的影响

本文通过非微扰求解薛定谔方程, 研究了强磁场磁化的等离子体环境中的原子能级结构和辐射动力学过程. 在较宽的磁场强度范围和等离子体屏蔽参数范围内, 给出了氢原子基态以及低激发态的能级、辐射跃迁能量和振子强度等重要的原子参数, 定量地描述了强磁场和等离子体屏蔽共同作用的综合效应. 相关的结果有助于增进对极端环境下原子光谱结构的认识, 在等离子体光谱诊断和天文光谱观测方面有一定的借鉴意义. 关键词： 强磁场 CWDVR谱方法 能级结构 振子强度     

紧凑型L波段磁绝缘线振荡器的粒子模拟

采取减小阴极杆半径和长度、阴阳极间隙、叶片的长度和厚度及慢波结构周期的办法构造了一种紧凑型磁绝缘线性振荡器（MILO），并用2.5维全电磁PIC方法对这一器件进行了粒子模拟研究。该装置主频为1.9GHz，饱和后平均输出功率达5.4GW，束波转换效率达12％。紧凑型MILO结构能避免电击穿，电子束发射的对称性较易控制。     

Dynamics of plasma channel in a parallel-plate plasma gun

Lumped parameter models for describing dynamics of the plasma channel in a parallel-plate plasma gun are compared with the experimental results obtained from two plasma guns with different rail geometries. Comparison between the experiments and the numerical calculations reveals that the lumped parameter models can be utilized to describe the dynamic motion of the plasma channel quite well. Parametric study shows that minimizing the line inductance and increasing the charging voltage on a capacitor as well as minimizing the gas injection time for reducing the mass of the plasma channel are the key factors to increase the flow velocity of the plasma jet ejected from the plasma gun.     

Experiments on the injection of dust jets into plasma

An experimental technique for studying the injection of dust jets into the plasma of a glow discharge in air is developed. The velocity and flight time of a dust jet are measured under different initial conditions. It is shown that the propagation of dust grains in plasma is accompanied by self-contraction instability along and across the discharge, which leads to dust agglomerization and clusterization.     

双阳极回旋管磁控注入电子枪设计

对真实磁场进行拟合,根据电子光学原理以及绝热压缩理论,运用EGUN软件,设计了工作模式为TE34,19的170 GHz回旋管双阳极磁控注入电子枪。最终得到的电子注速度比约为1.3,速度零散小于3%。分析了调节磁场位置、阴阳极间距、阳极间距等因素对电子注性能的影响。结果表明：电子注的速度比和速度零散对于这些影响因子的变化比较敏感,随着阴阳极间距以及阳极间距的增加,速度比逐渐减小,速度零散先减小后增大。设计的双阳极电子枪已应用于整管实验中。     

双阳极回旋管磁控注入电子枪设计

对真实磁场进行拟合,根据电子光学原理以及绝热压缩理论,运用EGUN软件,设计了工作模式为TE34,19的170 GHz回旋管双阳极磁控注入电子枪。最终得到的电子注速度比约为1.3,速度零散小于3%。分析了调节磁场位置、阴阳极间距、阳极间距等因素对电子注性能的影响。结果表明:电子注的速度比和速度零散对于这些影响因子的变化比较敏感,随着阴阳极间距以及阳极间距的增加,速度比逐渐减小,速度零散先减小后增大。设计的双阳极电子枪已应用于整管实验中。     

Oblique angle deposition of TiO2 thin films prepared by electron-beam evaporation

Optical, structural and photocatalytic properties of TiO₂ thin films obliquely deposited on quartz glass substrate using an electron-beam evaporation method were investigated. The photocatalytic activity of the films was evaluated by photodecomposition of methylene blue. An increase in incident deposition angle increased the porosity and surface roughness of the TiO₂ films. As a result, the photocatalytic activity was enhanced with incident deposition angle up to 60°. However, a further increase in incident deposition angle to 75° reduced the photocatalytic activity due to a lack of the crystalline phase.     

电子束辐照对玻璃微球储氚性能的影响

以研究氚衰变β电子对玻璃微球保气性能为目标,利用XPS在线测量技术研究了电子束照射下碱式硼硅酸盐玻璃中K+离子的迁移以及由此引发的空心玻璃微球保气性能的下降。研究表明：在阈值剂量以上,随着玻璃组分中K+含量的增加,由于K+离子迁移导致的阻气特性的下降效应越明显;对于一定组成的玻璃微球,电子照射剂量越大,通道网络的形成越容易,玻璃微球的保气性能下降越迅速。     

The effect of magnetic field on plasma particles in dusty plasma

In this work, we present the investigation of the formation features and internal structure of dust clouds created in plasma of glow discharge in the external magnetic field corresponding to a range of moderate and strong fields, at which the ion component is magnetized. The analysis of the plasma magnetization in the presence of dust components is carried out. We defined the values of magnetic induction at which the changes in dynamics of plasma particles in magnetic field in light inert gases are expected. The experimental setup was built in two versions. For the purpose of generating of magnetic field, the first setup was equipped with ordinary magnetic coils, and the second one included a superconducting solenoid. The discharge tubes, the main chambers where plasma was ignited and maintained in a glow discharge in lowered pressure, also have certain peculiarities, which we describe below. While using helium as a bulk gas, our study focused only on the dust trap in the region of narrowing discharge current. For neon, we used two traps: the striation trap and one just mentioned above placed in the narrowing of the discharge tube. As a result, the steady dust structures in a glow discharge under the magnetization of ions and electrons were obtained for the first time. Dust structures were rotated and tended to form a dust cluster and shell structure. A number of parameters of magnetization achieved in experiments were calculated.     

New mode of operating a magnetized coaxial plasma gun for injecting magnetic helicity into a spheromak

By operating a magnetized coaxial plasma gun continuously with just sufficient current to enable plasma ejection, large gun-voltage spikes (approximately 1 kV) are produced, giving the highest sustained voltage approximately 500 V and highest sustained helicity injection rate observed in the Sustained Spheromak Physics Experiment. The spheromak magnetic field increases monotonically with time, exhibiting the lowest fluctuation levels observed during formation of any spheromak (B/B>/=2%). The results suggest an important mechanism for field generation by helicity injection, namely, the merging of helicity-carrying filaments.     

Decay of plasma cluster accelerated by coaxial gun

In this paper the decay of air cluster accelerated into the vacual tube is studied. The time dependence of electron density and electron temperature is introduced and the influence of various recombination processes is discussed. The observed plasma decay shows an exponential law, and is for various gun regimes independent and may be explained by ambipolar diffusion to the tube walls.     

Some methods of electron-beam entry into a dense gas

A system is considered of pumping a laser with an electron beam that moves relative to the active medium. The problem of planar two-dimensional gas flow through a bounded heat-releasing medium, a problem analogous to that of rectilinear motion of a beam with constant velocity, is solved analytically. It is proposed to admit an electron beam into a dense gas through aerodynamic ports. The effect of perturbations induced by the beam passage on the flow of gas in an aerodynamic port with a rarefaction wave is analyzed.Translated from Trudy Ordena Lenina Fizicheskogo Institute im. P. N. Lebedeva AN SSSR, Vol. 145, pp. 160–171, 1984.