真空二极管辐射微波的机理分析

在研究真空开关的过程中,发现真空二极管能辐射出宽带微波.这种器件只由带触发装置的阴极和平板阳极组成,不存在金属波纹慢波结构,所以真空二极管的辐射机理与等离子体填充微波器件不同,不能直接套用等离子体填充微波器件的相关理论.本文描述了真空二极管产生辐射的物理过程,建立了真空二极管辐射的数学模型,通过求解波动方程得到产生辐射的色散关系,并绘制出了色散曲线.将理论分析得到的色散曲线与已经测得的微波辐射进行比较,两者能很好地符合.理论分析和实验结果表明,电子束和磁化等离子体的相互作用是真空二极管产生微波辐射的原因.

泛布尔代数在数字电路设计中的应用

泛布尔代数是一种新兴的逻辑方法,已经在多个领域内有了应用。在研究和使用泛布尔代数的过程中,发现其在数字电路设计领域中也能得到很好的运用,这种新的设计方法给数字电路设计带来一些新的思维。本文将新方法与传统方法进行一些比较,介绍了新方法的一些特点以及设计中的优势。

真空电弧等离子中提取重频电子束的实验研究

为满足高功率微波辐射源对电子束的长脉宽高重频要求,文中提出了一种从小电流真空直流电弧等离子体中提取重频电子束的装置,该装置放电部分阴极采用铜圆盘电极,阳极为圆筒型空心阳极结构,其底部覆有不锈钢金属网,顶部开圆形引出孔。设计了以DSP为控制核心、MOSFET管为主功率器件的低压脉冲提取电源,从空心阳极真空电弧等离子体阴极中提取电子束。同时,利用自触发电路解决了直流电弧灭弧后立即重燃问题,有效保证了电弧放电的持续放电时间和稳定性。实验结果表明：电子束脉冲频率和占空比受到提取电压的调制,得到了连续可调的电子束脉冲;在一定范围内电子束电流大小随着提取电压的增加而增大,并存在一个饱和极限,最大束流接近1 A;同时提取电压过高的脉冲频率和脉宽不利于电子束电流的稳定。

Key design parameters and optimum method of medium- and high-velocity synchronous induction coilgun based on orthogonal experimental design

The energy conversion efficiency of a multistage synchronous induction coilgun(MSSICG) has become one of the key factors that restricts its industrialization. To improve the launch efficiency of medium-and high-velocity MSSICG,we propose an optimization design scheme combining orthogonal experimental design(OED) and self-consistent design method in this paper. The OED is introduced to reduce the number of iterations and improve the identification accuracy and efficiency. A self-consistent design model is established to overcome a defect that the parameters that need to be optimized will multiply as the number of coil stages increases. The influence of six factors(radial thickness of armature, axial length of armature, axial length of coil, capacitance, wire diameter, and slip speed) on the launch efficiency are then evaluated by range analysis. This work presents a valuable reference for optimizing medium-and high-velocity MSSICG.

Mechanism analysis of radiation generated by the beam-plasma interaction in a vacuum diode

When we were studying the vacuum switch,we found that the vacuum diode can radiate a broadband microwave.The vacuum diode is comprised of a cathode with a trigger device and planar anode,there is not a metallic bellows waveguide structure in this device,so the radiation mechanism of the vacuum diode is different from the plasma filled microwave device.It is hard to completely imitate the theory of the plasma filled microwave device.This paper analyzes the breakdown process of the vacuum diode,establishes the mathematical model of the radiating microwave from the vacuum diode.Based on the analysis of the dispersion relation in the form of a refractive index,the electromagnetic waves generated in the vacuum diode will resonate.The included angle between the direction of the electromagnetic radiation and the initial motion direction of electron beam is 45 degrees.The paper isolates the electrostatic effect from the beam-plasma interaction when the electromagnetic radiation occurs.According to above analyses,the dispersion relations of radiation are obtained by solving the wave equation.The dispersion curves are also obtained based on the theoretical dispersion relations.The theoretical dispersion curves are consistent with the actual measurement time-frequency maps of the radiation.Theoretical deduction and experiments indicate that the reason for microwave radiating from the vacuum diode can be well explained by the interaction of the electron beam and magnetized plasma.

电子束用聚焦静电透镜的优化设计

在分析静电透镜电子光学理论的基础上,提出电场优化计算的目标函数,借助ANSYS软件确定了透镜电极中心点电位、优化设计透镜极的尺寸;同时利用Magic粒子模拟软件得到电子束包络线,聚焦效果满足设计指标.实验结果表明,随着外加电压逐步增加,收集极上的光斑向中心汇聚,亮度增强,电压过高时出现光斑发散.电压为60kV时,具有理想的聚焦效果,束斑直径在10mm左右,达到了设计要求.