高通鸟笼线圈激发螺旋波等离子体特性研究

研制了高通鸟笼线圈,使用氩气作为工质气体对射频天线的工作性能进行了初步评估。利用COMSOL5.4模拟出了鸟笼天线在13.56MHz的工作频率下,电场和磁场呈线性极化分布。对鸟笼线圈进行了电路结构解剖,推导出了其谐振频率计算公式。利用热耦合红外测温仪测试了正常工作状态下的鸟笼线圈外表温度明显低于传统射频天线,电容器最高温度仅65.8°。使用光谱仪对螺旋波等离子体放电光谱特性进行诊断。通过朗缪尔探针诊断了不同压强和磁场强度下螺旋波等离子体密度,在1.0Pa、600Gs、射频功率700W条件下等离子体密度达到1.62×10¹⁸m^-3。诊断了正向功率和反向功率对应的等离子体密度,其与磁滞现象变化趋势雷同。测试了螺旋波等离子体的径向密度分布,其在轴心处密度达到最高。探究了无磁场条件下等离子体特性,其密度值不会发生大幅度跃迁,纵向磁场是引发螺旋波等离子体放电的关键因素,低压条件下有利于得到更低的电子温度,最低达到2.67eV。表明鸟笼线圈低热耗、高馈入的特性使其在激发大体积的高密度螺旋波等离子体方面具有明显优势,可以投入到下一阶段氢气螺旋波等离子体的激...     

一种基于双环差分结构的脉冲磁场传感器

雷击近场等强电场环境下的磁场测量是电磁脉冲测量技术中的难点之一,由于输出端结构的径向非对称性,传统的环天线很难避免电场干扰。针对于此,研制了一种基于双环差分结构的脉冲磁场传感器,该传感器由双环天线和光传输系统组成。根据近场电磁场量的分布特性,双环天线选择平行镜像对称放置的方式,从而能够将终端电压区分为磁场响应分量和电场响应分量,再通过末端差分电路即可去除电场响应分量,得到纯净的磁场响应分量。试验表明,在邻近雷击环境模拟装置中,双环传感器相较于单环传感器具备更强的抗电场干扰能力,能够实现磁场的准确测量。     

A Compact Monopulse Radial Line Slot Array Antenna at Millimeter Wavelengths

This paper describes the design and performance of a radial line slot array antenna (RLSA) which generates sum or difference far field patterns. The antenna consists of rectangular waveguide to radial line transition, radial line and slot arrays etched on the upper plate of the radial line. A novel rectangular waveguide to radial line transition is designed to build up the dominate TEM mode in radial line to excite the slot arrays which are arranged in concentric rings on the upper plate of the radial line. The antenna radiates linear polarization at Ka band. Monopulse operation is obtained by a sum and difference network which is a compact eight-port comparator consisting of coplanar magic tees. The sum and difference network is waveguide structure whose loss is less than that of microstrip structure at millimeter wave lengths. The monopulse performances can be used in monopulse tracking and anti-collision application etc. Genetic algorithm (GA) is applied to optimize the parameters of the transition and antenna to obtain good performances. Note: Part of this paper has been presented in the oral session ThuA5 on Transmission Lines and Antennas in IRMMW-THz2006 Conference, pages: 535.Number: 376636Title: Radial line slot array antenna at millimeter wave lengths     

A Helical Launching Structure for Alfvén Wave Heating in the Proto-Cleo Stellarator

A helical wave launching structure is analyzed to determine the spectrum of Alfvén waves that it can excite. Using an ideal MHD plasma model, the effectiveness of this helical coil for producing Alfvén wave heating in the Proto-Cleo stellarator is investigated. It is found that significant energy absorption should occur. The amount of absorption and the frequency range over which it is greatest are dependent on the shape of the radial profiles of the confining magnetic field and the plasma density.     

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分析了电磁波以任意角度入射到有限磁场中的激光等离子体通道天线(LPCA)时的电磁散射特性。根据LPCA的工作原理建立了其电磁分析模型,推导出广义柱坐标系下各向异性磁化等离子体中纵向分量所满足的波动方程和纵向场与横向场的关系,得到LPCA和周围媒质中的电磁场,利用边界切向电磁场连续,得出了散射系数方程。通过计算实例,将结果与文献结果比较,吻合较好。该研究结果预期可应用于高功率微波武器系统的研究。     

KT—5B托卡马克上阿尔芬波加热实验中天线阻抗的测量

一、引 言 托卡马克等离子体中的阿尔芬波加热实验研究自80年代初以来取得了许多有价值的实验结果。在阿尔芬波加热实验中,天线辐射阻抗的测量是十分重要的。天线辐射阻抗的变化不仅直接反映了阿尔芬波与等离子体之间的能量耦合情况,而且也反映了波在等离子体中传播过程的某些物理特性。例如,出现离散阿尔芬波(DAW模)或表面静电波(SEW模)便会使阻抗出现较大的峰值。因此,探索一种简便易行又能反映阻抗随放电时间变化的细微     

异面带状线馈电的宽带双极化蝶形天线

针对通信与雷达系统对双极化与宽带天线的要求,提出了一种基于带状线馈电的双极化蝶形天线。通过两对互相正交的蝶形阵子实现了天线的双极化,并采用一种新型的微带线转异面带状线的巴伦给两对正交蝶形阵子平衡馈电。异面带状线为平衡传输线,满足了蝶形阵子对于平衡馈电的要求。在馈电点处由同轴线对微带线馈电,经渐变微带线转化为异面带状线,最后由两组异面带状线给两对正交蝶形阵子馈电。测得该天线实现了69.23%的阻抗带宽,在6.8~14GHz频带内电压驻波比(VSWR)小于2。为使天线单向辐射且改善天线增益,将天线放置于反射吸收腔内。测得天线在6.8~18GHz的频宽内VSWR基本小于3,天线增益在8~12GHz频带内大于0.11dB,天线前后瓣比大于15dB。因此,所提出的双极化蝶形天线可用于宽带通信系统中。     

等离子体填充金属光子晶体慢波结构色散特性研究

等离子体填充慢波器件为高效率、高功率真空电子微波源的发展提供了新的途径, 但其仿真和理论都具有一定的难度. 本文将通过轮辐天线加载激励信号的方法引入到等离子体填充金属光子晶体慢波结构(SWS)的色散特性仿真分析中, 研究了慢波结构参数和等离子体密度对等离子体填充慢波结构色散特性的影响. 结果表明, 无等离子体填充时, 通过轮辐天线加载激励信号方式得到的色散特性与其他方法差别不大; 与已有结果对比表明, 该方法适用于等离子体填充慢波结构的分析. 为了减小轮辐天线对腔体谐振频率的影响, 需要适当减薄轮辐天线的厚度, 并尽可能缩短其与反射面之间的距离. 天线的厚度越大越能激励慢波场, 越小谐振模式越容易被激励; 慢波结构周期膜片外半径和厚度对色散特性影响不大, 周期长度和膜片内半径对色散特性影响较大; 频率和相速色散曲线随等离子体密度上升而整体向高频区移动; 等离子体填充对低频模点的影响要大于对高频模点的影响; 对于慢波器件, 需要选择高频模点工作模式, 以减少腔的尺寸并降低电子注的初速度.     

Dispersion and matching properties of inhomogeneous plasma waveguides

The dispersion characteristics and the field structure of axisymmetric modes channeled by a high-density plasma inhomogeneity stretching along the external magnetic field are determined in the whistler range. The feasibility of matching a small antenna to the background plasma by means of plasma inhomogeneity is demonstrated theoretically and experimentally.Nizhni Novgorod State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 2, pp. 163–172, February, 1991.     

近地面三阵子天线估计电磁波到达角和极化参数

从自由空间中的三阵子天线求入射电磁波极角和方位角的基本原理出发, 结合电场各个分量与极化方式之间的关系给出了左手极化波计算波达角的公式, 及地球表面上方三阵子天线判断入射波极化方向的方法; 本文提出了一种新颖的滤除地面反射波的方法, 保证了波达角的求解精度; 利用获得的高精度的波达角和测得的电场强度, 计算出了电磁波的各种极化参数, 这些极化参数可以作为电离层研究和电磁波在电离层中传播研究的参考. 关键词： 地球表面 三阵子天线 波达角 极化参数     

Measurements of the MHD dynamo in the quasi-single-helicity reversed-field pinch

The first experimental study of the MHD dynamo in a quasi-single-helicity (QSH) reversed-field pinch toroidal plasma is presented. In QSH plasmas, a dominant wave number appears in the velocity fluctuation spectrum. This velocity component extends throughout the plasma volume and couples with magnetic fluctuations to produce a significant MHD dynamo electric field. The narrowing of the velocity fluctuation spectrum and the single-mode character of the dynamo are features predicted by theory and computation, but only now are observed in experiment.     

A numerical simulation of surface wave excitation in a rectangular planar-type plasma source

The principle of surface wave plasma discharge in a rectangular cavity is introduced simply based on surface plasmon polariton theory. The distribution of surface-wave electric field at the interface of the plasma-dielectric slab is investigated by using the three-dimensional finite-difference time-domain method (3D-FDTD) with different slot-antenna structures. And the experimental image of discharge with a novel slot antenna array and the simulation of the electric field with this slot antenna array are both displayed. Combined with the distribution of surface wave excitation and experimental results, the numerical simulation performed by using 3D-FDTD is shown to be a useful tool in the computer-aided antenna design for large area planar-type surface-wave plasma sources.     

KT-5B托卡马克等离子体中剪切Alfven波的激发特性

本文报道最近在KT-5B托卡马克装置上进行Alfven波激发特性研究的实验结果。结果表明:Alfven波存在比较宽的激发区域,耦合强度随等离子体电流、纵向磁场的上升而增强。观测到温度阈值效应,并初步得到表面静电波的实验证据。 关键词：     

Analysis and Calculations on Dispersion Relation and Coupling Resistance of Periodic Plasma-Cavities

The plasma tensor dielectric permittivity and electromagnetic field accurate expressions in the external axial magnetic field are obtained from the Maxwell’s equations and the double component plasma particle linear movement equations. Further, the flux of energy inside the plasma-cavity drift channel is presented. Based on them, some of the property of cavity passband dispersion and coupling resistance of plasma-filled coupled-cavities slow wave structure in different plasma density and magnetic field conditions is analyzed according to the numerical calculation.     

Theoretical study of two-element array of equilateral triangular patch microstrip antenna on ferrite substrate

The radiation characteristics of a two-element array of equilateral triangular patch microstrip antenna on a ferrite substrate are studied theoretically by considering the presence of bias magnetic field in the direction of propagation of electromagnetic waves. It is found that the natural modes of propagation in the direction of magnetic field are left- and right-circularly polarized waves and these modes have different propagation constants. In loss-less isotropic warm plasma, this array antenna geometry excites both electromagnetic (EM) and electroacoustic plasma (P) waves in addition to a nonradiating surface wave. In the absence of an external magnetic field, the EM- and P-waves can be decoupled into two independent modes, the electroacoustic mode is longitudinal while the electromagnetic mode is transverse. The far-zone EM-mode and P-mode radiation fields are derived using vector wave function techniques and pattern multiplication approaches. The results are obtained in both plasma medium and free space. Some important antenna parameters such as radiation conductance, directivity and quality factor are plotted for different values of plasma-to-source frequency.     

Dispersion relation for space-charge waves in a warm plasma-filled elliptical waveguide in an infinite axial magnetic field

A perfectly conducting elliptical cylinder filled with a warm plasma and immersed in an infinite axial magnetic field is considered. Using Maxwell’s equations and dielectric tensor, a Mathieu differential equation for axial component of electric field is obtained. Considering the boundary conditions, dispersion relation for waves in a plasma of warm electrons and immobile ions, which fills an elliptical waveguide and it is under the action of infinite axial magnetic field are calculated. Furthermore, dispersion relation and scalar potential in the quasi-static approximation in a cold magnetized plasma elliptical waveguide is calculated. The obtained results are graphically presented.     

Determination of the wave number of an electromagnetic wave propagating in high-frequency jet discharge plasma

The measurements of the amplitude-phase characteristics of the electromagnetic field in a high-frequency jet discharge burning in air and argon have been performed. Experimentally obtained radial distributions of the radial component of the electric field gave the base to determine the value of the wave number of an electromagnetic wave which propagates in the HF jet discharge plasma. The axial distribution of the radial component of the electric field has been calculated from the model of a jet discharge channel formed as a finite-length electric line.     

射频激励等离子体非线性效应的FDTD数值模拟

在考虑热运动、电子复合、扩散等效应后，建立电磁波与等离子体相互作用模型，验证了射频激励等离子体时产生的二次、多次谐波以及各个不同频段信号的调制现象，得到了不同激励功率、产生电子的电场阈值、电子能量等参数对电磁波频谱的影响，这对于射频激励等离子体的电路匹配、耦合器件以及等离子体天线传输、电磁兼容等设计很有帮助. 关键词： 射频 谐波 等离子体 非线性     

Faraday shield effects on a half-turn loop antenna used for ICRFplasma heating

The characteristics of a half-turn loop antenna having a Faraday shield (used for ion-cyclotron RF plasma heating) have been systematically investigated. The main interest is to clarify the Faraday shield effects on the near-zone electric field distribution. It has been confirmed that, in the presence of the Faraday shield, undesirable field components are sufficiently suppressed, and the heating component E _y, which otherwise is strongly localized as an end effect, has been found to be distributed uniformly along the antenna in the case of a short electric length. It is found that the shielding strips should be uniformly distributed over the entire region around the half-turn loop antenna