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1.
Dispersion characteristics of two-dimensional unmagnetized dielectric plasma photonic crystal 总被引:1,自引:0,他引:1 下载免费PDF全文
This paper studies dispersion characteristics of the transverse magnetic(TM) mode for two-dimensional unmagnetized dielectric plasma photonic crystal by a modified plane wave method.First,the cutoff behaviour is made clear by using the Maxwell-Garnett effective medium theory,and the influences of dielectric filling factor and dielectric constant on effective plasma frequency are analysed.Moreover,the occurence of large gaps in dielectric plasma photonic crystal is demonstrated by comparing the skin depth with the lattice constant,and the influence of plasma frequency on the first three gaps is also studied.Finally,by using the particle-in-cell simulation method,a transmission curve in the Γ-X direction is obtained in dielectric plasma photonic crystal,which is in accordance with the dispersion curves calculated by the modified plane wave method,and the large gap between the transmission points of 27 GHz and 47 GHz is explained by comparing the electric field patterns in particle-in-cell simulation. 相似文献
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本文介绍一种新型毫米波准光学可调辐射源,它采用由面对称三反射镜准光学谐振腔和绕射光栅组成高频互作用系统,利用中等能量级的相对论带状电子注激励,产生频率可调的宽带毫米波、远红外波段的辐射。这种新方案的机理性实验在电子科技大学首次获得成功,其主要实验参数:电子注的能量为400~500kV,电压脉冲宽度70ns,同步脉冲磁场强度1.2T; 磁场脉冲宽度10ms,带状电子注尺寸10nm×1mm;通过热测实验,我们成功地检测到3mm波段的高频信号,其峰值功率达到数十千瓦量级。 相似文献
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以圆柱开槽波导、螺旋摇摆器为模型,考虑了电子初始速度零散、引导磁场等效应对放大器饱和特性的影响,导出了自洽的注波互作用三维非线性方程组.并在此基础上编制了相应的计算软件,通过数值分析的方法研究了圆柱开槽波导自由电子激光放大器的饱和效率、频带宽度等高频特性. 相似文献
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拟线性双曲组解的奇性形成和特征包络 总被引:1,自引:0,他引:1
一、引言如所知,对一阶拟线性双曲型方程组,即使其初值充分光滑,其柯西问题的解一般说来也要在有限时间内产生奇性,即经典解要发生破裂(Blow up),这在力学上对应于激波的产生等自然现象。通常认为奇性的发生起因于同族特征线产生包络。这一事实在力学上虽已多次应用,但在一般情况下其实还只是一个猜测,有必要在理论上加以分析和讨论。本文对可化约拟线性双曲组的柯西问题肯定地回答了上述的问题,所得的结果对一般情形的讨论也将有一定的启发。 相似文献
5.
Three-dimensional simulation of Ka-band relativistic Cherenkov source with metal photonic-band-gap structures 总被引:1,自引:0,他引:1 下载免费PDF全文
This paper presents a three-dimensional particle-in-cell (PIC) simulation of a Ka-band relativistic Cherenkov source with a slow wave structure (SWS) consisting of metal photonic band gap (PBG) structures. In the simulation, a perfect match layer boundary is employed to absorb passing band modes supported by the PBG lattice with an artificial metal boundary. The simulated axial field distributions in the cross section and surface of the SWS demonstrate that the device operates in the vicinity of the π point of a TM01-like mode. The Fourier transformation spectra of the axial fields as functions of time and space show that only a single frequency appears at 36.27 GHz, which is in good agreement with that of the intersection of the dispersion curve with the slow space charge wave generated on the beam. The simulation results demonstrate that the SWS has good mode selectivity. 相似文献
6.
提出了一种变态光子带隙结构,研究了由这种结构构成的周期慢波系统的Cherenkov辐射源的特性. 利用高频仿真软件以及三维粒子模拟软件对变态及常态光子带隙慢波系统中类TM01模的色散特性及注-波互作用物理过程进行了模拟研究. 结果表明,在变态光子带隙慢波系统中,类TM01模纵向场分量沿角向分布均匀性得到明显改善,能有效抑制非对称模式,提高输出频谱纯度及注-波互作用效率.
关键词:
Cherenkov辐射源
变态光子带隙结构
慢波系统
三维粒子模拟 相似文献
7.
利用根与系数的关系.证明了特征方程没有零实部根的充要条件,给出了矩阵特征值至少具有一个正实部的充分条件,最后通过示例计算验证了该方法的有效性. 相似文献
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9.
Based on an improvement of the Karman-Pohlhausen's method, using nonlinear polynomial fitting and numerical integral, the axial distributions of pressure and its gradient in an axisymmetric rigid vessel with stenosis were obtained, and the distributions related to Reynolds number and the geometry of stenotic vessel were discussed. It shows that with the increasing of stenotic degree or Reynolds number, the fluctuation of pressure and its gradient in stenotic area is intense rapidly, and negative pressure occurs subsequently in the diverging part of stenotic area. Especially when the axial range of stenosis extends, the flow of blood in the diverging part will be more obviously changed. In higher Reynolds number or heavy stenosis, theoretical calculation is mainly in accordance with nast experiments. 相似文献
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