Excitation of a waveguide transformer

Integral immitance equations for steady-state excitation of a shielded waveguide transformer with any number of arbitrarily arranged adjoint semi-infinite waveguides are derived in the general formulation. Excitation can be carried by arbitrary inner sources (extraneous electric and magnetic currents), as well as by normal modes incident from infinity. The results are extended to the case of nonideal walls for magnetodielectric and metallic inclusions. The results give a generalization of the familiar integral impedance and admittance equations for inhomogeneous waveguides.     

基于二维特异材料波导的表面电磁波的慢波实验研究

本文在理论分析的基础上,实验研究了二维MNG/DPS/MNG(磁单负材料/双正材料/磁单负材料)表面波波导中的慢波效应.该波导的色散曲线随着电路参数(单元电容)的改变而改变,而且在色散曲线的截止频率点,电磁波的群速度理论上等于零.因此可以通过改变MNG区域的电路参数,得到在不同截止频率的慢波特性.另外,本文还通过改变MNG区域的电路参数实现在某一固定频率下波速度渐变的慢波效应.实验结果与仿真结果相一致.     

Excitation of ion-acoustic-like waves by subcritical currents in a plasma having equal electron and ion temperatures

The effect of a magnetic-field-aligned plasma flow with a transverse velocity gradient on the excitation of current-driven ion-acoustic-like waves in a plasma having equal electron and ion temperatures (T(e) = T(i)) was investigated experimentally. In agreement with theoretical predictions, the presence of sheared plasma flow substantially reduces the critical electron drift velocity needed to produce the ion-acoustic instability.     

Crumpling a thin sheet

Crumpled sheets have a surprisingly large resistance to further compression. We have studied the crumpling of thin sheets of Mylar under different loading conditions. When placed under a fixed compressive force, the size of a crumpled material decreases logarithmically in time for periods up to three weeks. We also find hysteretic behavior when measuring the compression as a function of applied force. By using a pretreating protocol, we control this hysteresis and find reproducible scaling behavior for the size of the crumpled material as a function of the applied force.     

低频调制场中钾原子的激发

本文用含时多态展开方法计算了里德堡钾原子在静电场、微波场和低射频场[a radio-frequency(rf)field]共同作用下方波振荡的激发特性.研究计算了通过改变微波场的频率、振幅和静电场的振幅以及用低射频锯齿波代替低射频余弦波后方波振荡的变化,获得了一些非常有趣的结果,并给出了理论解释.     

Complex waves in a two-layer circular shielding waveguide

Certain dispersion properties of natural complex waves are considered in a two-layer circular shielded waveguide. The results of a solution of the dispersion equation on an electronic computer are presented for the case of complex waves.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 15, No. 1, pp. 112–116, January, 1972.     

Solitary waves in a binary nonlinear waveguide array

Based on the coupled-mode theory, the propagation of light pulses is studied analytically for a system of an infinite number of tunnel-coupled parallel equidistant waveguides of optically nonlinear materials; in the considered system, waveguides with a positive refractive index alternate with waveguides with a negative refractive index. Partial solutions to a system of nonlinear equations describing the evolution of these pulses are found in the case in which fields in adjacent waveguides differ only in the phase factor. For a solitary wave formed by coupled wave packets localized each in its own waveguide, these solutions describe the stationary propagation in a definite direction. It is shown that the coupling strength between waveguides has an effect on the propagation rate of the obtained stationary pulses.