共查询到20条相似文献,搜索用时 31 毫秒
1.
Jia-sheng Tian Tian-lin Dong 《International Journal of Infrared and Millimeter Waves》2002,23(6):931-935
Transverse propagation eigen equations for dielectric waveguide array (DWA) are derived and eigen solutions can be uncoupled into TE and TM modes. Numerical results shows that much stronger space harmonic interaction exists so that a series of interesting physical effect of canonical two-dimensionally periodic (2DP) medium can obviously be observed in DWA and related devices can be predicted, designed and realized much easier. 相似文献
2.
Jia-sheng Tian Tian-lin Dong 《International Journal of Infrared and Millimeter Waves》2004,25(6):981-988
Based on the established rigorous theory for two-dimensionally periodic (2DP) medium, Longitudinal propagation in Dielectric Waveguide Array (DWA) was analyzed in detail. Firstly, given longitudinal wave vector (k
z), Brillouin dispersion relations between transversal wave vectors were analyzed. Interactions between space harmonics were also studied. Secondly, on condition that transversal wave vector k
x equaled k
y, dispersion relations between longitudinal and transversal wave vectors were analyzed in detail. Because of interactions between space harmonics increasingly getting stronger with k
z or modulation coefficients increasing, stop-bands could be distinctly displayed and thus longitudinal propagation in DWA could be comprehensively analyzed. The applications about longitudinal propagation in DWA were also discussed. 相似文献
3.
Tian-lin Dong 《International Journal of Infrared and Millimeter Waves》1992,13(8):1163-1174
Rigorous analysis of planar waveguides with two-dimensionally periodic (2DP) layer is presented. Characteristic solutions in periodic layer are exactly represented by a double Fourier series known as the Floquet solutions. The vector amplitudes of space harmonics are proved to be governed by five-term recurrence relation in the operator-vector form for sinusoidal modulation. A general transmission-line network representation of two-dimensionally periodic medium and multiport network representation of uniform-periodic-medium interface are introduced. Any layered structures cascading with periodic ones can be analyzed. Numerical results based on the established theory are also presented to illustrate characteristics of 2DP medium and structure. 相似文献
4.
Two types of dielectric wall accelerator (DWA) structures, a bi-polar Blumlein line and zero integral pulse line (ZIP) structures were investigated. The high gradient insulator simulated by the particle in cell code con rms that it has little in uence on the axial electric field. The results of simulations using CST microwave studio indicate how the axial electric field is formed, and the electric eld waveforms agree with the theoretical one very well. The in uence of layer-to-layer coupling in a ZIP structure is much smaller and the electric eld waveform is much better. The axial of the Blumlein structure's electric field has better axial stability. From both of the above, it found that for a shorter pulse width, the axial electric field is much higher and the pulse stability and delity are much better. The CST simulation is very helpful for designing DWA structures. 相似文献
5.
La-min Zhan Tian-lin Dong 《International Journal of Infrared and Millimeter Waves》2004,25(6):973-979
Rigorous analysis shows that independent longitudinally guided TE and TM modes are possible in dielectric waveguide array (DWA) as a two dimensionally periodic medium. Especially, purely longitudinally guidance is also possible and investigated in detail. 相似文献
6.
Jian-sheng Tian Tian-lin Dong 《International Journal of Infrared and Millimeter Waves》2003,24(4):613-618
The eigen equation for Dielectric Waveguide Array (DWA) established by [1] was discussed. The convergence of the eigen equation was also analyzed in detail. Numerical results for a particular rectangular DWA was presented. Compared with those obtained by previous different ways, faster convergence for the eigen equation was reached easily. The characteristics of the eigen equation for DWA was particularly useful in computer propramming and engineering. 相似文献
7.
La-min Zhan Tian-lin Dong 《International Journal of Infrared and Millimeter Waves》2004,25(8):1231-1236
It's not adequate to just obtain eigenvalue for solving eigenvalue problem. Since the eigenvalues associated with longitudinal characteristic modes in dielectric waveguide array (DWA) has been studied, the paper concentrates on the corresponding eigenvector, namely, the amplitude of these characteristic modes. Through numerical study of the amplitude of longitudinal guided TE and TM modes in DWA, space harmonic (SH) coupling and energy conversion effect have been discovered. The paper not only contribute to deep understand the mechanism of SH interaction, but also do good to analyze the resonance, radiation problem in DWA. 相似文献
8.
基于绝缘微堆技术的直线加速器由于其能够实现较高的粒子加速梯度,尤其在质子加速及肿瘤治疗领域的优势得到高度关注。目前该种加速器处于研发阶段,有一系列技术和工程问题有待解决。介绍了课题组在过去的两年里围绕建立一台1 MeV质子注入器原型样机在固态脉冲功率系统、绝缘微堆及质子束源等方面取得的研究进展。实现了耐压梯度接近20 MV/m的环形绝缘微堆样品,样品内径30 mm,外径50 mm,厚度15 mm,基本达到设计要求;固态脉冲功率系统实现了光导开关多路稳定工作模式,开关直流偏置耐压达到20 kV,采用激光二极管触发同步系统在15路同步时实现了低于1 ns的抖动,输出300 kV的电压脉冲,输出电压脉冲宽度10 ns;进行了低能质子加速束流动力学的初步分析和模拟工作,模拟结果表明采用微堆结构可以实现质子束的有效加速和传输。 相似文献
9.
基于绝缘微堆技术的直线加速器由于其能够实现较高的粒子加速梯度,尤其在质子加速及肿瘤治疗领域的优势得到高度关注。目前该种加速器处于研发阶段,有一系列技术和工程问题有待解决。介绍了课题组在过去的两年里围绕建立一台1 MeV质子注入器原型样机在固态脉冲功率系统、绝缘微堆及质子束源等方面取得的研究进展。实现了耐压梯度接近20 MV/m的环形绝缘微堆样品,样品内径30 mm,外径50mm,厚度15mm,基本达到设计要求;固态脉冲功率系统实现了光导开关多路稳定工作模式,开关直流偏置耐压达到20kV,采用激光二极管触发同步系统在15路同步时实现了低于1ns的抖动,输出300kV的电压脉冲,输出电压脉冲宽度10ns;进行了低能质子加速束流动力学的初步分析和模拟工作,模拟结果表明采用微堆结构可以实现质子束的有效加速和传输。 相似文献
10.
Tian-lin Dong Jia-sheng Tian 《International Journal of Infrared and Millimeter Waves》2000,21(12):2047-2054
Based on the modal solution of one dimensionally periodic structure with piecewise uniform dielectric constant distribution, characteristic solutions for two dimensionally Dielectric Waveguide Array (DWA) are rigorously formulated. By satisfying periodic boundary conditions in the interfaces inside a unit cell, semi-closed-form dispersion relation for DWA can be established. Numerical results are presented and compared with a previous method. A class of guidance and radiation problems can be solved with much more simplicity and accuracy. 相似文献
11.
Emine Bulut 《Journal of Macromolecular Science: Physics》2014,53(5):902-917
Microspheres of blends of sodium alginate (NaAlg) and sodium carboxymethyl cellulose (NaCMC) were prepared by a water-in-oil (w/o) emulsion crosslinking method and used for the release of donepezil hydrochloride (DP), which is an Alzheimer's drug. The microspheres were characterized with Fourier transform infrared spectroscopy (FTIR), differantial scanning calorimetry (DSC), and scanning electron microscopy (SEM). The microsphere characteristics, including DP entrapment efficiency, particle size, equilibrium swelling degree (ESD), and DP release kinetics, were determined. The effects of the preparation conditions, including the NaAlg/NaCMC (w/w) ratio, drug/polymer (w/w) ratio, cross-linker concentration and time of exposure to the cross-linker, on the release of DP were investigated for successive gastrointestinal tract pH values of 1.2, 6.8, and 7.4 at 37°C. The release of DP increased with the increase in NaAlg/NaCMC (w/w) ratio and drug/polymer (d/p) ratio, while it decreased with increasing extent of cross-linking. The optimum DP release was obtained as 99.13% for a NaAlg/NaCMC (w/w) ratio of 2/1, d/p ratio of 1/4, CaCl2 concentration of 5% and crosslinking time of 30 min. It was also observed from release results that DP release from the microspheres through the external medium was higher at low pH (1.2) values than that at high pH (6.8 and 7.4) values. The DP release of the microspheres followed either Fickian transport below a value of n < 0.5 or anomalous transport (n = 0.5–1.0). 相似文献
12.
介绍了介质壁加速器(DWA)的原理和几种可能实现的结构。通过对多层介质圆柱的平面波电磁散射的研究,用FORTRAN语言编写程序计算和分析了DWA加速管三层介质柱体结构的平面波电磁散射的散射宽度与几何结构参数、材料参数的关系,用以优化设计介质壁加速管结构。计算结果表明:当加速管材料和等势环介电常数一定时,平面波电磁散射宽度随半径增大而增大;当加速管内外径一定时,加速管材料和等势环介电常数增大时散射宽度变化不明显,但最小散射宽度显著减小。当加速管半径和材料一定时,总能找到使散射宽度达到最小的等势环介质厚度。 相似文献
13.
Rigorous Analysis of Electromagnetic Wave Propagation in Cylindrical Dielectric Waveguide Array 总被引:1,自引:0,他引:1
Jia-sheng Tian Tian-lin Dong 《International Journal of Infrared and Millimeter Waves》2003,24(11):1885-1891
Cylindrical Dielectric Waveguide Array(CDWA) should be considered as a kind of two-dimensionally periodic(2DP) medium. Based on the established rigorous theory for 2DP medium, a great amount of numerical results for CDWA were presented. Wave propagation in CDWA was analyzed in detail in this paper. Firstly, given the longitudinal wave vector (k
z=0), Brillouin dispersion relations between transverse wave vectors were analyzed when modulation coefficients or the rate of different dielectric areas in a unit cell varied. Interactions between space harmonics were also studied. Secondly, when the area of dielectric cylinder in the unit cell varied within a given range, CDWA dispersion relations were compared with Rectangle Dielectric Waveguide Array's, some interesting conclusions were obtained. 相似文献
14.
介绍了介质壁加速器(DWA)的原理和几种可能实现的结构。通过对多层介质圆柱的平面波电磁散射的研究,用FORTRAN语言编写程序计算和分析了DWA加速管三层介质柱体结构的平面波电磁散射的散射宽度与几何结构参数、材料参数的关系,用以优化设计介质壁加速管结构。计算结果表明:当加速管材料和等势环介电常数一定时,平面波电磁散射宽度随半径增大而增大;当加速管内外径一定时,加速管材料和等势环介电常数增大时散射宽度变化不明显,但最小散射宽度显著减小。当加速管半径和材料一定时,总能找到使散射宽度达到最小的等势环介质厚度。 相似文献
15.
为了在介质壁加速器中增大轴向加速电场, 提高加速梯度的同时抑制径向电场对束包络的扩张, 提出了在每个加速电极上添加金属栅网结构。采用基于粒子云网格方法的电磁粒子模拟软件对不加栅网与添加栅网的电极结构进行了数值仿真, 分析了不同结构下加速管道中的电场分布和束包络变化。通过实验对比了两种不同结构下经过相同的加速长度获得的粒子能量。结果表明:添加金属栅网结构相对于不加栅网的金属小孔式结构, 轴向加速电场强度提高20%, 同时径向电场得到有效抑制;栅网结构下, 被加速的粒子束在自由漂移空间中的径向发散基本得到抑制;在相同的加速长度下加速H3+粒子, 栅网结构得到的能量增益提高了一倍。 相似文献
16.
为了在介质壁加速器中增大轴向加速电场, 提高加速梯度的同时抑制径向电场对束包络的扩张, 提出了在每个加速电极上添加金属栅网结构。采用基于粒子云网格方法的电磁粒子模拟软件对不加栅网与添加栅网的电极结构进行了数值仿真, 分析了不同结构下加速管道中的电场分布和束包络变化。通过实验对比了两种不同结构下经过相同的加速长度获得的粒子能量。结果表明:添加金属栅网结构相对于不加栅网的金属小孔式结构, 轴向加速电场强度提高20%, 同时径向电场得到有效抑制;栅网结构下, 被加速的粒子束在自由漂移空间中的径向发散基本得到抑制;在相同的加速长度下加速H3+粒子, 栅网结构得到的能量增益提高了一倍。 相似文献
17.
为了研究尾场效应引起的束流不稳定性,建立了由非对称Blumlein脉冲形成线、导体层和微堆层构成的介质壁加速器单元模块模型,用有限积分法对强流电子束在此结构中产生的尾场进行了计算,分别计算单组元和2组单元加速模块中的尾场势和尾场阻抗。从模拟的结果来看,x, y方向的尾场势和尾场阻抗都很小,束流尾场对横向的影响比较小。z方向的尾场势和尾场阻抗影响较大,尾场阻抗达到100 Ω量级。证明了由于介质壁加速器结构在加速腔长度和束流通过路径的连续性方面都具有很大的优势,横向阻抗小,束流尾场效应在束流不稳定性方面的影响相对较小,束流传输时的要求也会降低。 相似文献
18.
对于大尺度运动目标的参数测量,固定相机存在着视场与空间分辨率之间的矛盾,并且当测量空中或海上目标时相机的标定也十分困难。跟踪式相机(如光电经纬仪)能解决此问题,但存在体积大、成本高和操作复杂等缺点。结合两者特点取长补短,将相机固定在二维旋转平台上,尽可能实现同心放置,组成准同心广义经纬相机进行中远场高精度测量,测量过程中转台实时跟踪目标并为相机提供外参数。此方法并没有光电经纬仪非常严格的同心同轴的安装要求。在合理假设基础上建立了经纬相机成像模型,提出了线性求解及平差优化相机参数的方法。大量仿真与实际测量验证了模型和标定方法的正确性和高精度。广义经纬相机测量系统组合巧妙、装拆和操作简单、体积小、成本低、可全视场测量且测量精度高,有广泛且重要的应用前景。 相似文献
19.
The applicability and accuracy of the “displaced-profile change-in-self-consistent-field” (DPΔSCF) formalism for the work function are demonstrated by calculations for the jellium metal surface. The DPΔSCF expression is as easy to evaluate as the usual Koopmans' theorem expression for the work function, but is much more accurate when the electron density is obtained from Rayleigh-Ritz variational calculations of the surface energy. Use of the method in calculations for real metals is indicated. 相似文献
20.
以三阶克尔型非线性波导为例,利用雅可比椭圆函数的特性,定义了一种新颖的雅可比椭圆余切振幅函数,以此建立了类似线性的在非线性条件下的色散关系,使形式简化、物理意义清晰。并利用这一关系分析了该情况下的模式特性和场特性。 相似文献