共查询到16条相似文献,搜索用时 656 毫秒
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给出了一种新的计算各向异性磁化色散介质的有限差分(FDTD)算法,称为移位算子FDTD(SO-FDTD)算法,它利用算子之间的移位递推关系,将一类色散介质的包含介电常数的表达式写成有理分式函数形式,进而导出FDTD中一系列相关量之间的关系.通过计算各向异性等离子体平板对电磁波的反射系数和透射系数,验证了该算法的高效性和高精度,与JEC算法相比,可使计算效率提高数倍.
关键词:
磁化等离子体
电磁波
FDTD方法
各向异性 相似文献
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本文建立了时变非磁化等离子体平板的一维模型,并采用时域有限差分(FDTD)方法对太赫兹(THz)电磁波在时变等离子体中传播时的反射、透射系数及吸收率进行了计算.然后根据计算结果分析了时变等离子体的上升时间、电子密度、温度以及等离子体平板厚度等参数对不同频段THz波在等离子体中传播特性的影响.分析结果表明:THz波在时变等离子体中传播时,其反射系数受等离子体电子密度和上升时间的影响较大;而吸收率则随着上升时间的减小、电子密度及平板厚度的增加而增大;此外,THz电磁波能够穿透量级为1020m-3的高密度等离子体层,可以作为再入段飞行器通信以及高密度等离子体诊断的理想工具. 相似文献
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提出了斜入射分层线性各向异性等离子体电磁散射的时域有限差分(FDTD)方法,通过将二维麦克斯韦方程等价地转换为一维麦克斯韦方程,避免了用二维时域有限差分方法分析该散射问题,极大地提高了计算效率.分析推导了TEz和TMz波斜入射线性分层各向异性等离子体电磁散射的FDTD方法,然后通过该方法计算不同入射角的各向异性等离子板的电磁波反射系数,并与其解析解进行比较,结果表明该方法的准确性和有效性.最后,将该算法应用于计算涂覆分层各向异性等离子体金属板在不同入射角下的反射系数,分析了不同入射角对反射系数的影响. 相似文献
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将弱电离尘埃等离子体复介电常数表示以jω 为自变量的分式多项式形式, 利用移位算子时域有限差分(SO-FDTD)方法, 给出了弱电离尘埃等离子体频域本构关系的时域形式. 推导了弱电离尘埃等离子体电磁特性的时域递推关系式. 用SO-FDTD方法计算了弱电离尘埃等离子体层的反射和透射系数, 分析了尘埃粒子浓度和尘埃粒子半径的变化对反射系数和透射系数的影响. 结果表明: 有尘埃粒子时的反射系数比没有尘埃粒子时反射系数小, 而透射系数要比没有尘埃粒子时的透射系数大; 当尘埃粒子浓度或尘埃粒子半径增大时, 其反射系数均减小. 相似文献
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高超声速飞行器再入地面的过程中,其周围等离子体的电子密度是非均匀且随时间变化的.对于不同的再入高度,飞行器周围的温度和压强也会发生改变.因此,研究电磁波在时空非均匀等离子体鞘套中的传播特性意义重大.首先建立了时变非均匀的等离子体鞘套模型,然后通过经验公式得到温度、压强与碰撞频率三者的关系.采用时域有限差分方法计算了太赫兹波段中不同电子密度弛豫时间、温度、压强时的反射系数、透射系数和吸收率.研究结果表明:在太赫兹波段中,电子密度的弛豫时间越长,温度越高,压强越大,电磁波越容易穿透等离子体;弛豫时间越短,温度越低,压强越小,等离子体对电磁波吸收率的变化越明显.这些结果为解决"黑障"问题提供了理论依据. 相似文献
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把金属平板前非均匀等离子体层简化为分层均匀的平板模型,采用等效输入阻抗方法,计算大气或真空边界入射波的总功率反射系数,分析其影响因素.计算结果表明:电子数密度大 小、等离子体层厚度、入射波频率和入射角是功率反射系数的主要影响因素,适当调整其中任何一个,都可以达到降低功率反射系数的效果.在低频段,电子数密度的分布对功率反射系数几乎没有影响;在高频段,电子数密度的分布对功率反射系数有影响.等离子体厚度、入射波频率、电子数密度分布对功率反射系数的影响几乎与波的极化方向无关.
关键词:
等离子体
电磁波
传输 相似文献
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In this paper, the dielectric constant of dispersive medium is written as rational polynomial function, and the relationship
between D and E is derived in time-domain. It is named shift operator FDTD (SO-FDTD) method. Compared to the analytical solution, the high
accuracy and efficiency of this method is verified by calculating the reflection coefficient of the electromagnetic wave through
a cold plasma slab. The effect on reflection coefficient is calculated by using the SO-FDTD method. The result shows that
some factors effect on reflection coefficient. They are as follows: plasma thickness, electron density, electron distribution
and incident frequency. And on most conditions, parabola distribution helps reduce reflection coefficient more effectively
than homogeneous distribution. 相似文献
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Hongwei Yang Wanchun Tang Xiangkun Kong 《International Journal of Infrared and Millimeter Waves》2007,28(7):547-556
In this paper, shift operator finite-difference time-domain (SO-FDTD) method is applied for the calculation of the dispersive
medium. The high efficiency and accuracy of this method is verified by calculating the reflection of the plane electromagnetic
wave impinging on a non-magnetized plasma slab with different electron density distributions. The results show that the average
electron density only determines overall trends of the reflection, and different distributions affect the oscillating process
of the reflection. If the average electron density maintains the same, the distribution of electron density with homogenous
or inhomogeneous alternation will sharply take effects on the reflection. And magnitude of alternation of electron density
affects the incident frequency directly when the reflection tends to uniform. 相似文献
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In this paper, the shift operator finite difference time domain (SO-FDTD) method and Runge-Kutta exponential time differencing (RKETD) method are introduced. The high accuracy and efficiency of the two methods are verified by calculating the reflection and transmission coefficients of electromagnetic waves through a collisional plasma slab. A comparison of computational efficiency of the two methods is presented by simulating the electromagnetic wave propagation in homogeneous non-magnetized plasma. The numerical results indicate that the calculation time using SO-FDTD method is less than that using RKETD method with almost the same accuracy. 相似文献
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Hongwei Yang R. S. Chen Yongchun Zhou 《International Journal of Infrared and Millimeter Waves》2007,28(9):751-758
In this paper, a novel finite-difference time-domain (FDTD) method with recursive relationships among operators is developed
for magnetized dispersive medium, named as the shift operator FDTD(SO-FDTD). The dielectric property of magnetized dispersive
medium is written as rational polynomial function, the relationship between D and E is deduced in time-domain. And its high accuracy and efficiency are verified by calculating the reflection and transmission
coefficients of electromagnetic waves through a collision plasma slab. 相似文献
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Propagation characteristics of oblique incidence terahertz wave through non-uniform plasma 下载免费PDF全文
《中国物理 B》2019,(1)
The propagation characteristics of oblique incidence terahertz(THz) waves through non-uniform plasma are investigated by the shift-operator finite-difference time-domain(SO-FDTD) method combined with the phase matching condition.The electron density distribution of the non-uniform plasma is assumed to be in a Gaussian profile. Validation of the present method is performed by comparing the results with those obtained by an analytical method for a homogeneous plasma slab.Then the effects of parameters of THz wave and plasma layer on the propagation properties are analyzed. It is found that the transmission coefficients greatly depend on the incident angle as well as on the thickness of the plasma, while the polarization of the incident wave has little influence on the propagation process in the range of frequency considered in this paper. The results confirm that the THz wave can pass through the plasma sheath effectively under certain conditions,which makes it a potential candidate to overcome the ionization blackout problem. 相似文献
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Reflection coefficients of electromagnetic waves in a nonuniform plasma layer with electrons, positive ions and negative ions, covering a metal surface are investigated by using the finite-difference-time-domMn method. It is shown that the reflection coemcients are influenced greatly by the density gradient on the layer edge, layer thickness and electron proportion, i.e., the effect of the negative ions. It is also found that low reflection or high attenuation can be reached by properly choosing high electron proportion, thick plasma layer, and smooth density gradient in the low frequency regime, but sharp density gradient in the high frequency regime. 相似文献