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The Xray fluence enhancement in the waterwindow region is sevenfold compared with a conventional carbon plate target.


The Xray tube was a glassenclosed coldcathode triode, composed of a tungsten plate target, a rodshaped graphite cathode, a meshtype trigger electrode made of tungsten wires, and a glass tube body.


We also placed a 4' by 8' metalplate target behind the wall of building 962 and measured returns.




 Radar cross section (RCS)of some typical geometries such as conducting plates and dihedral corners in low frequency has been calculated by numerical method. Through comparison of the calculated results with those in high frequency published by other authors, we obtained these conclusions:① with the reduction of electric size of plates and dihedral corners,their RCS versus incident angle becomes more smooth;② with the reduction of electric size of plates and dihedral corners, their RCS (dB/λ2 or dBsm)decreases;③... Radar cross section (RCS)of some typical geometries such as conducting plates and dihedral corners in low frequency has been calculated by numerical method. Through comparison of the calculated results with those in high frequency published by other authors, we obtained these conclusions:① with the reduction of electric size of plates and dihedral corners,their RCS versus incident angle becomes more smooth;② with the reduction of electric size of plates and dihedral corners, their RCS (dB/λ2 or dBsm)decreases;③ with the reduction of electric size of plates, the RCS difference between different polarizations becomes more obvious; ④ even though the shapes of plates and dihedral corners are different, when their electric aperture areas are approximately equal in lower frequency, the amplitudes of their RCS(dB/λ2) are also approximately equal.  通过数值方法对完纯导电平板，两面角反射器等典型几何体低频雷达散射截面进行计算，并与已有的高频解相比较。计算分析表明：①随着平板、两面角的电尺寸减小，其ＲＣＳ随方位的变化曲线逐步变得平坦；②随着平板、两面角的电尺寸减小，其ＲＣＳ（ｄＢ／λ２或ｄＢｓｍ）是逐步下降的；③随着电尺寸的减小，平板目标在不同极化状态下ＲＣＳ的区别趋于明显；④虽然平板和两面角形状区别较大，但在较低频率下，当它们的电尺寸口径面积接近时，其ＲＣＳ（ｄＢ／λ２）峰值也接近。  In this paper, the analysis of the electromagnetic scattering from a plate over the fractal sea/ground rough surface is made. The surface is medeled by use of a fractal function. The interaction between the target and the rough surface is represented to be the double bounce by using the Kirchhoff approximation. And some factors, such as the roughness, incident angle, polarization and rough surface varying with time et al, are investigated which influence on composite scattering characters between the target... In this paper, the analysis of the electromagnetic scattering from a plate over the fractal sea/ground rough surface is made. The surface is medeled by use of a fractal function. The interaction between the target and the rough surface is represented to be the double bounce by using the Kirchhoff approximation. And some factors, such as the roughness, incident angle, polarization and rough surface varying with time et al, are investigated which influence on composite scattering characters between the target and the rough surface. The numerical results indicate the method is effective to solve the problem of the composite scattering between the target and the sea/ground rough surface.  利用分形函数来模拟海地粗糙表面，在考虑到粗糙面的粗糙度，入射波极化方式以及粗糙面的动态和静态等因素对电磁散射特性影响的情况下，运用克希霍夫近似条件，对粗糙面上方平板目标电磁散射的物理机制进行了分析和研究。理论分析和数值结果表明，本文所述方法物理图象清晰，是一种有效分析实际粗糙面与目标相互作用的方法。  The near\field scattering characteristics for the conduct plate is studied by using of the physics optics method, and a calculation method of convolution integration for near field scattering is discussed. This method can accomplish fast calculation by FFT. With the changes of plate characteristic, size wavelength and the distanc from the observation plate to the scattering body, found by computer modeling, the scattering field exists a relation, and there are two different similarities in the scattering field... The near\field scattering characteristics for the conduct plate is studied by using of the physics optics method, and a calculation method of convolution integration for near field scattering is discussed. This method can accomplish fast calculation by FFT. With the changes of plate characteristic, size wavelength and the distanc from the observation plate to the scattering body, found by computer modeling, the scattering field exists a relation, and there are two different similarities in the scattering field distribution, the strict similarity when electronical size is constant and the asymptotic similarity when it changes.  用物理光学法研究导电平板目标近场散射特性，为了提高计算效率，文中采用了卷积积分法．通过计算机的模拟发现，当特征尺寸、入射场波长及观察点离目标的距离改变时，其散射场存在一定的换算关系，散射场出现近似的或严格的相似性   << 更多相关文摘 
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