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横向聚焦波荡器可用于电子束能量较低、函数较小的情况。在现有横向聚焦波荡器设计方案的基础上,通过倾斜磁块端面和磁极面提出了几种不同结构的横向聚焦波荡器方案。利用三维磁场模拟程序Radia,对这些波荡器的聚焦场特性进行了模拟计算,对其聚焦特性与主要参数的关系进行了研究,并与现有其他横向聚焦波荡器的聚焦特性进行了对比。对弱聚焦和强聚焦两种情况,分别给出较好的结构方案。对于弱聚焦,平均聚焦梯度随中心场强的增大而略有增大,变化不明显;对于强聚焦,平均聚焦梯度随中心场强的增大而明显增大,呈高次曲线关系。 相似文献
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文提出了一种新型磁通聚焦器和谐振器. 磁通聚焦器引入了单互补开环谐振器结构 (单CSRR); 谐振器则采用环绕着绕磁通聚焦器的发夹型3阶阶梯阻抗谐振器 (SIR). 采用ANSYS HFSSv.11高频结构仿真软件对提出的磁通聚焦器和谐振器进行了仿真, 并对单CSRR进行了理论分析. 仿真和理论分析表明: 单CSRR的引入, 提高了磁通聚焦器的聚磁效果, 改善了磁通聚焦器与RF SQUID垫圈的耦合(耦合系数ksc为引入单CSRR前的2倍), 并且有效面积增大到1.227 mm2. 相似文献
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Kinoform单透镜可以高效聚焦硬X射线至纳米量级, 在X射线纳米显微学和纳米光谱学领域有着重要的应用前景. 基于衍射光学和傅里叶光学理论, 给出了X射线经由Kinoform单透镜聚焦的物理模型, 基于数值模拟, 研究了不同材料、光子能量、台阶数量和顶点曲率半径对Kinoform单透镜聚焦性能的影响. 结果表明, 孔径为1 mm的Kinoform单透镜对30 keV的X射线聚焦, 可以得到14 nm焦斑、62 μm焦深, 且可实现4个量级的光强增益和大于30%的光强透过率. 相似文献
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通过采用二极铁之间色散函数的相空间匹配所带来的约束条件,从而无需依赖具体的磁聚焦结构,利用Mathematica软件进行计算,得到了在三块二极铁弯转半径相等情况下,两种应用普遍的三块弯铁消色散(TBA)磁聚焦结构的最小发射度所对应的最小结构比例参数。得到了在TBA结构三块二极铁长度及弯转半径任意的情况下,TBA结构能取得的最小结构比例参数,以及TBA结构中三块二极铁长度及弯转半径所要满足的关系。由于计算中无需考虑具体的磁聚焦结构,得到的理论结果及其分析过程具有较强的通用性。 相似文献
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基于麦克斯韦方程组在不同坐标系下具有形式不变性以及变换光学理论, 通过设计材料的本构参数(介电常数和磁导率)来引导电磁波的传播, 提出了具有电磁透明和电磁聚集两种功能的新型电磁器件-椭圆形透明聚集器的设计方法. 电磁波透明体不会阻挡电磁波的传播并且能够与斗篷内部进行交互; 电磁波聚集器是当电磁波入射到该装置上时, 电磁波能够被设计的装置按照要求集中到一个区域或者一个点, 实现电磁波能量的集中. 本文利用压缩变换和扩展变换推导出了这种电磁器件中各层的相对介电常数和相对磁导率的张量表达式, 并利用基于有限元算法的电磁仿真软件对该电磁器件进行了全波仿真验证, 得到了入射波从各个不同方向入射时磁场z 分量的分布图, 仿真结果证实了该设计方法和电磁参数的正确性. 最后还讨论了电磁器件存在损耗时的情况, 当损耗逐渐增大时, 器件的功能在一定程度上受到了削弱. 本文的设计方法为其他新型电磁器件的设计提供了一种新的思路. 相似文献
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作为一种高效的热能收集与俘获技术,热集中器最近引起了研究者的关注.本文从热传导方程和坐标变换关系出发,导出了圆柱形热集中器温度分布的解析表达式,并通过与COMSOL数值仿真结果比较证实了表达式的正确性.分析了热集中器性能与材料各向异性和器件几何结构二者之间的联系,结果表明,包层热超材料的各向异性越大,集中器的热集中性能越好;包层与内核的半径比越大,集中器的热聚焦能力越强.利用包层与背景媒质之间的温度关系,进一步研究了用常规材料实现热集中器的方法,通过将两种常见的天然材料沿角向按周期交替排列并调整各自面积的大小,可观察到不同程度热集中现象. 相似文献
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为有效提高空间太阳能聚光器的聚光效率,提出了一种用于太阳能热推进器的具有伞状龙骨结构的可折叠展开式抛物面太阳能聚光器设计方案,该方案可以克服充气展开式抛物面聚光器和刚性固定抛物面聚光器具有的技术难题。设计了一个聚光功率100 kW,开口圆半径4.9 m的可折叠展开式伞状龙骨结构正焦抛物面聚光器,利用Fluent软件,对太阳能热推进器进行了模拟和性能预示,以氢气为工质气体,得到系统的推力和比冲可以分别到达10.23 N和701.4 s。结果表明:这种推进器具有比冲高、推力适中的特点,可以用于微小卫星、纳卫星的轨道转换及姿态控制。 相似文献
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Tokunaga Y Kaneko Y Okuyama D Ishiwata S Arima T Wakimoto S Kakurai K Taguchi Y Tokura Y 《Physical review letters》2010,105(25):257201
Magnetic and magnetoelectric (ME) properties have been studied for single crystals of Sc-doped M-type barium hexaferrites. Magnetization (M) and neutron diffraction measurements revealed that by tuning Sc concentration a longitudinal conical state is stabilized up to above room temperatures. ME measurements have shown that a transverse magnetic field (H) can induce electric polarization (P) at lower temperatures and that the spin helicity is nonvolatile and endurable up to near the conical magnetic transition temperature. It was also revealed that the response (reversal or retention) of the P vector upon the reversal of M varies with temperature. In turn, this feature allows us to control the relation between the spin helicity and the M vectors with H and temperature. 相似文献
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PbSe量子点在太阳能荧光聚集器中的应用研究 总被引:1,自引:0,他引:1
将PbSe量子点成功引入到了太阳能荧光聚集器(LSC)的应用中,利用光子追踪的方法,成功建立了一种基于Monte Carlo模拟方法的模型,通过实验测量,得到PbSe量子点相关数据, 在这些数据基础上,对PbSe量子点LSC的各个参数进行模拟优化,并在优化的条件下,对基于PbSe量子点LSC对太阳能电池单位输出能量造价进行考察,发现通过PbSe量子点LSC的引入,太阳能电池的造价可以降低49.2%,说明PbSe量子点非常适用于LSC体系。 相似文献
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A solar concentrator combining primary paraboloidal and secondary hyperboloidal mirrors is numerically designed by using the ray tracing method to obtain higher concentration ratio when the concentrator tracing error exists. It is found that, when the concentrator tracing errors are 0.5° or 1°, the concentration ratios are about 2027 or 1220 without the detector in the radial-direction, and the concentration ratios are about 5447 or 4701 with the detector in the radial-direction. It is shown that such method can increase the concentration solar flux by two folds when the concentrator tracing error exists. Obviously, it is an effective method to reduce the effect of concentrator tracing error even when the angle of concentrator tracing error is considered. In addition, when the angle of concentrator tracing error is small than 1°, a set of mirror shapes is suggested where the primary mirror has a f-number of 0.22 and the secondary mirror has a numerical aperture (NA) of 0.61. 相似文献
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The order parameter of the second order magnetic phase transition in Ho at 131 K has been measured in a magnetic field by neutron diffraction. It was expected that the applied field would change the number of components (n) of the order parameter from four to two. Such a change would be visible in the order parameter exponent β. However, in a field of 40 kOe, β is found to be 0.38 ± 0.02, in agreement with the zero field measurement and with an n = 4 model and in contradiction to an n = 2 model. 相似文献
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Wang YR Zhang H Zhang SY Fan L Sun HX 《The Journal of the Acoustical Society of America》2012,131(2):EL150-EL155
A two-dimensional cylindrical acoustic concentrator is designed with multilayered alternative homogeneous materials, which can focus acoustic field and enhance acoustic energy in a given area. The frequency response analysis of the acoustic concentrator demonstrates that the acoustic energy can be concentrated within the device over a wide frequency band. Meanwhile, there are contradictory relations between the acoustic concentrating performances in the inner region and the scattering properties in the outer region of these concentrators. When the contradictory relations satisfy compromise balance, the concentration ratio can reach at least 70%. 相似文献
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V. K. Aswal J. V. Joshi P. S. Goyal Rajesh Patel R. V. Upadhyay R. V. Mehta 《Pramana》2004,63(2):285-290
Small-angle neutron scattering studies have been carried out to check the structural integrity of citryltrimethylammonium
bromide (CTABr) micelles in a magnetic fluid for different magnetic fluid concentrations at two different temperatures 303
and 333 K. It is found that the CTABr micelles grow with increasing magnetic fluid concentration and there is a decrease in
the micellar size with increase in temperature. 相似文献
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Abbasher M. Gismelseed H. Widatallah A. D. Al-Rawas I. Al-Omari M. Elzain A. Yousif 《Hyperfine Interactions》2008,184(1-3):105-110
Magnesium-substituted nickel–chrome ferrites have been studied using X-ray diffraction and Mössbauer spectroscopy. A single cubic spinel phase was obtained in the range 0.0?≤?x?≤?0.4. The lattice parameter was found to decrease with the increase of Mg concentration. The Mössbauer spectra measured at 295 and 78 K of all samples showed magnetic patterns interpreted in term of the tetrahedral and octahedral sites occupancies. The magnetic hyperfine field of both sites decrease with the increase of the Mg concentration. The magnetic properties as a function of the Mg concentration have been explained on the basis of the cation distribution among the two crystallographic sites driven from the Mössbauer measurements. 相似文献