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从半径渐变波导的耦合波方程出发,利用龙格-库塔法进行优化数值迭代,得到在3 mm波段,TE03-TE02, TE02-TE01高效率模式变换器的设计参数。通过优化程序,设计出了6周期TE03-TE02和3周期TE02-TE01模式变换器优化尺寸。利用CST微波工作室电磁仿真软件对结构尺寸进行优化仿真,仿真结果与优化程序计算结果基本一致。以此数据设计中心频率94 GHz的TE03-TE02,TE02-TE01模式变换器功率转换效率可以达到98.5%以上,90%功率转换的绝对带宽分别达到3.5和7.0 GHz以上,优于设计要求。 相似文献
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Clover detector has been used as a Compton polarimeter to measure the linear polarization of γ-rays produced in heavy ion
fusion reaction. The polarization sensitivity of the clover detector has been measured over γ-ray energies ranging from 386
to 1368 ke V. The E1 multipolarity of the 1117 keV transition in 99Rh has been established using this polarimeter. This has resulted in the assignment of negative parity to the band head at
3710 keV in 99Rh. 相似文献
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O. Brodier T. Neicu A. Kudrolli 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,23(3):365-372
We report a numerical study of the flexural modes of a plate using semi-classical analysis developed in the context of quantum
systems. We first introduce the Clover billiard as a paradigm for a system inside which rays exhibit stable and chaotic trajectories.
The resulting phase space explored by the ray trajectories is illustrated using the Poincare surface of section, and shows
that it has both integrable and chaotic regions. Examples of the stable and the unstable periodic orbits in the geometry are
presented. We numerically solve the biharmonic equation for the flexural vibrations of the Clover shaped plate with clamped
boundary conditions. The first few hundred eigenvalues and the eigenfunctions are obtained using a boundary elements method.
The Fourier transform of the eigenvalues show strong peaks which correspond to ray periodic orbits. However, the peaks corresponding
to the shortest stable periodic orbits are not stronger than the peaks associated with unstable periodic orbits. We also perform
statistics on the obtained eigenvalues and the eigenfunctions. The eigenvalue spacing distribution P(s) shows a strong peak and therefore deviates from both the Poisson and the Wigner distribution of random matrix theory at
small spacings because of the C4v symmetry of the Clover geometry. The density distribution of the eigenfunctions is observed to agree with the Porter-Thomas
distribution of random matrix theory.
Received 12 February 2001 and Received in final form 17 April 2001 相似文献
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基于金属包覆磁性波导结构的磁光Bragg器件特性分析 总被引:1,自引:0,他引:1
使用金属包覆磁性波导中的磁光耦合理论分析了静磁表面波与导波光在金属/电介质/钇铁石榴石/钆镓石榴石结构中的磁光共线作用,讨论了金属覆层和斜向场对磁光模式转换效率的影响。计算表明,金属包覆波导可以提高磁光作用,通过调节金属覆层与磁性薄膜间距得到了比空气/4a铁石榴石/钆镓石榴石的传统三明治波导情形高8.7dB的模式转换效率;而同时优化偏置磁场方向和金属包覆波导参数,模式转换效率可以进一步提高5.25dB。因此,金属包覆波导可以用于提高磁光Bragg器件性能,在微波和光信息处理等方面具有广阔的应用前蒂。 相似文献
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I. Abt A. Caldwell K. Kröninger J. Liu X. Liu B. Majorovits 《The European Physical Journal A - Hadrons and Nuclei》2008,36(2):139-149
The GERmanium Detector Array (GERDA) is designed for the search for “neutrinoless double-beta decay” ( 0ν2β with germanium
detectors enriched in 76Ge . An 18-fold-segmented prototype detector for GERDA Phase II was exposed to an AmBe neutron source to improve the understanding
of neutron-induced backgrounds. Neutron interactions with the germanium isotopes themselves and in the surrounding materials
were studied. Segment information is used to identify neutron-induced peaks in the recorded energy spectra. The Geant4-based
simulation package MaGe is used to simulate the experiment. Though many photon peaks from germanium isotopes excited by neutrons
are correctly described by Geant4, some physics processes were identified as being incorrectly treated or even missing. 相似文献
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A molecular far-infrared (FIR) laser optically pumped by a high-power CO2 laser, which is a powerful source for testing detectors and mixers and for FIR spectroscopy, is constructed and the performance is examined through experiments. At frequencies between 580GHz and 4.25THz, FIR output power is more than 2030m W by pumping power of 3581W. Amplitude stability of ±3% is obtained at 100m W output at 2.52THz for over 30 minutes when the FIR tube is cooled at 5°C by a chiller.As an application to testing mixers, FIR laser lines up to 4.25 THz are detected by Schottky barrier diodes (SBD). Further, using a SBD, performance of absolute frequency stability at 693GHz of HCOOH oscillation is measured by harmonic mixing with a 115.5GHz millimeter wave from a phase-locked Gunn oscillator. The resultant center-frequency stability is 100kHz per 10 minutes. 相似文献
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透射光栅衍射率的实验标定和数值计算 总被引:6,自引:0,他引:6
简要介绍了实验室中使用的三种透射光栅的结构,在北京同步辐射源上实验标定了这些光栅的相对衍射效率。借助于光栅模型,得到了光栅的重要结构参数,并对光栅的绝对衍射效率进行模拟计算和讨论。 相似文献
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Coexisting hidden attractors in a 4D segmented disc dynamo with one stable equilibrium or a line equilibrium 下载免费PDF全文
This paper introduces a four-dimensional(4D) segmented disc dynamo which possesses coexisting hidden attractors with one stable equilibrium or a line equilibrium when parameters vary. In addition, by choosing an appropriate bifurcation parameter, the paper proves that Hopf bifurcation and pitchfork bifurcation occur in the system. The ultimate bound is also estimated. Some numerical investigations are also exploited to demonstrate and visualize the corresponding theoretical results. 相似文献
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为研究808 nm和879 nm两种泵浦光对Nd:GdVO4晶体激光输出特性的影响,并比较两种不同波长泵浦所得连续输出光的效率高低,分析了Nd:GdVO4晶体的能级结构和两种泵浦光作用下的激光输出特性,发现在879 nm也有较强的吸收峰.用808 nm和879 nm两种不同波长泵浦Nd:GdVO4晶体的过程是不同的,808 nm泵浦是一种间接方式能量转移的过程,在此过程中有明显的热负载产生.而879 nm泵浦是将粒子直接激励到激光辐射上能级,降低无辐射弛豫过程产生的热量.从理论上可知,879 nm的泵浦量子效率要高于808 nm的泵浦量子效率,对减少晶体的热产生有很强的优势.实验中采用激光二极管端面泵浦Nd:GdVO4晶体直腔方案,研究了两种不同泵浦光泵浦Nd:GdVO4晶体以获得1 063 nm的连续光,得到了两种光抽运时的斜效率,发现在同样实验条件下,879 nm泵浦的输出光斜效率在小功率泵浦时略高于808 nm|而在大功率泵浦的情况下明显高于808 nm,最高达到38%.同时,在808 nm抽运时,实验上获得了1 341 nm波长的激光,为光通讯的应用提供了一种光源. 相似文献
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单光子探测器量子效率绝对自身标定方案 总被引:1,自引:0,他引:1
参考已有的方案,提出了一种更简单的方案来实现单光子探测器量子效率的绝对自身标定。我们利用同轴线缆和数据采集卡代替已有方案中的符合测量电路和计数器,通过精确设定同轴线缆的长度,利用电脉冲在同轴线缆的短路终端反射回波的特性,对一个测量周期中单个脉冲和连续两个脉冲进行区分,用数据采集卡记录区分结果,分别得到探测器探测到两个孪生光子的计数和仅探测到其中任意一个光子的计数,从而算出单光子探测器的量子效率。此方案不需要其他任何的参考标准或者另一个探测器. 相似文献
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WANG Hua-Lei SONG Li-Tao ZHAO Wei-Juan LIU Zhong-Xia ZHANG Yu-Hu ZHOU Xiao-Hong GUO Ying-Xiang LEI Xiang-Guo 《中国物理C(英文版)》2010,34(3)
The resolution and the summing characteristics of an EXOGAM segmented Clover germanium detector has been studied for use it in γ spectroscopic experiments. The measurements have been performed with standard radioactive sources of 152Eu, 133Ba and β-delayed γ-rays from 176Ir decay. The data analytic results, realized by software, are presented in this paper. 相似文献
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全带隙光子晶体中依赖原子位置的衰减动力学性质 总被引:2,自引:0,他引:2
介绍一个二能级原子在全带隙光子晶体带边附近的衰减动力学行为 .发现原子位置的变化会根本地改变激发原子的衰减特性 :由于光场和原子之间局域耦合强度的巨大差异 ,导致Weisskopf Wigner和非Weisskopf Wigner衰减现象 .预言可通过控制原子的位置来实现人工剪裁荧光光谱 相似文献
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The resolution and the summing characteristics of an EXOGAM segmented Clover germanium detector has been studied for use it in y spectroscopic experiments. The measurements have been performed with standard radioactive sources of ^152Eu, ^133Ba and β-delayed γ-rays from 176Ir decay. The data analytic results, realized by software, are presented in this paper. 相似文献
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利用喷雾热解法合成了Tm、Tb及Eu离子掺杂的铝酸钡(BaAl2O4)发光膜,研究了合成条件对其结构和发光特性的影响.在退火温度达到700℃时,生成了BaAl2O4膜.Tm3+和Tb3+掺杂的BaAl2O4膜分别发蓝光和绿光,而Eu3+掺杂的BaAl2O4膜的发光既有Eu2+的特征发射——宽的蓝光发射带,也有Eu3+的特征发射——窄的红光发射峰.BaAl2O4:Tm3+的发射主峰位于462nm,在电压为5kV和电流密度为57μA/cm2的条件下,其阴极射线发光(CL)亮度可达25cd/m2,效率可达0.11lm/W.BaAl2O4:Tb3+的发射主峰位于549nm,在相同的条件下,其阴极射线发光亮度可达120cd/m2,效率可达0.55lm/W.BaAl2O4:Eu3+的发射主峰位于616nm,其阴极射线发光亮度为50cd/m2,效率为0.23lm/W.BaAl2O4:Eu2+发蓝光,峰值位于452nm,其阴极射线发光亮度为640cd/m2,效率为2.93lm/W. 相似文献
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主要研究了如何利用飞秒激光测量绝对长度。解析和数值计算结果显示当飞秒激光通过理想的法布里一珀罗干涉仪时,利用干涉仪透射最大值可以实现绝对标准长度的测量。据此提出了标准频率与绝对长度一一对应的标准。 相似文献