空间电荷效应对热场致发射中诺廷汉效应的影响

热场致发射阴极所产生的强流电子束具有很强的空间电荷效应,为研究该效应对热场致发射过程中诺廷汉（Nottingham）效应的影响机理,在理论分析的基础上,用数值方法研究了不同逸出功和多个外加电场条件下考虑空间电荷效应对诺廷汉效应结果的影响,并与不考虑空间电荷效应时的情形进行了对比. 结果表明：空间电荷效应的强弱会显著影响到阴极表面的稳态电场,进而对诺廷汉效应产生不可忽略的影响;当逸出功在3.0–4.52 eV、外加电场在3×10⁹–9×10⁹ V/m范围内时,考虑空间电荷效应的影响后,热场致发射电子所带走的平均能量较不考虑空间电荷效应时增加0–2.5 eV,且温度越高或外加电场越大时,该增加值越大;考虑空间电荷效应对诺廷汉效应的影响后,热场致发射电子从阴极带走的平均能量随外加电场的增加呈非线性下降规律;当阴极表面温度较高时,诺廷汉效应中的冷却效应随二极管间隙距离的变大而增强. 关键词： 热场致发射 诺廷汉效应 空间电荷效应 阴极表面电场     

共形转塔气动光学效应时空特性研究

研究了相同马赫数、相近雷诺数、不同口径(400 mm和2 000 mm)共形转塔的气动光学效应, 系统地给出了发射方向不同时气动光学效应导致的光束倾斜角和光束质量因子的时间变化特性、统计特性以及时间相关特性。发现多数场景下气动光学效应中平均流场效应占主要部分, 平均流场效应的特征频率由绕流流场的特征频率决定。尺寸效应的研究表明,缩比实验可以有效模拟实际飞行状态下气动光学效应的统计特性, 但无法准确模拟其时间相关特性。开展了前向发射时发射方向的优化选择, 指出发射方向在中轴线上天顶角约为40°时, 气动光学效应导致的波前畸变统计值和涨落值最小, 并且发射光束半径增加会导致平均流场效应快速增加, 但湍流效应基本不变。     

尾波场与相对论效应对激光脉冲自相位调制及频移影响的比较研究

对共振和非共振情形下尾波场效应与相对论效应对强激光脉冲在稀薄等离子体中传输的影响 作了详细比较.尾波场效应导致脉冲自相位调制的不对称性，其大小与初始脉冲形状和脉宽 大小有关.在长脉冲极限下，尾波场效应远小于相对论效应，从而可以忽略；在短脉冲极限 下，尾波场效应可以抵消相对论效应.在共振情况下，尾波场效应导致脉冲内大部分光子减 速. 关键词： 脉冲传输 等离子体 相对论效应 尾波场效应 自相位调制     

探测激光入射角对猫眼效应反射特性的影响

 光电装备的光学窗口对入射激光有较强的反射特性，即猫眼效应现象。为了研究利用猫眼效应来进行主动探测的适用条件，弄清探测激光入射角对猫眼效应反射特性的影响，建立了斜入射猫眼效应反射模型，分析并仿真了探测激光在目标系统处的入射角不同的情况下的后向反射激光特性，以及探测系统所能够接收的原路返回激光的远场能量分布情况。结果表明：对于特定的目标系统，猫眼效应现象只存在于一定的探测激光入射角范围之内，在此范围之内，猫眼效应反射特性与探测激光的入射角关系密切；基于猫眼效应的激光主动探测、定位等应用也是可行的。     

双极晶体管的系统电磁脉冲与剂量率综合效应

建立典型半导体器件系统电磁脉冲与剂量率综合效应计算模型,对在瞬态X射线辐照下电缆末端典型n+-p-n-n+结构的双极晶体管负载的系统电磁脉冲与剂量率综合效应进行研究,得到了综合效应现象,分析了综合效应机理,总结了综合效应规律。在系统电磁脉冲与剂量率综合效应作用下,双极晶体管内部,由于载流子数量剧增,其反向击穿阈值降低,综合效应比单一效应更易造成双极晶体管的毁伤。编制的系统电磁脉冲与剂量率综合效应计算程序可用于分析电子学系统中其他类型半导体器件的效应机理与规律。     

分层视角下无线通信网络高空电磁脉冲效应

从分层视角研究无线通信网络高空电磁脉冲效应,提出了一种具有层级属性的网络级效应评估方法。设计研制了一种无线通信网络效应试验仿真平台,网络使用典型全连通拓扑结构,网络节点使用超外差式收发机,网络运行在超短波频段。开展了小型网络脉冲辐照效应试验和效应机理分析,网络仿真研究了网络规模不同条件下节点失效概率对网络性能的影响。得到以下结论:（1）设备级效应对低层级效应具备一定冗余容错能力,这取决于效应评价指标的选择和损伤组件的功能属性;（2）网络级效应对设备级效应具有潜在放大效果,个别节点失效可能造成网络性能严重下降甚至瘫痪。     

高功率脉冲光隔离器非线性及热效应分析

从理论上分析了脉冲情况下,磁光晶体横向温度梯度引起的光弹效应、消光比以及克尔效应对光隔离器隔离度的影响,并与连续入射情况进行了对比。结果表明:在平均功率相同的情况下,脉冲光束入射比连续光束入射情况隔离度更低;当平均功率较小时,消光比对隔离度的影响较大;当平均功率较大时,消光比对隔离度的影响有限,主要表现出光弹效应对隔离度的影响;当峰值功率密度较大时,克尔效应将显著降低隔离度,并且峰值功率密度越大,对隔离度的降低程度越大。     

Linking the Dynamical Casimir Effect to the Collective Excitation Effect at Finite Temperature

Thermal effects on the dynamical Casimir effect and the collective excitation effect are investigated in a resonantly vibrating cavity filled with an ensemble of two-level atoms. The results show that the moving mirror of the cavity results in the dynamical Casimir effect and the collective excitation effect of the two-level atoms,and the finite temperature enhances the number of created photons and created excitons by several orders of magnitude. The relevance experiments of the finite-temperature effects for the dynamical Casimir effect and the collective excitation effect are addressed.     

Impact of Colored Noise on Population Model with Allee Effect

We study a population model with strong and weak Allee effect driven by internal noise and external noise.Firstly, a single-species population model with Allee effect under environmental colored noise is established, then stable and unstable states are analyzed and interpreted in biology. After that, stationary probability distribution(SPD) of population is derived based on Fokker-Planck equation. Next, mean first-passage time(MFPT) is defined in order to quantify the transition between extinction state and survival state with Allee effect. It is found that population will not extinct when weak Allee effect exists. It is not beneficial to survival of the population with the increase of Allee threshold no matter whether strong Allee effect or weak Allee effect. When strong Allee effect occurs, the correlation time of multiplicative noise plays a positive role in survival of population, while the correlation time of additive noise has a negative effect. Crucially, the phenomenon of resonant activation is firstly discovered in population dynamics with Allee effect. The conclusions we obtain can be applied to the further research of population dynamics in ecology.     

光自旋霍尔效应中的交叉偏振特性研究

从光束角谱理论出发建立了描述光自旋霍尔效应的傍轴传输模型, 利用这一模型分析了光自旋霍尔效应中的交叉偏振特性. 通过分析交叉偏振效应强度和入射角变化的规律, 发现交叉偏振效应越强, 光自旋霍尔效应中的自旋分裂越大. 为便于实验观察, 将入射角选在光自旋霍尔效应较强的布儒斯特角附近, 观测到了强的交叉偏振效应. 增大交叉偏振分量的同时减小初始偏振分量, 可显著增强光自旋霍尔效应. 这一调控方法为研制基于光自旋霍尔效应的新型光子器件提供了理论基础.     

Orbitronics: the intrinsic orbital current in p-doped silicon

The spin Hall effect depends crucially on the intrinsic spin-orbit coupling of the energy band. Because of the smaller spin-orbit coupling in silicon, the spin Hall effect is expected to be much reduced. We show that an electric field in p-doped silicon can induce a dissipationless orbital current in a fashion reminiscent of the spin Hall effect. The vertex correction from impurity scattering vanishes and the effect is robust against disorder. The orbital Hall effect leads to accumulation of local orbital momentum at the edge of the sample, and can be detected by the Kerr effect.     

Effect of the motion of particles on the Mössbauer effect in small iron particles

A large effect is observed of the motion of particles on the Mössbauer effect in small iron particles (100 and 1000 Å average diameter). This effect is explained in a classical theory of the Mössbauer effect.     

Phenomena of optic-bound effect on fibre optic gyro

The optic-bound effect on fibre optic gyro (FOG) precision is analysed theoretically, and formulas describing the change of FOG light power under the action of optic-bound effect are given. It is confirmed that optic-bound effect is a main instantaneous non-reciprocity effect of FOG in addition to the Sagnac effect and can lead to a dynamic error of FOG in practical environments. An approach to suppressing or eliminating the error due to the optic-bound effect is presented and verified experimentally. The result shows that the approach is valid and the precision of FOG is improved observably.     

Spin Nernst effect in the absence of a magnetic field

We study the spin Nernst effect of a mesoscopic four-terminal cross-bar device with the Rashba spin–orbit interaction (SOI) in the absence of a magnetic field. The interplay between the spin Nernst effect and the seebeck coefficient is investigated for a wide range of the Rashba SOI. When no peaks appeared in the seebeck coefficient, an oscillatory spin Nernst effect still occurs. In addition, the disorder effect on the spin Nernst effect is also studied. We find that the spin Nernst effect can be enhanced up to threefold by disorder. Besides, due to the interface effect, the counter propagating of the charge current to the direction of the temperature gradient is possible for a nonuniform system.     

Anomalous acoustoelectric effect in La0.67Ca0.33MnO3 films

We have studied the acoustoelectric (AE) effect produced by surface acoustic waves (SAW) in a monolithic layered structure, composed of a piezodielectric LiNbO3 substrate and a La0.67Ca0.33MnO3 film. The experiments unexpectedly revealed in the longitudinal AE effect an anomalous contribution, invariant upon reversal of SAW propagation, which coexists with the ordinary (odd in wave vector) effect. The anomalous effect dominates near the metal-insulator transition, while the ordinary effect prevails at high and low temperatures. We show that the anomalous effect is caused by strong modulation of the film conductivity produced by the SAW elastic deformations.     

光在一维光子晶体中的全反射贯穿效应

为了研究一维光子晶体中光波的全反射贯穿效应,利用传输矩阵法计算了TE波和TM波在大于全反射角入射一维光子晶体的透射率.在透射波中发现了全反射贯穿效应,得出了全反射贯穿效应随入射角的变化规律、全反射贯穿效应的波长特性以及全反射贯穿效应随介质光学厚度的变化规律.利用波的量子理论和渐逝波的理论对一维光子晶体的全反射贯穿效应作出了理论解释.     

Coupled flexural-torsional vibration band gap in periodic beam including warping effect

The propagation of coupled flexural-torsional vibration in the periodic beam including warping effect is investigated with the transfer matrix theory. The band structures of the periodic beam, both including warping effect and ignoring warping effect, are obtained. The frequency response function of the finite periodic beams is simulated with finite element method, which shows large vibration attenuation in the frequency range of the gap as expected. The effect of warping stiffness on the band structure is studied and it is concluded that substantial error can be produced in high frequency range if the effect is ignored. The result including warping effect agrees quite well with the simulated result.     

Ag掺杂熔融织构YBCO峰效应研究

本文对Ag掺杂熔融织构YBCO材料的峰效应进行了研究.磁测量结果表明,Ag掺杂不会影响峰效应的产生,但能显著改变峰效应对温度和磁场的依赖关系;峰效应出现的磁场随Ag掺杂量的增加而增高,且适量的Ag掺杂使得高温下仍能出现峰效应.该研究表明,Ag掺杂可以作为显著提高熔融织构YBCO材料磁场下临界电流密度的有效手段,从而可使其在高场下的性能得以显著改善.     

The becquerel effect

It is shown that the Becquerel effect (the photogalvanic effect) consists of an effect analogous to the Dember effect in semiconductors combined with the appearance of a photo-emf, accompanied by a photoadsorption effect at the electrode surfaces.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 8, pp. 104–107, August, 1969.     

Slow light and slow current

It is shown that the effect of hole-burning under conditions of coherent population oscillations as well as the light pulse delay in a saturable absorber (a modification of the so-called slow light effect) can be interpreted, in a comprehensive way, in terms of the intensity spectrum of the light and intensity-related susceptibility of the medium. The physical content of these effects is illustrated by a simple electric circuit with a non-linear resistor which realizes a full analog of the saturable absorber. In this case the effect of hole-burning in the absorption spectrum of the medium is converted into the effect of hole-burning in the frequency dependence of resistance of the resistor and the effect of slow light into the effect of slow current.