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强外加电场与大调制度下光折变动力学光栅形成研究 总被引:1,自引:0,他引:1
强外加电场与大调制度在光折变效应的研究中已经得到了广泛应用。采用PDECOL算法,严格求解光折变带输运方程,得到外加电场时不同调制度下光折变晶体中随时间变化的空间电荷场、载流子浓度,并讨论了外加电场对它们的影响。通过将物质方程与耦合波方程联立数值求解,可得到光折变光栅形成过程中两波耦合增益系数以及光束条纹相位的变化。模拟结果表明,在强外加电场作用下,两束记录光之间的光强与相位耦合都得到了增强,而原有的解析式忽视了强外加电场与大调制度对空间电荷场相位耦合的影响,此时不再适用。同时发现折射率光栅与记录光束条纹均发生弯曲,并不再保持平行。 相似文献
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外加电场对光折变高阶响应影响的微扰分析 总被引:2,自引:2,他引:0
应用微扰展开法了“跳跃模型”给出了空间电荷场前三阶分量随时间,外加电场等变化的解析表达式,同时讨论了外加电场对各阶空间电荷场建立的影响,当扩散与外加电场可比拟时,外加电场对空间电荷场的影响不大,随着空间电荷场阶数的提高,其达到最大饱和值所需的外加电磁越小,在外加电场作用下,空间电荷场各阶分量随时间呈振荡衰减,直到达到饱和,外加是场越大,振荡越强烈,周期越短,在考虑高阶分量的贡献后,空间电荷场的振荡 相似文献
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Q有机聚合物材料中光生载流子传输的跳跃输运 总被引:3,自引:3,他引:0
本文描述了跳跃模型在有机聚合物光折变材料中空间电荷场理论上的应用.在Feinberg针对无机光折变晶体提出的电荷传输过程模型-跳跃模型(Hopping Model)基础上,根据有机聚合物光折变材料的特点,考虑了光生载流子产生过程中的电子空穴对的复合过程(对复合和双分子复合过程)和激发光场的频率(即激发光子的能量)对光生载流子产生的影响,给出了有机聚合物材料中光生载流子产生的量子效率和光生载流子的分布密度及其跳跃率的新表示,完成外加调制光场和静电场同时作用下有机聚合物材料中光生载流子传输的跳跃方程,得到空间电荷场建立的动态过程和稳态时的解析表达式及其数值计算结果. 相似文献
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在强电场条件下,由阴极通过场致发射产生的电子具有很强的空间电荷效应,因此真空二极管的空间电荷限制电流是设计高功率微波源等强流电子束器件时需要考虑的重要参数.场致发射电流密度只和阴极材料、阴极表面电场等有关,而空间电荷效应则会受二极管电压、间隙距离等因素的影响.为研究二极管间隙距离对场致发射过程中空间电荷效应的影响,建立了由场致发射阴极构成的一维平板真空二极管物理模型,利用第一性原理的粒子模拟方法,研究了二极管间隙距离和外加电压等参数变化时的阴极表面电场随时间的演变特性,得到了阴极表面稳态电场和二极管间隙距离之间的关系.结果表明,场致发射过程开始后,阴极表面电场先有个振荡过程,随后趋于稳定;在同一外加电场条件下,间隙距离越长,稳态电场的绝对值越小,且达到稳态所需的时间也越长;间隙距离越短,当阴极表面电场达到稳定状态时,二极管间隙区的电场分布变化越剧烈. 相似文献
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根据适用于光折变聚合物系统的空间电荷场形成的动力学微分方程,将陷阱情况分为四类,分别讨论了光折变聚合物中光生载流子的量子产生效率及其迁移率对空间电荷场的稳态和动态特性的影响.结果发现空间电荷场的稳态特性相对于光生载流子的量子产生效率的变化比较敏感,而空间电荷场的动态特性则易受到载流子的迁移变化的影响. 相似文献
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《Journal of Electrostatics》2014,72(4):252-260
In this paper, space charge dynamics under DC electric field of −100 kV/mm in low-density polyethylene (LDPE) and its nanocomposite containing a small amount of MgO nanoparticles were measured using an improved pulsed electro-acoustic (PEA) system. Unlike negative packet-like space charge accumulating in LDPE films, no remarkable space charge was observed in LDPE/MgO nanocomposite films, which indicated that the introduction of MgO nanoparticles played a key role on the space charge suppression. Different with current qualitative models, this paper describes space charge suppression on the basis of simulation using the bipolar charge transport model, which featured bipolar charges injection, transport, trapping, recombination, and extraction process. It was shown from the simulation that trap depth, trap concentration, local electric field and charge injection barrier height were all significant factors on the space charge suppression process. A deeper trap depth in LDPE/MgO nanocomposites made it easier for traps to capture mobile carriers. And a larger trap concentration effectively slowed down the whole carrier movement although there seemed a trap concentration threshold less than 30 Cm−3, above which this effect became slight. In addition, both the high permittivity of LDPE/MgO nanocomposites and low local electric field in the vicinity of cathode led to a larger injection barrier height based on the Schottky injection law, which would tremendously block the charge injection. At last, the suppression mechanism of space charge formation in the LDPE/MgO nanocomposites is presented. 相似文献
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An analytical solution to the problem of the ion velocity distribution evolution after turn-on of a periodic electric field is derived. The solution is constructed for the case of resonance charge exchange at a constant collision frequency (charge exchange model). The specific features of the transient process at the early stage of evolution are revealed. The phase shift between the applied field and the ion current at the periodic stage of the process is analyzed. The distribution function exhibits abrupt steps propagating in the velocity space. A method is proposed to study the ion-atom interaction cross section using a periodic electric field. The method is based on analysis of the current toward the electrode with a retarding potential. 相似文献
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Self-deflection of bright soliton in a separate bright-dark screening soliton pair based on higher-order space charge field 总被引:1,自引:0,他引:1
Based on the interaction of the separate soliton pair, the self-deflection of the bright screening soliton in a bright-dark pair is studied by taking the higher order space charge field into account. Both numerical and analytical methods are adopted to obtain the result that the higher order of space charge field can enhance the deflection process of the bright soliton and varying the peak intensity of the dark soliton can influence the self-deflection strongly. The expression of the deflection distance with the dark soliton's peak intensity is derived, and some corresponding properties of the self-deflection process are figured out. 相似文献
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V. G. Pavlov 《Technical Physics》2004,49(12):1610-1616
It is shown that the conventional technique of substituting the field strength at the space charge-emitter interface that
is calculated with the Poisson equation into the Fowler-Nordheim formula considerably overestimates the effect of space charge
on field electron emission. In this work, the space-charge-induced field attenuation as a function of the emission current
density and radius of curvature of the emitter surface is derived using the model of a planar space-charge layer. It is argued
that field electron emission cannot be studied in terms of the spherical diode model, since it assumes the presence of a space
charge on the back (nonemitting) emitter surface, which is in fact absent. It is stated that one should consider the discrete
character of the charges when investigating the space charge in field electron emission, because the mean spacing between
the electrons emitted far exceeds the emission barrier width. 相似文献
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P. K. Anastasovski T. E. Bearden C. Ciubotariu W. T. Coffey L. B. Crowell G. J. Evans M. W. Evans R. Flower S. Jeffers A. Labounsky B. Lehnert M. Mészáros P. R. Molnár J. P. Vigier S. Roy 《Foundations of Physics Letters》2000,13(2):179-184
It is shown that the Lehnert field equations in vacuum, with concomitant space charge and current, can be derived straightforwardly from standard gauge theory applied in vacuum, using the concept of covariant derivative and Feynman's universal influence. The Lehnert and Proca field equations are shown to be inter-related through the well-known de Broglie theorem, in which the photon mass can be interpreted as finite. These ideas go some way towards addressing the inconsistency inherent in Maxwell's famous displacement current, which has no concomitant vacuum space charge. 相似文献
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低密度聚乙烯材料中的空间电荷包现象通常会引起严重电场畸变而影响其击穿特性. 本文借鉴半导体中的耿氏效应的负微分迁移率机理来描述电荷包的形成机理,并结合载流子的注入条件及体内陷阱对电荷迁移的影响等因素,对文献中报道的两类外加场强不同且迁移趋势各异的空间电荷包行为进行了模拟仿真,模拟的电荷包大小随电场变化规律,电荷包迁移速率随时间变化规律等与相应实验结果符合.模拟结果表明,产生耿氏效应的负微分迁移率是造成电荷包非弥散传输的主要原因,其与材料电极注入情况及体内陷阱态的共同作用导致了空间电荷包行为迁移的多样性.
关键词:
空间电荷包
耿氏效应
模拟仿真
负微分迁移率 相似文献
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Yuanxiang Zhou Yunshan Wang Guangfan Li Ninghua Wang Yingyan Liu Bo Li Peng Li Huanchao Cheng 《Journal of Electrostatics》2009,67(2-3):417-421
The wide use of high voltage direct current (HVDC) equipments, such as convert transformer, DC bushing, DC cables, makes the research of oil-paper material insulation extraordinarily important. The space charge effect is the key insulation problem of HVDC equipments. This paper studied the space charge characteristics of oil-paper insulation materials by Pulsed Electro-Acoustic (PEA) method. In this paper, we studied and discussed the relationship between space charge and breakdown in oil-paper. The results show that the space charge comes from ionization at lower field intensity. When the stress is getting higher, injection of homo carriers occurs first at cathode and later at anode. The space charge inside oil-paper sample results in an electrical field distortion up to 40%. The conductivity of oil-paper insulation material is much larger than that of polyethylene, so the space charge dissipates fast when depolarized. The fast dissipation of space charge will play a key role of oil-paper insulating performance in condition of polarity reversal under HVDC. When the applied negative electrical field rose to between 50 kV/mm and 57 kV/mm, the oil-paper material got breakdown in a short time. During this process, an obvious movement of space charge was observed. 相似文献
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M. N. Levin E. N. Bormontov O. V. Volkov S. S. Ostroukhov A. V. Tatarintsev 《Technical Physics》2001,46(3):316-321
The field dependence of photoemission currents in a MIS structure was derived for the case when the space charge is randomly
distributed over the insulating layer. It was found analytically that the position of the top of the potential barrier for
electrons photoinjected from the gate into the insulator is defined by the derivative of this barrier with respect to the
external field strength. A method for correctly determining the space charge profile in a MIS insulator is suggested. The
profile is derived from a family of spectral characteristics taken at different gate voltages. The method is especially suitable
for profiling the negative charge in MIS insulators. 相似文献