共查询到20条相似文献,搜索用时 156 毫秒
1.
利用二维三角格子金属光子带隙谐振腔代替回旋管的传统柱形谐振腔,并对腔体进行了TE波模式的计算与分析.综合考虑腔体内外的结构特征,给出了光子带隙谐振腔冷腔模式理论的研究方法,发现腔内存在单模工作的可能与条件以及非角对称情况下的电磁模式分布特征.研究结果表明,利用光子带隙谐振腔代替回旋管的传统腔体,可使回旋管在不受腔体横向尺度限制的条件下实现单模工作.这对于提高回旋管的功率容量、有效实现高次单模与高次回旋谐波耦合条件下的注-波互作用、降低工作磁场并从物理上根本改变回旋管的工作状态提供了理论依据.
关键词:
回旋管
金属光子带隙
谐振腔 相似文献
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回旋管是最有希望应用于正在实施的国际热核实验反应堆计划的微波源器件,然而研究设计符合要求的回旋管还存在很多困难需要解决.对170 GHz兆瓦级光滑同轴回旋管的注-波互作用进行了研究.选取模式谱相对稀疏的TE31,12作为工作模式,利用Matlab编制源程序,计算了同轴回旋管的注-波耦合系数、起振电流.在考虑电子速度零散、腔壁电阻率和单模近似的基础上,对光滑同轴谐振腔的优化设计和注-波互作用进行了仿真,给出了磁场、电压、电流和内导体倾角等参量与回旋管效率的关系.结果表明,电压和磁场对回旋管效率影响较大,电子速度零散对回旋管效率影响较小,因而可降低电子枪的设计要求.此外,优化内导体倾角和同轴谐振腔结构参数可提高注-波互作用效率,降低电子速度零散对互作用效率的影响,获得了约50%的电子效率及1.7 MW输出功率. 相似文献
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定义了光子带隙谐振腔(photonic-band-gap cavity, PBGC)的等效半径,论证了使用该半径将PBGC等效为具有模式选择性的金属圆柱谐振腔的有效性,揭示了其在PBGC设计过程中的指导性作用.基于等效半径的运用,建立起光子带隙谐振腔回旋管振荡器(PBG回旋管)的自洽非线性理论,并对工作于TE32模的PBG回旋管作了理论分析和数值计算.目前的研究表明:高频电磁场沿角向呈行波或驻波的不同极化形式对PBG回旋管的注-波互作用过程具有较大的影响;较之电子回旋基波,该器件中二
关键词:
光子带隙谐振腔
等效半径
回旋管
自洽非线性理论 相似文献
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准光共焦波导具有功率容量大、模式密度低的特点,能够有效地减少模式竞争对回旋管互作用的影响,有利于高次谐波太赫兹回旋管的设计.为提高太赫兹准光回旋管的互作用效率,在共焦柱面波导的基础上,研究了一种新型高频互作用结构——双共焦波导结构,设计了一种330 GHz二次谐波双共焦结构回旋管谐振腔并对其进行了理论分析和粒子模拟.研究结果表明,双共焦谐振腔中的高阶模式能够与高次电子回旋谐波发生稳定的相互作用,并且没有模式竞争现象,具备工作在太赫兹波段的潜力.相比普通共焦波导谐振腔,双共焦谐振腔能够增强准光回旋管的注波互作用强度,提高回旋管的输出功率和工作效率.此外,结果还表明双共焦波导中的电磁波模式是一种由两个独立的共焦波导模式叠加而成的混合模式.利用这种混合模式有望实现太赫兹回旋管的单注双频工作,为新型太赫兹辐射源的研究提供了新的途径. 相似文献
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分析了光子晶体谐振腔的模式选择功能,实现光子晶体谐振腔回旋管振荡器高阶电磁模与高次电子回旋模的有效耦合,并成功抑制了模式竞争。通过对光子晶体谐振腔禁带特性的分析,定出了工作模式为TE23模,还建立了光子晶体谐振腔回旋管的等效半径的概念,设计了自洽非线性理论和相关的计算机数值模拟程序。研究发现TE23模能有效地与电子的二次回旋谐波相互作用,其耦合频率为206 GHz,并极大地降低了对工作磁场的要求。在考虑诸多物理因素影响的情况下,对该二次谐波光子带隙谐振腔(PBGC)回旋管振荡器进行了参数优化,得到了电压40 kV、电流4.2 A、磁场3.925 T、输出功率35 kW、互作用效率21%的二次谐波TE23模PBGC回旋管振荡器。 相似文献
7.
以电子回旋脉塞非线性理论为基础, 结合三维电磁仿真软件, 通过导入高频场数值解替代理论解析的方法, 对波瓣波导谐振腔高次谐波太赫兹回旋管进行了理论和模拟研究. 给出了该类回旋管的起振电流、耦合系数以及注波互作用效率等重要参数, 并在此基础上设计了一只工作频率为0.4 THz, 工作模式TE33模三次谐波波瓣波导谐振腔回旋管, 其电子注参数为1.0 A, 40.5 kV, 横纵速度比1.5,互作用区引导磁场为5.09 T, 输出功率达到3.3 kW. 相似文献
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A theoretical evolutionary model for new nonlinear self‐gravitational fluctuations associated with the solar plasma system is developed. The lowest‐order inertial correction of the plasma thermal electrons is considered. We try to present our calculation scheme leading to the fluctuation patterns evolving as a new class of nonlinear coherent structures. It is demonstrated that they are mainly monotonous shock‐like eigenmodes governed by a unique type of driven Korteweg‐de Vries Burger (d ‐KdVB) equation obtained by multiscale analysis over the gravito‐electrostatic equilibrium structure equations. The self‐consistent new and unique nonlinear driving source here appears due to the inclusion of weak electron inertia. The d ‐KdVB system is studied analytically, graphically and numerically in detail to show the detailed features of the eigenmodes. Our conclusions are in good qualitative agreement with multispace satellite and imaging detections made by others. Main results significant to diverse solar, stellar and other astrophysical contexts along with future directions are summarily highlighted. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
12.
《中国光学快报(英文版)》2016,(3)
An improved model-based wavefront sensorless adaptive optics algorithm is proposed for laser beam cleanup.Deformable mirror(DM) eigenmodes are used to replace traditional Lukosz modes in order to avoid DM fitting errors. The traditional method is based on a sophisticated calibration process and solving linear equations. In our method, coefficients of DM eigenmodes are estimated by adding bidirectional modal biases into the system and then solving parabolic equations. The calibration process is omitted in our method, which makes it more feasible.From simulation and experimental results, the corrective accuracy of the improved method is higher than the traditional one. 相似文献
13.
R. Monasson 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,12(4):555-567
The spectral properties of the Laplacian operator on “small-world” lattices, that is mixtures of unidimensional chains and
random graphs structures are investigated numerically and analytically. A transfer matrix formalism including a self-consistent
potential à la Edwards is introduced. In the extended region of the spectrum, an effective medium calculation provides the density of states
and pseudo relations of dispersion for the eigenmodes in close agreement with the simulations. Localization effects, which
are due to connectivity fluctuations of the sites are shown to be quantitatively described by the single defect approximation
recently introduced for random graphs.
Received 23 March 1999 相似文献
14.
A systematic approach to the problem of dispersion interaction between small macroscopic crystals of various shapes is developed, based on the Hamiltonian describing the surface optical vibration eigenmodes of such crystals and their electrostatic interaction. Its diagonalization allows a systematic calculation of the interaction energy and eigenmodes of the coupled system. 相似文献
15.
提出了一种利用单个谐振腔测量直线加速器束团长度的新方法。不同于传统的双谐振腔束团长度监测器,该方法仅需要使用单个谐振腔,省去了用于辅助测量的参考腔,从而简化了装置结构,节省了空间。针对国家同步辐射实验室基于可调谐红外激光的能源化学研究大型实验装置进行了监测器的物理设计。通过设定同轴探针的插入位置,解决了双模信号互相干扰的问题,利用微扰金属改变调节工作频率,克服了双模难以同时谐振的困难。利用CST软件进行建模和仿真。仿真结果表明,该监测器可实现2~5 ps束团长度的诊断,测量误差小于5%。 相似文献
16.
M. Filoche B. Sapoval 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(4):755-763
The flux across resistive irregular interfaces driven by a force deriving from a Laplacian potential is computed on a rigorous
basis. The theory permits one to relate the size of the active zone to the derivative of the spectroscopic impedance with respect to the surface resistivity r through: . It is shown that the macroscopic transfer properties through a system of arbitrary shape are determined by the characteristics
of a first-passage interface-interface random walk operator . More precisely, it is the distribution of the harmonic measure (or normalized primary current) on the eigenmodes of this
linear operator that controls the transfer. In addition, it is also shown that, whatever the dimension, the impedance of a
weakly polarizable electrode for any irregular geometry scales under a homothety transformation as Ld-1, L being the size of the system and d its topological dimension. In this new formalism, the question addressed in the title is transformed in a open mathematical
question: “Knowing the distribution of the harmonic measure on the eigenmodes of the self-transport operator, can one retrieve
the shape of the interface?”
Received 3 November 1998 相似文献
17.
A. Deveikis 《Physics of Particles and Nuclei Letters》2009,6(7):542-545
An efficient procedure for antisymmetrization of an arbitrary system of identical fermions is presented. The approach is based
on a simple enumeration scheme for antisymmetric A-particle states and an efficient algorithm for calculation of the coefficients of fractional parentage (CFPs) for a single
j-shell with isospin. The developed approach is implemented in a new procedure for the calculation of the electric quadrupole
moment matrix elements of light atomic nuclei in the isospin formalism. 相似文献
18.
Discrete Alfvn eigenmodes in international thermonuclear experimental reactor operations with negative magnetic shear 下载免费PDF全文
Discrete Alfvén eigenmodes in steady-state operation scenarios with negative magnetic shear in the international thermonuclear experimental reactor are investigated in this paper. These magnetohydrodynamic eigenmodes are trapped by the α -induced potential wells along the magnetic field line. Here α =-q2Rdβ/d r with q being the safety factor, β the ratio between plasma and magnetic pressures, and R the major radius, and r the minor radius. Due to negligible continuum damping via wave energy tunneling, these Alfvén eigenmodes could be readily destabilized by energetic particles. 相似文献
19.
在传统遗传算法的基础上提出了单母体遗传算法(single-parent genetic algorithm, SPGA),通过对母体团簇实施两种不同的变异操作对结构进行优化,给出了分子团簇结构优化的算法实现. 结合TIP3P模型势函数,研究了水分子团簇(H2O)n(n≤14)的稳定结构. 优化结构和已有理论及实验结果一致. 计算结果表明当n<8时,平均结合能随n增加较快;当n≥8时有小的起伏. n=4,8,10,12的团簇结构具有较高对称性,比较稳定.
关键词:
单母体遗传算法
水分子团簇
结构优化 相似文献
20.
We propose a framework for quantitative evaluation of dynamical tendency for polarization in an arbitrary random variable that can be decomposed into a pair of orthogonal subspaces. The method uses measures based on comparisons of given dynamics to its counterpart with statistically independent components. The formalism of previously considered X-distributions is used to express the aforementioned comparisons, in effect putting the former approach on solid footing. Our analysis leads to the definition of a suitable correlation coefficient with clear statistical meaning. We apply the method to the dynamics induced by pure-glue lattice QCD in local left–right components of overlap Dirac eigenmodes. It is found that, in finite physical volume, there exists a non-zero physical scale in the spectrum of eigenvalues such that eigenmodes at smaller (fixed) eigenvalues exhibit convex X-distribution (positive correlation), while at larger eigenvalues the distribution is concave (negative correlation). This chiral polarization scale thus separates a regime where dynamics enhances chirality relative to statistical independence from a regime where it suppresses it, and gives an objective definition to the notion of “low” and “high” Dirac eigenmode. We propose to investigate whether the polarization scale remains non-zero in the infinite volume limit, in which case it would represent a new kind of low energy scale in QCD. 相似文献