共查询到20条相似文献,搜索用时 93 毫秒
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超导变厚微桥的电流相位关系可以从金兹堡-朗道方程得到。本文利用迭代法获得了桥长为一个相干长度的一维微桥的电流相位解析关系,并通过数值积分获得了临界电流和桥长的关系曲线以及自由能和电流的关系曲线. 相似文献
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利用数字示波器对电压电流的测量数据,通过各种电参数计算和谐波分析,研究了气体放电的等离子体一维壁稳弧通道模型,并对放电管的负载性质进行了讨论. 相似文献
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相对论电子束虚阴极静电振荡的粒子模拟 总被引:2,自引:0,他引:2
本文运用有限大小粒子模型,用等离子体粒子模拟方法,对相对论电子束的虚阴极振荡作了一维静电粒子模拟。结果表明,在注入电流小于空间电荷极限电流时,电子束能稳定传输并能全部通过。当注入电流超过空间电荷极限电流时,传输是不稳定的,将有部分电子反射,部分通过。空间电荷形成的虚阴极的位置和电势周期性地振荡。电流越大,虚阴极位置越靠近注入面且变化范围越小,虚阴极电势越低且振幅越大,振荡频率越高且大于电子束等离子体频率。 相似文献
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用一维粒子模拟的方法对正交场平板二极管间隙中电子束的动力学行为进行了研究, 模拟结果表明: 注入电流存在着一个临界值, 当注入电流超过这个临界值时, 电子束的行为将由层流态变化到扰动态。当考虑相对论效应时, 这种由层流态到扰动态的中间过程较为明显, 且电流临界值突然下降, 与外加电压和磁场的关系不再是一个简单的单调递增关系。 相似文献
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G. V. Ostrovskaya 《Technical Physics》2013,58(4):523-533
The structure of the current sheet magnetic fields are numerically calculated for different distributions of the current density across the current sheet width. The structural features of the magnetic fields of current sheets with current density double-humped distributions are revealed. 相似文献
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Jan Tauc 《Czechoslovak Journal of Physics》1956,6(2):108-122
Phenomena connected with the transfer of current carrier concentrations as a result of a temperature gradient in semi-conductors with two kinds of current carriers are theoretically studied. The paper first deals with the general equations which are valid at a certain point of the semi-conductor with a temperature gradient for the concentrations of current carriers and density of electric and thermal current. From this the distribution of the concentrations of current carriers is found for a typical case, the phenomenon of thermal emission of minority current carriers is discussed, relations are derived for the dependence of the thermal emf on the magnitude of the temperature gradient, the possibility is discussed of thermal rectification and equations are given for the thermal conductivity of a semi-conductor with non-equilibrium concentrations of current carriers. 相似文献
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运用约束路径量子蒙特卡罗方法,对二维、三带Hubbard模型中的环形电流相进行数值模拟。在数值模拟过程中定义了表征环流相的不同算符及其关联函数,并且选用合理的模型Hamiltonian量中的参数。通过模拟发现,对应于闭合环形的关联函数在相同距离上要比其他所有没有闭合的关联函数大得多,因此证明在三带Hubbard模型中存在环形电流相。 相似文献
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利用Harris模型,通过求解等离子体平衡方程,计算俘获粒子份额,分别对常规剪切和中心负剪切下tokamak中的自举电流的大小和剖面准直性进行了计算和分析.自举电流分布与等离子体平衡电流分布之间的剖面准直性可以通过调整等离子体的密度、温度和电流分布参数,以及描述等离子体形状的拉长度k和三角变形因子d来获得.中心负剪切位形有利于自举电流产生,并有好的剖面准直性.通过计算比较,分别在常规剪切位形下和中心负剪切位形下获得了一组优化的等离子体参数,在这组参数下,自举电流有较大的份额和好的剖面准直性
关键词:
tokamak
自举电流
剖面准直性 相似文献
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It is necessary to develop HTS conductors with a large current capacity and low AC loss characteristics for practical use of HTS power devices. For large capacity power applications, HTS tapes such as Bi-2223 tapes and YBCO coated conductors are assembled. So, it is important to evaluate the characteristics of current distributions in such assembled HTS tapes. However, an adequate measurement method has not been established. In this study, we have tried the development of an indirect measurement method to evaluate the current distributions in stacked HTS tapes. In this method, the current distributions are indirectly found from the results of the field distributions measured by a pickup coil located around the surface of the sample tapes. To confirm the accuracy and the sensitivity of this method, current distributions in a test conductor made of copper tapes are measured. Numerical and measured current distributions are compared. Using this method, the current distributions in stacked Bi-2223 tapes are measured at room temperature and 77 K. On the basis of the obtained results, the characteristics of the AC current distributions in the HTS tapes are discussed. 相似文献
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在给定等离子体密度分布下,从电子、离子的能量方程出发,根据不同运行模式下等离子体的热传导率不同,分别求出了中心负剪切模式,常规剪切H模式和L模式下的等离子体温度分布,然后通过求解波迹方程与相对论情况下的Fokker-Planck方程,分别计算了这些模式下的电子回旋波电流驱动和波功率沉积.得到在中心负剪切下,驱动电流最大,驱动效率最高,功率沉积和电流分布区间跨度大;在常规剪切H模式下,驱动电流较小,分布区间跨度比较窄,驱动效率相对较低;在常规剪切L模式,驱动电流效率最低,分布区间跨度也非常集中.
关键词:
托卡马克
电子回旋波电流驱动
中心负剪切
常规剪切 相似文献
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针对色散效应导致聚光多结太阳电池性能降低的问题,使用分布式三维等效电路模型计算高倍聚光下GaInP/GaInAs/Ge三结太阳电池的输出特性,通过分析电池各层的电压分布、暗电流分布以及横向电流分布,研究了不同电池尺寸下色散效应对电池性能影响的机理.结果表明:色散使多结太阳电池在局部区域的光生电流变得不匹配,随着电池尺寸的减小,局部区域之间失配的光生电流能够以横向电流的形式相互补偿,使电池整体的电流更加匹配,从而减小色散效应的影响.当电池芯片尺寸较大(20 mm×20 mm)时,色散主要降低电池的短路电流密度,色散光斑下电池的效率仅相当于无色散时的94%;当电池芯片尺寸减小到2 mm×2 mm时,短路电流密度与无色散时相等,但横向电阻降低了电池的填充因子.当电池芯片尺寸进一步减小到0.4 mm×0.4 mm时,色散与无色散光斑下电池的各项性能几乎没有差别,效率均约为34.5%,色散效应的影响可忽略不计. 相似文献
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Xiaodong Wang Yulu Chen Xiaoyao Chen Bingbing Wang Chuansheng Zhang Haoxing Zhang Ming Pan 《Optical and Quantum Electronics》2017,49(12):419
Dark current transport mechanism associated with acceptor concentration in GaAs-based blocked-impurity-band (BIB) detectors has been investigated. Device structure, numerical models and simulation techniques are described in detail. By careful model and parameter calibration, the numerical simulation is completely consistent with the analytical calculation, proving the validity of simulation methods. Our results reveals that the carrier-transport modes of GaAs-based BIB detectors can be classified into two categories (i.e., electron current and hopping current), and the hopping current can be neglected compared with the electron current. Besides, it is demonstrated that the dark current of GaAs-based BIB detector is dominated by the drift–diffusion current and the generation-recombination current, and the both current components are monotonically decreasing functions of the acceptor concentration. 相似文献