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第二篇电机与拖动篇第三章交流电动机若干问题浅说3.1驻波与行波磁场讲解背景二十世纪五十年代,我在讲授《电工基础》课时,曾讲解过驻波和行波的公式。后来在《电机学》课里讲授旋转磁场,较通俗的讲法是用图解,比较繁复;完全用公式推导,又比较抽象。于是想,如果把驻波和行波的概念形象化地结合到电动机里,理解起来是否轻松些。试验的结果,学生们的反映颇为热烈。 相似文献
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永磁Wiggler磁场的设计和小周期数装置的实验 总被引:1,自引:0,他引:1
Wiggler磁场是自由电子激光器的重要组成部分。根据计算分析和自由电子激光器的总体设计要求,提出了Wiggler磁场的设计考虑。研制出小周期数装置,在改变磁隙、周期、磁块尺寸以及材料的情况下进行了测量,同时测量了磁场的正弦分布。结果表明,设计并研制的小周期数Wiggler磁场满足总体要求,可用于自由电子激光器。 相似文献
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所谓“自由电子激光器”和谐振腔激光器一样都产生光波。用作波发生器(波纹机)翁自由电子激光器是具有可变极性磁场的直线型装置,以致于电子束绘出正弦形的轨迹。这样的电子束能够看成是振动着的偶极子,因此,沿运动方向发射出电磁波,而且它的能量越高,则波长越短。由此可以认为,按爱因新坦相对论,对自由电子而言,电子束方向上磁场周期缩短。 相似文献
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本文介绍一种用于电镜透镜球差矫正系统中的磁六极透镜的磁场分布实验测定原理及方法,并给出较详细的测量数据。测量结果说明这种透镜内磁场分布是以3θ为宗量的正弦和余弦规律,随r的变化是二次方规律。 相似文献
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为了提高行波管用电磁聚焦系统的效率,在一体化电磁聚焦系统的无加载设计基础上,进行了加载技术的研究,通过使用CST软件和MTSS软件进行仿真设计,然后进行装管验证。研究结果表明:对某X波段大功率耦合腔行波管的一体化电磁聚焦系统进行加载后,可实现对电磁聚焦磁场的局部调节,且基本不影响相临区域的磁场,在获得相同磁场强度的条件下,线包的耗散功率降低了3%左右。因此,对一体化电磁聚焦系统进行加载技术的研究有较好的实际意义。 相似文献
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Monzurul M. Ehsan Dikshitulu K. Kalluri 《Journal of Infrared, Millimeter and Terahertz Waves》2003,24(8):1215-1234
The transformation of an elliptically polarized standing wave in a cavity by a suddenly and uniformly created plasma is discussed. Theoretical expressions for the plasma induced wiggler magnetic field as well as the frequency-upshifted standing wave are derived. By choosing appropriate values of the source wave parameters and plasma parameters, one can get wiggler magnetic field of desired magnitude, direction and wiggler wavelength. A few representative results are discussed. 相似文献
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Huang Y.C. Wang H.C. Pantell R.H. Feinstein J. Lewellen J.W. 《Quantum Electronics, IEEE Journal of》1994,30(5):1289-1294
A staggered-array wiggler for a far-infrared free-electron laser (FEL) has been built at Stanford, and its magnetic properties have been tested. This type of wiggler has several desirable features: high wiggler field at short wiggler periods, wavelength tuning by a solenoid current, electron beam confinement by a solenoid field, and looser machining tolerances. A 10.8-kilogauss peak wiggler field has been measured at a 7.0-kilogauss solenoid field for a 1.0-cm wiggler period and a 2.0-mm gap. The small-signal gain has been calculated analytically and by computer simulation for a 0.5-m long wiggler. For an 8-A, 9-ps current pulse and a 3.3-MeV electron beam, 5-dB gain is predicted. Twenty- to thirty-percent wavelength tuning can be achieved by adjusting the solenoid field and still maintain reasonable small-signal gain. The pulsed-wire technique was employed to test the field uniformity of this novel wiggler, and the measured field variation was about 1% 相似文献
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本文提出当Wiggler磁场参数K≥2时,用高次谐波运转的储存环自由电子激光器,不仅可以得到更短波长的自由电子激光,而且比同样波长在基波运转时有更高的增益,同时所需要的初始激光强度也比同样波长在基波运转时低.给出了一种可能的实验方案. 相似文献
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A constant parameter wiggler free electron laser using a dc electric field for efficiency enhancement is compared to several tapered wiggler efficiency enhancement schemes. Analytical expressions for the efficiency in the plane wave, infinitesimally small radius electron beam limit are derived and compared. Numerical simulations for a Gaussian radiation field and finite radius electron beam with an output radiation wavelength of 2 μm are presented. For finite radius electron beams, the extraction efficiency using a dc electric field is somewhat greater than or equal to that using proposed tapering schemes. While the dc field offers flexibility in efficient, tunable laser design, the required field strengths for visible radiation are in the megavolt/meter range. 相似文献
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提出了利用多层膜作自由电子激光器的摇摆器,利用虚光子和康普顿散射讨论了运动电子在多层膜摇摆器中的自发辐射。(Fe/Cr)N等铁磁-非磁层状材料的铁磁层之间存在反铁磁耦合,因此可以利用磁性多层膜制作自由电子激光器的摇摆器。考虑到静磁场的空间周期只有7.8nm,要精确计算电子在多层膜摇摆器中运动的自发辐射的波长和辐射功率就必须考虑电子的反冲。给出了运动电子在多层膜摇摆器中的自发辐射波长和辐射功率的精确计算表达式。结果发现,自发辐射波长和辐射功率表达式中都含有康普顿波长。 相似文献
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By loading the wiggler cavity of a free-electron laser (FEL) with hydrogen gas, it is possible to tune the FEL to below 130 nm, just above the electronic resonance of molecular hydrogen. The change in wavelength results from the refractive index of the gas, which alters the phase velocity of the wave and so modifies the synchronism condition. Using the parameters of the wiggler on the beamline of the Stanford Superconducting Accelerator, this FEL can be tuned from 500 to 130 nm with a pressure ranging from 0 to 55 torr. The calculated electronic gain varies between 5.6 and 11% over this wavelength interval, comparable to the gain in vacuum 相似文献
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A small-period wiggler constructed of edgy-wound bifilar-helical conducting sheets with ferromagnetic cores, which is intended for free-electron lasers, is presented. The performance characteristics of the wiggler fields with a 100 mm period are measured. A field as high as 1500 G has been obtained. Free-electron lasers with this small-period wiggler have been investigated numerically with a three-dimensional nonlinear theory. Simulation results estimated that a radiation power of 20.2 MW and a frequency of 170 GHz with an efficiency of 5.1% can be obtained. It is feasible to make Raman free-electron lasers with this type of wiggler operating in the millimeter and submillimeter wavelength range with a relatively low electron energy (<500 keV) beam 相似文献
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The modification of the free-electron laser (FEL) on the Stanford superconducting accelerator to operate as a gas-loaded FEL (GFEL) is described. The addition of a gas to the wiggler chamber of a FEL changes the phase velocity of the electromagnetic wave, and so provides a simple method for wavelength tuning without changing beam energy or wiggler parameters. A wavelength shift of over 950 Å has been achieved from a vacuum wavelength of 1.6 μm by using 15 torr of hydrogen gas, in agreement with the GFEL synchronism condition incorporating the index of refraction of the gas 相似文献
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A detailed analysis of the electromagnetic standing wave wiggler for free-electron lasers (FEL's) is conducted for both circular and linear wiggler polarizations, following a single-particle approach. After determination of the unperturbed electron orbits in the wiggler field, the single-particle spontaneous emission spectrum and subsequently the gain in the low gain Compton regime (using the Einstein coefficient method) are explicitly calculated. This analysis results in a clear understanding of the resonance conditions and the coupling strength associated with each resonance of this type of FEL. In particular, a striking feature obtained from this investigation is that the electromagnetic standing wave wiggler FEL, under certain circumstances, exhibits a rich harmonic content. This harmonic content is caused by the presence of both the forward and backward wave components of the standing wave wiggler field. In addition, the nonlinear self-consistent equations for this type of FEL are also presented, permitting further investigation of it by the theoretical techniques and numerical codes developed for conventional FEL's. 相似文献
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Shi-Chang Zhang 《Journal of Infrared, Millimeter and Terahertz Waves》2010,31(3):249-258
A planar electrostatic wiggler is formed by two parallel metallic plates, where the upper-plate is corrugated with sinusoidal
ripples and connected to a negative voltage and the lower-plate is smooth and grounded. The field distribution is mathematically
derived in detail. It is demonstrated that this planar electrostatic wiggler can efficiently modulate the motion of relativistic
electrons just as a magneto-static wiggler does in a free-electron laser. Results obtained here will provide basis to analyze
the amplification mechanism of a fast wave by a relativistic electron beam in a planar electrostatic wiggler. 相似文献