查询词典 electron beam

As the beam further propagation, self-reconstruction of the Bessel beam generated. The divergence of the self-reconstruction beam causes the beam intensity decreasing and the bright spot size increasing as the beam propagating.

当光束继续传播，贝塞尔光发生自重建(Self-reconstruction)，但重建的Bessel光将会发散，光强随着传播距离增大而迅速下降，且中心亮斑尺寸也迅速增大。

A circle is placed at the launch point to improve the interaction between the electron beam and the fields supported by the slow wave structure, thus to control the beam current density at the launch point, and to minimize the loss of the electron beam energy. The inaner radii of the extractor vanes are slightly larger than those of other SWS vanes, which increases the axial group velocity and enhances the microwave output power and efficiency. Implementation of two RF choke vanes stops the leakage of microwave pulse power toward the diode, and makes the device more compact than the conventional MILO.

该振荡器在阴极电子发射起点加圆环，控制此处电子束的发射密度，来减少电子能量的损耗，改善束－波互作用；逐渐加大慢波结构的后两个叶片的内半径，增大微波群速度，便于谐振腔中的能量输出，提高微波输出效率；采用两个扼流片有效地阻止了微波功率向二极管区泄漏，相应减小了器件的尺寸。

The results show that:(1) The space-charge fields(include dc space-charge fields and ac space-charge fields) have important effect on the beam-wave interaction output power, make the saturated output power lower, saturated position delay;(2) The back-radio excited by the electron beam has little effect on the output power, and can be ignored;(3) The transverse motions of electron beam has some effect of the output power;(4) The means of phase velocity taped and bunch compression can improve the relativistic TWT efficiency, especially bunch compression can greatly improve the efficiency.

五、分析了相对论行波管三维非线性特性，分析结果表明：(1)空间电荷场（包含直流和交流空间电荷场）对注波互作用输出功率影响很大，会造成饱和输出功率减小，饱和位置推后；(2)电子注激发的反向辐射对输出功率影响比较小，基本上可以忽略不计；(3)电子注横向运行对注波互作用的直接影响比较大；(4)通过改变耦合腔内半径来调节慢波结构相速，采用相速跳变和预群聚的方法可以改善相对论行波管的效率，特别是采用预群聚方法，可以尽量提高相对论行波管的效率。

The good characteristics of the deflection system of electron gun can be obtained by optimizing the velocity and the location of emitting electron beam and by the aclinic emission of the electron beam, that can be achieved by making the end of the anode and the middle part of the cathode level.

研究结果表明：电子枪阳极板端点与阴极灯丝中心点保持水平可满足电子水平出射；非均匀分布的磁场对e型电子枪中电子束具有良好的聚焦作用；所设计的偏转聚焦系统在电子束流为50~100 mA时，束斑小于3 mm。

In order to testify our whether correction to Rossi's exchange term andthe potential of electron and nucleus is reasonable, we calculate 〓 moleculeelastic differential scattering cross section by electron impact on 100eV, ourresult is obviously better than Rossi's. Then we calculate elastic differentialscattering cross section at 150eV. In order to check the program thatcalculates molecule excitation cross section by electron impact, we calculatehydrogen excitation cross section from ground state to 〓 state at 20eVand 30eV, oxygen excitation cross section from ground state to 〓 state at15eV and 20eV. These calculations are in agreement with other theoreticresults, and experiment measure. Finally, we calculate sulfur moleculeexcitation〓 cross section by electron impact at5eV,7eV,9eV, 11eV, 13eV,15eV, and draw curve of excitation total crosssection corresponding to incident electron energy.

为了核对我们修改的计算激发态的程序是否正确，计算了电子与氢分子碰撞从基态激发到〓态入射能量分别为20eV和30eV时的微分截面以及电子与氧分子碰撞从基态激发到〓态入射能量分别为15eV和20eV时的微分截面，与别人的理论计算结果、实验的测量值基本一致，最后计算了电子与硫分子在5eV、7eV、9eV、11eV、13eV、15eV时的碰撞激发〓截面，作出了电子的入射能量与激发总截面的关系曲线，找出了总截面最大时对应的电子入射能量大约是11电子伏。

Using the method we calculate the 〓 elasticdifferential scattering cross section, excitation differential scattering crosssection, and excitation cross section of electron collision with 〓 We transform the electron and molecule problem into electron problemby Born-Oppenheimer approximate. Mr Rossi, Dr. the Flinders University ofSouth Australia, calculated electron collision with molecule, but theexchange term he used become bigger and bigger as incident energyincreases, it is unreasonable, besides, the potential of electron and nucleus heused is somewhat rough. At present we correct these two terms. The potentialconsists of static potential, exchange potential, polarization potential.

电子与分子的碰撞过程的相互作用势主要是由静态势、交换势和极化势三部分决定的，这里对这三部分在动量空间中进行分波展开，推导出易于计算的表达形式，根据这些公式，并参考Rossi的弹性碰撞程序编写了计算电子与分子碰撞激发截面的程序，利用程序计算出势能矩阵元，通过求解Lippmann-Schwinger方程求得T矩阵元，便可求得散射截面。

For example of atom of hydrogen, it must be enough surrounding electrons so can be form a "electron space", it could be form gravitation among electron and proton, at first whole gravitation line may acts with proton ,but if the quantity of electron go to much ,every one can got gravitation line from proton would be lower, the gravitation between proton and electron would be drop, when it is reached fixed lever, this power is equal to expulsive force which between electrons , so it would be reach balance, the electron can't much more.

之间形成引力，质子向外发出的引力线本来可以全部同外围电子作用，但是，电子多了，每一枚电子从质子分到的作用引力线便减少，它们同质子间的引力要下降，下降到一定程度，此力等于电子间的斥力，达到平衡，电子便不能再多。

The five prosthetic groups (FAD, [2Fe-2S], [4Fe-4S], [3Fe-4S] and heme group) required for electron transfer from succinate to ubiquinone were unambiguously assigned into the electron density map. Besides, we find there are some electron densities around the Qp pocket at the matrix side and we believe it represents the head structure of ubiquinone, which is proved by the inhibitor bound structure that 2-TTFA just locating at the Qp site. At the same time, we find there is the second 2-TTFA binding site, locating the inter-membrane side. This finding will change our knowledge about the electron transfer inside Complex II and the ubiquinone transfer between Complex II and Complex III, and endow a new role of Complex II in electron transfer chain.

除了对各个电子传递体（ FAD ，[2Fe-2S]，[4Fe-4S]，[3Fe-4S]以及血红素分子）进行精确定位外，我们在该结构跨膜区靠近线粒体基质一端的口袋 Qp 中，发现了一些电子密度，认为是所结合的辅酶 Q 的头部结构，这一点被与抑制剂结合的复合体的结构所证明，在该结构中， 2－ TTFA 恰好结合在口袋 Qp 中，同时，我们还发现了第二个2－ TTFA 的结合位点，位于跨膜区靠近线粒体膜间隙一端的口袋 Qd 中，这个发现具有全新的意义，将影响人们对电子在复合物 II 中传递以及辅酶 Q 在复合物 II 与 III 之间转移的认识，促使人们重新复合物 II 在线粒体呼吸链中的角色。

The maximum increase of electron temperature in ionospheric F region is in the vicinity of reflect point of radio waves, and the changes of electron density have increase and decrease. The time scale of balance of electron temperature is tens of second, which is shorter than that of electron density, that is 2～3 minutes, and heating time scale for electron is good symmetry with that of cooling.

电子温度达到平衡态的时间大约为几十秒，而电子密度达到平衡态的时间则较长，大约为2～3分钟的量级，电子温度的加热时标和冷却时标具有很好的对称性，而且热传导过程十分明显。

Checking and the setting of camber are to be discussed. Firstly, the categories of scaffolds and applying condition of all kinds of scaffolds are simply introduced. Then structure design for beam -column scaffold over sea, beam-column scaffold on land, beam scaffold over sea, ramp bridge scaffold and column scaffold on land are presented. And corresponding formulas and the finite element analysis software of Midas/Civil are used to check strength, stiffness and stability on these scaffolds in detail. Then calculating methods on construction camber of cast-in-place beam scaffold and setting methods are introduced.

本文简要介绍了现浇梁支架的分类、各种支架的使用条件，然后简述了海上梁柱式支架、陆上梁柱式支架、海上梁式支架、匝道桥梁式支架以及陆上立柱式支架的结构设计；并应用相关公式和大型有限元计算软件MIDAS/Civil对各种类型的支架结构详细进行了强度、刚度和稳定性验算；接着介绍了现浇梁支架的施工预拱度计算方法及设置方法。

This paper designs the communication system of radio telescope FAST.

针对500m口径球面射电望远镜FAST分布式控制系统的特点完成了其通信系统的设计。

Political sheep's step-by-step a large number of fossils unearthed in the county soil Ma Ali after rural village in the middle of sallow pelitic siltstone.

步氏和政羊化石大量出土于广河县阿力麻土乡后山村，产于灰黄色泥质粉砂岩中。