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moskvich

金虫 (小有名气)

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注册: 2013-04-30
专业: 红外物理与技术

[求助] 求教：about electron bunch/bunching的释义

在翻译一些材料，里面涉及电子加速器物理学，出现了大量electron bunch/bunching字眼，甚至有electron beam bunches这样的字样，不知道这个bunch什么意思，与beam怎么区分，自己理解应该是一段一段的电子束，相当于电子束脉冲，但是标准的译文应该是怎样的呢？（顺便问一下，经常听说一个“电子注”的叫法，是什么意思，查不到。）
加速器物理领域中“form factor”（如第5例中）应该译作什么？成型系数？

A very useful application of S-P radiation is as a diagnostic tool for the study of high-energy electron beam bunches, typically 1–10 ps long with a bunch spacing of a few ns. If a blazed diffraction grating (Sect. 6.2) is placed adjacent to the electron beam, SP signals are emitted over a wide angular spread. By studying this angular spread and the power emitted, both the length and shape of the electron bunch can be obtained. Thismethod for the study of electron beams has proved to be very versatile and has been employed over beam energies from 2 MeV up to 28.5GeV [114].

Although the accelerating voltages in gyrotrons are comparatively low, typically 10–100kV, this increase in electron mass is sufficient to produce instabilities. As the electrons travel toward the resonant cavity into an increasing magnetic field, the electron orbital momentum increases. The relativistic electrons are initially randomly distributed in their cyclotron orbits but phase bunching occurs due to the mass change of the electrons. This can be understood by realizing that electrons which lose energy to the electromagnetic field become lighter and build up a phase lead while those that gain energy have a phase lag. Both groups of electrons tend toward an equilibrium phase and with sufficient bunching of the electrons they radiate coherently.When the wave frequency is slightly greater than the cyclotron frequency, a large percentage of the electron beam energy is converted to electromagnetic radiation.

……Considering the large number of electrons in a bunch (typically 10^10), the intensity gain for CSR is huge.……

……This is one for a point-like source with full coherence, and zero in the incoherent case of a long bunch.……

……The form factor is given by the modulus squared of the Fourier-transform of the longitudinal charge density n.z/ of the bunch……

……CSR was experimentally discovered using electron bunches in a linear particle accelerator (linac)……

……Up to 400 electron bunches, each with up to 10^10 electrons, can be stored……

……In this case, the bursting threshold was at about 10A per bunch.……

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