2born (2born) wrote,

В разделе "Физика ускорителей" сегодня сразу две интересные статейки по электродинамике

Space charge fields in azimuthally symmetric beams: integrated Green's function approach: https://arxiv.org/abs/2102.01250
Petr M. Anisimov, Nikolai Yampolsky
Electromagnetic fields induced by the space charge in relativistic beams play an important role in Accelerator Physics. They lead to emittance growth, slice energy change, and the microbunching instability. Typically, these effects are modeled numerically since simple description exists only in the limits of large- or small-scale current variations. In this paper we consider an axially symmetric charged beam inside a round pipe and find the solution of the space charge problem that is valid in the full range of current variations. We express the solution for the field components in terms of Green's functions, which are fully determined by just a single function. We then find that this function is an on-axis potential from a charged disk in a round pipe, with transverse charge density ρ⊥(r), and it has a compact analytical expression. We finally provide an integrated Green's function based approach for efficient numerical evaluation in the case when the transverse charge density stays the same along the beam.

Excitation of bulk and surface wakefields by a relativistic electron bunch in plasma of semiconductors and semimetals: https://arxiv.org/abs/2102.01446
V.A. Balakirev, I.N. Onishchenko
The spatio-temporal structure of the bulk wakefields excited by a relativistic electron bunch in plasma of semiconductors and semimetals is studied. It is shown that these wakefield consists of the field of longitudinal plasmons and Cherenkov electromagnetic radiation, which is a set of eigen electromagnetic waves of the semiconductor or semimetal waveguide. A branch of the surface plasmons appears in a waveguide with an axial vacuum channel. The process of wake excitation of the surface plasmons by the relativistic electron bunch is also investigated. The intensity of the excited wake surface wave is determined.
Comments: arXiv admin note: substantial text overlap with arXiv:2012.08949

Wake excitation of volume and surface polaritons by a relativistic electron bunch in an ion dielectric: https://arxiv.org/abs/2012.08949
V. A. Balakirev, I. N. Onishchenko
The process of wake fields excitation by a relativistic electron bunch in ion dielectric media is considered. The space-time structure of the excited wakefield in an ion dielectric waveguide is investigated. It is shown that the wake field in the infrared (terahertz) ranges consists of the field of longitudinal polaritons and Cherenkov radiation, which is a set of electromagnetic eigen waves (transverse polaritons) of a dielectric waveguide. A branch of surface polaritons appears in a dielectric waveguide with an axial vacuum channel. The process of wakefield excitation of surface polaritons by a relativistic electron bunch is also considered.
Tags: КлЭД, Мегаучебник или Что я читал и похвалил, разгребая arXiv'ы, техника

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