arXiv subjects

R. R. Kniaziev

Publications and source records attributed to R. R. Kniaziev.

4 recordsLinked to original sources

arXiv2026

Start-to-end simulations of non-relativistic electron acceleration along reflective grating structure by front-tilted laser pulse

A comprehensive (start-to-end) simulation was performed regarding the formation of a front-tilted laser pulse and the subsequent acceleration of non-relativistic electrons moving along a reflective grating structure. The laser pulse tilt was formed using another diffraction grating -- either reflective or transmissive. The pulse had a spectral range (FWHM) of 803--863 nm and an initial duration of approximately 17 fs. Acceleration under normal laser pulse incidence was also calculated for comparison. Research results indicate that the use of a femtosecond laser pulse with a front, tilted by means of a reflective diffraction grating, significantly enhances the efficiency of laser acceleration of non-relativistic electrons compared to the case of a pulse at normal incidence. Furthermore, it was found that using a transmissive diffraction grating to shape the tilted pulse front also increases acceleration efficiency relative to normal incidence on the accelerating grating, although the acceleration rate is lower than when a reflective diffraction grating is used.

physics.optics↗

arXiv2025

Acceleration gradients in dielectric laser accelerators with triangular-shaped gratings

The study investigated transparent on-chip structures with a rectangular profile and triangular profiles with grating ridge base angles of $α= 36^\circ$, $30^\circ$, and $20^\circ$. Each triangular structure had both left- and right-handed profile orientations. For all variants, a modified version with a reflective gold coating was additionally considered. The maximum energy gains and accelerating gradients were determined and quantified for all structure classes: transparent and reflective (with both rectangular and triangular profiles).

physics.optics↗

arXiv2021

Acceleration and focusing of positron bunch in a dielectric waveguide accelerator with homogeneous plasma in transport channel

The paper presents the results of numerical PIC-simulation of positron bunch focusing when acceleration in a plasma dielectric wakefield accelerator. The wakefield was excited by drive electron bunch in quartz dielectric tube, embedded in cylindrical metal waveguide. The internal area of dielectric tube has been filled with radially homogeneous plasma having in general case the vacuum channel along waveguide axis. Results of numerical PIC simulation have shown that it is possible a simultaneous acceleration and focusing of test positron bunch in the wakefield. The dependence of transport and acceleration of positron bunch on size of vacuum channel and waveguide length is studied.

physics.acc-ph↗

arXiv2019

BBU instability in rectangular dielectric resonator

Studies were made into the arise and an evolution of the beam breakup (BBU) instability in a rectangular dielectric resonator under excitation by a sequence of relativistic electron bunches. The dielectric resonator is a metal rectangular waveguide $R_{26}$ $(45mm\times 90mm)$ with Teflon dielectric slabs $8.2mm$ thick (dielectric constant $\varepsilon=2.051$) located along the wide side of the resonator. The wavelength of the $LM_{21}$ operating mode having a symmetric profile of the longitudinal electric field component is $53.2mm$. The electron energy of bunches is $4.5MeV$ , the charge of each bunch is $6.4nC$, the bunch repetition period is equal to twice the wavelength of the $LM_{21}$ mode. By the use of numerical PIC simulations, the charge losses of electron bunches on the dielectric plates were investigated as the bunches were displaced relative to the cavity axis. It is found that the charge losses on the dielectric slabs due to the BBU instability do not exceed $5\%$. When the bunch repetition period is changed to a multiple of another eigenfrequency (e.g., the $LM_{11}$ mode), the charge losses of drive bunches do not change appreciably.

physics.acc-ph↗