arXiv subjects

T. Liseykina

Publications and source records attributed to T. Liseykina.

4 recordsLinked to original sources

arXiv2025

Probing the radiation-dominated regime of laser-plasma interaction in multi-beam configurations of petawatt lasers

We model numerically the ultrarelativistic dynamics of a dense plasma microtarget in a focus of several intersecting femtosecond laser pulses of multi-petawatt power each. The aim is to examine perspective future experimental approaches to the search of the Inverse Faraday Effect induced by radiation friction. We show that multi-beam configurations allow lowering the single beam peak laser power required to generate a detectable quasi-static longitudinal magnetic field excited due to the radiation reaction force. The effect is significant at angles around $10^{\rm o}$ between the beam propagation axes, almost vanishes when the angle exceeds $20^{\rm o}$, and remains rather stable with respect to variations of relative phases and amplitudes of the beams. Quantum recoil accounted within semi-classical approach is shown to considerably suppress the longitudinal magnetic field, which however remains sizable. We conclude that using four infrared femtosecond linearly polarized pulses, 15 petawatt power each, crossing at angles $\approx 10^{\rm o}$, the radiation-dominated regime of laser-plasma interaction can be experimentally demonstrated.

physics.plasm-ph↗

arXiv2019

Acceleration of Cosmic Rays in Supernova Shocks: elemental selectivity of the injection mechanism

Precise measurements of galactic cosmic rays revealed a significant difference between the rigidity spectral indices of protons and helium ions. This finding is a notable contrast to the commonly accepted theoretical prediction that supernova remnant (SNR) shocks accelerate protons and helium ions with the same rigidity alike. Most of the earlier explanations for the "paradox" appealed to SNR environmental factors, such as inhomogeneous $p$/He mixes in the shock upstream medium, variable ionization states of He, or a multi-SNR origin of the observed spectra. The newest observations, however, are in tension with most of them. In this paper, we show by self-consistent hybrid simulations that such special conditions are not vital for the explanation of the cosmic ray rigidity spectra. In particular, our simulations prove that an SNR shock can modify the chemical composition of accelerated cosmic rays by preferentially extracting them from a homogeneous background plasma without additional, largely untestable assumptions. Our results confirm the earlier theoretical predictions of how the efficiency of injection depends on the shock Mach number $M.$ Its increase with the charge-to-mass ratio saturates at a level that grows with $M.$ We have convolved the time-dependent injection rates of protons and helium ions, obtained from the simulations, with a decreasing shock strength over the active life of SNRs. The integrated SNR rigidity spectrum for $p$/He ratio compares well with the AMS-02 and PAMELA data.

astro-ph.HE↗

arXiv2015

Ion-acoustic shocks with reflected ions: modeling and PIC simulations

Non-relativistic collisionless shock waves are widespread in space and astrophysical plasmas and are known as efficient particle accelerators. However, our understanding of collisionless shocks, including their structure and the mechanisms whereby they accelerate particles remains incomplete. We present here the results of numerical modeling of an ion-acoustic collisionless shock based on one-dimensional (1D) kinetic approximation both for electrons and ions with a real mass ratio. Special emphasis is made on the shock-reflected ions as the main driver of shock dissipation. The reflection efficiency, velocity distribution of reflected particles and the shock electrostatic structure are studied in terms of the shock parameters. Applications to particle acceleration in geophysical and astrophysical shocks are discussed.

physics.plasm-ph↗

arXiv2015

Collisionless absorption, hot electron generation, and energy scaling in intense laser-target interaction

Among the various attempts to understand collisionless absorption of intense ultrashort laser pulses a variety of models has been invented to describe the laser beam target interaction. In terms of basic physics collisionless absorption is understood now as the interplay of the oscillating laser field with the space charge field produced in the plasma. A first approach to this idea is realized in Brunel's model the essence of which consists in the formation of an oscillating charge cloud in the vacuum in front of the target. The investigation of statistical ensembles of orbits shows that the absorption process is localized at the ion-vacuum interface and in the skin layer: Single electrons enter into resonance with the laser field thereby undergoing a phase shift which causes orbit crossing and braking of Brunel's laminar flow. This anharmonic resonance acts like an attractor for the electrons and leads to the formation of a Maxwellian tail in the electron energy spectrum. Most remarkable results of our investigations are the Brunel-like hot electron distribution at the relativistic threshold; the minimum of absorption at $Iλ^2 \cong (0.3-1.2)\times 10^{21}$ W/cm$^2μ$m$^2$, in the plasma target with the electron density of $n_e λ^2\sim 10^{23}$cm$^{-3}μ$m$^2;$ the drastic reduction of the number of hot electrons in this domain and their reappearance in the highly relativistic domain; strong coupling of the fast electron jets with the return current through Cherenkov emission of plasmons. The hot electron energy scaling shows a strong dependence on intensity in the moderately relativistic domain $Iλ^2 \cong (10^{18} - 10^{20})$ W/cm$^2μ$m$^2$, a scaling in vague accordance with current published estimates in the range $Iλ^2 \cong (0.14-3.5)\times 10^{21}$ W/cm$^2μ$m$^2$, and a distinct power increase beyond $I=3.5\times 10^{21}$ W/cm$^2μ$m$^2$.

physics.plasm-ph↗