Plasma Physics Reports最新文献

The possibility of using the PIV (particle image velocimetry) method as an alternative to the existing methods used to analyze the dynamics of solar plasma during a coronal mass ejection is considered. P-IVLab software was used to perform a comprehensive analysis of a coronal mass ejection dynamics. The linear speed and the velocity field of the coronal mass ejection were calculated. The study showed that the software is capable of measuring changes in the coronal structure and record the processes that lead to the observed changes.

Using DFT and DPLNO-CCSD(T) quantum chemistry methods, thresholds for elementary reactions occurring during atomic-layer etching of SiO₂ in fluorocarbon plasma, as well as binding energies of key structures and adsorption energies of CF₂ and F on the SiO₂ surface were calculated. Calculations were made for two proposed etching mechanisms: at the SiO₂/C_xF_y interface layer and through the formation of free F atoms in the fluorocarbon film. Calculations show that in the first case, the reaction is limited by the removal of reaction products, and in the second case, by the cleavage of C–F bonds in the fluorocarbon film under ion bombardment. In practice, the joint implementation of both mechanisms is possible. The diffusion of fluorine atoms across the C_xF_y film does not limit the process.

3D particle-in-cell (PIC) simulation is used to study bulk stochastic heating of a cluster (dust, droplet) plasma containing submicrometer particles of heavy atoms (gold) upon irradiation of the cluster medium by an ultrashort (15 fs) laser pulse of moderately relativistic intensity (( gtrsim )10¹⁸ W/cm²). Characteristics of the short X-ray pulse generated mainly due to the bremsstrahlung effect are obtained. Contribution of X‑ray radiation of synchrotron type emitted by electrons with trajectories of stochastic walks between clusters to the radiation yield is discussed. Generation of hard X-ray bremsstrahlung is caused by the appearance of a well-pronounced high-energy plateau, or tail, in the distribution function of the laser-heated electrons. Calculated conversion coefficient to the broadband X-ray radiation for the microcluster medium exceeds 10^–5, which allows the cluster medium to compete with the solid targets while having an advantage when used with the lasers emitting high-contrast pulses at a high repetition rate.

The system of magnetic probes and data acquisition system have been developed and created at the L-2M stellarator for measuring phase velocities of fast magnetosomic (FMS) waves. Using this system of magnetic probes, toroidal and azimuthal wave numbers of FMS waves excited in the L-2M stellarator plasma were determined in the ohmic heating regime at 1-kW-power of radiation introduced into the plasma, plasma densities in the range of (0.5–2.0) × 10¹⁹ m^–3 and magnetic fields in the range of 1–1.4 T. The conditions for the density and magnetic field strength under which FMS wave can propagate in one of the toroidal directions in the L-2M stellarator plasma were determined in the ohmic heating regime.

Control of laser-driven ion beams and, in particular, their divergence is an important problem actively studied by numerous research groups. This work considers a collimation system based on the use of a laser driven micro-wire target. Using Particle-In-Cell modeling, we demonstrate that kilotesla-level quasistationary azimuthal magnetic fields excited around the wire in the process of its irradiation by a relativistic laser pulse with ({sim} {{10}^{{19}}}) W/cm² intensity can collimate ( {simeq} 10) MeV protons created via the TNSA mechanism. The proposed scheme is very simple and compact, does not require additional high-power sources and can be further optimized to increase its efficiency.

The dynamics of shock wave collisions in a strongly coupled dusty plasma consisting of inertial negatively charged dust grains, Maxwellian distributed electrons and ions was investigated. Employing the extended Poincaré–Lighthill–Kuo method, a couple of Burgers’ equations are derived to describe the evolution of dust acoustic shock waves in the presence of strong coupling and dissipation. The one-fold and two-fold solutions of coupled Burgers’ equations are systematically described through Hirota’s bilinear formalism, allowing for an analytical exploration of nonlinear interactions between shock structures. The study reveals that the shock wave collisions exhibit distinct features influenced by the fold structure, such as variations in amplitude, width, and waveform shape, as determined through an analysis of temporal behavior and the impact of collision frequency on the plasma system’s morphology and dynamics. Three-dimensional visualizations further illustrate the parametric dependence of shock interactions, providing deep insight into the collective behavior of nonlinear structures in strongly coupled dusty plasmas.

Experimental results of electron cyclotron (EC) resonance plasma heating using an extraordinary wave at the TEXTOR tokamak are presented, which indicate that in the EC region, no more than one third of the microwave power launched into the plasma is absorbed. It is shown that in these experiments, a low-threshold absolute parametric decay instability of the pump wave is possible, which results in the excitation of daughter electron Bernstein waves.

The impact of an active screen cage into a helium–nitrogen (He–N₂) radiofrequency (RF) plasma discharge has been systematically investigated using optical emission spectroscopy. In this regard, the key plasma parameters including emission intensity, electron temperature, and electron density were evaluated across a range of gas composition ratios, operating pressures, and RF power levels. The inclusion of the active screen cage consistently enhanced plasma performance, leading to increased electron concentration within the discharge, higher emission intensity, and elevated energy levels. These improvements are attributed to enhanced confinement and modified electric field distributions introduced by the cage geometry, which collectively facilitate more efficient excitation and ionization processes. Optimal plasma activity was observed at a He : N₂ ratio of 10 : 90, a pressure of 3 mbar, and elevated RF power, conditions under which Penning effects and energy retention in the plasma are maximized. These results highlight the effectiveness of active screen configurations in tailoring plasma characteristics, offering significant potential for applications in surface engineering, thin film deposition, and plasma-assisted materials processing.

Mass spectrometry has been used to study the composition and evolution of concentrations of nitrogen oxides, ozone, nitrous acid, and nitric acid in plasma generated by a continuous beam of fast electrons in an N₂ : O₂ : H₂O gas mixture at atmospheric pressure. Dependences of the concentrations and temporal dynamics of these components on the composition and volumetric gas flow rate and the electron beam current are presented. The results are compared with experimental data on the corrosion rate of iron samples placed in the studied plasma. A strong correlation between the metal corrosion rate and the concentration of nitrogen-containing plasma-chemical products and a weak correlation with the ozone concentration are established. A qualitative explanation for the obtained regularities is given. A conclusion about the decisive role of nitrogen-containing products of plasma-chemical reactions in the mechanism of radiation corrosion of iron is drawn.

The kinetic characteristics of electrons in CO₂/N₂/H₂O mixtures are calculated by numerically solving the Boltzmann equation for the electron energy distribution function in mutually perpendicular electric and magnetic fields. The drift velocity of electrons, their average energy, electron energy balance, and ionization and dissociative attachment rate constants are calculated over a wide range of reduced electric (E/N) and magnetic (B/N) field values as follows: E/N = (0.5–2000) × 10^–17 V cm²; B/N = (0–4000) × 10^‒21 T cm³. Based on the results of calculations, the dependence is investigated on the induction of the applied magnetic field, specifically at the critical value of the reduced electric field, defined by the condition of equality between the ionization and attachment frequencies. It is also shown that the influence of the magnetic field В ≤ 3 T on the kinetic characteristics of electrons in the above gas mixtures is low at atmospheric pressure.