Contributions to Plasma Physics最新文献

We developed a traditional computational framework coupling time-dependent external circuit equations with a 2D3V axisymmetric Particle-in-Cell/Monte Carlo (PIC/MC) model. By solving circuit equations at each time step, this framework establishes bidirectional feedback between plasma dynamics and self-bias voltage evolution. Moreover, the superposition of Laplace and Poisson solutions is introduced to avoid solving iteratively for the potential on the boundary, which demands extra Laplace solvers for the direct implicit scheme. To improve computational efficiency, a generative network, named Conditional Variational Autoencoder (CVAE), is implemented to predict self-bias voltage effects, achieving a remarkable 25,000× acceleration compared to the circuit solver while maintaining > 90% waveform fidelity. The grid-independent nature of the CVAE architecture enables parametric studies with arbitrary resolution and reverse-optimization targeting desired self-bias voltages and currents. Furthermore, a novel hybrid framework combining the PIC/MC model with the CVAE surrogate is proposed to enhance computational efficiency in plasma simulations. Numerical simulations of voltage-driven CCPs under varied gap conditions demonstrate the hybrid PIC/MC-CVAE model's capability to quantify self-bias effects, revealing their dependence on electrode configurations. This methodology successfully bridges plasma kinetics and macroscopic circuit behavior, providing an efficient and robust tool for optimizing CCP-based industrial processes.

This manuscript studies the helicon discharge of chlorine (Cl₂) when radio frequency (RF) power of 13.56 MHz is applied from 300 to 1500 W for two different magnetic fields (300 and 400 G) and three different working pressures—7 × 10⁻⁴, 10⁻³, and 2 × 10⁻³ mbar. Plasma parameters are determined by using RF matching parameters and the actinometry procedure of optical emission spectroscopy (OES). Transition from capacitive-inductive (E-H) mode to helicon (W) mode is observed as RF power increases in the source chamber. Observed jumps in plasma density profile with RF power confirm the mode transition in chlorine discharge. The electron impact ionization increases in the higher power range to sustain the helicon mode. Positive chlorine ion (Cl⁺) density with the variation of RF power is also determined for all the working pressures. Cl⁺ density is found to be higher in the helicon mode with a sharp increase in the density and intensity of the Cl⁺ emission lines.

This work derives the nonlinear Schrödinger equation (NLSE) for unmagnetized dusty plasmas using reductive perturbation methods, investigating the instability occurring in dust acoustic envelope waves. The analysis reveals the existence of stable dark envelope solitons and examines how dust particle size distributions influence wave dispersion characteristics. Our results demonstrate significant variations in solitary wave properties when comparing different size distribution models, including discontinuous and continuous power-law distributions. Notably, for dust size ratios c > 1 (where c represents the maximum-to-minimum particle size ratio), plasmas with power-law distributed particles exhibit greater solitary wave mass and velocity compared to those with uniform average-sized particles. These findings provide important insights into nonlinear wave behavior in complex dusty plasma systems.

Induced Compton scattering (CS) is a quantum nonlinear interaction between an intense electromagnetic field and a rarefied plasma. Although the induced CS is expected to occur in radiation fields with high brightness temperatures such as pulsars in nature, the principle of induced CS has not been proven experimentally. Therefore, we conducted a proof-of-principle experiment of induced CS using an ultra-intense laser. We measured the scattered spectra due to the interaction between the ultra-intense laser and plasma. The observed spectrum shows a nonlinear redshift, which can be explained by induced CS. We also performed particle-in-cell simulations, in which induced CS is not included, and found that the experimental results are not explained by classical plasma physics.

This study investigates the synthesis of carbon nanoparticles in DC glow discharge plasma using acetylene as a precursor. Characterization of the deposited nanoparticles showed clear differences between the anode and cathode surfaces, with the anode having a more amorphous, oxidized structure and the cathode containing more crystalline, graphitic carbon, as confirmed by Raman and XPS analyses. These differences in surface composition were related to the plasma conditions and the role of electric fields in nanoparticle deposition. In addition, electron temperature measurements showed a transient increase after acetylene injection, followed by stabilization as nanoparticle agglomeration reduced the particle density in the plasma. Taken together, the results highlight the interconnectedness of the processes governing nanoparticle synthesis and provide insight into the influence of plasma dynamics on nanoparticle formation and properties.

In this paper, dense plasma is studied using the pseudopotential approach to account for the effect of the bound electrons on the electron-ion potential shape near the ion core. The impact of the ion core effect on the structural and thermodynamic properties of dense plasmas is investigated taking into account both shielding effects and exchange-correlation screening. The effects of electronic exchange and correlation are considered by using the static local field correction in the long-wavelength limit. The ion core significantly affects the radial distribution functions and thermodynamic properties at a considered range of plasma parameters, including non-isothermal plasma conditions. The radial distribution functions indicate strong electron clustering for a smaller minimum depth due to stronger screening, while larger steepness of the core edge shifts the peaks to shorter distances, while for the same cases the non-ideality corrections increase.

Evolution of DC- and AC-driven charged dust-grain systems initially lattice-like pinned at randomly distributed pin sites is investigated. Molecular dynamics simulations show that mode-locking of the evolving system can occur when the effects of the DC and AC drivers balance. Intermittent mode-locking and plastic flow behavior in the evolution can also occur, depending on the characteristics (such as the magnitude and frequency) of the drivers as well as the initial kinetic temperature of the dust grain system.

Jupiter's magnetospheric data reveal unusual plasma expansion and Alfvén wave-driven stochastic acceleration of plasma particles, affecting navigation satellites, planetary and lunar weather patterns, solar wind dynamics, and more. Observations of Jupiter's equatorial plasma sheet show the excitation of Alfvénic disturbances and wave–particle interaction of Alfvén waves at kinetic scales, thereby accelerating electrons to keV–MeV energy ranges by the key mechanism of Landau damping. In this work, we investigate the features of kinetic Alfvén wave in high-latitude regions of Jupiter plasma sheet, highlighting the ion mass effects on wave dispersion, polarization properties, and the decay of Poynting flux associated with these waves. The resonance conditions are affected by temperature, wave fields, and parallel wave number, resulting in lower flux decay for hotter electrons and stronger ambient magnetic field. The electron heating rate associated with the kinetic dissipation of Alfvén waves along the background magnetic field lines, as a consequence of wave–particle resonant interaction, is also investigated under the drift-kinetic approximation for colder ions. The results indicate that kinetic Alfvén waves are among the drivers of particle acceleration, causing energization parallel to the magnetic field in the inner plasma sheet, as observed in the satellite data.

We develop an analytical formalism of two-plasmon decay (TPD) of laser in a rippled density plasma. The density ripple could be produced by using a machining laser beam or it could be the ion acoustic wave produced in the stimulated Brillouin scattering process. The density ripple couples with the decay Langmuir waves (of the TPD process), producing short wavelength space charge quasi-modes, heavily Landau damped on electrons. The quasi-modes act as energy drains on the Langmuir waves and enhance their damping rates (nearly as the square of amplitude of ripple density). This leads to a higher threshold laser intensity for the onset of TPD and a reduction in the growth rate of the parametric instability. The effect is more pronounced at higher electron temperatures.