Laser-Induced Plasma Atomic and Ionic Emission During Target Ablation

This paper investigates the spectroscopy of plasma that resulted from the bombardment of ZnSe by using the optical emission spectroscopic (OES) technique. The plasma can be generated by the reaction between an Nd:YAG laser, with a wavelength of 1064[Formula: see text]nm with a repeat rate of 6[Formula: see text]Hz (as well as 9[Formula: see text]ns pulse duration), and a solid target, where the density of the electron (ne), the temperature of the electron ([Formula: see text]), the frequency of the plasma ([Formula: see text]) and the Debye length ([Formula: see text]) as plasma parameters, in addition to the particles’ number of Debye ([Formula: see text]) and plasma parameter ([Formula: see text]) have been calculated by picking up the spectrum of plasma at different energies (100, 200, 300, 400, 500) mj using Selenium (Se), Zinc (Zn) and the mixture (ZnSe) at ([Formula: see text]). It is found that the electron temperatures of Zn and Se ranged between (0.257–0.267)[Formula: see text]eV and (1.036–1.055) eV, respectively, while that of ZnSe ranged between (1.15–1.28)[Formula: see text]eV. This indicates that the electron temperature of ZnSe is higher than the temperatures of each Zn and Se.

Plasma-Profile Control in an ICP Reactor

ICP is widely used in electromagnetic scattering due to its high electron density and simple structure. The distribution of plasma parameters can affect the electromagnetic scattering, so the control of plasma parameter distribution is very important for aircraft stealth. Firstly, the effect of the number of coil turns on the plasma parameter distribution is analyzed. With the increase of the number of coil turns, the peak value of induced magnetic field decrease, the width of magnetic field increase and the homogeneity of plasma increase. Then, the Boltzmann solver is used to calculate the plasma electron energy distribution function at different positions under the four-turn coil. Finally, the influence of external circuit capacitance on plasma parameter distribution is analyzed. In this cavity structure, the electron density first increases and then decreases with the external circuit capacitance increase, and the peak value is on 75 pF. In this study, we propose a method to further regulate the plasma parameter distribution by using terminal capacitance to control the induced magnetic field.

Investigation of Nonthermal Plasma Jet Excitation Mode and Optical Assessment of Its Electron Concentration

The results of a study of a plasma jet of atmospheric-pressure helium driven by a capacitive discharge using sine and pulsed modes of excitation are presented. The homogeneous discharge of a multi-channel plasma jet at gas temperature of 34 °C and helium flow rate of 0.5 L/min was achieved with short pulse excitation. A digital holography method is proposed to estimate a basic plasma parameter, i.e., its electron concentration. An automated digital holographic interferometry set-up for the observation and study of a nonthermal plasma jet in a pulse mode is developed and described. The synchronization features of recording devices with the generation of plasma pulses are considered. The electron concentration of the plasma jet is also estimated. The disadvantages of the proposed technique and its further application are discussed.

Bridging the gap between collisional and collisionless shock waves

While the front of a fluid shock is a few mean-free-paths thick, the front of a collisionless shock can be orders of magnitude thinner. By bridging between a collisional and a collisionless formalism, we assess the transition between these two regimes. We consider non-relativistic, non-magnetized, planar shocks in electron–ion plasmas. In addition, our treatment of the collisionless regime is restricted to high-Mach-number electrostatic shocks. We find that the transition can be parameterized by the upstream plasma parameter $\varLambda$ which measures the coupling of the upstream medium. For $\varLambda \lesssim 1.12$ , the upstream is collisional, i.e. strongly coupled, and the strong shock front is about $\mathcal {M}_1 \lambda _{\mathrm {mfp},1}$ thick, where $\lambda _{\mathrm {mfp},1}$ and $\mathcal {M}_1$ are the upstream mean free path and Mach number, respectively. A transition occurs for $\varLambda \sim 1.12$ beyond which the front is $\sim \mathcal {M}_1\lambda _{\mathrm {mfp},1}\ln \varLambda /\varLambda$ thick for $\varLambda \gtrsim 1.12$ . Considering that $\varLambda$ can reach billions in astrophysical settings, this allows an understanding of how the front of a collisionless shock can be orders of magnitude smaller than the mean free path, and how physics transitions continuously between these two extremes.

Spectroscopic diagnostic complex based on the magnetron sputtering device with a digital method of the data mining

A diagnostic complex based on a magnetron sputtering device is proposed for studying a magnetron discharge plasma parameter by optical emission spectroscopy, using two spectroscopic systems: photographic and photoelectric. Software for digital processing of the obtained emission spectra is developed. The results obtained by the two spectroscopic systems are compared.