Том 43, № 10 (2017)
- Год: 2017
- Статей: 6
- URL: https://journals.rcsi.science/1063-780X/issue/view/11657
Magnetic Confinement Systems
Local synthesis of 3D magnetic surfaces
Аннотация
Local synthesis of nested 3D toroidal magnetic surfaces is carried out on the basis of the general theory of surfaces by using magnetic coordinates (generally unknown a priori). An equilibrium magnetic surface is calculated by specifying two functions on the surface (the absolute value of the magnetic field and the distance to the nearest magnetic surface) and three parameters (the rotational transform, pressure gradient, and poloidal current). The choice of the parameters is restricted by the requirement that the surface should be closed toroidally. A method of synthesis of a closed magnetic surface is proposed when two functions—the absolute value of the magnetic field and the major radius—are specified. A set of harmonics of a new type of poloidally preudosymmetric configuration (a toroidal mirror with a large mirror ratio and small rotational transform) is obtained.
Dusty Plasma
Nonlinear screening of dust grains and structurization of dusty plasma: II. formation and stability of dust structures
Аннотация
The second part of the review on dust structures (the first part was published in Plasma Phys. Rep. 39, 515 (2013)) is devoted to experimental and theoretical studies on the stability of structures and their formation from the initially uniform dusty plasma components. The applicability limits of theoretical results and the role played by nonlinearity in the screening of dust grains are considered. The importance of nonlinearity is demonstrated by using numerous laboratory observations of planar clusters and volumetric dust structures. The simplest compact agglomerates of dust grains in the form of stable planar clusters are discussed. The universal character of instability resulting in the structurization of an initially uniform dusty plasma is shown. The fundamental correlations described in the first part of the review, supplemented with effects of dust inertia and dust friction by the neutral gas, are use to analyze structurization instability. The history of the development of theoretical ideas on the physics of the cluster formation for different types of interaction between dust grains is described.
Space Plasma
System of kinetic equations describing large-scale processes in collisionless space plasma
Аннотация
A system of kinetic equations describing relatively slow large-scale processes in collisionless magnetoplasma structures with a spatial resolution of about the characteristic gyroradius is derived. Plasma is assumed to be quasineutral, while the magnetic and electric fields are determined by the instantaneous distributions of the particle and current densities and the stress tensor of all plasma components in the longrange instantaneous interaction approximation. A special version of equations is derived for the case of magnetized electrons described by the Vlasov equation in the drift approximation. The obtained system of equations can be used to develop a global numerical kinetic model of the Earth’s magnetosphere with a spatial resolution of about 100 km, as well as local models of certain regions of the Earth’s magnetosphere with a higher resolution.
Low-Temperature Plasma
Analysis of applicability of triplet-state emission of molecular hydrogen for spectral diagnostics of a DC discharge
Аннотация
The applicability of emission of the N3Λσ triplet states of molecular hydrogen for spectral diagnostics of the positive column of a dc glow discharge in hydrogen at translational gas temperatures of 360–600 K, specific absorbed powers of 0.8–4.25 W/cm, gas pressures of p = 0.3–15.0 Torr, reduced fields of E/N = 30–130 Td, and electron densities of ne = 4.0 × 109–6.5 × 1010 cm–3 is analyzed by using an advanced level-based semi-empirical collisional−radiative model. It is found that secondary processes make the main contribution to the population and decay of the N3Λσ = a3Σ+g, c3Πu, g3Σ+g, h3Σ+g, and i3Πg triplet states. The dipole-allowed transitions e3Σ+g → a3Σ+g, f3Σ+g → a3Σ+g, g3Σ+g and k3Πu → a3Σ+g can be used for spectral diagnostics of a dc discharge within a simplified coronal model.
Pulsed high-voltage discharge in air with a pressure gradient
Аннотация
Results of experiments on high-voltage discharges in air with a pressure gradient are presented. The experiments were carried out at the setup developed at the Institute of Applied Physics, Russian Academy of Sciences. The goal of the experiments was laboratory modeling of high-altitude atmospheric discharges―sprites and jets. The setup and diagnostic techniques are described. The experimental results include the distribution of the gas pressure in the vacuum chamber formed by means of pulsed air puffing, photographs of discharges in air with a pressure gradient, and the dependences of the discharge current and optical emission intensity on the initial conditions.
Brief Communications
Determination of the lifetime of D2− and HD− ions
Аннотация
A method for determining the lifetime of unstable ions is described. The method is based on measuring the decrease in the ion beam current onto a fixed detector with increasing path length of the ion beam from the ion source to the detector. The measurements performed for D−2 and HD− molecular ions have shown that their lifetimes are 3.5 ± 0.1 and 4.4 ± 0.1 μs, respectively.