卷 45, 编号 10 (2019)

A review of studies of coronal mass ejections (CMEs) and the propagation of the resulting interplanetary coronal mass ejections (ICMEs) in the heliosphere is presented. The main parameters of ICMEs, their differences from other types of solar wind (SW) streams, and correlation of the ICME occurrence rate with the state of solar activity are considered. Special attention is paid to the formation and simulation of the ion composition of the CME/ICME plasma, which is one of the key factors in identifying the types and sources of SW streams, especially in complex structures formed in the heliosphere during the interaction of streams. Models for predicting the parameters of SW streams from observational data are considered. The review also presents the lists of literature sources on coronal ejections and databases on the parameters of SW streams, as well as numerous references to the works on the phenomena under study.

A self-consistent model of the formation and evolution of dusty plasma structures in the ionospheres of the Earth and Mars is presented. The model allows describing the formation of a stratified dust structure as a result of dust cloud evolution in the Earth’s ionosphere. The structure forms due to the splitting of the primary cloud and is characterized by the presence of a cluster of dust grains at altitudes corresponding to noctilucent clouds and polar mesosphere summer echoes. The characteristic formation time of polar mesospheric clouds in the Earth’s ionosphere obtained within this model agrees with observational data. The possibility of the formation of oversaturated carbon dioxide clouds in the Martian ionosphere, similar to noctilucent clouds in the Earth’s ionosphere, is shown. It is demonstrated that phenomena similar to polar mesosphere summer echoes on the Earth can also take place in the Martian ionosphere. The theoretically estimated dimensions and charges of dust grains in the Martian ionosphere agree with observational data.

A special regime of the lower ionosphere sounding at altitudes of about 100 km reveals radio reflections from fairly dense (with a line density of 10¹⁴–10¹⁶ m^–1) ionized meteor trails with a characteristic lifetime from a few tens of seconds to several tens of minutes. During the first 250 s, radio reflections from ionized trails with a line density of (2–3) × 10¹⁵ m^–1 exhibit a power-law time dependence of the frequency of the reflected radio signal, \(f \propto {{t}^{{ - \gamma }}}\), with γ = 0.5 (classical diffusion mode). Less dense trails decay more slowly (γ < 0.5, subdiffusion mode), while denser ones decay faster (γ > 0.5, superdiffusion mode). It is shown that different modes of diffuse spreading of meteor trails can be caused by the high inhomogeneity of the medium and depend on the scale of ionized trails arising upon destruction of meteoroids.

Electron motion in a classical three-block model of the stationary plasma thruster (SPT) invented by A.I. Morozov is analyzed. It is demonstrated that the motion of electrons produced with a zero initial velocity due to working gas ionization critically depends on the position of the starting point along the accelerating channel axis. While the electron trajectories in the cathode region are regular, they become ergodic closer to the anode, which is accompanied by enhanced particle transport along the thruster channel. This transition is associated with the presence of a boundary at which erosion of the discharge chamber wall takes place in the experiment. The discovered ergodization of electron trajectories can be responsible for the anomalous electron conductivity in the near-anode region of the SPT.

An investigation of energetic ion beam emission from a low-energy (1.5 kJ) Mather-type plasma focus (PF) device operating with argon gas is studied with an operating pressure ranging from 2 × 10⁻² to 1 Torr. The device has been energized by 30.84-μF capacitors charged up to 10 kV, giving a peak discharge current up to 120 kA with a rise time of 3 μs. A Faraday cup (FC) and its operation has been studied. This device is utilized to perform time-of-flight (TOF) measurements in order to characterize the beams of charged particles. The FC is placed at 20 cm from the tip of anode electrode at 0° with respect to anode axis to detect the ions. The FC operating in bias ion collector mode has been developed for measuring and characterizing pulsed ion beam. Energy and velocity of ions are determined with the TOF method, taking into account distance from the center electrode to the detection plane. The surface morphology of the pristine and irradiated ZnOCo_0.04 samples is investigated as imaged by scanning electron microscope (SEM). The untreated sample showed rather relatively smooth surface; meanwhile, the SEM micrographs of bombarded samples display numerous small voids on the surface of the ZnOCo_0.04 samples as a result of ion beam emission from PF device. X-ray fluorescence analysis showed that there are some new elements appeared on the surface of the sample after exposed to the ion beam; these elements and their concentrations are recorded. The surface roughness values for the pristine and the irradiated ZnOCo_0.04 sample with Ar ion beam at different plasma shots are measured. A Vickers microhardness tester is used to measure the surface hardness, and the results demonstrate a significant increase in the hardness depending on the ion dose and decreases by increasing the applied load at 0° angular position.

It is proposed to determine the propagation velocity of a self-sustained subthreshold microwave (SSM) discharge by measuring the beatings between the reflected radiation and the reference signal. It is shown that the velocity of the head part of the SSM discharge determined from the fundamental frequency harmonic of the beating signal coincides with the velocity of the front of UV discharge radiation. The proposed method allows one to measure the velocity of the head part of the discharge along the microwave beam path, variations in this velocity caused by changes in the microwave beam power, the reduction in the gas density along the beam path, and the time delay in the initiation of the burning wave in methane–air mixtures.

Experimental results are presented on the current commutation in a low-power gas discharge with external plasma injection. Correlation between current commutation and cathode spot ignition is established. It is shown that the cathode spot is ignited synchronously with the filling of the discharge gap with dense plasma and quenched synchronously with the release (gas-dynamic unloading) of the gap from the plasma. It is found that the spot is ignited over 1–30 ns due to the local explosive heating of the cathode surface (at a heating rate of higher than 10¹² K/s) by the field emission current. It is also shown that the spot is quenched over a time of less than 100 ps and that the processes leading to the quenching develop simultaneously in all cells of the cathode spot.

At the present time, some ECR ion sources use a high-frequency powerful microwave radiation of modern gyrotrons for plasma heating. Due to high radiation power, such systems mainly operate in a pulsed mode. This type of ECR ion sources was developed at the Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS), and most experimental research was performed at the SMIS 37 facility, at which 37 gyrotrons with 37.5- and 75-GHz frequencies and 100- and 200-kW maximum powers, respectively, were used for plasma production. Such heating microwaves allow creating plasma with unique parameters: electron density >10¹³ cm^–3, electron temperature of 50–300 eV, and ion temperature of about 1 eV. The principal difference between these systems and conventional ECR sources is a so-called quasi-gas-dynamic regime of plasma confinement. In accordance with the confinement regime, such sources have been called “gas-dynamic ECR sources.” Typically, plasma lifetime in such systems is about several tens of microseconds, which, in combination with the high plasma density, leads to the formation of plasma fluxes from a trap with a density of up to 1–10 A/cm². The possibility of production of multiply charged ion beams (nitrogen, argon) and proton (or deuterium) beams with currents of up to a few hundred mA and normalized rms emittance of about 0.1π mm mrad was demonstrated. The next step in the research is a transition to continuous wave operation. For this purpose, a new experimental facility is under construction at the IAP RAS. A future source will utilize 28- and 37.5-GHz gyrotron radiation for plasma heating. An overview of the obtained results and the status of the new source development is presented.