scholarly journals Пылевые звуковые солитоны в плазме запыленной экзосферы Луны

Author(s):  
С.И. Копнин ◽  
С.И. Попель

This paper shows a possibility of the existence and propagation of dust acoustic solitons in plasmas of dusty exosphere of the Moon, which contains, in addition to electrons and ions of the solar wind and photoelectrons from the lunar surface, also charged dust particles, as well as photoelectrons emitted from the surfaces of these particles. Soliton solutions are found and the ranges of possible velocities and amplitudes of such solitons are determined depending on the height above the lunar surface for different subsolar angles.

Author(s):  
С.И. Копнин ◽  
С.И. Попель

A possibility of propagation of localized wave structures, such as dust acoustic solitons, in dusty ionospheric plasmas, which contain photoelectrons, electrons and ions, as well as charged dust particles, is considered. The regions of possible velocities and amplitudes of solitons are determined. Soliton solutions are found for various sizes and number densities of dust particles in the dusty ionospheric plasmas.


2013 ◽  
Vol 79 (4) ◽  
pp. 405-411 ◽  
Author(s):  
SERGEY I. POPEL ◽  
LEV M. ZELENYI

AbstractFrom the Apollo era of exploration, it was discovered that sunlight was scattered at the terminators giving rise to “horizon glow” and “streamers” above the lunar surface. Subsequent investigations have shown that the sunlight was most likely scattered by electrostatically charged dust grains originating from the surface. A renaissance is being observed currently in investigations of the Moon. The Luna-Glob and Luna-Resource missions (the latter jointly with India) are being prepared in Russia. Some of these missions will include investigations of lunar dust. Here we discuss the future experimental investigations of lunar dust within the missions of Luna-Glob and Luna-Resource. We consider the dusty plasma system over the lunar surface and determine the maximum height of dust rise. We describe mechanisms of formation of the dusty plasma system over the Moon and its main properties, determine distributions of electrons and dust over the lunar surface, and show a possibility of rising dust particles over the surface of the illuminated part of the Moon in the entire range of lunar latitudes. Finally, we discuss the effect of condensation of micrometeoriod substance during the expansion of the impact plume and show that this effect is important from the viewpoint of explanation of dust particle rise to high altitudes in addition to the dusty plasma effects.


Author(s):  
Alexander V. Zakharov

The surface of the Moon, as well as the surface of an airless body of the solar system, is subject to constant bombardment of micrometeorites, the effects of solar radiation, solar wind, and other space factors. As a result of the impact of high-speed micrometeorites for billions of years, the silicate base of the lunar surface is crushed, turning into particles with an approximately power-law-sized distribution. Given the explosive nature of the occurrence, these particles are characterized by an extremely irregular shape with pointed edges, either droplets close to spheres or conglomerates sintered at high temperatures. The plasma of the solar wind and the solar radiation, especially its ultraviolet part of the spectrum, when interacting with the upper layer of regolith causes a charge of the regolith upper layer and creates a near-surface double layer and an electric field. In this field, regolith particles of micron and submicron sizes can break away from the surface and levitate above the surface. Such dynamic processes lead to the transfer of dust particles over the surface of the Moon, as well as to the scattering of sunlight on these particles. Glows above the lunar surface of this nature were observed by television systems of American and Soviet landers in the early stages of lunar exploration. The American astronauts who landed on the lunar surface during the Apollo program experienced the aggressive properties of lunar dust. The results of the Apollo missions showed that dust particles are one of the main causes of danger to humans, spacecraft systems, and activities on the lunar surface. Based on the results of late 20th- and early 21st-century lunar research, as well as the proposed models, the article discusses the formation of the lunar regolith and the near-surface exosphere of the Moon under the influence of external factors in outer space. Relevant considerations include the causes and conditions of dust particle dynamics, the consequences of these processes as well as possible threats to humans, engineering systems during the implementation of planned research programs, and the exploration of the Moon. Also of relevance are models of the formation of a plasma-dust exosphere, the dynamics of dust particles in the near-surface region, and dust clouds at a distance of several tens of kilometers from the Moon’s surface, based on the available experimental data. The main unresolved problems associated with the dynamics of the dust component of lunar regolith are given, and methods for solving problematic issues are discussed. The Moon research programs of leading space agencies and their role in the study of Moon dust, its dynamics, human impact, and its activities in the implementation of promising programs for the study and exploration of the Moon are examined.


1976 ◽  
Vol 31 ◽  
pp. 233-237 ◽  
Author(s):  
Otto E. Berg ◽  
Henry Wolf ◽  
John Rhee

In December, 1973, a Lunar Ejecta and Meteorites (LEAM) experiment was placed in the Taurus-Littrow area of the moon by the Apollo 17 Astronauts. Objectives of the experiment were centered around measurements of impact parameters of cosmic dust on the lunar surface. During preliminary attempts to analyze the data it became evident that the events registered by the sensors could not be attributed to cosmic dust but could only be identified with the lunar surface and the local sun angle. The nature of these data coupled with post-flight studies of instrument characteristics, have led to a conclusion that the LEAM experiment is responding primarily to a flux of highly charged, slowly moving lunar surface fines. Undoubtedly concealed in these data is the normal impact activity from cosmic dust and probably lunar ejecta, as well. This paper is based on the recognition that the bulk of events registered by the LEAM experiment are not signatures of hypervelocity cosmic dust particles, as expected, but are induced signatures of electrostatically charged and transported lunar fines.


2013 ◽  
Vol 31 (1) ◽  
pp. 39-44 ◽  
Author(s):  
I. Mann ◽  
M. Hamrin

Abstract. In a recent paper, Treumann and Baumjohann (2011) propose that the contribution of dust particles to the solar wind dynamic pressure can cause large compressions of the Earth's magnetopause and suggest that this occurs when Earth encounters meteoroid streams. In this paper we estimate the contribution from charged dust particles to the solar wind dynamical pressure, and we exclude that the dust associated to meteoroid streams can influence the extension of the magnetopause according to the proposed model. A sufficient coupling to the solar wind is only expected for so-called nanodust. However, the dynamic pressure of the nanodust is orders of magnitudes below that of the solar wind, making it unlikely that its variation can be observed in displacements of the magnetopause. We also discuss the equation that the authors use for estimating the extension of the Earth's magnetopause, and conclude that this is not applicable due to the large gyroradius of the nanodust. We finally note that an influence of dust on the extension of a magnetosphere might be quite possible in other astrophysical systems and based on other processes.


2007 ◽  
Vol 73 (5) ◽  
pp. 671-686 ◽  
Author(s):  
S. K. MAHARAJ ◽  
R. BHARUTHRAM ◽  
S. R. PILLAY

AbstractThe nonlinear propagation of the dust-acoustic wave is investigated in a weakly non-ideal plasma comprising Boltzmann electrons, non-thermal ions characterized by a non-thermal parameter α and a negatively charged dust fluid. The non-ideal dust fluid is represented by the van der Waals equation of state. Arbitrary amplitude soliton solutions are found to occur for both supersonic and subsonic values of the Mach number. Upper and lower limits of the range of values of α for which solitons exist are examined as a function of the non-ideal parameters associated with the effects of volume reduction and the cohesive forces, for both the supersonic and subsonic cases.


Author(s):  
Joseph E. Borovsky ◽  
Gian Luca Delzanno

When the Earth’s moon is in the supersonic solar wind, the darkside of the Moon and the lunar plasma wake can be very dangerous charging environments. In the absence of photoelectron emission (dark) and in the absence of cool plasma (wake), the emission or collection of charge to reduce electrical potentials is difficult. Unique extreme charging events may occur during impulsive solar-energetic-electron (SEE) events when the lunar wake is dominated by relativistic electrons, with the potential to charge and differentially charge objects on and above the lunar surface to very-high negative electrical potentials. In this report the geometry of the magnetic connections from the Sun to the lunar nightside are explored; these magnetic connections are the pathways for SEEs from the Sun. Rudimentary charging calculations for objects in the relativistic-electron environment of the lunar wake are performed. To enable these charging calculations, secondary-electron yields for impacts by relativistic electrons are derived. Needed lunar electrical-grounding precautions for SEE events are discussed. Calls are made 1) for future dynamic simulations of the plasma wake in the presence of time-varying SEE-event relativistic electrons and time-varying solar-wind magnetic-field orientations and 2) for future charging calculations in the relativistic-electron wake environment and on the darkside lunar surface.


2015 ◽  
Vol 81 (6) ◽  
Author(s):  
U. Zakir ◽  
Q. Haque ◽  
N. Imtiaz ◽  
A. Qamar

The properties of dust acoustic and drift waves are investigated in a charge varying magnetized dusty plasma. The plasma is composed of non-thermal electrons and ions with dynamic dust particles. The mathematical expression which describes the dust charge fluctuation is obtained using ${\it\kappa}$-distribution for both the electrons and ions. A dispersion relation is derived and analysed numerically by choosing space plasma parameters. It is found that the inclusion of variable dust charge along with the non-thermal effects of electrons and ions significantly affect linear/nonlinear properties of the dust acoustic and dust drift waves. The effects of different physical parameters including spectral index (${\it\kappa}$), dust charge number ($Z_{d}$), electron density ($n_{e}$) and ion temperature ($T_{i}$) on the wave dispersion and instability are presented. It is found that the presence of the non-thermal electron and ion populations reduce the growth rate of the instability which arises due to the dust charging effect. In addition, the nonlinear vortex solutions are also obtained. For illustration, the results are analysed by using the dusty plasma parameters of Saturn’s magnetosphere.


2013 ◽  
Vol 91 (7) ◽  
pp. 582-587 ◽  
Author(s):  
Amandeep Singh Bains ◽  
Nareshpal Singh Saini ◽  
Tarsem Singh Gill

An investigation has been made to study the properties of large-amplitude electrostatic solitary waves in dusty plasma containing both negatively and positively charged dust fluids in the presence of superthermal electrons and ions. The energy balance equation is derived by using the Sagdeev pseudopotential approach. The influence of the physical parameters (e.g., superthermality of electrons or ions, density concentration of positive and negative dust particles, solitary speed) on the amplitude of dust acoustic solitary waves has been discussed in detail. It is observed that there exists a critical value of density, below which negative potential solitary structures exist and above which positive potential solitary structures exist.


Sign in / Sign up

Export Citation Format

Share Document