We consider the formation of the periodic structures named dunes, which were observed during auroral events and were presented in the form of a set of almost horizontal stripes of green emission with an estimated period of 45 +/- 14 km at some altitude in the altitude range of 90-110 km. Most observations of this event refer to October, the time when the high-speed meteor shower Draconids occurs. During high-speed meteor showers ablation of meteors in the lower ionosphere and subsequent condensation of the evaporated substance results in the formation of a dusty ionospheric plasma (Kopnin S.I. et al., Phys. Plasmas 16 , 063705 (2009)). At the altitudes of about 100 km the modulational instability in dusty plasmas can develop leading to an appearance and growth of dust acoustic waves. If the growth is not compensated by other effects at early stage, the wave perturbations can become intensive enough to form a nonlinear periodic wave structure. We show that the formation of the dunes observed in the altitude range of 90-110 km during the period of Draconids meteor shower can be associated with such nonlinear periodic dust acoustic wave structures.
Dust acoustic solitons and nonlinear periodic waves propagating in the ionosphere of Mars in plasma–dust clouds at altitudes of about 100 km have been considered. The dependence of the soliton amplitude on the charge of dust particles and plasma electron density has been studied. It is shown that an important factor influencing the soliton parameters is the adiabatic capture of plasma electrons (ions). The possibility of the existence of nonlinear periodic waves in the ionosphere of Mars has been studied. It is shown that the spatial period of the wave can be sufficient for its recording by a spacecraft. The possibility of the occurrence of dust acoustic wave perturbations in the ionosphere of Mars should be taken into account when processing and interpreting observation data.
A theoretical model is presented that describes the settling regime of plasma-dust clouds in the mesosphere of Mars. The values of the characteristic sizes of cloud dust particles predicted by the model are calculated. It is shown that an important factor influencing the formation of plasma-dust structures in the Martian atmosphere is the Rayleigh–Taylor instability, which limits (from above) the permissible sizes of dust particles in the cloud.
The ion-acoustic instability in the tails of meteoroids as a result of their passage through the Earth’s atmosphere is studied and the conditions under which it develops are given. The development of this instability occurs as a result of the relative motion of the plasma of meteoroid tails and the dusty plasma of the Earth’s ionosphere. Dust, in turn, creates conditions when this instability can develop in a situation of approximately equal ion and electron temperatures, which is observed in the plasma–dust system under consideration. The mechanism of the excitation of ion-sound waves as a result of the development of the ion-acoustic instability in meteoroid tails is shown. The growth rates of the ion-acoustic instability and the characteristic times of its development are found. It is shown that the instability has time to develop during the time of passage of a meteoroid body in the Earth’s atmosphere and the formation of a meteoroid trail, which has values much greater than the time of development of ion-acoustic instability in the system under consideration. The wave vectors and velocities of meteoric bodies, at which the development of the ion-acoustic instability is expected, are found. It is noted that the instability can reach a nonlinear regime at possible large wave amplitudes.
It is assumed that the low-frequency noise recorded on the surface of Mars may be associated with a charged dust component in its atmosphere and the occurrence of sound perturbations in such a dust system that modulate the electromagnetic wave from the Sun. It is also shown that it can be associated with plasma-dust processes in meteoroid tails. The mechanism for the excitation of modulational instability of an electromagnetic wave associated with a dust acoustic mode in the Martian atmosphere, namely in dust clouds at an altitude of 60 and 100 km, where the dusty plasma with particles of frozen carbon dioxide is detected, is described. It is shown that the development of modulational instability is due to the influence of high-frequency electromagnetic waves on the dusty plasma in the Martian atmosphere from both natural sources (solar radiation, lightning discharges) and anthropogenic nature (from equipment from space satellites and from stations on the surface of the planet). The parameters of electromagnetic pump waves, at which the active development of modulational instability of electromagnetic waves associated with the dust acoustic mode is expected, and the modulational instability growth rates are found. The development of the modulational instability in the dusty plasma of Martian clouds, in turn, can explain the occurrence of low-frequency noise recorded by equipment on the surface of Mars. The relation between observed radio noise in the range of 3 Hz–3 kHz and plasma-dust processes in the Martian atmosphere, in particular, in dust clouds at 60 and 100 km, as well as in dusty plasma meteroid tails, where the dust concentration is high, is discussed.
A mechanism of formation of plasma-dust system above the surface of Enceladus, the Saturn moon, illuminated by the solar radiation is proposed. It is demonstrated that the photoelectric effect caused by the sunlight and the influence of the solar-wind plasma create conditions for lifting of dust particles above the surface of the moon as a result of electrostatic repulsion. Based on a self-consistent model describing the electrostatic field and plasma components, including photoelectrons emitted from the Enceladus surface and those emitted from the surface of the dust particles, distribution functions of photoelectrons, dust particles, and their electrostatic charges are determined as functions of altitude and the angle between the local normal and the direction to the Sun. Also determined are the altitude profiles of the electrostatic fields for the corresponding angles between the local normal and the direction of the solar radiation. It is demonstrated that the photoelectric effect plays an important role in formation of dusty plasma near the Enceladus surface despite considerable distance from the Sun. It is established that concentration of photoelectrons above the Enceladus surface can exceed concentration of electrons and ions of the solar wind by an order of magnitude, and the size of the levitating particles is larger than the characteristic size of dust particles lifted above the surface of the Moon due to the fact that Enceladus is much smaller than the Moon. On the contrary, the size of particles levitating above Enceladus is much smaller than the size of particles levitating above the surface of celestial objects smaller than the Enceladus, e.g., the Martian satellites Phobos and Deimos.
The anomalous dissipation related to the effect of charging of dust particles that gives rise to new physical phenomena, effects, and mechanisms represents one of the main specific features of dusty plasma that makes it different from conventional plasma containing no charged dust particles. We analyze the process of anomalous dissipation in the context of description of the dynamics of dust particles in dusty plasma of the Mercury’s exosphere. An analytical description of oscillations of a dust particle above the surface of Mercury is presented. The frequency of charging of dust particles that characterizes the anomalous dissipation determines the damping of such oscillations. It is demonstrated that the anomalous dissipation is important for substantiation of the model of levitating dust particles that is used for description of dusty plasma above Mercury. The results of numerical simulations that justify the use of the discussed model are presented.
A description is given of low-frequency nonlinear dust acoustic waves in Saturn’s dusty magnetosphere, which contains electrons of two types (hot and cold) obeying the kappa distribution, magnetospheric ions, and charged dust particles. For the corresponding conditions, the derivation of the Zakharov–Kuznetsov equation is given, which describes the nonlinear dynamics of dust acoustic waves in the case of low frequencies and a pancake-shaped wave packet along an external magnetic field. It is shown that under the conditions of Saturn’s magnetosphere there exist solutions of the Zakharov–Kuznetsov equation in the form of one-dimensional and three-dimensional solitons. Possible observations of the considered solitons in future space missions are discussed.
A brief review of theoretical studies of circumlunar dusty plasma, the important factors in the formation of which are electrostatic processes and impacts of micrometeoroids on the lunar surface, is given. Observation data of dust particles in the vicinity of the Moon, obtained within the “Luna-25” mission, are described for the first time. It is shown that there is at least one reliable observation of a dust particle either of lunar origin or associated with the high-speed Perseid stream. The need to improve the Lunar Dust Monitor device on the “Luna-27” lander is discussed. The improvement is associated with the need to install a rod for placing electrostatic sensors at a sufficient distance from the device, which is desirable to reduce disturbances of the surrounding plasma and the near-surface electrostatic field because of the influence of the lander.
Dusty plasma processes in the physics of comets are considered. The distribution functions of photoelectrons, the altitude dependences of the charges and sizes of dust particles, as well as electric fields are determined using a physicomathematical model for the self-consistent description of densities of photoelectrons and dust particles above the illuminated part of a comet nucleus. It has been shown that dusty plasma processes are significantly manifested when a comet is sufficiently far from the Sun. The dusty plasma near the comet nucleus with the parameters close to the parameters of the nucleus of Halley’s comet at distances to the Sun no less than 2.5–3.5 AU is formed due to the electrostatic interactions similar to the formation of dusty plasmas near other atmosphereless bodies (e.g., the Moon, satellites of Mars, and asteroids). The dynamics of dust particles at closer distances from the Sun is determined by the gas flow from the comet nucleus.
Представлена теоретическая модель, описывающая режим оседания плазменно-пылевых облаков в мезосфере Марса. Рассчитаны значения характерных размеров пылевых частиц облака, предсказываемые моделью. Показано, что важным фактором, влияющим на процесс формирования плазменно-пылевых структур в марсианской атмосфере, является неустойчивость Рэлея–Тейлора, ограничивающая (сверху) допустимые размеры пылевых частиц облака.
One of the main features that distinguishes dusty plasma from ordinary (not containing charged dust particles) plasma is anomalous dissipation associated with the process of charging dust particles, leading to new physical phenomena, effects and mechanisms. The process of anomalous dissipation is considered in the context of describing the dynamics of dust particles in the dusty plasma of atmosphereless bodies of the Solar System. A description of the oscillations of a dust particle over the surfaces of Mercury, the Moon, and the Martian satellites Phobos and Deimos is presented, the attenuation of which is determined by the charging frequency of the dust particles, which characterizes anomalous dissipation. The possibility of using an approach that takes into account anomalous dissipation to describe plasma-dust processes in the vicinity of comets is discussed. It is shown that anomalous dissipation plays a significant role in determining the possibility of using the model of levitating dust particles in describing dusty plasma over the surfaces of atmosphereless bodies of the Solar System. The results of numerical calculations are presented, confirming the possibility of using this model for a number of atmospherelesso cosmic bodies.
In the Earth’s atmosphere at altitudes of 80–120 km during high-speed meteor showers, conditions are created for the appearance of a dusty plasma system. As a result of the development of the modulation instability of the electromagnetic waves, in the dusty ionospheric plasma, linear and nonlinear dust acoustic waves can be excited. The new phenomenon observed above the Scandinavian countries, the so-called dunes, which are, in fact, periodic wave structures that extend to far distances in the horizontal direction and have a characteristic spatial period of about 45 km, can be one of the manifestations of the nonlinear dust acoustic waves. The maximum number of dunes was recorded in October, when the Draconids meteor shower is observed. We consider the nonlinear periodic dust acoustic waves that can develop in the dusty plasma with parameters that correspond to the ionospheric plasma during meteor showers.
We review studies of physical processes associated with the impact of external factors in outer space flows of micrometeoroids and solar radiation on the lunar regolith. Under the influence of these factors, regolith microparticles can detach from the surface and levitate. Near-surface plasma and levitating dust particles form a plasma-dust exosphere of the Moon. Under anthropogenic effects on the lunar environment, charged levitating microparticles can have an extremely negative impact on the engineering systems of lunar landers and on the activity and health of astronauts on the Moon. Based on information gained by automated and manned lunar missions and in laboratory experiments, we discuss modern ideas about physical processes occurring near the Moon's surface. Unsolved problems associated with the plasma-dust exosphere of the Moon are considered, and the principal strategies for their solution are outlined.
Since the first automatic missions to the Moon, the activity of dust particles from atmosphereless bodies has been recorded. Since then, a lot of theoretical and experimental studies of this effect have been carried out, but at present there is no clear understanding of the influence of external actions on the dynamics of this phenomenon. This paper presents the results of experiments to determine the effect of hard UV radiation on the activity of dust particles, which makes a significant contribution to particle dynamics. The result of determining the conditions for particle removal from the surface is in accordance with theoretical calculations.
— The mode of subsidence of layered structures in the ionosphere of Mars has been studied taking into account the compositional features of the Martian atmosphere. The characteristic sedimentation rates of dust particles, their sizes and charges, as well as the sedimentation time of layered structures are calculated. The results obtained can be used in the study of atmospheric phenomena on Mars in the course of upcoming space missions.
Представлено двумерное описание нелинейных пылевых звуковых волн в запыленной магнитосфере Сатурна, которая содержит электроны двух сортов (горячие и холодные), подчиняющиеся каппа-распределению, ионы магнитосферы, а также заряженные пылевые частицы. Для условий запыленной магнитосферы Сатурна приведен вывод уравнения Кадомцева–Петвиашвили, описывающего нелинейную динамику почти одномерных волновых структур. Рассмотрена возможность распространения локализованных волновых структур типа пылевых звуковых солитонов. Показано, что в условиях магнитосферы Сатурна существуют решения уравнения Кадомцева–Петвиашвили в виде одномерных солитонов и двумерных N -солитонов. Обсуждаются возможные наблюдения рассматриваемых солитонов в будущих космических миссиях.