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Dust hazards are considered to be one of the technical challenges for future lunar exploration. In our past work a new dust mitigation technology was introduced utilizing an electron beam to remove dust particles from various surfaces. This technology was developed based on a patched charge model, which shows that the emission and re-absorption of electron beam induced secondary electrons inside microcavities between dust particles can lead to sufficiently large charges on the dust particles, causing their release from the surface due to strong repulsive forces. In this paper an improvement in the effectiveness of this technology is demonstrated with varying the beam incident angle on dust-covered sample surfaces by rotating the samples relative to the beam. Due to random arrangements of the microcavities, more of them will be exposed to the beam with various incident angles, thereby causing more dust release from the surface. The cleaning performance is tested against three samples: glass, spacesuit, and a photovoltaic (PV) panel. Lunar simulant (

We analyze the origin of dust particles in the near-surface layer of the Moon, the fluxes of which were measured in the Chang’e 3 lunar mission carried out by the People’s Republic of China (PRC). We consider the lunar regolith particles rising above the lunar surface due to either electrostatic processes or impacts of meteoroids. It turns out that the main contribution to the observed mass fluxes of dust was made by micron-size dust particles, which originate from the regolith matter ejected from the lunar surface due to meteoroid impacts. We perform theoretical calculations of the mass flux of dust particles accumulated on the measuring surface of the Chang’e 3 lander, which is at a height of 190 cm above the lunar surface. The result is that the theoretical estimate is roughly seven times higher than the value of the dust mass flux measured in the course of the Chang’e 3 mission. This disagreement may be caused by both (i) the inaccuracy in the parameters used in calculations to characterize the conditions on the Moon and the properties of the lunar regolith and (ii) the fact that the main mass of dust rising above the lunar surface due to meteoroid impacts is contained in micron-size particles, a significant portion of which could crumble from the measuring surface of the Chang’e lander and, consequently, was not covered by the measurements.

The dust removal efficiency of the existing dust control technologies for coal yards involving multiple dust production spots is low and cannot satisfy the requirements stipulated by the existing standards. This paper proposes a new type of vortex blowing suction dust control technology. The principle of dust control was examined through numerical simulations. The dust control efficiency of the single suction and vortex blowing suction methods was compared experimentally. The results indicated that most of the dust particles were collected by the vortex, and they moved in a spiral from the bottom to the top. The highest vortex airflow performance corresponded to an optimal blowing ratio of 4.814. The experimental comparison indicated that the dust removal performance of the vortex blowing suction technique was better. Specifically, for the formal and latter techniques, dust removal efficiency was 93.25% and 41.19%, and dust escape rate was 6.31% and 46.60%, respectively.

Проведены расчеты температурного баланса и орбитальной эволюции силикатных и графитовых пылевых частиц в области сублимации около белого карлика G29-38. Темп сублимации (испарения) задается температурой нагрева пылевых частиц в зависимости от расстояния до звезды, параметров материала и радиусов пылинок в пределах от 0.01 до 100 мкм. Учитывалось влияние давления радиации и эффекта торможения Пойнтинга-Робертсона на динамику пыли. В расчётах предполагается, что частицы срываются с родительских тел, движущихся по круговым орбитам. Наши расчёты показали, что гранулы могут образовать резкую границу области сублимации на определённом расстоянии от звезды в зависимости от материала частиц. Если около звезды с параметрами, близкими к G29-38, преобладают силикатные частицы, то внутренняя граница зоны сублимации для крупных гранул радиусами s > 5 мкм образуется на расстоянии около 45 Rstar ≈ 0.6Rsun. Малые силикатные частицы радиусами s < 0.1 мкм не могут приблизиться к звезде на расстояние ближе 300Rstar ≈ 4Rsun из-за быстрого испарения. Если преобладают графитнокарбоновые частицы, то граница зоны сублимации для частиц радиусами s > 0.2 мкм возможна на расстоянии около 12.5 Rstar ≈ 0.16 Rsun. Карбоновые частицы радиусами s < 0.1 мкм испаряются за пределами расстояния 0.6Rsun. Если согласно Rearch (2009) температура пыли Т = 950К, то наблюдаемая часть пылевого облака (диска) соответствует расстоянию от звезды около 1Rsun, где могут существовать только крупные силикатные частицы радиусами s > 5 мкм или карбоновые радиусами s > 0.5 мкм.

In this work, the correlations between the parameters of a DC glow discharge and dust particles in a lowtemperatureplasma is studied. The formation of voids inside the dust cloud was studied, depending on thecharacteristics of the discharge (discharge pressure, type of gas and discharge current) and dust particles(quantity and size). We have demonstrated that the ion drag force could lead to the formation of voids inthe center of the cloud of dust grains, which levitate in the field of a stratified positive column. It has alsobeen demonstrated that the accumulation of dust particles affects the discharge plasma in a non-local way,i.e., the density distribution of dust grains and the charge of each individual particle depend on the plasmaparameters outside the dust cloud. The presented qualitative estimates are important for understanding theprocesses occurring in complex plasma of a glow discharge.

Dust mobilized on the lunar surface due to natural processes and/or human activities can readily stick to spacesuits, optical devices, and mechanical components, for example. This may lead to dust hazards that have been considered as one of the technical challenges for future lunar exploration. Several dust mitigation technologies have been investigated over the past years. Here we present a new method utilizing an electron beam to shed dust off of surfaces. Recent studies on electrostatic dust lofting have shown that the emission and absorption of secondary electrons or photoelectrons inside microcavities forming between dust particles can cause the buildup of substantial negative charges on the surrounding particles. The subsequent repulsive forces between these particles can cause their release from the surface. Fine-sized lunar simulant particles (JSC-1A

The theme of this article is to inspect the scientific and theoretical outcomes of wall shear stress on dusty viscoelastic fluid. Where the flow is taken in between inclined vertical plates with the angle of inclination α from the x− axis. The governing equation for fluid and dust particles is formulated as a set of the partial differential equation. The perturbed solution is finding out by Poincaré–Lighthill perturbation technique (PLPT). Results are obtained and plotted in graphs by using Mathcad-15 software. It is finding out that the increase of inclination angle controls the flow of fluid and dust particles.

The results of experimental studies of the terminal velocity of peat dust in an air flow with different size distributions of dust particles are presented, and the particle sizes and shapes were examined by microscopic methods. The aerodynamic drag of peat particles of various sizes in an air flow was studied, and a criterion relationship between the drag coefficient CD and the Reynolds number (Re) was determined. The experimental results on the terminal velocity of peat dust were compared with data calculated using well-known methods, and recommendations for their application in the design of pneumatic fuel supply systems were given.

The phenomenon of thermophoresis in a gas discharge in neon is studied in the presence of structures of charged dust particles. This system can simulate gas with combustion products in the form of a condensed dispersed phase. The relationship of the thermophoresis force acting on charged dust particles in a plasma with their concentration and gas pressure is analyzed. It is shown that with decreasing gas pressure the dependence of the thermophoresis force on the concentration of dust particles increases due to the mutual screening of the dust particles.

For a long time, the logistic of transportation of bulk materials, such as iron dust and other minerals, has been of great interest for industrial propositions. Along with the necessity of enhancement of such process, there is also the environmental concerns, since handling these materials generates a large amount of air pollution due to the spreading of thin dust to the atmosphere. In this work, we propose a mathematical model for the propagation of the aerial dust in an open field, based on the principle that the movement of the dust occurs in the quasi-static regime, i.e., a low Reynolds number condition. By using an air-dust mixed fluid-like model, four flow pattern zones were identified and showed a conceptual indicator of the zones serving as a potential source of dust spreading if subjected to an external force. This model consists of solving a Poisson EDP with proper boundary conditions given by the structure of the problem.

Dust particles need to grow efficiently from micrometre sizes to thousands of kilometres to form planets. With the growth of millimetre to meter sizes being hindered by a number of barriers, the recent discovery that dust evolution is able to create `self-induced' dust traps shows promises. The condensation and sublimation of volatile species at certain locations, called snow lines, is also thought to be an important part of planet formation scenarios. Given that dust sticking properties change across a snow line, this raises the question: how do snow lines affect the self-induced dust trap formation mechanism? The question is particularly relevant with the multiple observations of the carbon monoxide (CO) snow line in protoplanetary discs, since its effect on dust growth and dynamics is yet to be understood. In this paper, we present the effects of snow lines in general on the formation of self-induced dust traps in a parameter study, then focus on the CO snow line. We find that for a range of parameters, a dust trap forms at the snow line where the dust accumulates and slowly grows, as found for the water snow line in previous work. We also find that, depending on the grains sticking properties on either side of the CO snow line, it could either be a starting or braking point for dust growth and drift. This could provide clues to understand the link between dust distributions and snow lines in protoplanetary disc observations., Comment: 14 pages, 14 figures

Formation of dust particles and clusters is observed in almost all modern fusion devices. Accumulation of dust in next-generation thermonuclear installations can significantly affect plasma parameters and lead to accumulation of unacceptably large amounts of tritium. The use of a specially developed electrostatic probe is planned in the international thermonuclear experimental reactor ITER to collect dust for further analysis. The article describes a numerical model of movement of dust particles in an electrostatic probe. Dust particle trajectories inside the probe are analyzed. Several electrostatic probe design modifications are proposed on the basis of the analysis in order to increase the efficiency of dust collection.

Hydrodynamical simulations show that a pair of spiral arms can form in the disk around a rapidly growing young star and that the arms are crucial in transporting angular momentum as the disk accretes material from the surrounding envelope1–4. Here we report the detection of a pair of symmetric spiral structures in a protostellar disk, supporting the formation of spiral arms in the disk around a forming star. The HH 111 VLA 1 source is a young Class I source embedded in a massive infalling protostellar envelope and is actively accreting, driving the prominent HH 111 jet. Previous observations showed a ring of shock emission around the disk’s outer edge5, indicating accretion of the envelope material onto the disk at a high rate. Now with ALMA observations of thermal emission from dust particles, we detect a pair of spiral arms extending from the inner region to the disk’s outer edge, similar to that seen in many simulations1–4. Additionally, the disk is massive, with a Toomre Q parameter near unity in the outer parts where the spiral structures are detected, supporting the notion that envelope accretion is making the outer disk gravitationally unstable. In our observations, another source, HH 111 VLA 2, is spatially resolved for the first time, showing a disk-like structure with a diameter of ~26 au and an orientation nearly orthogonal to that of the HH 111 VLA 1 disk. ALMA observations have revealed a pair of symmetric spiral arms in the protostellar disk around HH 111 VLA 1. This discovery would seem to confirm hydrodynamical models that suggest that symmetric spiral structures arise in disks as a consequence of active accretion.

Detection of areas of increased density of cosmic dust in near-Earth space is important from both theoretical and practical points of view. To continue our explication of the phenomenon of appearance-disappearance of the Kodylewski dust clouds, we consider dynamics of charged dust particles in the small vicinity of Lagrange libration point. The masses of particles are comparable to the masses of protons and electrons. These particles induce a self-consistent electric as well as a self-consistent gravitational fields. As a result, we obtain an existence of periodically changing stable configuration of an ensemble of the charged particles. It should be taken into account when planning space missions.

The charging of fine particles within the photoelectron cloud is the key in characterizing the dusty plasma environment over sunlit locations. In this work, based on the statistical mechanics and charging kinetics of the floating dust particles within the photoelectron sheath over the sunlit lunar surface, the distribution of charge over floating particles has been investigated. The natural randomization of the dust charging currents, the anisotropy in sheath photoelectron population and electric field/ potential, and half Fermi Dirac velocity distribution of the emitted photoelectrons have been consistently accounted for in the formulation. In this framework, due to natural fluctuation, the charge on the floating dust particles is shown to be distributed over a wide range (∼100 e). This random fluctuation in charge might alter the static equilibrium of the floating dust particles and induce an altitudinal fluctuation (∼10%) about its mean position within the sheath. The concept and results suggest that the natural fluctuation of the dust charge could be a reason that the strict dust levitation under static force equilibrium is less likely to exhibit over the sunlit lunar surfaces. This effect of dust charge and subsequent altitudinal fluctuations have been found pronounced at larger latitudes (near the terminator region) and higher lunar altitudes.

The photoevaporation of protoplanetary discs by nearby massive stars present in their birth cluster plays a vital role in their evolution. Previous modelling assumes that the disc behaves like a classical Keplerian accretion disc out to a radius where the photoevaporative outflow is launched. There is then an abrupt change in the angular velocity profile, and the outflow is modelled by forcing the fluid parcels to conserve their specific angular momenta. Instead, we model externally photoevaporating discs using the slim disc formalism. The slim disc approach self consistently includes the advection of radial and angular momentum as well as angular momentum redistribution by internal viscous torques. Our resulting models produce a smooth transition from a rotationally supported Keplerian disc to a photoevaporative driven outflow, where this transition typically occurs over ~4-5 scale heights. The penetration of UV photons predominately sets the radius of the transition and the viscosity's strength plays a minor role. By studying the entrainment of dust particles in the outflow, we find a rapid change in the dust size and surface density distribution in the transition region due to the steep gas density gradients present. This rapid change in the dust properties leaves a potentially observable signature in the continuum spectral index of the disc at mm wavelengths. Using the slim disc formalism in future evolutionary calculations will reveal how both the gas and dust evolves in their outer regions and the observable imprints of the external photoevaporation process., Accepted for publication in MNRAS

Previous simulation studies of dust particles movement behavior in open-pit coal mines only aimed at a single operation link, and the macro simulation is lacking. This study seeks to explore microscopic migration and macroscopic diffusion of dust particles in the mining area by numerical simulation method. The movement characteristics revealed, and the distribution law of the dust particles in a stable state with the corresponding migration paths in the mining area were obtained respectively. The results showed that the increase amplitude of dust particles diffusion velocity was inversely proportional to particle size, which was vital for dust pollution in the mine. And the larger the particle size in the mining pit was, the lower the escape rate of the dust particles was. Dust particles distributed over a wide range that were not limited by space height, and the distribution characteristics of dust particles at different heights were basically the same. Meanwhile, it is found that the dust distribution in the two places is relatively concentrated due to the circulation phenomenon of the mining pit and the west dump. And wind action would accelerate the moving dust particles to reach a stable distribution state.

We have calculated the mass fluxes and dust particle fluxes the presence of which in orbits around Mars is due to collisions between meteoroids with Phobos and Deimos. The size distributions of dust particles captured in orbits around Mars are determined. Knowledge of the parameters of these particles is important when planning experiments to dust study in the system of Mars as part of future space missions.

We consider the features of the mechanisms of the electric charging of dust particles, emergence of electric fields, and discharges in the atmospheres of planets and near the surface of the Moon. We find a significant difference in the nature of the influence of electric fields (discharges) on the vortex motions of two-phase (gas and dust) in the atmospheres of the planets and single-phase (dust) near the surface of the Moon.

Recent observations have revealed that protoplanetary discs often exhibit cavities and azimuthal asymmetries such as dust traps and clumps. The presence of a stellar binary system in the inner disc regions has been proposed to explain the formation of these structures. Here, we study the dust and gas dynamics in circumbinary discs around eccentric and inclined binaries. This is done through two-fluid simulations of circumbinary discs, considering different values of the binary eccentricity and inclination. We find that two kinds of dust structures can form in the disc: a single horseshoe-shaped clump, on top of a similar gaseous over-density; or numerous clumps, distributed along the inner disc rim. The latter features form through the complex interplay between the dust particles and the gaseous spirals caused by the binary. All these clumps survive between one and several tens of orbital periods at the feature location. We show that their evolution strongly depends on the gas-dust coupling and the binary parameters. Interestingly, these asymmetric features could in principle be used to infer or constrain the orbital parameters of a stellar companion - potentially unseen - inside the inner disc cavity. Finally, we apply our findings to the disc around AB Aurigae., 12 pages, 13 figures, accepted for publication in MNRAS

We have studied the characteristics of the Dust Acoustic Solitary Wave (DASW) in a five component cometary plasma composed of two components of electrons (one hotter and one colder), hydrogen ions and a pair of oppositely charged dust particles (heavier ions). The Korteweg – deVries wave equation has been derived for the system and its solitary wave solution obtained. The dust acoustic solitary wave amplitude is almost a constant with varying temperatures of the hot electron component but decreases with increasing hydrogen ion densities. A comparison with a complementary nonlinear wave, the Dust Ion Acoustic Solitary Wave, has also been made. Keywords: Dust acoustic solitary wave, K dV equation, kappa distributed ions and electrons Cite this Article Neethu Theresa Willington, Sijo Sebastian, Chandu Venugopal. Dust Acoustic Solitary Waves in a Five Component Plasma-Application to Comets. Research & Reviews: Journal of Physics . 2019; 8(2): 44–51p.

We consider a mixture composed of a gas and dust particles in a very rarefied setting. Whereas the dust particles are individually described, the surrounding gas is treated as a Knudsen gas, in such a way that interactions occur only between gas particles and dust by means of diffuse reflection phenomena. After introducing the model, we prove the existence and the uniqueness of the solution and provide a numerical strategy for the study of the equations. At the numerical level, we focus our attention on the phenomenon of energy transfer between the gas and the moving dust particles.

The electrodynamic screen (EDS), which transports particles by electrodynamic waves, is a promising technology to repel deposited dust from solar devices in places where water resources are scarce. As gravitational force may impede dust removal on concave or parabolic solar concentrators, this study aimed to determine the feasibility of the EDS to transport dust either upward or laterally, for application to concave solar devices. A discrete element method was used to computationally simulate the transport, collision, and adhesion of charged dust particles that were subject to traveling waves on an inclined EDS. High electric field strength (>2 kVp-p mm−1), short distance between electrodes, and a low adhesion circumstance resulted in the best cleaning efficiency with a wave that traveled up the incline. Over half of the particles moved up the incline successfully under this operational condition. To improve the cleaning efficiency, a new EDS configuration wherein the wave transported particles laterally along the surface (instead of up the incline against gravity) was proposed. With the new configuration, the performance clearly improved in all cases. Although some particles moved down the incline under most conditions, the application of EDS to clean dust off solar concentrators is achievable with optimal parameters.

We study a dust-air flow near a vertical rotating cylinder with suction unit placed on the lateral surface. On the basis of the developed computer model of this suction unit, we determine the influence of the disks mounted on the cylindrical surface on the intake air flow and on the capture of dust particles by the suction unit. We also determine the design and operating parameters of the proposed disk cylindrical suction unit promoting the decrease in the dust loss. The influence of the size of disks, their number, and the aspirated air flow on the dust removal is established. The proposed design of a rotating disk cylinder suction unit can be used in the aspiration shelters equipped with the function of dust-collecting chamber.

An optico-electronic dust meter that functions on the basis of the method of fluctuations is proposed. The error of continuous variation of the concentration of dust can be substantially reduced because of the design of the device, and the average size of the dust particles in the particular medium determined. The occurrence of occupational diseases may be predicted on the basis of the obtained results.

A mathematical model of vortex dedusting is proposed. Equations for calculating the magnitude of the reduction in the required energy of the total absorption of dust particles, the effective wetting angle and the minimum diameter of the absorbed dust particles as a function of the angular velocity of rotation of liquid droplets are obtained. It is shown that vortex hydrodusting significantly reduces the size of the dispersed dust composition, water consumption, increasing the efficiency of dust suppression. Ill. 2. Ref. 12.

An approach for computing the electrostatic charging of an aircraft flying in a soil dust cloud is discussed. This approach combines a semi-empirical equation obtained by flight test data, atmospheric dust particle concentrations obtained either by numerical weather forecasting models or in situ measurements, a vortex lattice-based aerodynamic simulation model, and the aerodynamic and inertial characteristics of soil dust particles. Application of the proposed approach showed that the aircraft acquires an equilibrium electrostatic charge in a matter of seconds. This means that the electrostatic charging of the aircraft due to soil dust is as important as any other source of electrostatic charging.

We explore in situ formation and subsequent evolution of close-in super-Earths and mini-Neptunes. We adopt a steady-state inner protoplanetary gas disc structure that arises from viscous accretion due to the magneto-rotational instability (MRI). We consider the evolution of dust in the inner disc, including growth, radial drift and fragmentation, and find that dust particles that radially drift into the inner disc fragment severely due to the MRI-induced turbulence. This result has two consequences: (1) radial drift of grains within the inner disc is quenched, leading to an enhancement of dust in the inner regions which scales as dust-to-gas-mass-flux-ratio at ~1 AU; (2) however, despite this enhancement, planetesimal formation is impeded by the small grain size. Nevertheless, assuming that planetary cores are present in the inner disc, we then investigate the accretion of atmospheres onto cores and their subsequent photoevaporation. We then compare our results to the observed exoplanet mass-radius relationship. We find that: (1) the low gas surface densities and high temperatures in the inner disc reduce gas accretion onto cores compared to the minimum mass solar nebula, preventing the cores from growing into hot Jupiters, in agreement with the data; (2) however, our predicted envelope masses are still typically larger than observed ones. Finally, we sketch a qualitative picture of how grains may grow and planetesimals form in the inner disc if grain effects on the ionization levels and the MRI and the back-reaction of the dust on the gas (both neglected in our calculations) are accounted for., Comment: Accepted for publication in MNRAS

Cost effective dust mitigation from surfaces is one of the challenges in various sectors. The reduction of dust adhesion on surfaces plays a vital role for dust mitigation from surfaces under the gravitational influence. Creating an avalanche effect on dusty surfaces improves the dust mitigation rate and provides an effective cleaning process. Hence, solution treatment of dust by low concentration hydrofluoric acid is considered towards reducing dust adhesion on glass surfaces. To increase the rate of dust mitigation, the avalanche influence is created by the higher density and larger size particles (5300 kg/m3 and ~ 50 µm) than the average size dust particles (2800 kg/m3 and 1.2 µm) via locating them in the top region of the dusty glass surfaces. Mitigation velocity of the dust particles is evaluated using a high-speed recording system and the tracker program. Findings revealed that solution treatment (curing) of the dust particles results in the formation of fluorine compounds, such as CaF2 and MgF2, on dust surfaces, which suppress dust adhesion on surfaces. OSHA Globally Harmonized System lists the fluorine compounds formed as environmentally non-harmful. Avalanche's influence results in dust mitigation at a smaller tilt angle of the glass surface (~ 52°) than that of the case with none-avalanche influence (63°). Area cleaned on the glass surface, via dust mitigation, is larger as the avalanche is introduced, which becomes more apparent for the solution treated dust particles. Dust mitigation under avalanche influence improves optical transmittance of the dusty glass samples by a factor of 98%.

The Landau damping of the dust ion-acoustic wave (DIAW) propagating in a dusty plasma with nonextensive distributed components is kinetically analyzed. The electron, ion, and dust particles are eff...

In this work, we aim to characterize the dust motion in the inner coma of comet 67P/Churyumov-Gerasimenko to provide constraints for theoretical 3D coma models. The OSIRIS camera on-board the Rosetta mission was able for the first time to acquire images of single dust particles from inside the cometary coma, very close to the nucleus. We analyse a large number of particles, performing a significant statistic of their behaviour during the post-perihelion period, when the spacecraft covered distances from the nucleus ranging between 80 and 400 km. We describe the particle trajectories, investigating their orientation and finding highly radial motion with respect to the nucleus. Then, from the particle brightness profiles, we derive a particle rotational frequency of ν < 3.6 Hz, revealing that they are slow rotators and do not undergo fragmentation. We use scattering models to compare the observed spectral radiance of the particles with the simulated ones in order to estimate their size, finding values that range from millimetres up to centimetres. The statistics performed in this paper provide useful parameters to constrain the cometary coma dynamical models. © 2021 The Author(s)., OSIRIS was built by a consortium of the Max-Planck-Institut fur Sonnensystemforschung in Gottingen, Germany; CISAS-University of Padova, Italy; the Laboratoire d'Astrophysique de Marseille, France; the Instituto de Astrofisica de Andalucia, CSIC, Granada, Spain; the Research and Scientic Support Department of the European Space Agency, Noordwijk, The Netherlands; the Instituto Nacional de Tecnica Aeroespacial, Madrid, Spain; the Universidad Politechnica de Madrid, Spain; the Department of Physics and Astronomy of Uppsala University, Sweden; and the Institut fur Datentechnik und Kommunikationsnetze der Technischen Universit at Braunschweig, Germany. The support of the national funding agencies of Germany (DLR), Italy (ASI), France (CNES), Spain (MEC), Sweden (SNSB), and the ESA Technical Directorate is gratefully acknowledged. GIADA was built by a consortium led by the Univ. Napoli Parthenope INAF-Oss. Astr. Capodimonte, in collaboration with the Inst. de Astrofisica de Andalucia, Selex-ES, FI and SENER. GIADA was managed and operated at INAF-IAPS. GIADA was funded and managed by the Agenzia Spaziale Italiana, IT, with the support of the Spanish Ministry of Education and Science MEC, ES. We thank the ESA teams at ESAC, ESOC, and ESTEC for their work in support of the Rosetta mission. This research has been supported by the Italian Space Agency (ASI) within the ASI-INAF agreements I/032/05/0, I/024/12/0, and ASI 2020-4-HH.0. Fernando Moreno acknowledges financial support from the Spanish plan National de Astrofisica y Astronomia LEONIDAS project RTI2018-095330-B-100, project P18-RT-1854 from Junta de Andalucia, and the Centro de Excelencia Severo Ochoa Program under grant SEV-2017-0709. Elisa Frattin acknowledges funding from Italian Ministry of Education, University and Research (MIUR) through the `Dipartimenti di eccellenza' project Science of the Universe.

Recent observations of extrasolar gas giants suggest super-stellar C/O ratios in planetary atmospheres, while interior models of observed extrasolar giant planets additionally suggest high heavy element contents. Furthermore, recent observations of protoplanetary disks revealed super-solar C/H ratios, which are explained by inward drifting and evaporating pebbles, enhancing the volatile content of the disk. We investigate how the inward drift and evaporation of volatile rich pebbles influences the atmospheric C/O ratio and heavy element content of giant planets growing by pebble and gas accretion. To achieve this goal, we perform semi analytical 1D models of protoplanetary disks including the treatment of viscous evolution and heating, pebble drift and simple chemistry to simulate the growth of planets from planetary embryos to Jupiter mass objects by accretion of pebbles and gas while they migrate through the disk. Our simulations show that the composition of the planetary gas atmosphere is dominated by the accretion of vapour, originating from inward drifting evaporating pebbles. This process allows the giant planets to harbour large heavy element contents. In addition, our model reveals that giant planets originating further away from the central star have a higher C/O ratio on average due to the evaporation of methane rich pebbles in the outer disk. These planets can then also harbour super-solar C/O ratios, in line with exoplanet observations. However, planets formed in the outer disk harbour a smaller heavy element content, due to a smaller vapour enrichment of the outer disk. Our model predicts that giant planets with low/large atmospheric C/O should harbour a large/low total heavy element content. We further conclude that the inclusion of pebble evaporation at evaporation lines is a key ingredient to determine the heavy element content and composition of giant planets., accepted for publication in A&A

The presence of dust in the interstellar medium was highlighted by Trumpler who, in an investigation of the diameters of Galactic clusters, found a poorly convincing result: their diameters were an increasing function of distance. The origin of this result was linked to the determination of the distances made with photometry, a distance that was overestimated precisely for the absorbing action of solid dust particles. The study of the spatial distribution of these led to the conclusion that dust was associated with the interstellar gas.

We present a novel mechanism for the outward transport of crystalline dust particles: the outward radial drift of pebbles. The dust ring structure is frequently observed in protoplanetary disks. One of the plausible mechanisms of the formation of dust rings is the accumulation of pebbles around the pressure maximum, which is formed by the mass loss due to magnetically driven disk winds. In evolving protoplanetary disks due to magnetically driven disk winds, dust particles can migrate outwardly from the crystallization front to the pressure maximum by radial drift. We found that the outward radial drift process can transport crystalline dust particles efficiently when the radial drift timescale is shorter than the advection timescale. Our model predicts that the crystallinity of silicate dust particles could be as high as 100% inside the dust ring position., Comment: 15 pages, 14 figures. Accepted for publication in ApJ

The properties (densities of electrons and metastable argon atoms, effective electron temperature and dust charge) of argon/dust and pure argon pulsed plasmas are studied using a spatially-averaged model. The calculated time-dependencies for the densities of electrons and metastable atoms are compared with the experimental measurements and are found to be in a good qualitative agreement. It is analyzed how the plasma properties depend on the shape of the electron energy probability function (EEPF), the pulsing frequency and the duty cycle for both dust-free and dusty plasma. The analysis reveals that the agreement between theory and experiment is better with Druyvesteyn EEPF than the Maxwellian EEPF. Further, the variation in the pulsing frequency νp differently affects the metastable density nm in a dust-free and in a dusty plasma. For large νp, the metastable density in the dust-free pulsed plasma is larger than in the continuous-wave (CW) discharge, while the opposite is obtained in the presence of dust particles. This difference probably arises because of faster variation in the effective electron temperature in the dusty plasma due to collection of electrons by dust particles. Our calculations also show that dust particles may affect the behavior of electron density in the beginning of the on-period due to an enhancement in electron collection by dust particles. This is the peer-reviewed version of the article: Denysenko I. B., Stefanović Ilija, Mikikian M., Kovačević E., Berndt J., "Argon/dust and pure argon pulsed plasmas explored using a spatially-averaged model" Journal of Physics D: Applied Physics, 54, no. 6 (2021):065202, [https://doi.org/10.1088/1361-6463/abc210]. Published version: [https://hdl.handle.net/21.15107/rcub_dais_9988]

Agricultural fires affecting grass-, crop- and shrublands represent a major, mainly anthropogenically driven disturbance of many ecosystems. In addition to emissions of carbonaceous aerosol, they were found to inject also mineral dust particles into the atmosphere. The fires can significantly modulate the near-surface wind patterns so that conditions suitable for dust emission occur. However, the exact emission mechanism has not been investigated so far, but is inevitable for the understanding of its impacts on the Earth system. Here, we test two dust emission parameterizations representing saltation bombardment (SALT) and direct aerodynamic dust entrainment by (convective) turbulence (convective turbulent dust emission, CTDE) in the context of fire-modulated wind patterns using large-eddy simulation with an idealized setup to represent typical agricultural fire settings. Favorable aerodynamic preconditions for the initialization of both emission processes are found, however, with sometimes significant differences in dust emission flux depending on specific wind and fire properties. The strong fire-induced modulations of the instantaneous momentum flux suggest that CTDE can be a very potent emission process in the fire vicinity. Nevertheless, fire impacts on the friction velocity can be significant too, so that dust emission through SALT is facilitated as well. Ultimately, the specific aerodynamic conditions within pyro-convectively modulated wind patterns require the development of a parameterization that can describe these unique fire-related dust emissions and their influencing factors properly. This will finally allow for considering fire-induced dust emissions in aerosol-atmosphere models and an investigation of its atmospheric impacts such as on the radiation budget. R. Wagner and K. Schepanski thank the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) for funding the project SCHE 1678/5–1. M. Klose has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 789630 and from the Helmholtz Association's Initiative and Networking Fund (grant agreement no. VH-NG-1533). The authors acknowledge the Center for Information Services and High performance Computing (ZIH) of the Technische Universität Dresden (TU Dresden) for providing computing capacity. The authors are grateful to the three anonymous reviewers for their valuable comments and suggestions that helped to improved the quality of the paper.

Electrostatic dust lofting has been suggested to explain a number of unresolved phenomena on airless planetary bodies such as the lunar horizon glow, the dust ponds on asteroid Eros, and the radial ‘spokes’ in Saturn’s rings. In this paper we report laboratory measurements of the size distribution of lofted dust particles in the range of 1 to 40 μ m in diameter. It is shown that the population of lofted dust increases with a decrease in dust size (i.e., smaller sized dust is easier to be lofted), which is in agreement with the theoretical expectation derived from the patched charge model (Wang et al., 2016a). Additionally, initial launch velocities are derived from transport distances of lofted particles following ballistic trajectories. It is shown that the initial velocity of lofted particles is inversely proportional to their size, in agreement with an earlier work that used a different measurement method (Carroll et al., 2020).

International audience; The first known interstellar object, 1I/2017 U1 'Oumuamua, displayed such unusual properties that its origin remains a subject of much debate. We propose that 'Oumuamua's properties could be explained as those of a fractal dust aggregate (a "dust bunny") formed in the inner coma of a fragmenting exo-Oort cloud comet. Such fragments could serve as accretion sites by accumulating dust particles, resulting in the formation of a fractal aggregate. The fractal aggregate eventually breaks off from the fragment due to hydrodynamic stress. With their low density and tenuously bound orbits, most of these cometary fractal aggregates are then ejected into interstellar space by radiation pressure.

Dark rings with bright rims are the indirect signposts of planets embedded in protoplanetary discs. In a recent first, an azimuthally elongated AU-scale blob, possibly a planet, was resolved with ALMA in TW Hya. The blob is at the edge of a cliff-like rollover in the dust disc rather than inside a dark ring. Here we build time-dependent models of TW Hya disc. We find that the classical paradigm cannot account for the morphology of the disc and the blob. We propose that ALMA-discovered blob hides a Neptune mass planet losing gas and dust. We show that radial drift of mm-sized dust particles naturally explains why the blob is located on the edge of the dust disc. Dust particles leaving the planet perform a characteristic U-turn relative to it, producing an azimuthally elongated blob-like emission feature. This scenario also explains why a 10 Myr old disc is so bright in dust continuum. Two scenarios for the dust-losing planet are presented. In the first, a dusty pre-runaway gas envelope of about 40 Earth mass Core Accretion planet is disrupted, e.g., as a result of a catastrophic encounter. In the second, a massive dusty pre-collapse gas giant planet formed by Gravitational Instability is disrupted by the energy released in its massive core. Future modelling may discriminate between these scenarios and allow us to study planet formation in an entirely new way -- by analysing the flows of dust and gas recently belonging to planets, informing us about the structure of pre-disruption planetary envelopes., Comment: Typos fixed, references and author list updated

Here, environmental dust cleaning from an inclined hydrophobic surface by rolling liquid droplets has been studied and the influence of fluid droplets on the dust removal rate has been examined. The distilled and carbonated water droplets at different volumes were incorporated and the inclination angle of the dusty hydrophobic surface on the droplet motion was explored in the experiments. We demonstrated that the carbonated water droplet had higher translational velocity than the distilled water droplet on the dusty hydrophobic surface. The bubbles formed around the droplet surface acted as gas cushions at the interface between the solid surface and the fluid droplet while lowering the friction and pinning forces and enhancing the droplet translational velocity on the surface. Collected environmental dust has various components, some of which can dissolve in water while creating resorption/nucleation centers for bubble formation in the carbonated water droplet. The interaction between the bubbles and the dust particles at the liquid–solid interface enhanced the rate of dust particle movement into carbonated water. For a small-volume droplet (20 μL) at a low surface inclination angle (δ = 1°), the rolling motion of the distilled and carbonated water droplets ceased on the hydrophobic surface at early periods.

Tiny meteoroids entering the Earth's atmosphere and inducing meteor showers have long been thought to originate partly from cometary dust. Together with other dust particles, they form a huge cloud around the Sun, the zodiacal cloud. From our previous studies of the zodiacal light, as well as other independent methods (dynamical studies, infrared observations, data related to Earth's environment), it is now established that a significant fraction of dust particles entering the Earth's atmosphere comes from Jupiter-family comets (JFCs). This paper relies on our understanding of key properties of the zodiacal cloud and of comet 67P/Churyumov-Gerasimenko, extensively studied by the Rosetta mission to a JFC. The interpretation, through numerical and experimental simulations of zodiacal light local polarimetric phase curves, has recently allowed us to establish that interplanetary dust is rich in absorbing organics and consists of fluffy particles. The ground-truth provided by Rosetta presently establishes that the cometary dust particles are rich in organic compounds and consist of quite fluffy and irregular aggregates. Our aims are as follows: (1) to make links, back in time, between peculiar micrometeorites, tiny meteoroids, interplanetary dust particles, cometary dust particles, and the early evolution of the Solar System, and (2) to show how detailed studies of such meteoroids and of cometary dust particles can improve the interpretation of observations of dust in protoplanetary and debris disks. Future modeling of dust in such disks should favor irregular porous particles instead of more conventional compact spherical particles., 15 pages, 5 figures, accepted for publication in Planetary and Space Science

Observational estimates of the lifetimes and inferred accretion rates from debris discs around polluted white dwarfs are often inconsistent with the predictions of models of shielded Poynting-Robertson drag on the dust particles in the discs. Moreover, many cool polluted white dwarfs do not show any observational evidence of accompanying discs. This may be explained, in part, if the debris discs had shorter lifetimes and higher accretion rates than predicted by Poynting-Robertson drag alone. We consider the role of a magnetic field on tidally disrupted diamagnetic debris and its subsequent effect on the formation, evolution, and accretion rate of a debris disc. We estimate that magnetic field strengths greater than $\sim$10kG may decrease the time needed for circularisation and the disc lifetimes by several orders of magnitude and increase the associated accretion rates by a similar factor, relative to Poynting-Robertson drag. We suggest some polluted white dwarfs may host magnetic fields below the typical detectable limit and that these fields may account for a proportion of polluted white dwarfs with missing debris discs. We also suggest that diamagnetic drag may account for the higher accretion rate estimates among polluted white dwarfs that cannot be predicted solely by Poynting-Robertson drag and find a dependence on magnetic field strength, orbital pericentre distance, and particle size on predicated disc lifetimes and accretion rates., Comment: Published in MNRAS, Final version

We characterized the 67P/Churyumov–Gerasimenko’s dust activity, by analysing individual dust particle velocity and momentum measurements of Grain Impact Analyser and Dust Accumulator (GIADA), the dust detector onboard the ESA/Rosetta spacecraft, collecting dust from tens to hundreds of kilometres from the nucleus. Specifically, we developed a procedure to trace back the motion of dust particles down to the nucleus, identifying the surface’s region ejecting each dust particle. This procedure has been developed and validated for the first part of the mission by Longobardo et al. and was extended to the entire GIADA data set in this work. The results based on this technique allowed us to investigate the link between the dust porosity (fluffy/compact) and the morphology of the ejecting surface (rough/smooth). We found that fluffy and compact particles, despite the lack of correlation in their coma spatial distribution (at large nucleocentric distances) induced by their different velocities, have common ejection regions. In particular, the correlation between the distributions of fluffy and compact particles is maintained up to an altitude of about 10 km. Fluffy particles are more abundant in rough terrains. This could be the result of past cometary activity that resurfaced the smooth terrains and/or of the comet formation process that stored the fluffy particles inside the voids between the pebbles. The variation of fluffy particle concentration between rough and smooth terrains agrees with predictions of comet formation models. Finally, no correlation between dust distribution on the nucleus and surface thermal properties was found.

The absorption coefficient of dusty plasma is deduced on the basis of considering the influence of dust particles electric potential, and its absorption characteristic in the near infrared region is discussed. The involved results manifest that the absorption coefficient of dusty plasma with the dust particles potential is considered is obviously bigger than that of not considered in the given temperature, pressure and frequency ranges, which proves the influence of dust particles potential can not be omitted. Besides, the results also indicate that the maximal absorption ability of the dusty plasma does not occur where the maximal electron number density (plasma resonance frequency) appears. Consequently, two conditions, which determine where the maximal absorption appears, are presented by a series of theoretical deduction.

Observations of protoplanetary disks with high angular resolution using an ALMA interferometer showed that ring-shaped structures are often visible in their images, indicating strong disturbances in the disks. The mechanisms of their formation are vividly discussed in the literature. This article shows that the formation of such structures can be the result of destructive collisions of large bodies (planetesimals and planetary embryos) accompanied by the formation of a large number of dust particles, and the subsequent evolution of a cloud of dust formed in this way., 13 pages, 2 figures

Solar energy is considered to be one of most promising renewable energy sources because of its availability and cleanliness. The phenomenon of dust deposition on solar mirrors greatly reduces the power generation of solar power plants. In this work, the motion behaviors and deposition mechanics of dust particles are analyzed by the discrete element method (DEM). The effects of environmental and solar mirror conditions and particle self-factors on dust deposition weight are systematically studied here. The research results show that dust particles, after particle collision, immediately adhere to the mirror or rebound and finally flow away from the mirror, or they otherwise may remain stationary after making some relative motion. Alternatively, they may glide for some distance and finally come to rest on the mirror or leave from the system. Different motion behaviors after particle collision depend on different leading forces. Here, the leading forces are the liquid bridge force (Fc) and the contact force (Fb). When the leading forces are Fc, or Fc, and Fb, the dust particles will be deposited on the solar mirror. Besides, the force Fc cannot be negligible when studying the motion processes of dust particles. The dust deposition weight on solar mirrors can be controlled by altering the environmental and solar mirror conditions, and particle self-factors. In essence, dust deposition weight on solar mirrors decreases when decreasing the leading force Fc or increasing the leading force Fb. The research results give theoretical guidance for the prevention and removal of dust deposition on solar mirrors.

In this paper, the adhesion between irregularly shaped Martian dust particles and the Martian probe in the dust storm is studied. First, the characteristics of irregularly shaped Martian dust particles are analyzed using fractal theory and the discrete element simulation model of irregularly shaped Martian dust particles is built. Second, the mechanical model of the adhesion of Martian dust onto the Martian probe is established, and the analytical solution of the critical wind speed is calculated. Finally, a series of simulations based on DEM-CFD are performed to analyze the creeping of irregularly shaped Martian dust particles in the Martian atmospheric environment. The research can provide a theoretical basis for the processes of dust protection and cleaning in a Martian dust storm.

The direct and indirect radiative impact of naturally produced dust particles influences climate from regional to global scale, introducing one of the largest uncertainties in future climate projections. By absorbing and scattering solar radiation, aerosols reduce the amount of energy reaching the earth's surface, while at the same time they enhance the greenhouse effect by absorbing and emitting longwave radiation (direct dust effect). In this study an attempt is made to quantify the feedback of this energy redistribution in the atmospheric water content in the Arabian Peninsula (one of the main sources of atmospheric mineral dust globally). To this end the SKIRON/dust modeling system was used for 2 years (2014–2015) and two sets of simulations were performed: in the first one the dust particles exert no feedback on the radiative transfer due to dust particles (control run), while in the second set dust interacts with radiation (direct radiative effect). Both simulations have been evaluated in their ability to describe the impacts on surface humidity, with the simulations including the dust feedback showing improved results. These direct feedbacks lead to an increase in the mass of water in the atmospheric column that can reach a maximum daily average of 0.5 g per kg of dry air. Water vapor is the most important greenhouse gas and through this process dust enhances its own greenhouse effect, further increasing the surface temperature and humidity, making life difficult for people living in an already harsh desert climate. © 2018 American Association for Aerosol Research. © 2018 American Association for Aerosol Research.

The removal of environmental dust particles from optically transparent glass surfaces is considered, and the dynamics of the dust particles on the inclined hydrophobic glass surface is examined. The glass surfaces are coated by functionalized nano-sized silica particles to create a hydrophobic wetting state on the surface. A thin layer of environmental dust particles, collected from the local area of Dammam in the Kingdom of Saudi Arabia (KSA), is deposited on the surface while mimicking the dust accumulation on the surfaces in the dusty days of KSA. In order to increase the removal rate of the dust particles from the inclined hydrophobic glass surfaces, high density particles, which are higher than the density of the dust particles, are locally distributed on the dust particle-deposited surface while generating the avalanche influence on the inclined surface. The motion of the dust and high density particles on the inclined surface is monitored using a high speed camera. The predictions of the dust particles' acceleration and velocity are compared to those obtained from the high speed camera data. It is found that the predictions of velocity and acceleration of the dust particles agree well with the experimental data. Local insertion of the high density particles generates avalanche influence on the inclined surface while initiating the removal of the dust particles from the hydrophobic surface at small inclination angles. The size of the area where the dust particles are removed from the inclined surface increases with enlarging coverage area of the high density particles. The dust-removed surface, under the avalanche influence, improves the UV-visible transmittance of the hydrophobic glass.

The charge and dynamics of dust particles in an afterglow plasma are studied using a 1D model in the diffusion approximation, taking into account the transition from ambipolar to free diffusion. It is analyzed how external conditions (dust particle size, neutral gas pressure and initial electron density) affect the dust motion. The dust particle dynamics has been examined in microgravity conditions and in presence of gravity. Without gravity, the location of dust particles in plasma volume may change essentially during the afterglow if the dust size and pressure are small (⩽10 nm and ⩽30 mTorr, respectively). At small pressures, in the very beginning of afterglow, small nanoparticles move to the plasma boundary because the ion drag force dominates over the electric force. At afterglow times when the electron temperature becomes time-independent, the ion drag force decreases faster with time than the electric force due to the ion density decrease, and dust particles may move to the slab center. In presence of gravity, the effect of gravity force on dust particles is important only at large afterglow times (t ⩾ 10 ms), when the electric and ion drag forces are small. The dust dynamics depends essentially on the initial plasma density. If the density is large (∼1012 cm−3), small nanoparticles (⩽10 nm) may deposit on plasma walls in the beginning of plasma afterglow because of an enhancement of the ion drag force.