scholarly journals Photophoresis on water-ice particles induced by thermal radiation in protoplanetary discs

2012 ◽  
Vol 58 ◽  
pp. 209-212
Author(s):  
J. van Eymeren ◽  
T. Kelling ◽  
G. Wurm ◽  
S. Hagenacker
Keyword(s):  
Thermal Radiation ◽  
Water Ice ◽  
Ice Particles ◽  
Protoplanetary Discs

scholarly journals Ice Condensation as a Planet Formation Mechanism

2013 ◽  
Vol 8 (S299) ◽  
pp. 382-383
Author(s):  
Katrin Ros
Keyword(s):  
Formation Mechanism ◽  
Time Scale ◽  
Planet Formation ◽  
Particle Growth ◽  
Dynamical Behaviour ◽  
Water Ice ◽  
Ice Particles ◽  
Size Evolution ◽  
Protoplanetary Discs

AbstractParticles in protoplanetary discs grow rapidly to millimetre-sizes via coagulation, but further growth to centimetre-sized pebbles is not yet completely understood. We investigate particle growth by ice condensation in a model where we take the dynamical behaviour of vapour and ice particles into account, as well as the size evolution due to condensation and sublimation. Our results show that efficient growth from dust to pebbles is possible close to the water ice line at ~3 AU, with particles growing from millimetres to decimetres on a time scale of 10000 yr.

scholarly journals THE STICKINESS OF MICROMETER-SIZED WATER-ICE PARTICLES

2014 ◽  
Vol 798 (1) ◽  
pp. 34 ◽  
Author(s):  
B. Gundlach ◽  
J. Blum
Keyword(s):  
Water Ice ◽  
Ice Particles

scholarly journals Synthesis of water ice particles in a plasma chamber

2010 ◽  
Vol 115 (D18) ◽  
Author(s):  
S. Shimizu ◽  
B. Klumov ◽  
T. Shimizu ◽  
H. Rothermel ◽  
O. Havnes ◽  
...  
Keyword(s):  
Water Ice ◽  
Plasma Chamber ◽  
Ice Particles

scholarly journals Micrometer-sized Water Ice Particles for Planetary Science Experiments: Influence of Surface Structure on Collisional Properties

2017 ◽  
Vol 848 (2) ◽  
pp. 96 ◽  
Author(s):  
S. Gärtner ◽  
B. Gundlach ◽  
T. F. Headen ◽  
J. Ratte ◽  
J. Oesert ◽  
...  
Keyword(s):  
Surface Structure ◽  
Planetary Science ◽  
Water Ice ◽  
Ice Particles

scholarly journals Effect of nucleation on icy pebble growth in protoplanetary discs

2019 ◽  
Vol 629 ◽  
pp. A65 ◽  
Author(s):  
Katrin Ros ◽  
Anders Johansen ◽  
Ilona Riipinen ◽  
Daniel Schlesinger
Keyword(s):  
Water Vapour ◽  
Vapour Pressure ◽  
Particle Growth ◽  
Total Surface Area ◽  
Ice Nucleation ◽  
Solid Particles ◽  
Water Vapour Pressure ◽  
Water Ice ◽  
Protoplanetary Discs ◽  
Heterogeneous Ice Nucleation

Solid particles in protoplanetary discs can grow by direct vapour deposition outside of ice lines. The presence of microscopic silicate particles may nevertheless hinder growth into large pebbles, since the available vapour is deposited predominantly on the small grains that dominate the total surface area. Experiments on heterogeneous ice nucleation, performed to understand ice clouds in the Martian atmosphere, show that the formation of a new ice layer on a silicate surface requires a substantially higher water vapour pressure than the deposition of water vapour on an existing ice surface. In this paper, we investigate how the difference in partial vapour pressure needed for deposition of vapour on water ice versus heterogeneous ice nucleation on silicate grains influences particle growth close to the water ice line. We developed and tested a dynamical 1D deposition and sublimation model, where we include radial drift, sedimentation, and diffusion in a turbulent protoplanetary disc. We find that vapour is deposited predominantly on already ice-covered particles, since the vapour pressure exterior of the ice line is too low for heterogeneous nucleation on bare silicate grains. Icy particles can thus grow to centimetre-sized pebbles in a narrow region around the ice line, whereas silicate particles stay dust-sized and diffuse out over the disc. The inhibition of heterogeneous ice nucleation results in a preferential region for growth into planetesimals close to the ice line where we find large icy pebbles. The suppression of heterogeneous ice nucleation on silicate grains may also be the mechanism behind some of the observed dark rings around ice lines in protoplanetary discs, as the presence of large ice pebbles outside ice lines leads to a decrease in the opacity there.

scholarly journals Polarimetry of Water Ice Particles Providing Insights on Grain Size and Degree of Sintering on Icy Planetary Surfaces

2018 ◽  
Vol 123 (10) ◽  
pp. 2564-2584 ◽  
Author(s):  
O. Poch ◽  
R. Cerubini ◽  
A. Pommerol ◽  
B. Jost ◽  
N. Thomas
Keyword(s):  
Grain Size ◽  
Planetary Surfaces ◽  
Water Ice ◽  
Ice Particles

Investigation of the Formation and the Applications of Ice Powder

2002 ◽  
Author(s):  
D. V. Shishkin ◽  
E. S. Geskin ◽  
B. Goldenberg
Keyword(s):  
Precision Machining ◽  
Water Ice ◽  
Ice Particles ◽  
Waterjet Machining ◽  
Hypothetical Mechanism ◽  
Auto Parts ◽  
Is Integration ◽  
Ice Powder ◽  
Set Up ◽  
Polished Metal

Water ice powder constitutes a potentially important manufacturing tool. Availability and cleanliness of this powder constitute its major advantage. It was shown that the ice particles can be used as an abrasive in the course of waterjet machining. Although the erosion potential of ice particle is inferior to that of the conventional abrasives the environmental soundness of ice enables us to expend the use of the ice abrasive jets on food industry, medicine, precision machining, etc. The principal issue in the use of the ice abrasives is particles formation. Analysis of various technologies showed that the most effective avenue in particles production is integration of the water freezing and ice decomposition. As the results, the desired flow rate of ice particles at the desired temperature and size distribution can be generated. The objective of the presented paper was the experimental investigation of the production of ice particles. An experimental set up was constructed and used for particles fabrication at controlled conditions. The acquired information was applied for the analysis of the phenomena leading to the particles formation. As the result a hypothetical mechanism of the ice decomposition was suggested and validated. The experiments involving the decontamination of the electronic devices, semiconductors, fabric, leather, food products, polished metal, soft plastics, rusted auto parts, etc were carried out in order to demonstrate the potential application of the ice blasting.

scholarly journals Charging of mesospheric aerosol particles: the role of photodetachment and photoionization from meteoric smoke and ice particles

2009 ◽  
Vol 27 (6) ◽  
pp. 2417-2422 ◽  
Author(s):  
M. Rapp
Keyword(s):  
Electron Capture ◽  
Aerosol Particles ◽  
Pure Water ◽  
Electron Attachment ◽  
Water Ice ◽  
Ice Particles ◽  
Repeated Observation ◽  
Meteoric Smoke ◽  
Positively Charged

Abstract. Time constants for photodetachment, photoemission, and electron capture are considered for two classes of mesospheric aerosol particles, i.e., meteor smoke particles (MSPs) and pure water ice particles. Assuming that MSPs consist of metal oxides like Fe2O3 or SiO, we find that during daytime conditions photodetachment by solar photons is up to 4 orders of magnitude faster than electron attachment such that MSPs cannot be negatively charged in the presence of sunlight. Rather, even photoemission can compete with electron capture unless the electron density becomes very large (>>1000 cm−3) such that MSPs should either be positively charged or neutral in the case of large electron densities. For pure water ice particles, however, both photodetachment and photoemission are negligible due to the wavelength characteristics of its absorption cross section and because the flux of solar photons has already dropped significantly at such short wavelengths. This means that water ice particles should normally be negatively charged. Hence, our results can readily explain the repeated observation of the coexistence of positive and negative aerosol particles in the polar summer mesopause, i.e., small MSPs should be positively charged and ice particles should be negatively charged. These results have further important implications for our understanding of the nucleation of mesospheric ice particles as well as for the interpretation of incoherent scatter radar observations of MSPs.

scholarly journals On the Climatic Impact of CO2Ice Particles in Atmospheres of Terrestrial Exoplanets

2012 ◽  
Vol 8 (S293) ◽  
pp. 303-308
Author(s):  
D. Kitzmann ◽  
A. B. C. Patzer ◽  
H. Rauer
Keyword(s):  
Radiative Transfer ◽  
Thermal Radiation ◽  
Greenhouse Effect ◽  
Outer Boundary ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Climatic Impact ◽  
Absorption Bands ◽  
Ice Particles ◽  
Stellar Radiation

AbstractClouds play a significant role for the energy budget in planetary atmospheres. They can scatter incident stellar radiation back to space, effectively cooling the surface of terrestrial planets. On the other hand, they may contribute to the atmospheric greenhouse effect by trapping outgoing thermal radiation. For exoplanets near the outer boundary of the habitable zone, condensation of CO2can occur due to the low atmospheric temperatures. These CO2ice clouds may play an important role for the surface temperature and, therefore, for the question of habitability of those planets. However, the optical properties of CO2ice crystals differ significantly from those of water droplets or water ice particles. Except for a small number of strong absorption bands, they are almost transparent with respect to absorption. Instead, they are highly effective scatterers at long and short wavelengths. Therefore, the climatic effect of a CO2ice cloud will depend on how much incident stellar radiation is scattered to space in comparison to the amount of thermal radiation scattered back towards the planetary surface. This contribution aims at the potential greenhouse effect of CO2ice particles. Their scattering and absorption properties are calculated for assumed particle size distributions with different effective radii and particle densities. An accurate radiative transfer model is used to determine the atmospheric radiation field affected by such CO2particles. These results are compared to less detailed radiative transfer schemes employed in previous studies.

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