TY  - JOUR
A1  - Brilliantov, Nikolai V.
A1  - Schmidt, Jürgen
T1  - Aggregation kinetics in a flow : the role of particle-wall collisions
N2  - Agglomeration in a fluid flow, when collisions of aggregates with channel walls are important is analyzed. We assume the diffusion-limited mechanism for clusters growth and the Stokes' force exerted on the agglomerates from the flow. Collisions of the particles with the channel walls are modeled by a random Poisson process. We develop an analytical theory for the size distribution of the aggregates and check the theoretical predictions by Monte Carlo simulations. The numerical data agree well with the analytical results.
Y1  - 2009
UR  - http://www.springerlink.com/content/1951-6355
U6  - https://doi.org/10.1140/epjst/e2009-01006-X
SN  - 1951-6355
ER  - 
TY  - JOUR
A1  - Jones, Geraint H.
A1  - Arridge, Christopher S.
A1  - Coates, Andrew J.
A1  - Lewis, Gethyn R.
A1  - Kanani, Sheila
A1  - Wellbrock, Anne
A1  - Young, David T.
A1  - Crary, Frank J.
A1  - Tokar, Robert L.
A1  - Wilson, R. J.
A1  - Hill, Thomas W.
A1  - Johnson, Robert E.
A1  - Mitchell, Donald G.
A1  - Schmidt, Jürgen
A1  - Kempf, Sascha
A1  - Beckmann, Uwe
A1  - Russell, Christopher T.
A1  - Jia, Y. D.
A1  - Dougherty, Michele K.
A1  - Waite, J. Hunter
A1  - Magee, Brian A.
T1  - Fine jet structure of electrically charged grains in Enceladus' plume
N2  - By traversing the plume erupting from high southern latitudes on Saturn's moon Enceladus, Cassini orbiter instruments can directly sample the material therein. Cassini Plasma Spectrometer, CAPS, data show that a major plume component comprises previously-undetected particles of nanometer scales and larger that bridge the mass gap between previously observed gaseous species and solid icy grains. This population is electrically charged both negative and positive, indicating that subsurface triboelectric charging, i.e., contact electrification of condensed plume material may occur through mutual collisions within vents. The electric field of Saturn's magnetosphere controls the jets' morphologies, separating particles according to mass and charge. Fine-scale structuring of these particles' spatial distribution correlates with discrete plume jets' sources, and reveals locations of other possible active regions. The observed plume population likely forms a major component of high velocity nanometer particle streams detected outside Saturn's magnetosphere.
Y1  - 2009
UR  - http://www.agu.org/journals/gl/
U6  - https://doi.org/10.1029/2009gl038284
SN  - 0094-8276
ER  - 
TY  - JOUR
A1  - Postberg, Frank
A1  - Kempf, Sascha
A1  - Schmidt, Jürgen
A1  - Brilliantov, Nikolai V.
A1  - Beinsen, Alexander
A1  - Abel, Bernd
A1  - Buck, Udo
A1  - Srama, Ralf
T1  - Sodium salts in E-ring ice grains from an ocean below the surface of Enceladus
N2  - Saturn's moon Enceladus emits plumes of water vapour and ice particles from fractures near its south pole(1-5), suggesting the possibility of a subsurface ocean(5-7). These plume particles are the dominant source of Saturn's E ring(7,8). A previous in situ analysis(9) of these particles concluded that the minor organic or siliceous components, identified in many ice grains, could be evidence for interaction between Enceladus' rocky core and liquid water(9,10). It was not clear, however, whether the liquid is still present today or whether it has frozen. Here we report the identification of a population of E-ring grains that are rich in sodium salts (similar to 0.5- 2% by mass), which can arise only if the plumes originate from liquid water. The abundance of various salt components in these particles, as well as the inferred basic pH, exhibit a compelling similarity to the predicted composition of a subsurface Enceladus ocean in contact with its rock core(11). The plume vapour is expected to be free of atomic sodium. Thus, the absence of sodium from optical spectra(12) is in good agreement with our results. In the E ring the upper limit for spectroscopy(12) is insufficiently sensitive to detect the concentrations we found.
Y1  - 2009
UR  - http://www.nature.com/nature/
U6  - https://doi.org/10.1038/Nature08046
SN  - 0028-0836
ER  - 
TY  - JOUR
A1  - Shepelyansky, Dima L.
A1  - Pikovskij, Arkadij
A1  - Schmidt, Jürgen
A1  - Spahn, Frank
T1  - Synchronization mechanism of sharp edges in rings of Saturn
N2  - We propose a new mechanism which explains the existence of enormously sharp edges in the rings of Saturn. This mechanism is based on the synchronization phenomenon due to which the epicycle rotational phases of particles in the ring, under certain conditions, become synchronized with the phase of external satellite, e. g. with the phase of Mimas in the case of the outer B ring edge. This synchronization eliminates collisions between particles and suppresses the diffusion induced by collisions by orders of magnitude. The minimum of the diffusion is reached at the centre of the synchronization regime corresponding to the ratio 2:1 between the orbital frequency at the edge of B ring and the orbital frequency of Mimas. The synchronization theory gives the sharpness of the edge in a few tens of meters that is in agreement with available observations.
Y1  - 2009
UR  - http://www3.interscience.wiley.com/cgi-bin/issn?DESCRIPTOR=PRINTISSN&VALUE=0035-8711
U6  - https://doi.org/10.1111/j.1365-2966.2009.14719.x
SN  - 0035-8711
ER  -