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Träfflista för sökning "WFRF:(Lebreton Jean Pierre) srt2:(2011-2014)"

Sökning: WFRF:(Lebreton Jean Pierre) > (2011-2014)

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1.
  • Holmberg, Mika (författare)
  • On the structure and dynamics of Saturn's inner plasma disk
  • 2013
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • This licentiate thesis presents our investigation of Saturn's inner plasma disk. The thesis gives an overview of the Cassini-Huygens project, what a plasma is and how we use the Langmuir probe to investigate it, various difficulties related to the measurements, the structure of the magnetosphere of Saturn, with special focus on the inner magnetosphere and the region around the Saturnian moon Enceladus. For our investigation we use the Cassini Langmuir probe to derive ion density and ion velocity in the region from 2.5 to 12 Saturn radii. We show that the dominant part of the plasma torus, ion density above ~15 particle/cm3, is located in between 2.5 and 8 Saturn radii (1 RS = 60,268 km) from the planet, with a north-southward extension of 2 RS. The plume of the moon Enceladus is clearly visible as an ion density maximum of 105 cm-3, only present at the south side of the ring plane, as expected since the Enceladus plumes are located in the south polar region. Also the azimuthal ion velocity vi,Θ is estimated, showing a clear general trend in the region between 3 and 7 RS, described by vi,Θ =1.5R2-8.7R+39. The average vi,Θ starts to deviate from corotation speed at around 3 RS and reaches down to ~68 % of corotation close to 5 RS. The Langmuir probe data show a clear day/night side asymmetry in both ion density and ion velocity, most prominent in the radial region 4-6 RS from the center of Saturn. The ion densities ni varies from an average of ~35 cm-3 for the lowest dayside values close to noon up to ~70 cm-3 for the highest nightside values around midnight. The azimuthal ion velocities vi,Θ varies from ~28-32 km/s at the lowest dayside values around noon to ~36-40 km/s at the highest nightside values around midnight. This gives an azimuthal ion velocity difference between noon and midnight of Δvi,Θ ~5-10 km/s. The day/night asymmetry is suggested to be due to dust-plasma interaction.
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2.
  • Janhunen, Pekka, et al. (författare)
  • Electric Solar Wind Sail in tailwind
  • 2011
  • Ingår i: EPSC-DPS Joint Meeting 2011.
  • Konferensbidrag (refereegranskat)abstract
    • The Electric Solar Wind Sail (E-sail) is a novelpropulsion concept that enables faster space travel tomany solar system targets. E-sail uses charged solarwind particles as the source of its propulsion. This isachieved by deploying long, conducting and chargedtethers, which get pushed by the solar wind byCoulomb drag [1].E-sail technology is being developed to technicalreadiness level (TRL) 4-5 by the European Union’sSeventh Framework Programme for Research andTechnological Development, EU FP7, in a projectnamed ESAIL (http://www.electric-sailing.fi/fp7).Prototypes of the key parts are to be produced. Thedesign will be scalable so that a real solar winddemonstration mission could be scaled up from them.We review here the latest results of the constantlyevolving E-sail project.
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