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INSTITUTET FÖR RYMDFYSIK UPPSALA
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Swedish Institute of Space Physics (59o50.272'N, 17o38.786'E)
Student project at IRF Uppsala

Project work / Examensarbete (30 hp)

Modelling of Cassini Langmuir probe measurements

Student: Thomas Nilsson, Uppsala University
Supervisor: Anders Eriksson
Period: Spring 2009

Background

NASA's Cassini mission is now in orbit around Saturn. Among the instruments onboard, the Langmuir probe instrument LP, built and operated by the Swedish Institute of Space Physics (IRF) in Uppsala as a part of the Radio and Plasma Wave Science instrument from the University of Iowa, is very useful for investigations of cold and thermal plasmas in all of Saturn's magnetosphere and in Titan's ionosphere. However, interpreting the data in terms of plasma properties (density and temperature) requires an understanding of the spacecraft-plasma interaction and its impact on the LAP measurements. This understanding is up to now semi-empirical: quantitative modelling involving numerical simulation is needed for deeper understanding of errors and uncertainties.

Project

In the project, the Cassini LP measurements were modelled for varying plasma conditions by use of the SPIS code package for s/c-plasma interaction studies. The project included:
  • Gathering background information on Cassini and the SPIS code
  • Setting up and running SPIS
  • Creating a model of Cassini and LP in SPIS
  • Running simulations and analyzing the results
  • Report writing and seminar presentation
There was close collaboration with the twin project on Rosetta and also with other SPIS users, including a visit to ESA/ESTEC in Noordwijk, Holland.

Results



[Cassini]
Figure: The electrostatic potential around Cassini for an electron density of 1 per cc, resulting from a particle-in-cell simulation using SPIS.

http://space.irfu.se/exjobb/2009_thomas_nilsson/index.html
last modified on Tuesday, 01-Feb-2011 09:30:58 CET