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Rosetta Langmuir probe performance
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
2013 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Several Langmuir probe voltage sweeps by a model of the ESA spacecraft Rosetta was simulated in a plasma with solar wind parameters using the ESA open source software SPIS 5. The simulations were carried out to in- vestigate the features of the spacecraft’s environment in the solar wind and the effect of photoemission from the spacecraft surface on the measurements made by the Langmuir probes on board Rosetta. We report a best fit to an existing probe sweep result in the solar wind near the Earth at 1 AU from 9 Nov 2009 for a 4 million particle simulation in SPIS of an 8 V positively charged spacecraft with the following parameters: Tph = 2 eV, Te = 12 eV, Ti = 5 eV, ne = 5 cm−3. We also report that the spacecraft is shielding the Langmuir probes on Rosetta from plasma electrons, and particularly low energy electrons. In one instance, this blocking is shown to lead to an over- estimation of solar wind electron temperature by 12% and underestimate the plasma density by 24% by the Langmuir Probe for a +10 V charged spacecraft in ne= 5 cm−3, Te = 12 eV solar wind. Two models used in lit- erature on photoemission, one for isotropical emission from a plane and the other for radial emission from a point, was used and compared. We report a clear preference to the approximation of a Maxwellian energy distribution of photoelectrons emitted radially from a point source model with our sim- ulation result on the Langmuir Probe aboard Rosetta. We also report the solar aspect angle dependence on the plasma potential and plasma density result, which are in overall agreement with Rosetta measurements from the second Earth fly-by. 

Place, publisher, year, edition, pages
2013. , 58 p.
Keyword [en]
Rosetta, SPIS, SPIS 5, Langmuir, Probe, Plasma, Probe sweep, Potential, Simulation, PIC, IRF, Swedish Institute of Space Physics, ESA
National Category
Astronomy, Astrophysics and Cosmology Fusion, Plasma and Space Physics
URN: urn:nbn:se:uu:diva-213146OAI: diva2:680862
External cooperation
IRF Uppsala
Educational program
Master Programme in Physics
2013-06-13, Ångströmlaboratoriet, Uppsala, 17:46 (English)
Available from: 2013-12-19 Created: 2013-12-18 Last updated: 2013-12-19Bibliographically approved

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