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The PhD defence and trial lecture are partly digital. The chair of the defence will moderate the disputation.
Ex auditorio questions: the chair of the defence will invite the audience physically present in the auditorium to ask ex auditorio questions.
Join the disputation digitally
- Download Zoom
- Request the thesis (.pdf)
(available until the disputation starts)
Trial lecture
Time and place: March 24, 2021; 3:15 PM, Lille Fysiske auditorium (V232) - Fysikkbygingen
Title:
"The physics and interpretation of dust impact signals
from electrostatic probes on spacecrafts"
Join the trial lecture digitally
Main research findings
Instabilities and turbulence in the Earth’s ionosphere represent the largest source of errors in global navigation satellite systems and are a major contributor to irregularities that disturb commercial radio communication. By using Langmuir probes, we can determine the temperature and the density of ionospheric plasma, providing in situ measurements that are essential for studying our ionosphere and to make robust, well-functioning electronics, that can endure the harsh environment.
For a Langmuir system, in a space environment, several external sources will affect the measurements, like charged objects close to the probe, contamination of the probe itself and temporal effects related to changes in the probe bias. Understanding these processes will lead to better designs of a Langmuir probe system, allowing higher sampling rates and better accuracy. Using computer simulations, and a Particle-In-Cell method, central design parameters have been studied. Especially with regard to the configuration of the probes, such as the distance between probes and how the system responds to changes in the bias that determine the sampling rate. In addition, non-linear effects of the system were explored which disclosed that a swept Langmuir probe exhibits essential properties described as the "fingerprint of memristors”.
Candidate contact information
Phone number: 99637764
Adjudication Committee
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Dr. Laila Andersson, Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, USA
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Professor Åshild Fredriksen, University of Tromsø – The Arctic University of Norway
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Professor Olav Fredrik Syljuåsen, Department of Physics, University of Oslo, Norway
Supervisors
- Professor Ketil Røed, Department of Physics, University of Oslo, Norway
- Professor Wojciech J. Miloch, Department of Physics, University of Oslo, Norway
- Professor Ørjan G. Martinsen, Department of Physics, University of Oslo, Norway
Chair of defence
- Head of the department Susanne F. Viefers, Department of Physics, University of Oslo, Norway
Contact information to Department: Line Trosterud Resvold