• English
    • Norsk
  • English 
    • English
    • Norsk
  • Administration
View Item 
  •   Home
  • Det matematisk-naturvitenskapelige fakultet
  • Fysisk institutt
  • Fysisk institutt
  • View Item
  •   Home
  • Det matematisk-naturvitenskapelige fakultet
  • Fysisk institutt
  • Fysisk institutt
  • View Item
JavaScript is disabled for your browser. Some features of this site may not work without it.

The Unstructured Particle-In-Cell Method with Applications for Objects in Ionospheric Plasmas

Marholm, Sigvald
Doctoral thesis
View/Open
PhD-Marholm-2020.pdf (5.462Mb)
Year
2020
Permanent link
http://urn.nb.no/URN:NBN:no-76155

Metadata
Show metadata
Appears in the following Collection
  • Fysisk institutt [2360]
Abstract
Spaceborn instruments such as the Langmuir probe are essential to understand our own ionosphere. In this dissertation we explore the behaviour of such instruments through computer simulations, and find that some of the assumptions about them may not be well justified, causing degraded performance. We also develop new theories to counteract these effects, as well as new methods for simulating such objects in plasmas.

One of the ways to measure the electron density in the ionosphere is by applying a positive voltage to a thin wire – a Langmuir probe – and then exposing it to the plasma in the ionosphere. The probe will then attract electrons, and using the so-called OML theory, this current of electrons can be used to calculate the electron density. However, the OML theory relies on several simplifying assumptions that are not always well satisfied, leading to a reduced accuracy.

Ionospheric plasmas containing objects can be simulated on a computer using the Particle-In-Cell method, and an unstructured, tetrahedral mesh allows for arbitrary geometries, such as that of Langmuir probes attached to a satellite. Using such simulations, we quantify the electron current collected by probes of short length, or situated in a non-Maxwellian plasma. This is not covered by the usual OML theory, and this knowledge may therefore be used to improve ionospheric measurements. We also revealed by simulations that multineedle Langmuir probes mounted on a small satellite may charge the satellite sufficiently to render the measurements invalid, unless care is taken. Finally, we have also contributed with new numerical methods for simulating objects connected in arbitrary circuits in plasmas.
List of papers
Paper I: Diako Darian, Sigvald Marholm, Mikael Mortensen and Wojciech J. Miloch. “Theory and simulations of spherical and cylindrical Langmuir probes in non-Maxwellian plasmas.” Plasma Physics and Controlled Fusion, 61, 2019. DOI: 10.1088/1361-6587/ab27ff. The article is included in the thesis. Also available at: https://doi.org/10.1088/1361-6587/ab27ff
Paper II: Sigvald Marholm, Richard Marchand, Diako Darian, Wojciech J. Miloch and Mikael Mortensen. “Impact of Miniaturized Fixed-Bias Multi-Needle Langmuir Probes on CubeSats.” IEEE Transactions on Plasma Science, 47, 2019. DOI: 10.1109/TPS.2019.2915810. The article is not available in DUO due to publisher restrictions. The accepted version is available in DUO: http://urn.nb.no/URN:NBN:no-75435
Paper III: Sigvald Marholm and Richard Marchand. “Finite-Length Effects on Cylindrical Langmuir Probes.” Submitted to Physical Review Research 08.07.19. The paper is not available in DUO awaiting publishing.
Paper IV: Sigvald Marholm, Diako Darian, Mikael Mortensen, Richard Marchand and Wojciech J. Miloch. “A Novel Method for Circuits of Perfect Electric Conductors in Unstructured Particle–In–Cell Plasma–Object Interaction Simulations.” Submitted to Journal of Computational Physics 28.06.18. The paper is not available in DUO awaiting publishing.
 
Responsible for this website 
University of Oslo Library


Contact Us 
duo-hjelp@ub.uio.no


Privacy policy
 

 

For students / employeesSubmit master thesisAccess to restricted material

Browse

All of DUOCommunities & CollectionsBy Issue DateAuthorsTitlesThis CollectionBy Issue DateAuthorsTitles

For library staff

Login
RSS Feeds
 
Responsible for this website 
University of Oslo Library


Contact Us 
duo-hjelp@ub.uio.no


Privacy policy