uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Nonlinearly generated plasma waves as a model for enhanced ion acoustic lines in the ionosphere
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
2007 (English)In: Geophysical Research Letters, ISSN 0094-8276, Vol. 34, no 18, L18101- p.Article in journal (Refereed) Published
Abstract [en]

Observations from the EISCAT Svalbard Radar, for instance, demonstrate that the symmetry of the naturally occurring ion line can be broken by an enhanced, non-thermal, level of fluctuations, i.e., Naturally Enhanced Ion-Acoustic Lines (NEIALs). In a significant number of cases, the entire ion spectrum can be distorted, with the appearance of a third line, corresponding to a propagation velocity significantly below the ion acoustic sound speed. By numerical simulations, we consider one possible model accounting for the observations, suggesting that a primary process can be electron acoustic waves excited by a cold electron beam. Subsequently, an oscillating two-stream instability excites electron plasma waves which in turn decay to asymmetric ion lines. Our code solves the full Vlasov equation for electrons and ions, with the dynamics coupled through the electrostatic field derived from Poisson's equation.

Place, publisher, year, edition, pages
2007. Vol. 34, no 18, L18101- p.
National Category
Physical Sciences
URN: urn:nbn:se:uu:diva-97955DOI: 10.1029/2007GL031513ISI: 000249683400008OAI: oai:DiVA.org:uu-97955DiVA: diva2:173085
Available from: 2009-01-01 Created: 2009-01-01 Last updated: 2011-01-25Bibliographically approved
In thesis
1. Numerical Simulation as a Tool for Studying Waves and Radiation in Space
Open this publication in new window or tab >>Numerical Simulation as a Tool for Studying Waves and Radiation in Space
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Plasma physics governs the area of interactions between charged particles. As 99% of the visible universe is in a plasma state, it is an important topic in astronomy and space physics, where we already at an altitude of 60 km reach the plasma environment surrounding our planet in the form of the ionosphere. The search for fusion, the source of power for the sun, as well as industrial use have been the main topics for earth bound plasma reasurch.

A plasma is composed of charged particles which interact by the electromagnetic force. In the kinetic description, via the Vlasov-Maxwell equations, the system is described in terms of probability distribution functions for each particle species, expressed in terms of particles position and velocity. The particles interact via self-consistent fields as determined by Maxwell's equations. For understanding the complex behaviour of the system, we need numerical solvers. These come in two flavours, Lagrangian methods, dealing with the moving around of synthetic particles, and Eulerian methods, which solve the set of partial differential, Vlasov and Maxwell equations. To perform the computations within reasonable time, we need to distribute our calculations on multiple machines, i.e. parallel programming, with the best possible matching between our computational needs and the need of splitting algorithms to adapt to our processing environment.

Paper I studies electron and ion beams within a Lagrangian and fluid model and compare the results with experimental observations. This is continued with studies of a full kinetic system, using an Eulerian solver, for a closer look at electron-ion interactions in relation to ionospheric observations, (Papers II and IV). To improve the performance of the Eulerian solver it was parallelised (Paper III). The thesis is ending with the possibility to observe ultrahigh energy neutrinos from an orbiting satellite by using the Moon's surface as a detector Paper V.

Place, publisher, year, edition, pages
Uppsala: Universitetsbiblioteket, 2008. 42 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 488
space physics, plasma physics, kinetic plasma, plasma simulations, beam instabilities
National Category
Fusion, Plasma and Space Physics
urn:nbn:se:uu:diva-9517 (URN)978-91-554-7384-6 (ISBN)
Public defence
2009-01-30, Siegbhansalen, Ångström Laboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Available from: 2009-01-01 Created: 2009-01-01 Last updated: 2010-03-09Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text
By organisation
Department of Astronomy and Space Physics
In the same journal
Geophysical Research Letters
Physical Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 159 hits
ReferencesLink to record
Permanent link

Direct link