Change search
ReferencesLink to record
Permanent link

Direct link
Mid-latitude ionospheric signature of a weak solar flare in winter
KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
SANSA Space Science, Hospital Street, Hermanus 7200, South Africa; School of Chemistry, University of KwaZulu-Natal, Durban, South Africa.
2013 (English)In: South African Journal of Science, ISSN 0038-2353, E-ISSN 1996-7489, Vol. 109, no 1-2, 83-87 p.Article in journal (Refereed) Published
Abstract [en]

Measurements of the amplitude and phase of very low frequency transmitter signals were used to evaluate the effects on the ionosphere of a moderate intensity solar flare that occurred on 13 December 2007. These measurements were compared to modelled results from the Long Wave Propagation Capability code. The ionospheric effects were found to be delayed by ∼1 min with respect to the 0.1-0.8 nm solar X-ray flux.

Place, publisher, year, edition, pages
2013. Vol. 109, no 1-2, 83-87 p.
Keyword [en]
VLF, solar flare, D-region, ionosphere, X-ray
National Category
Physical Sciences
URN: urn:nbn:se:kth:diva-106984DOI: 10.1590/sajs.2013/802ISI: 000320212900016ScopusID: 2-s2.0-84873638665OAI: diva2:574303

QC 20130320. Updated from accepted to published.

Available from: 2012-12-05 Created: 2012-12-05 Last updated: 2013-12-11Bibliographically approved
In thesis
1. A Simulation Approach to High-Frequency Plasma Waves
Open this publication in new window or tab >>A Simulation Approach to High-Frequency Plasma Waves
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Electrostatic waves in the form of Broadband Electrostatic Noise (BEN) have been observed in the Earth's auroral region associated with high geomagnetic activity. This broad frequency spectrum consists of three electrostatic modes, namely electron plasma, electron acoustic and beam-driven modes. These modes are excited in a plasma containing three electron components: hot, cool and beam electrons.

A 1D Particle-in-Cell (PIC) simulation was developed to investigate the characteristics of the electrostatic waves found in such a plasma. Dispersion, phase space and spatial electric field diagrams were constructed from the output of the PIC simulation which were used to describe the wave dispersion and spatial field structures found in a plasma. The PIC code used a three electron component plasma with Maxwellian distributions to describe the electron velocity distributions. Beam-driven waves were found to dominate the frequency spectrum while electron plasma and electron acoustic waves are damped for a high beam velocity. Furthermore, for a high beam velocity, solitary waves are generated by electron holes (positive potentials), giving rise to a bipolar spatial electric fi eld structure moving in the direction of the beam. Increasing the beam temperature allows the beam electrons to mix more freely with the hot and cool electrons, which leads to electron plasma and electron acoustic waves being enhanced while beam-driven waves are damped. Decreasing the beam density and velocity leads to damping of beam-driven waves, while electron plasma and electron acoustic waves are enhanced.

Measurements in Saturn's magnetosphere have found the co-existence of two electron (hot and cool) components. The electron velocities are best described by a kappa-distribution (instead of a Maxwellian) which has a high-energy tail. Using an adapted PIC simulation the study of electron plasma and electron acoustic waves was extended by using a kappa-distribution to describe the electron velocities with low indices. Electron acoustic waves are damped over most wave number ranges. Electron plasma waves are weakly damped at low wave numbers and damped for all other wave numbers.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. x, 33 p.
Trita-EE, ISSN 1653-5146 ; 2012:64
National Category
Fusion, Plasma and Space Physics
urn:nbn:se:kth:diva-106822 (URN)
2012-12-13, Seminarierum, Teknikringen 31, KTH, Stockholm, 13:00 (English)

QC 20121205

Available from: 2012-12-05 Created: 2012-12-05 Last updated: 2012-12-05Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Koen, Etienne J.Collier, Andrew B.
By organisation
Space and Plasma Physics
In the same journal
South African Journal of Science
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: 60 hits
ReferencesLink to record
Permanent link

Direct link