Formation of VLF chorus frequency spectrum: Cluster data and comparison with the backward wave oscillator model

0089472 - ÚFA 2008 RIV US eng J - Journal Article
Trakhtengerts, V. Y. - Demekhov, A. G. - Titova, E. E. - Kozelov, B. V. - Santolík, Ondřej - Macúšová, Eva - Gurnett, D. A. - Pickett, J. S. - Rycroft, M. J. - Nunn, D.
Formation of VLF chorus frequency spectrum: Cluster data and comparison with the backward wave oscillator model.
[Formovaní frekvenčního spectra VLF chorusu: Porovnání dat z družíc Cluster s modelem oscilátoru se zpětnou vazbou.]
Geophysical Research Letters. Roč. 34, č. 2 (2007), L02104/1-L02104/5. ISSN 0094-8276. E-ISSN 1944-8007
R&D Projects: GA ČR GA205/06/1267
Institutional research plan: CEZ:AV0Z30420517
Keywords : Backward wave oscillator * Steplike deformation in the distribution function * Source pozition * Resonant electrons
Subject RIV: BL - Plasma and Gas Discharge Physics
Impact factor: 2.744, year: 2007

The dependence of the frequency spectrum of individual chorus elements on the position of the observation point in and near the generation region is analyzed using recent Cluster data obtained on two different geomagnetically active days. The source of night-side chorus is localized using multicomponent measurements of the wave electric and magnetic fields. We have revealed that the spectrum of the chorus elements lacks the lower frequencies at the center of the source region. One possible explanation of this effect is provided by applying the backward wave oscillator model of chorus generation to these data. According to this model, the chorus frequency is determined by the parallel velocity corresponding to a steplike deformation in the distribution function of resonant electrons. This velocity decreases during the generation of an element as the electrons move through the source region. Thus, only a part of a chorus element is visible inside this region.

Vývoj frekvenčních spekter v závislosti na pozici zdrojové oblasti. Změna frekvence s paralelní rychlostí a porovnání se schodovitou změnou distribuční funkce.
Permanent Link: http://hdl.handle.net/11104/0150674