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| Titel |
Plasma parameter analysis of the Langmuir decay process via Particle-in-Cell simulations |
| VerfasserIn |
M. A. Diaz, M. Zettergren, J. L. Semeter, M. Oppenheim |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 30, no. 8 ; Nr. 30, no. 8 (2012-08-16), S.1169-1183 |
| Datensatznummer |
250017253
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| Publikation (Nr.) |
 copernicus.org/angeo-30-1169-2012.pdf |
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| Zusammenfassung |
| The beam-plasma mechanism, based on the Langmuir decay process, has been
proposed to explain naturally enhanced ion-acoustic lines (NEIALs), which are
spectral distortions in incoherent scatter radar (ISR) data frequently
observed in the vicinity of auroral arcs. In this work the effect of the Langmuir
decay process on the ISR spectrum is studied and compared with an analytical
model for different plasma parameters by using an electrostatic parallel
particle-in-cell (EPPIC) code. Simulations show that the code is working in
accordance with theory for a wide range of beam and plasma values and that
the features of the spectrum are sensitive to changes of those values. These
results suggest that the EPPIC code might be used to build a spectrum-plasma
parameter model which will allow estimation of beam and plasma parameters
from observed spectra. Simulations also confirm that background electron
density (ne) plays an important role in determining the maximum detectable
wavenumber of the enhancement. Specifically, results demonstrate that an
increase in ne makes the enhancements of the ion acoustic more likely line
at large wavenumbers, a finding consistent with statistical studies showing
more frequent NEIAL occurrence near solar maximum. Finally, the simulations
expose some inaccuracies of the current theoretical model in quantifying the
energy passed from the beam to the Langmuir waves as well as with the range
of enhanced wavenumbers. These differences may be attributable to the weak
Langmuir turbulent regime assumption used in the theory. |
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