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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 30, issue 8
Ann. Geophys., 30, 1169–1183, 2012
https://doi.org/10.5194/angeo-30-1169-2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 30, 1169–1183, 2012
https://doi.org/10.5194/angeo-30-1169-2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.

Regular paper 16 Aug 2012

Regular paper | 16 Aug 2012

Plasma parameter analysis of the Langmuir decay process via Particle-in-Cell simulations

M. A. Diaz1, M. Zettergren2, J. L. Semeter3, and M. Oppenheim4 M. A. Diaz et al.
  • 1Electrical Engineering Department, University of Chile, Santiago, Chile
  • 2Physical Sciences Department, Embry-Riddle Aeronautical University, Daytona Beach, FL, USA
  • 3Electrical and Computer Engineering Department and Center for Space Physics, Boston University, Boston, MA, USA
  • 4Astronomy Department, Boston University, Boston, MA, USA

Abstract. 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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