*Earth Planets Space,* Vol. 58 (No. 9), pp. 1213-1217, 2006

## Kinetic effects on the parametric decays of Alfvén waves in relativistic pair plasmas

V. Muñoz^{1,2}, T. Hada^{1}, and S. Matsukiyo^{1}

^{1}Department of Earth System Science and Technology, Kyushu University, Japan

^{2}Departamento de Física, Facultad de Ciencias, Universidad de Chile

(Received November 10, 2005; Revised April 13, 2006; Accepted April 17, 2006; Online published September 29, 2006)

**Abstract: **
Parametric decays of a circularly polarized wave propagating along a constant magnetic field in an electron-positron plasma are studied. Fully relativistic effects on the particle velocity in the wave field are considered, as well as kinetic effects in the parallel direction, by means of a one-dimensional relativistic Vlasov equation. In this approximation, a dispersion relation is found for the parametric decays which describes the coupling between normal modes of the system, namely electromagnetic sideband modes and Langmuir waves.

**Key words: **
Parametric decays, Alfvén waves, relativistic plasma, electron-positron plasma.

Corresponding author E-mail: vmunoz@macul.ciencias.uchile.cl

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