Characteristics of plasma turbulence and radio emission from an interplanetary shock wave

Abstract

Aims. We investigate the characteristics of energetic electron beams, plasma turbulence and radio emission from interplanetary shock waves. Methods. Numerical calculations of spectra and Landau damping of hot plasma eigen oscillations in the magnetic field are used. Results. It is shown that the longitudinal wave spectrum, excited in the solar wind plasma, extends with the increase of the refractive index n over range of values n >10. This result allows us to explain the broad band of emission, the constant value of the average ratio of frequency-band to radio emission frequency from interplanetary shock wave fronts, and to estimate the electron beam density and amplitude of Langmuir waves at the shock. It is shown that a spectrum of radio emission is determined by the spectrum of Langmuir waves excited upstream of the interplanetary shock wave by heated electrons escaping from the shock wave front.

The planetary–exoplanetary environment: A nonlinear perspective

“…Plasma radio emissions generated by Langmuir-ion acoustic turbulence through nonlinear three-wave interactions (Melrose, 1991;Chian and Abalde, 1995;Rizzato et al, 2003) have been observed in planetary foreshocks (Kuncic and Cairns, 2005), type-III solar radio bursts (Lin et al, 1986;Henri et al, 2009) and type-II radio bursts from interplanetary shocks (Ledenev et al, 2008). A schematic diagram depicting the emission of nonthermal radio emissions by nonlinear wave-wave interactions in plasmas, via either a Langmuir-Alfvén turbulence or a Langmuirion acoustic turbulence, is shown in Fig.…”