Kinetic theory of electromagnetic ion waves in relativistic plasmas

A kinetic theory for electromagnetic ion waves in a cold relativistic plasma is derived. The kinetic equation for the broadband electromagnetic ion waves is coupled to the slow density response via an acoustic equation driven by ponderomotive force like term linear in the electromagnetic field amplitude. The modulational instability growth rate is derived for an arbitrary spectrum of waves. The monochromatic and random phase cases are studied.Comment: 7 pages, 4 figures, to appear in Physics of Plasma

Spectrum of the seismic-electromagnetic and acoustic waves caused by seismic and volcano activity

International audienceModeling of the spectrum of the seismo-electromagnetic and acoustic waves, caused by seismic and volcanic activity, has been done. This spectrum includes the Electromagnetic Emission (EME, due to fracturing piezoelectrics in rocks) and the Acoustic Emission (AE, caused by the excitation and the nonlinear passage of acoustic waves through the Earth's crust, the atmosphere, and the ionosphere). The investigated mechanism of the EME uses the model of fracturing and the crack motion. For its analysis, we consider a piezoelectric crystal under mechanical stresses, which cause the uniform crack motion, and, consequently, in the vicinity of the moving crack also cause non-stationary polarization currents. A possible spectrum of EME has been estimated. The underground fractures produce Very Low (VLF) and Extremely Low Frequency (ELF) acoustic waves, while the acoustic waves at higher frequencies present high losses and, on the Earth's surface, they are quite small and are not registered. The VLF acoustic wave is subject to nonlinearity under passage through the lithosphere that leads to the generation of higher harmonics and also frequency down-conversion, namely, increasing the ELF acoustic component on the Earth's surface. In turn, a nonlinear propagation of ELF acoustic wave in the atmosphere and the ionosphere leads to emerging the ultra low frequency (ULF) acousto-gravity waves in the ionosphere and possible local excitation of plasma waves

Electromagnetic emission from magnetite plate cracking under seismic processes

International audienceElectromagnetic emission generated by cracking of a magnetite plate is theoretically investigated. The non-stationary mechanical stresses, produced by moving the tip of a crack and a wave of mechanical unloading in the plate are considered as the sources of the radiation. It is demonstrated that the radiation is produced by the appearance of a non-stationary magnetic moment in the plate

Interpretation of the microwave non-thermal radiation of the Moon during impact events

The results of recent observations of the non-thermal electromagnetic (EM) emission at wavelengths of 2.5cm, 13cm, and 21cm are summarized. After strong impacts of meteorites or spacecrafts (Lunar Prospector) with the Moon's surface, the radio emissions in various frequency ranges were recorded. The most distinctive phenomenon is the appearance of quasi-periodic oscillations with amplitudes of 3–10K during several hours. The mechanism concerning the EM emission from a propagating crack within a piezoactive dielectric medium is considered. The impact may cause the global acoustic oscillations of the Moon. These oscillations lead to the crackening of the Moon's surface. The propagation of a crack within a piezoactive medium is accompanied by the excitation of an alternative current source. It is revealed that the source of the EM emission is the effective transient magnetization that appears in the case of a moving crack in piezoelectrics. The moving crack creates additional non-stationary local mechanical stresses around the apex of the crack, which generate the non-stationary electromagnetic field. For the cracks with a length of 0.1–1µm, the maximum of the EM emission may be in the 1–10GHz range

Dusty plasma in space

Intensos estudios de la física de plasmas realizados desde hace alrededor de 10 años han visto el surgimiento de una nueva línea de investigación: la física de plasmas polvosos, que consisten de electrones, iones y partículas de polvo cargadas. Se observan en varios medios astrofísicos como nebulosas, colas cometarias, anillos planetarios, ionosferas planetarias, etc. La presencia de partículas de polvo pesadas y cargadas puede influenciar significativamente varios parámetros del plasma al crear, por ejemplo, estructuras en su interior en un rango muy amplio de cientos a decenas de millones de kilómetros. En este trabajo presentamos una revisión y un análisis del espectro del volumen y ondas superficiales, estabilidades y solitones en un plasma polvoso. doi: https://doi.org/10.22201/igeof.00167169p.1998.37.2.39