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Thermally induced fluctuations in plasmas

agosto 25 / 1:15 pm - 2:15 pm

Juan Alejandro Valdivia,

Departamento de física

Facultad de Ciencias

Universidad de Chile

 

Recently, there has been quite a lot of discussion about the relevance of thermally induced magnetic fluctuations in plasma, particularly in laboratory and solar wind situations. In the case of the solar wind, the distribution of events and of these electromagnetic fluctuations are usually organized in the so called β-A diagram; with β as the ratio between the thermal parallel energy and the magnetic energy, and A as the thermal anisotropy. There has been a number of proposed explanations about the existence of these electromagnetic fluctuations under
quasi-stable conditions. We propose that a relevant component of these fluctuations can be produced by the random motion of particles in the plasma so that their understanding requires a kinetic treatment that relies on an extension of the fluctuation-dissipation theorem for
anisotropic plasmas [Navarro et al., PRL, 2014] . Beyond β and A, it is important to understand the relevance of the parallel and perpendicular (with respect to a background magnetic field) modes and fluctuations in this β-A diagram, as well as the relevant time scales involved. It is important to mention that at first sight the observations seem to be bounded by oblique instabilities (actual perpendicular), but that depends on the time scales involves in the system. We will combine both theory and observations to study these issues, in a hope to provide some additional insight about our understanding of turbulence and wave excitation in the solar wind.

 

 

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Detalles

Fecha:
agosto 25
Hora:
1:15 pm - 2:15 pm

Lugar

Sala Seminarios 3er piso, DFI
Av Blanco Encalada 2008
Santiago, Chile
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