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On this page we show recent hightlights of Miracle Science.
Strong Ripples in the Sun's 'Electric Wind'
Many different types of waves are observed throughout the Solar Wind, which is a plasma ('gas' of electrically charged particles) that continually flows outwards from the Sun and throughout the Solar System. Among these are *Langmuir* waves, which are in a class of waves that transport energy from place to place in the Solar Wind flow through fluctuations or 'ripples' in the electric field and in the density of charged particles (ions and electrons). If the density fluctuations grow to large enough amplitudes, these waves undergo complex reflections and refractions in the plasma, which are observed as fluctuations in electric field by instruments such as those aboard the STEREO spacecraft.The diagrams above show the results of computer simulations of the solar wind plasma by Patrick Guio (UCL), using the equations originally developed by Zakharov (1972) to describe the non-linear evolution of plasma density and electrostatic potential. The upper panels show (left) the plasma density fluctuation pattern and (right) the corresponding electric field on a colour scale, as a function of spatial position and time.
The lower panels show analogous results for a Solar Wind plasma with density fluctuations which have amplitudes about ten times as large. Note that in this case the electric field develops with time into characteristic, localised intensifications - the result of the Langmuir waves being multiply reflected and 'trapped' in density 'wells'. This type of simulation produces statistical properties of the electric field in remarkable agreement with those from STEREO, and is the subject of a collaborative study with Arnaud Zaslavsky from Centre for Astrophysics (Harvard).
Page last modified on 24 feb 11 18:38 by Dugan K Witherick