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    STUDIA AMBIENTUM - Ediţia nr.1-2 din 2012  
         
  Articol:   MAGNETOSPHERE DOUBLE LAYERS AND AURORA BOREALIS. ACCELERATION MECHANISMS AND INSTABILITIES.

Autori:  OANA NICULESCU, MARIUS MIHAI CAZACU, MIHAIL NICOLAE DANILA, DAN GHEORGHE DIMITRIU, SILVIU OCTAVIAN GURLUI, MARICEL AGOP.
 
       
         
  Rezumat:   As it was confirmed that the aurora borealis can be assimilated to laboratory plasma, a series of experiments are performed in order to emphasize the mechanisms of double layers formation and to study their properties. To this extent, in our work, the double layers are obtained in front of a positively biased electrode that is immersed in a cold, steady-state diffusion plasma, when the biasing voltage exceeds a threshold value. In certain experimental conditions, complex space charge structures are obtained in the form of multiple double layers. In this case, it was found that the potential profile is very similar to the aurora borealis stair-step diagram. Further experiments were carried out to study the influence of uniform magnetic fields on the formation and dynamics of a simple double layer, in order to simulate the conditions from the Earth magnetosphere. The results showed that, even at low intensity magnetic fields, the double layer behavior changes dramatically. Also the study of instabilities (Buneman instabilities, ion-acoustic instabilities) that arise in such plasma structures was proved to be very similar to those encountered in northern lights. These series of experiments can provide important information about the formation of the magnetospheric double layers and their possible role in creating the aurora.

Key words: aurora borealis, plasma double layers
 
         
     
         
         
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