Generation of kinetic ion-acoustic waves in preflare atmosphere of a solar active region
|1Kryshtal, AN, 1Gerasimenko, SV, 2Voitsekhovska, AD |
1Main Astronomical Observatory of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
2Main Astronomical Observatory of the NAS of Ukraine, Kyiv, Ukraine
|Kosm. nauka tehnol. 2013, 19 ;(3):37–46|
|Publication Language: Russian|
We investigated the process of rise and development of instability of low-frequency waves in plasma in the area near the foot-point of coronal loops which corresponds to the lowmiddle preflare chromosphere. The study was carried out under the assumption of the quasi-potential form of magnetic field of a single loop when its amplitude at a given part of current circuit changed from 1 to 3 mT. The existence of a weak large-scale electric field in the loop and slow drift motions of plasma due to spatial inhomogeneities of its temperature and density were considered as the main reasons of instability. The identification of the obtained solution of dispersive relation allowed us to establish that for semiempirical model of the solar atmosphere FAL the waves generated during the linear stage of instability development are kinetic ion-acoustic waves. The most important properties of the waves under consideration are a low degree of plasma nonisothermality which is necessary for the instability appearance and its extremely low threshold expressed in the units of the local dreicer field’s amplitude. Kinetic ion-acoustic waves which are generated as well as kinetic Alfven waves have their own longitudinal electric field. Due to this field all these waves can effectively accelerate charge particles in preflare atmosphere of a solar active region.
|Keywords: kinetic ion-acoustic waves, plasma, solar coronal loops|
28. Vernazza J. E., Avrett E. H., Loeser R. Structure of the solar chromosphere. III. Models of the EUV brightness components of the quite Sun, Astrophys. J. Suppl. Ser., 45, 635—725 (1981).