ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Copernicus Publications Göttingen, Germany 10.5194/angeo-26-2975-2008 Non-thermal particle effects on the Hα and Hβ line profiles in the 18 August 2002 solar flare Kashapova L. K. 1 Kotrč P. 2 Kupryakov Yu. A. 2 3 Institute of Solar-Terrestrial Physics, Irkutsk, Russia Astronomical Institute, Ondřejov, Czech Republic GAISH, MGU, Moscow, Russia 15 10 2008 26 10 2975 2982 Copyright: © 2008 L. K. Kashapova et al. 2008 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://angeo.copernicus.org/articles/26/2975/2008/angeo-26-2975-2008.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/26/2975/2008/angeo-26-2975-2008.pdf

We present results of the 18 August 2002 flare analysis as an example for developing a diagnostic tool for thermal and non-thermal processes in chromospheric lines. Taking into account the hard X-ray (HXR) emission, we attempted to derive the Hα and Hβ line properties which were caused by the non-thermal electron contribution and could be useful for diagnostic purposes. The flare itself was a sequence of harder and softer bursts in HXR and we investigated three flare kernels associated with them. Two of the kernels appeared simultaneously. This phase of the flare could be observed in a broad band of wavelengths (HXR, UV, optical and microwaves). Kernel 1 did not clearly coincide with any HXR source but its intensity increased with the HXR flux rise. The flare kernel~3 did not show any significant response in microwaves, however, the related HXR flux was comparable with the flux of the previous kernels. We carried out an analysis of the difference between the Hα/Hβ profile rate in the line center at the distance of 0.5 Å from the line center. Only kernel 2 showed parameter fluctuations that were related to HXR flux evolution. The supposition of the non-thermal electron effect on the Hα/Hβ profile ratio was confirmed only at the kernel connected with the 25–50 keV HXR source. We found further confirmation that the Hα/Hβ line intensity ratio could be used as a diagnostic tool for non-thermal electron presence.

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