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- Title
Quasi-periodic Variations in the Hard X-ray Emission of a Large Arcade Flare.
- Authors
Jakimiec, J.; Tomczak, M.
- Abstract
We investigated the quasi-periodic oscillations of the hard X-ray (HXR) emission of the large flare of 2 November 1991 using HXR light curves and soft X-ray and HXR images recorded with the Yohkoh X-ray telescopes. We analysed these observations and report five main results: i) The observations confirm that electrons are accelerated in oscillating magnetic traps that are contained within the cusp magnetic structure. ii) The chromospheric upflow increases the density within the magnetic traps, which in turn together with the higher amplitude of the trap oscillations increases the amplitude of the HXR pulses. iii) This increase stops when the density inside the traps increases progressively and inhibits the acceleration of electrons. iv) The model of oscillating magnetic traps is able to explain the time variation of the electron precipitation, the strong asymmetry in the precipitation of the accelerated electrons, and the systematic differences in the precipitation of 15 and 25 keV electrons. v) We have obtained direct observational evidence that strong HXR pulses are the result of the inflow into the accelerated volume of dense plasma from chromospheric evaporation.
- Subjects
SOLAR flares; X-ray telescopes; ELECTRONS; SOLAR energetic particles; DENSE plasmas; SOLAR chromosphere; EVAPORATION (Chemistry)
- Publication
Solar Physics, 2013, Vol 286, Issue 2, p427
- ISSN
0038-0938
- Publication type
Article
- DOI
10.1007/s11207-013-0275-y