Abstract
Observations of impulsive solar flare X-rays ≳ 10 keV by the OGO-5 satellite and the measurements of energetic solar electrons made with the Explorer-35 and Explorer-41 (IMP-5) satellites during the period March 1968–September 1969 have been analyzed in order to determine the ion density in the X-ray source region as well as the location of the electron acceleration region in the solar atmosphere. If we assume that the efficiency of escape of the accelerated electrons into interplanetary space is ∼ 10−3, the observations are found to be consistent with the following interpretation: (i) the ion density in the X-ray source region varies from event to event and lies between 109 and 1011 ions cm−3 for those events in which the impulsive X-ray emission could be detected; (ii) for those events in which no impulsive emission was detected above threshold, the ion density in the X-ray source was < 109 ions cm−3; (iii) at least in some small solar flares the region where the electrons are accelerated during the flash phase is located in the lower corona.
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Kane, S.R., Lin, R.P. Location of the electron acceleration region in solar flares. Sol Phys 23, 457–466 (1972). https://doi.org/10.1007/BF00148108
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DOI: https://doi.org/10.1007/BF00148108