Grant E. Kocharov

Soft X-rays in the 00:18 UT solar flare on April 22, 1994

Abstract The IRIS spectrometer employs scintillation and proportional counters with large-sized windows. It offers possibility for measuring X-ray flux of flare precursors and micro- and nanoflares as well as studying fine time structures in hard X-rays during the impulsive phase of strong solar flares. Characteristics of the spectrometer (time resolution, number of energy channels, sensitivity to soft X-rays) are automatically changeable depending on measured X-ray flux. The essential properties of the IRIS spectrometer are listed in Table 1 (for detailed description see Kocharov et al , 1989, and Charikov et al , 1997).

Energy release in the 00:18 UT solar flare on April 22, 1994☆

Abstract We discuss the energy release process in a solar flare. The onset of this flare in soft X-rays was detected at 00:18 UT on April 22nd, 1994, by the IRIS X-ray spectrometer, which was a component of the scientific payload in the international complex research project on solar-terrestrial phenomena on board the CORONAS-I automatic orbital station. An analysis of energy spectra and time profiles of soft X-ray radiation indicates that no usual expansion of flaring volume occurred at the decay of this flare. On the contrary, thermal insulation of the hot plasma could be in effect.

Characteristics of solar X-ray radiation in March and April 1994 obtained in the IRIS experiment on board KORONAS-I

The first brief report on the results obtained in the IRIS experiment is presented. The IRIS instrument is an X-ray spectrometer based on proportional and scintillation counters designed for the measurement of solar X-ray radiation in the 2–200 keV range. Data on the 12 flares observed in March and April 1994 are reported, and examples of the flare radiation spectra are given.