Abstract:
The experimental results of X-ray bursts about spectral characteristics, spatial distribution and directivity measurements carried out with PVO/ISEE-3 spacecraft imaging instruments of HXIS and Hard X-ray burst spectrometers during solar Maximun Mission are briefly reviewed. The observed results about the above characteristics are discussed in detail in terms of a non-thermal and a thermal model. It is shown that the results can be interpreted in terms of beamed thick target model in which electrons stream down to the loop foot points and produce the hard X-rays through electron-ion bremsstrahlung