Further gamma-ray work has provided important information on abundances of both the ambient medium and the accelerated particles. Concerning the ambient medium, the analysis of gamma-ray lines has shown that in the gamma ray production region the abundances of elements with low first ionization potential (FIP) are enhanced relative to those of elements of high FIP. This FIP bias has been discovered previously using accelerated particle data and atomic spectroscopy. The nuclear spectroscopy is telling us that the bias sets in quite deep in the solar atmosphere, probably already in the chromosphere where the bulk of the gamma rays are produced. This result, which was not known prior to the gamma-ray work, has important implication on the dynamics of the solar atmosphere. Another interesting result concerns the photospheric 3He abundance. Studies of the time dependence of the 2.223 MeV neutron capture gamma-ray line emission, suggest that the 3He/H ratio in the solar photosphere is lower than that previously estimated suggesting that there is no significant mixing into the photosphere of 3He made in the solar interior. Concerning the accelerated particles, the gamma-ray work has shown that these particles exhibit large abundance enhancements for the heavy ions, particularly Fe. This has important implications for the particle acceleration mechanism, strongly suggesting that the acceleration is due to resonant particle interactions with plasma turbulence. The rising portion of solar cycle 22 (1988-1993) was observed until 1989 with SMM. The maximum of this cycle, however, was only studied with non-dedicated instruments: Phebus/ GRANAT; GAMMA-1; CGRO. Nevertheless, these instruments found exceptionally interesting results, for example, the observation of pion decay emission and nuclear line emission lasting for hours. This indicates that in post-flare conditions it is possible to either trap or accelerate over extended time periods ions of energies as high as several GeV. While long lasting flare emissions have been known previously, this was the first instance that such time extended emission could be associated with GeV ions. These observations were only possible because of the very good sensitivities of the new instruments, in particular CGRO. There are no approved future high-energy solar missions. Solar flare gamma-ray observations with detectors of much higher sensitivity and better energy resolution than those of the previously employedinstruments should allow important new investigations. For example, much more detailed abundance studies will be possible, including the determination of accelerated particle abundance as a function of time with good time resolution, leading to the most direct tracing of the acceleration process. These studies will include observations of the gamma-ray signatures of 3He, due to the reactions 4He(3He,p)6Li*3.56 MeV and 16O(3He,p) 18F*0.937, 1.04,1.08 MeV. The abundance of 3He, which in the solar atmosphere is only a few times 10-4 relative to 4He, routinely becomes comparable to that of 4He in the accelerated particles from impulsive flares, most likely due to gyroresonant interactions of the particles with plasma waves. In addition, observations of the Sun with a high sensitivity gamma-ray detector will allow some entirely new types of investigations. For example, it will be possible to observe the relatively long lived radioactivity (e.g., 56Co) produced by accelerated particle interactions in flares, thereby allowing the study of the dynamics of the atmosphere. Finally, the flare observations could be used as a local laboratory for the testing of the various proposed models of the galactic sources of gamma-ray line emission.
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