About the nature of 3He isotope content increase in the region of 2.223 MeV gamma line generation in the period of solar flare

The intense solar flare on January 20, 2005 is studied based on the SONG-D/AVSF/ KORONAS-F data. The data on time profiles of the 2.223 MeV neutron line and narrow nuclear lines are involved in the analysis. Model calculations of neutrons propagating from their generation region in the corona to the neutron line formation region in the lower chromosphere and photosphere are performed. Coulomb energy losses of helium-3 ions in the case of their allowed acceleration in the flare are calculated. The increase in the relative 3He concentration during the flare is numerically analyzed. The study performed in combination with independent data on the helium-3 content in the flare region and helium-3 fluxes in interplanetary space lead to the conclusion that the acceleration region is the most probable immediate source of the increased content of accelerated helium-3 isotope ions.