An operational regime for achieving high ion temperatures in the GAMMA10central cell has been experimentally investigated by analysing the correlationbetween ion temperatures and electron density profiles measured under variousexperimental conditions performed over the last 10 years. The analysis showsthat broadened density profiles or excessive high ion temperatures (or both)induce significant degradation of the stored energy. It has been found thatthe peaked density profile is a necessary condition to achieve high iontemperatures and high stored energy. The analysis reveals the presence of theoperational regime to achieve high ion temperature plasmas. The change of themagnetic field line shape in the central cell has successfully contributed toachieve a high ion temperature of about 10 keV at the plasma centre due to theformation of the peaked density profile in the GAMMA10 central cell.