Density gradient evolution effect on ion cyclotron waves excitation in TUMAN-3M tokamak ohmic discharges

In TUMAN-3M tokamak ohmic hydrogen and deuterium discharges oscillations with ion cyclotron (IC) frequency were detected. Fast magnetic probes poloidal array in TUMAN-3M is capable of detecting several harmonics of IC frequency of main plasma isotope. Fuel pellet injection significantly reduces IC oscillations intensity, though after complete pellet evaporation returns to initial level. IC oscillations localization and excitation conditions are of certain interest. Based on drift-cyclotron instability excitation theory and numerical modeling of scenarios with ohmic LH-transition and pellet-injection plasma parameters (density gradient primarily) effect on IC oscillations excitation was studied.