Geodesic Acoustic Mode Temporal Parameters Effect on the LH-Transition Initiation Possibility in TUMAN-3M Tokamak

Abstract

Geodesic acoustic mode (GAM) observations in TUMAN-3M tokamak show that in ohmic discharges with low plasma density GAM have intermittent character; transition to high confinement regime (LH-transition) is usually preceded by a short (up to 5 ms) GAM burst series with distinctive frequency drop, or there exists long (up to 30 ms) GAM burst series evolution with several characteristic timescales and varying amplitude. To determinate the effect of GAM temporal parameters on the possibility of LH-transition initiation numerical modeling of plasma density profile evolution under the effect of GAM burst sequence with varying frequency and amplitude was carried out.