Application of Doppler backscattering diagnostics for studying edge localized modes on the GLOBUS-M2 tokamak

In the high confinement mode with an edge transport barrier (H-mode), large pressure gradients at the plasma periphery are observed, which leads to the appearance of edge localized modes (ELMs). On the spherical tokamak Globus-M2 ELMs can be divided into 2 types: synchronized with sawtooth oscillations in the center of the plasma and independent of them or desynchronized. In this paper, we present a study of synchronized edge localized modes by Doppler backscattering diagnostics. It is shown that the turbulence level changes dramatically during ELMs. In addition, the radial electric field profiles were constructed for synchronized edge localized modes of different amplitude.