Effect of the toroidal magnetic field the on energy and fast particle confinement in the Globus-M spherical tokamak

Abstract

The experiments with auxiliary heating by neutral beam injection (NBI) were carried out before the spherical tokamak Globus-M was upgraded to Globus-M2. The aim of the experiments was to determine the dependence of the confinement time on toroidal magnetic field. The total stored energy was obtained by diamagnetic loops, and verified with ASTRA modelling based on kinetic measurements. The absorbed heating power was estimated using 3D fast ion tracking modeling. The obtained dependence of the energy confinement time is similar to the MAST and NSTX results but contradicts the conventional IPB98(y,2) scaling. The toroidal Alfvén eigenmodes study was performed in a set of discharges with NBI at the early stage of the discharge. The experiments have shown that fast particle losses decrease with the increase of the toroidal magnetic field and plasma current.