Abstract
The work presents the results of the energy confinement study carried out on the compact spherical tokamak (ST) Globus-M2 with toroidal magnetic field (BT) as high as 0.8 T. A reproducible and stable discharge was obtained with the average plasma density (5-10) 1019 m-3. Despite the increase in the magnetic field, the neutral beam injection (NBI) led to clear and reproducible transition to the H-mode accompanied by a decrease in the turbulence level at the plasma edge. NBI allowed effectively heat the plasma: electron and ion temperatures in the plasma core exceeded 1 keV. In comparison with the previous experiments carried out with BT=0.4 T plasma total stored energy was increased by a factor of 4. The main reason of this phenomenon is a strong dependence of the energy confinement time (τE) on the toroidal magnetic field in the spherical tokamak. It was experimentally confirmed that such kind of dependence is valid for ST with magnetic field up to 0.8 T. It also has been shown that the enhancement of the energy confinement in the Globus-M2 with collisionality decrease is associated with an improvement of both electron and ion heat transport.
Effect of the toroidal magnetic field the on energy and fast particle confinement in the Globus-M spherical tokamak
