Overview of GLOBUS-M2 spherical tokamak results at the enhanced values of magnetic field and plasma current

The paper provides an overview of the results obtained on the spherical tokamak Globus-M2 in 2019-2020. The experiments were performed with the toroidal magnetic field up to 0.8 T and plasma current up to 0.4 MA (80% of the design values). The temperature of electrons 1 keV and ions 800 eV at the plasma density of 10(20) m(-3) were recorded at neutral beam injection (850 kW, 28.5 keV). Heat conductivity analysis was made by means of the codes ASTRA 7.0, NCLASS, SPIDER, NUBEAM, 3D fast ion tracking algorithm on the basis of the experimental data. A scaling for spherical tokamaks, which demonstrates strong tau (E) dependence on magnetic field and moderate dependence on plasma current, has been confirmed for the magnetic field up to 0.8 T. For Globus-M/M2 it is tau EGLB similar to Ip0.43 +/- 0.22BT1.19 +/- 0.1 . The dependence of the normalized energy confinement time (B (T) tau (E)) on collisionality (nu*) in a wide range 0.02 < nu* < 0.2 was determined as BT tau E similar to nu*-0.74

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This paper provides an overview of the research results obtained on the spherical tokamak Globus-M2 from 2019 to 2020. The study confirms the scaling relationship for spherical tokamaks and determines the dependence of the normalized energy confinement time on collisionality through experimental data and analysis.