On the Globus-M2 spherical tokamak, experiments on ion cyclotron resonance heating (ICRH) of plasma were conducted in discharges with a toroidal magnetic field above 0.7 T under conditions of Ohmic-only heating and additional heating by a neutral beam injector to study the effect of ICRH on the energy distribution of plasma components. The RF heating was performed in the frequency range of 5 to 12 MHz with a power of up to 0.1 MW. The experiments demonstrated the generation of fast particles. In discharges with RF heating in a regime with two ion species (D, H), ions with energies exceeding 20 ion temperatures (up to 22.5 keV) were observed. A 50% increase in hydrogen ion temperature and a 15% increase in deuterium ion temperature were observed. RF heating in deuterium discharges with neutral beam injection increased the population of fast particles with energies above the injection energy by up to a factor of 10. When RF heating was applied in a regime with three ion species (H, D, 3He), a 15% increase in electron temperature was observed near the spatial localization of the fundamental helium-3 resonance at an ICRH frequency of 5.7 MHz.
Solokha et al. (Sun,) studied this question.