Ion cyclotron resonance heating system in the RT-1 magnetospheric plasma

We have developed an ion cyclotron resonance frequency (ICRF) heating system for the Ring Trap 1 (RT-1) magnetospheric device. We excite slow waves from the polar region of the dipole magnetic field. The target helium plasma is produced by electron cyclotron heating. The electrons comprise high-temperature (>10 keV) and low-temperature (<100 eV) components with both typically exhibiting densities of the same order of magnitude. The ICRF heating causes an increase in the ion temperatures and toroidal flow velocities in the core plasma region. We observe appreciable temperature differences between the different ion species (main He⁺ and impurity C²⁺), suggesting a strong influence of the charge-exchange loss, which caused the bulk ions to remain relatively cold (∼20 eV) compared to the impurity ions (∼40 eV). By developing an electro-optical measurement system, we have measured the local wave electric field in the plasma.