Ion Heating and High-Energy-Particle Production by Ion-Cyclotron Heating in the Large Helical Device

Ion-cyclotron heating was applied to the Large Helical Device. When the proton-cyclotron resonance was near the saddle point of the magnetic field-strength plane, strong ion-cyclotron damping occurred. Under these conditions efficient plasma heating was achieved for more than one minute. A high-energy ion tail was observed, and the effective tail temperature was determined by a balance between the wave acceleration and the electron-drag relaxation. There was no apparent sign of particle orbit loss effect in the investigated density range of $0.8–1.3\times {10}^{19}{\mathrm{m}}^{-3\mathrm{}}$.