Lower hybrid experiments in the ASDEX tokamak

Interaction of lower hybrid waves at 1.3 GHz with ions and electrons was studied in the density range 0.2-5*1013 cm-3 in the ASDEX tokamak. At high densities, ne>or approximately=4*1013 cm-3, fast ions with mainly perpendicular velocities are produced by the RF power at the plasma periphery. They are not well confined and do not lead to any bulk plasma heating. At lower densities, 2*1013<or approximately=ne<or approximately=4*1013 cm-3, electron and ion heating is observed. The heating is better in deuterium than in hydrogen plasmas. At very low densities, ne<or approximately=2*1013 cm-3, the discharge becomes suprathermal as soon as the RF power is switched on. Launching an asymmetric spectrum of waves in a low density plasma leads to the generation of an RF-driven DC-plasma current.