Profile Control With Lower-Hybrid Waves On Asdex

Controlled modification of the radial profiles of the plasma current, electron temperature and density was achieved in the ASDEX divertor tokamak with lower hybrid waves. Variation of the lower hybrid power and current deposition profiles was accomplished by tailoring the launched wave spectra or by compound antenna phasing. The current and temperature profiles could be largely decoupled. MHD modes were strongly influenced by the current profile modifications. Sawteeth and m = 1 modes were suppressed up to the density limit of lower hybrid current drive on ASDEX (nBAR(e) = 5 x 10(19) m-3). The electron temperature profile peaked in this case and the global confinement was improved.