Synergy between LH and ECH waves in the FTU tokamak

Experiments on the effects of simultaneous injection of LH and ECH power have been carried out in FTU, with up to PLH=! MW and PECH=0-75 MW. In the absence of the cold ECH resonance in the plasma, the ECH power is absorbed on the suprathermal electron tail sustained by LHCD, as predicted theoretically, and causes the central electron temperature Teo to increase up to 1.2 keV. With the cold resonance at the centre, in a sawteeth and MHD free plasma, almost fully sustained by LHCD, a quasi-stationary electron transport barrier is built-up in a region r/a < 0.5. Teo rises by more than 4 keV, for only 0.35 MW of ECH power.