IMPORTANCE OF THE ECH/ECCD SYSTEM TO SUSTAIN AN INTERNAL TRANSPORT BARRIER IN ITER

A new scenario for ITER has been developed by means of the combined injection of three radio frequency power sources: Ion cyclotron resonant heating, lower hybrid current drive and Electron Cyclotron Heating and Current Drive (ECH/ECCD), which have been used to obtain a steady state plasma with 97% of noninductive current, Q ≈ 6.5 and a burning time of t ≈ 3000 s. In this scenario, the main role is played by ECCD, which is used to trigger and keep an Internal Transport Barrier (ITB) robustly fixed at normalized radius ρ ≈ 0.45. A threshold on the total power from ECH system has been found in order to provide the negative shear needed for sustaining the ITB.