Overview of FTU Results

Full text: Since last IAEA-FEC, FTU has extended operations with Liquid Lithium Limiter (LLL) to assess its potentials as a plasma facing component in harsh fusion plasmas environment. The use of lithized walls had widened FTU parameter space producing ohmic plasmas at peaked density profile (peaking factor 2.5) up to 1.6 times Greenwald limit. New discharges at 700 kA confirm the spontaneous transition to an enhanced confinement regime, 1.2 - 1.3 times ITER-97-L, for density values characteristic of the saturated ohmic confinement regime, when density peaking factor is above a threshold value of 1.7 - 1.8. The ameliorated confinement is ascribed to the stabilization of ITG modes. D2 pellets have been injected for the first time in Lithized discharges. A preliminary analysis of particle transport shows a Bohm gyro-Bohm type diffusion coefficient. RF heated plasma profited of cleaner plasma conditions. Lower Hybrid waves penetration was clearly demonstrated at, and above, ITER densities with good control of edge parameters obtained by using the external poloidal limiter and the lithized walls to control the recycling. Flexibility and reliability of Electron Cyclotron heating system allowed FTU contributing to ITER relevant issues such as MHD control: sawtooth crash was actively controlled and disruptions at density limit were avoided. ECRH injected perpendicularly, demonstrated to be more efficient than oblique's, reducing by a factor 3 the minimum electric field required at breakdown. The theoretical effort in developing model to interpret high frequency fishbones on FTU and other experiments continued. The GFLDR framework was used for implementing an extended version of the hybrid MHD gyrokinetic code HMGC. The upgraded version of HMGC will be able to handle fully compressible nonlinear gyrokinetic equations and 3D MHD. (author)