Chapter 2: Highlights of the Physics Studies in the FTU

The main physics results achieved in the recent years in the Frascati Tokamak Upgrade (FTU) are reviewed. The main focus of research has been the development of performance plasmas at high densities (up to 4 × 10²⁰ m^-3), high magnetic field (up to 8 T) and plasma current (up to 1.6 MA), that are therefore in a domain of relevance for burning physics experiments such as ITER. The main tools consist in the development of plasma conditioning techniques and the use of various electron heating and current drive systems. Improved confinement regimes have been developed, including (a) the production of steady electron internal transport barriers at high density and electron temperature (up to central electron temperature of 11 keV at a central density of 0.9 × 10²⁰ m³), (b) the production of repetitive pellet enhanced plasma modes with deep pellet deposition leading to a substantial increase of the neutron yield (and a record FTU value of the fusion product n_iT_iE up to 0.8 × 10²⁰ m^-3 keVs), and (c) the production of radiation improved modes at high magnetic field. Main results on the supporting physics program will also be given in the domain of plasma wave physics (lower hybrid current drive, electron cyclotron resonance frequency, ion Bernstein waves), heat and impurities transport, and magnetohydrodynamic studies.