Overview of TCV results

This overview highlights the progress accomplished on tokamak configuration variable (TCV) during the past two years, along five research avenues: particle, energy and momentum transport, edge physics, H-mode physics under strong electron heating, electron cyclotron (EC) heating and electron cyclotron current drive physics, scenarios with internal transport barriers and large non-inductive current fractions. Peaked density profiles are measured in the absence of a Ware pinch or a core particle source. Decreasing the plasma triangularity leads to a significant reduction in χ_e. Measurements of the plasma toroidal rotation in the absence of external torque are inconsistent with diffusion of toroidal momentum from the edge. Scrape-off layer fluctuation measurements and the relevant modelling using a fluid turbulence code indicate radial interchange motion of plasma filaments as the cause of cross-field transport. Third harmonic EC heating (1.5 MW) applied to ELMy H-modes leads to β_N ∼ 2, large ELMs and peaked density profiles, significant ion heating (T_i ∼ 1 keV, with T _i/T_e ∼ 0.4) and to quasi-stationary ELM-free H-modes lasting for many energy confinement times. Supra-thermal electrons produced during strong EC heating and following sawtooth crashes are shown to undergo rapid cross-field transport. Electron Bernstein wave heating is demonstrated in the O-X-B conversion scheme. Electron internal transport barriers are generated in a variety of scenarios, leading to significant confinement improvement and bootstrap current fractions in excess of 70%.