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International audience; TCV is acquiring a new 1 MW neutral beam and 2 MW additional third-harmonic electron cyclotron resonance heating (ECRH) to expand its operational range. Its existing shaping and ECRH launching versatility was amply exploited in an eclectic 2013 campaign. A new sub-ms real-time equilibrium reconstruction code was used in ECRH control of NTMs and in a prototype shape controller. The detection of visible light from the plasma boundary was also successfully used in a position-control algorithm. A new bang-bang controller improved stability against vertical displacements. The RAPTOR real-time transport simulator was employed to control the current density profile using electron cyclotron current drive. Shot-by-shot internal inductance optimization was demonstrated by iterative learning control of the current reference trace. Systematic studies of suprathermal electrons and ions in the presence of ECRH were performed. The L?H threshold power was measured to be ?50?75% higher in both H and He than D, to increase with the length of the outer separatrix, and to be independent of the current ramp rate. Core turbulence was found to decrease from positive to negative edge triangularity deep into the core. The geodesic acoustic mode was studied with multiple diagnostics, and its axisymmetry was confirmed by a full toroidal mapping of its magnetic component. A new theory predicting a toroidal rotation component at the plasma edge, driven by inhomogeneous transport and geodesic curvature, was tested successfully. A new high-confinement mode (IN-mode) was found with an edge barrier in density but not in temperature. The edge gradients were found to govern the scaling of confinement with current, power, density and triangularity. The dynamical interplay of confinement and magnetohydrodynamic modes leading to the density limit in TCV was documented. The heat flux profile decay lengths and heat load profile on the wall were documented in limited plasmas. In the snowflake (SF) divertor configuration the heat flux profiles were documented on all four strike points. SF simulations with the EMC3-EIRENE code, including the physics of the secondary separatrix, underestimate the flux to the secondary strike points, possibly resulting from steady-state E × B drifts. With neon injection, radiation in a SF was 15% higher than in a conventional divertor. The novel triple-null and X-divertor configurations were also achieved in TCV.

Recent experiments have been performed on the Tokamak a configuration variable (TCV) to investigate the confinement properties of high density plasmas and the mechanism behind the density limit. In a limiter configuration with plasma elongation kappa = 1.3-1.4 and triangularity delta = 0.2-0.3 the operational density range has been extended up to 0.65 of the Greenwald density at I-p = 200 kA (q(95) = 3.7) and even to the Greenwald value at low plasma current I-p = 110 kA (q(95) = 7). A transition from the linear to the saturated ohmic confinement regime is observed at high density similar to 0.4n(GW). A further density increase leads to sawtooth stabilization and is accompanied by a decrease of the energy and particle confinement times. The development of the disruption at the density limit was preceded by sawtooth stabilization. It is shown that electron cyclotron heating leads to the prevention of sawtooth stabilization and then to the increase of the density limit value.