Real time control of the plasma current and elongation in tokamaks using ECRH actuators

Real time control of the plasma elongation and plasma current using electron cyclotron resonance heating (ECRH) actuators has been demonstrated on TCV. Tokamak plasmas may be elongated by off-axis ECRH. The associated flattening of the current density profile increases the plasma's vertical stability, enabling higher elongations to be obtained, at lower currents than would be possible in Ohmic conditions. Successful experiments were carried out on TCV to control, in real time, the magnitude of the elongation and the ECRH deposition location using second harmonic ECRH power and ECRH launcher mirror angle actuators. Plasma current control in fully non-inductive plasmas using ECRH actuators to drive ECCD was also demonstrated.