Real time plasma current and elongation control using ECRH actuators

Experiments have been carried out on TCV using Electron Cyclotron Resonance Heating (ECRH) actuators to control the plasma current and elongation in real time. In fully non-inductive plasmas, the plasma current may be driven entirely by ECCD on TCV. By replacing the Ohmic coils with the gyrotron power supplies, we were able to control the plasma current in real time. In tokamak plasmas, the elongation is usually controlled by the quadrupole magnetic field from the poloidal field coils. Applying off-axis ECRH, the current profile is flattened reducing the plasma internal inductance, and at constant quadrupole field, the plasma elongates (κ ~ 2.4) [1]. This paper reports on experiments to control the plasma elongation using a real time elongation observer and the ECRH power actuator to control the current profile. As the plasma elongates, the ECRH deposition becomes more central. Therefore a deposition tracking control was developed which tracked the ECRH deposition at constant ρ by controlling the ECRH launcher mirror position.

Published in:
34th EPS Conference on Plasma Physics
Presented at:
34th EPS Conference on Plasma Physics, Warsaw Congress Centre, Poland, 2-6 July 2007

 Record created 2009-12-08, last modified 2018-10-07

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