Direct measurement of the plasma response in TCV
Experiments have recently been performed on the Tokamak à Configuration Variable (TCV) tokamak to measure the plasma response to variations of the poloidal field control coil voltages. This technique uses multiple sinusoidal perturbation of these voltages, during normal plasma operation, with all of the feedback control loops functional. A new analysis technique allows extraction from the data a direct measurement of the �open loop� plasma response, in spite of the feedback loop being operational. This original approach thereby provides a complete description of the reaction of any given plasma parameters to all of the 18 poloidal field coil voltage inputs. This measured open loop plasma response has been compared directly with open loop plasma models, a significant advance beyond previous work which could only compare closed loop responses with closed loop models. The signal-to-noise of these experimental measurements is much better than had been hoped and has allowed quite detailed comparisons to be made. Several plasma response models have been compared, including a perturbed equilibrium model (CREATE-L), a rigid current displacement model of the vertical movement and a rigid current distribution model of both the radial movement and the plasma current variation. The agreement between the CREATE-L model and the experimental results is excellent, although some systematic differences have become apparent.
Bibliographic Reference: Article: 1998 International Congress on Plasma Physics, 25th EPS Conference on Controlled Fusion and Plasma Physics, Prague (CZ), June 29 � July 3, 1998
Record Number: 199811273 / Last updated on: 1998-10-27
Original language: en
Available languages: en