Fluctuation Mitigation and Azimuthal Velocity Profile Regulation by Extremum Seeking in HELCAT

Z. Ilhan, J. Barry, H. Wang, E. Schuster, M. Gilmore, A. Ware

Symposium on Fusion Engineering

San Francisco, California, USA, June 10-14, 2013

Abstract

Turbulence, and turbulence-driven transport are ubiquitous in magnetically confined plasmas, where there is an intimate relationship between turbulence, transport, desta- bilizing mechanisms like gradients and currents, and stabilizing mechanisms like shear. Active control of fluctuations via manipulation of flow profiles is investigated in a magnetized laboratory plasma device (HELCAT). Measurements of the azimuthal velocity are assumed available at several radial points within the plasma and ExB flow profiles are controlled via biased ring electrodes. An optimal control algorithm is proposed in this work to reproduce as closely as possible a prescribed desired radial azimuthal velocity profile. The effectiveness of the controller is analyzed via numerical simulations.