Non-Model-Based Optimal Fluctuation Mitigation by ExB Actuation in HELCAT
Q. Wang, E. Schuster, S. Xie, M. Gilmore, A. Ware
Division of Plasma Physics (DPP) Annual Meeting of the American Physical Society (APS)
Chicago, Illinois, November 8-12, 2010
Abstract
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Turbulence, and turbulence-driven transport are ubiquitous in
magnetically confined plasmas, where there is an intimate relationship
between turbulence, transport, destabilizing mechanisms like gradients
and currents, and stabilizing mechanisms like shear. We investigate
active control of fluctuations via manipulation of flow profiles in a
magnetized laboratory plasma device (HELCAT). Fluctuations and particle
transport are monitored by electrostatic probes, and E×B flow profiles
controlled via biased ring electrodes. A non-model-based optimization
algorithm is implemented to seek control inputs that minimize a cost
function related to the fluctuation amplitude. The algorithm is also
able to identify radial poloidal flow profiles associated with low RMS
fluctuations. The long-term goal is to develop model-based feedback
controllers to regulate the radial poloidal flow profiles around the
identified low-fluctuation profiles.