Neural network evaluation of tokamak current profiles for real time control (abstract)

Journal Article · Wed Jan 01 00:00:00 EST 1997 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.1147773· OSTI ID:451919

Wroblewski, D ^[1]

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1. ORINCON Corporation, San Diego, California 92121-3017 (United States)

Active feedback control of the current profile, requiring real-time determination of the current profile parameters, is envisioned for tokamaks operating in enhanced confinement regimes. The distribution of toroidal current in a tokamak is now routinely evaluated based on external (magnetic probes, flux loops) and internal (motional Stark effect) measurements of the poloidal magnetic field. However, the analysis involves reconstruction of magnetohydrodynamic equilibrium and is too intensive computationally to be performed in real time. In the present study, a neural network is used to provide a mapping from the magnetic measurements (internal and external) to selected parameters of the safety factor profile. The single-pass, feedforward calculation of output of a trained neural network is very fast, making this approach particularly suitable for real-time applications. The network was trained on a large set of simulated equilibrium data for the DIII-D tokamak. The database encompasses a large variety of current profiles including the hollow current profiles important for reversed central shear operation. The parameters of safety factor profile (a quantity related to the current profile through the magnetic field tilt angle) estimated by the neural network include central safety factor, q{sub 0}, minimum value of q, q{sub min}, and the location of q{sub min}. Very good performance of the trained neural network both for simulated test data and for experimental data is demonstrated. {copyright} {ital 1997 American Institute of Physics.}

• OSTI ID: 451919
• Report Number(s): CONF-960543-; ISSN 0034-6748; TRN: 97:006276
• Journal Information: Review of Scientific Instruments, Vol. 68, Issue 1; Conference: 11. annual high-temperature plasma diagnostics conference, Monterey, CA (United States), 12-16 May 1996; Other Information: PBD: Jan 1997
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION
TOKAMAK DEVICES
PLASMA DIAGNOSTICS
NEURAL NETWORKS
PLASMA SIMULATION
REAL TIME SYSTEMS
ELECTRIC CURRENTS
PLASMA RADIAL PROFILES
MAGNETIC FIELDS
plasma toroidal confinement
current distribution
feedforward neural nets
multilayer perceptrons
learning by example
physics computing
nuclear engineering computing
physical instrumentation control
electric current control