AIP Digital Archive
Electrical Engineering, Measurement and Control Technology
The various operating modes of TFTR require the use of a sophisticated system of magnetic diagnostics integrated with a feedback control system. This system has successfully controlled the plasma current and position over a range of major and minor radii, during strong compression, and will soon be used during intense neutral beam heating. Current and position values are held constant to within 2 kA and 1 cm. A wide variety of preoperational field measurements were required to determine proper compensation for dynamic stray fields due to eddy currents. Data from plasma profile diagnostics, such as bolometer arrays, Thomson scattering, soft x-ray diode array, and the scanning radiometer, have been compared to the absolute position deduced from magnetics. In addition to control functions, magnetic diagnostics on TFTR provide data on plasma current asymmetry, βθ, MHD fluctuations, loop voltage, and flux consumption. This paper will discuss the mechanical and electronic design constraints, as well as the analytic and calibration techniques required.
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