Power Supply Changes for NSTX Resistive Wall Mode Coils
Authors: S. Ramakrishnan, C. Neumeyer, R. Mozulay, E. Baker, R. Hatcher, J. Lawson, W. Que, X. Zhao
Abstract:The National Spherical Torus Experiment (NSTX) has been designed
and installed in the existing facilities at Princeton Plasma Physics
Laboratory (PPPL). Most of the hardware, plant facilities, auxiliary
sub-systems, and power systems originally used for the Tokamak
Fusion Test Reactor (TFTR) have been used with suitable
modifications to reflect NSTX needs. Prior to 2004, the NSTX power
system was feeding twelve (12) circuits in the machine. In 2004 the
Resistive Wall Mode (RWM) Coils were installed on the machine to
correct error fields. There are six of these coils installed around the
machine in the mid-plane. Since these coils need fast and accurate
controls, a Switching Power Amplifier (SPA) with three sub-units
was procured, installed and commissioned along with other power
loop components. Two RWM Coils were connected in series and fed
from one SPA sub-unit. After the initial RWM campaign, operational
requirements evolved such that each of the RWM coils now requires
separate power and control. Hence a second SPA with three sub-units
has been procured and installed. The second unit is of improved
design and has the controls and power components completely
isolated. The existing thyristor rectifier is used as DC Link to both of
the Switching Power Amplifiers. The controls for the RWM are
integrated into the overall computer control of the DC Power systems
for NSTX. This paper describes the design changes in the RWM
Power system for NSTX.
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Submitted to: SOFE 2013 Proeedings (June 0213) 25th Symposium on Fusion Engineering, San Francisco, CA (June 10-14, 2013)
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Download PPPL-4922 (pdf 1.45 MB 5 pp)
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