Initial Operation of NSTX with Plasma Control
Authors: D. Gates, M. Bell, J. Ferron, S. Kaye, J. Menard, D. Mueller, C. Neumeyer, and S. Sabbagh
Date of PPPL Report: June 2000
Presented at: the 27th European Physical Society's (EPS) Conference on Controlled Fusion and Plasma Physics, June 12-16, 2000, Budapest, Hungary. A "Provisional Collection of Submitted Contributions" can be found at the following web site: http://www.eps2000.kfki.hu (active as of August 16, 2000). Papers are in PDF format.
First plasma, with a maximum current of 300kA, was achieved on NSTX in February 1999. These results were obtained using preprogrammed coil currents. The first controlled plasmas on NSTX were made starting in August 1999 with the full 1MA plasma current achieved in December 1999. The controlled quantities were plasma position (R, Z) and current (Ip). Variations in the plasma shape are achieved by adding preprogrammed currents to those determined by the control parameters. The control system is fully digital, with plasma position and current control, data acquisition, and power supply control all occurring in the same four-processor real time computer. The system uses the PCS (Plasma Control Software) system designed at General Atomics. Modular control algorithms, specific to NSTX, were written and incorporated into the PCS. The application algorithms do the actual control calculations, with the PCS handling data passing. The control system, including planned upgrades, will be described, along with results of the initial controlled plasma operations. Analysis of the performance of the control system will also be presented.