Plasma Modeling Results and shape control improvements for NSTX
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Princeton Univ., Princeton, NJ (United States)
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
New control implementations and dynamics studies on the National Spherical Torus eXperiment (NSTX) are summarized. In particular, strike point (SP) position, X-point height and squareness control, and two new system-identification methods / control-tuning algorithms were put into operation.The PID controller for the SP was tuned by analyzing the step response of the SP position to the poloidal coil currents, employing the Ziegler-Nichols method. The resulting SP controller was successfully employed to achieve the “snowflake” divertor configuration in NSTX. An offline system identification of the plasma response to the control inputs based on ARMAX input-output models was implemented. With this tool, rough estimates of the improvements were realized and several control improvements were identified.An online automatic relay-feedback PID tuning algorithm was implemented, which has the advantage of tuning the controller in one shot, thus optimizing the use of experimental time. Furthermore, using these new capabilities, we implemented LLD scenarios with control for theall four upper/lower/inner/outer SPs and with a combined X-point height, SP radius control. Separately, an independent squareness control was implemented.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- DOE Contract Number:
- AC52-07NA27344
- OSTI ID:
- 1524726
- Report Number(s):
- LLNL-JRNL-465267; 462011
- Journal Information:
- Nuclear Fusion, Vol. 51, Issue 11; ISSN 0029-5515
- Publisher:
- IOP Science
- Country of Publication:
- United States
- Language:
- English
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