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Title: The Resistive Wall Mode Feedback Control System on DIII-D

Abstract

One of the primary instabilities limiting the performance of the plasma in advanced tokamak operating regimes is the resistive wall mode (RWM) [1]. The most common RWM seen in the DIII-D tokamak is originated by an n=1 ideal external kink mode which, in the presence of a resistive wall, is converted to a slowly growing RWM. The mode causes a reduction in plasma rotation, a loss of stored energy, and sometimes leads to plasma disruption. It routinely limits the performance of a tokamak operating near reactor relevant parameter levels. A system designed to actively control the RWM has recently been installed on the DIII-D tokamak for the control of low m n=1 modes. In initial experiments, the control system has been capable of delaying the onset of RWMs in energetic discharges for several hundred milliseconds. The feedback control system consists of detector coils connected via control software to high power current amplifiers driving the excitation coils. The three pairs of excitation coils are each driven by a current amplifier and a DC power supply. The control signal is derived from a set of six sensor coils that measure radial flux as low as one Gauss. The signals are digitally processedmore » by realtime software in the DIII-D Plasma Control System (PCS) to create a command that is sent to the current amplifier, with a cycle time of approximately 100 {micro}s. The amplifiers, designed and fabricated by Robicon Corporation to a specification developed by PPPL and GA, are bipolar devices capable of {+-}5 kA at 300 V, with an operating bandwidth of approximately 800 Hz (-3 dB).« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
General Atomics, San Diego, CA (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
766806
Report Number(s):
GA-A23256
TRN: US0109393
DOE Contract Number:  
AC03-99ER54463; AC02-76CH03073
Resource Type:
Conference
Resource Relation:
Conference: 18th IEEE/NPSS Symposium on Fusion Engineering, Albuquerque, NM (US), 10/25/1999--10/29/1999; Other Information: PBD: 1 Nov 1999
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; AMPLIFIERS; COMPUTERIZED CONTROL SYSTEMS; DOUBLET-3 DEVICE; EXCITATION; FEEDBACK; PERFORMANCE; PLASMA DISRUPTION; DESIGN

Citation Formats

Scoville, J T, Kellman, D H, Pronko, S G.E., Nerem, A, Hatcher, R, O'Neill, D, Rossi, G, and Bolha, M. The Resistive Wall Mode Feedback Control System on DIII-D. United States: N. p., 1999. Web.
Scoville, J T, Kellman, D H, Pronko, S G.E., Nerem, A, Hatcher, R, O'Neill, D, Rossi, G, & Bolha, M. The Resistive Wall Mode Feedback Control System on DIII-D. United States.
Scoville, J T, Kellman, D H, Pronko, S G.E., Nerem, A, Hatcher, R, O'Neill, D, Rossi, G, and Bolha, M. 1999. "The Resistive Wall Mode Feedback Control System on DIII-D". United States. https://www.osti.gov/servlets/purl/766806.
@article{osti_766806,
title = {The Resistive Wall Mode Feedback Control System on DIII-D},
author = {Scoville, J T and Kellman, D H and Pronko, S G.E. and Nerem, A and Hatcher, R and O'Neill, D and Rossi, G and Bolha, M},
abstractNote = {One of the primary instabilities limiting the performance of the plasma in advanced tokamak operating regimes is the resistive wall mode (RWM) [1]. The most common RWM seen in the DIII-D tokamak is originated by an n=1 ideal external kink mode which, in the presence of a resistive wall, is converted to a slowly growing RWM. The mode causes a reduction in plasma rotation, a loss of stored energy, and sometimes leads to plasma disruption. It routinely limits the performance of a tokamak operating near reactor relevant parameter levels. A system designed to actively control the RWM has recently been installed on the DIII-D tokamak for the control of low m n=1 modes. In initial experiments, the control system has been capable of delaying the onset of RWMs in energetic discharges for several hundred milliseconds. The feedback control system consists of detector coils connected via control software to high power current amplifiers driving the excitation coils. The three pairs of excitation coils are each driven by a current amplifier and a DC power supply. The control signal is derived from a set of six sensor coils that measure radial flux as low as one Gauss. The signals are digitally processed by realtime software in the DIII-D Plasma Control System (PCS) to create a command that is sent to the current amplifier, with a cycle time of approximately 100 {micro}s. The amplifiers, designed and fabricated by Robicon Corporation to a specification developed by PPPL and GA, are bipolar devices capable of {+-}5 kA at 300 V, with an operating bandwidth of approximately 800 Hz (-3 dB).},
doi = {},
url = {https://www.osti.gov/biblio/766806}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1999},
month = {11}
}

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