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Title: Advanced Control Techniques and High Performance Discharges on DIII-D

Abstract

The advancement of plasma control techniques has enabled significant progress to be made toward the scientific understanding and realization of Advanced Tokamak operation on DIII-D. The Advanced Tokamak features fully noninductive current drive, operation at high plasma pressure and high energy confinement time. These features require efficient current drive systems, simultaneous control of plasma current and pressure profiles, and active feedback control of plasma instabilities. A number of key systems on DIII-D have been developed to provide this control capability. A versatile electron cyclotron heating and current drive system is routinely providing in excess of 2 MW of power for pulse lengths from 2 to 5 s. This system has been used to provide offaxis current drive, direct electron heating and pressure profile modification, and stabilization of the Neoclassical Tearing Mode instability. A combination of control of magnetic error fields, neutral beam induced plasma rotation, and active feedback stabilization using both external and internal nonaxisymmetric coil systems has been used to stabilize the Resistive Wall Mode at high values of plasma pressure. Control of the ELM instability has recently been demonstrated using the newly installed internal coil system. The higher speed and expanded realtime diagnostic capability of our recently upgradedmore » plasma control system permits these various control techniques to be simultaneously integrated to achieve our high performance discharges. This has resulted in fully noninductively driven plasmas with {beta}{sub N} = 3.5 and {beta}{sub T} = 3.6% sustained for up to 1 s. Upgrades and facility modifications to further enhance our control and scientific capabilities including rotation of a neutral beamline, expanded EC system power, and installation of a new lower divertor are discussed.« less

Authors:
 [1]
  1. General Atomics (United States)
Publication Date:
OSTI Identifier:
20849894
Resource Type:
Journal Article
Journal Name:
Fusion Science and Technology
Additional Journal Information:
Journal Volume: 47; Journal Issue: 3; Other Information: Copyright (c) 2006 American Nuclear Society (ANS), United States, All rights reserved. http://epubs.ans.org/; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1536-1055
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CONFINEMENT TIME; CONTROL; CONTROL SYSTEMS; DIVERTORS; DOUBLET-3 DEVICE; ECR HEATING; EDGE LOCALIZED MODES; ELECTRIC CURRENTS; ELECTRONS; FEEDBACK; INSTALLATION; NEOCLASSICAL TRANSPORT THEORY; OPERATION; PERFORMANCE; PLASMA; PLASMA PRESSURE; PULSES; ROTATION; STABILIZATION; TEARING INSTABILITY

Citation Formats

Kellman, A G. Advanced Control Techniques and High Performance Discharges on DIII-D. United States: N. p., 2005. Web.
Kellman, A G. Advanced Control Techniques and High Performance Discharges on DIII-D. United States.
Kellman, A G. 2005. "Advanced Control Techniques and High Performance Discharges on DIII-D". United States.
@article{osti_20849894,
title = {Advanced Control Techniques and High Performance Discharges on DIII-D},
author = {Kellman, A G},
abstractNote = {The advancement of plasma control techniques has enabled significant progress to be made toward the scientific understanding and realization of Advanced Tokamak operation on DIII-D. The Advanced Tokamak features fully noninductive current drive, operation at high plasma pressure and high energy confinement time. These features require efficient current drive systems, simultaneous control of plasma current and pressure profiles, and active feedback control of plasma instabilities. A number of key systems on DIII-D have been developed to provide this control capability. A versatile electron cyclotron heating and current drive system is routinely providing in excess of 2 MW of power for pulse lengths from 2 to 5 s. This system has been used to provide offaxis current drive, direct electron heating and pressure profile modification, and stabilization of the Neoclassical Tearing Mode instability. A combination of control of magnetic error fields, neutral beam induced plasma rotation, and active feedback stabilization using both external and internal nonaxisymmetric coil systems has been used to stabilize the Resistive Wall Mode at high values of plasma pressure. Control of the ELM instability has recently been demonstrated using the newly installed internal coil system. The higher speed and expanded realtime diagnostic capability of our recently upgraded plasma control system permits these various control techniques to be simultaneously integrated to achieve our high performance discharges. This has resulted in fully noninductively driven plasmas with {beta}{sub N} = 3.5 and {beta}{sub T} = 3.6% sustained for up to 1 s. Upgrades and facility modifications to further enhance our control and scientific capabilities including rotation of a neutral beamline, expanded EC system power, and installation of a new lower divertor are discussed.},
doi = {},
url = {https://www.osti.gov/biblio/20849894}, journal = {Fusion Science and Technology},
issn = {1536-1055},
number = 3,
volume = 47,
place = {United States},
year = {2005},
month = {4}
}