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Title: QUIESCENT H-MODE, AN ELM-FREE HIGH-CONFINEMENT MODE ON DIII-D WITH POTENTIAL FOR STATIONARY STATE OPERATION

Abstract

OAK-B135 The quiescent H-mode (QH-mode) is an ELM-free and stationary state mode of operation discovered on DIII-D. This mode achieves H-mode levels of confinement and pedestal pressure while maintaining constant density and radiated power. The elimination of edge localized modes (ELMs) and their large divertor loads while maintaining good confinement and good density control is of interest to next generation tokamaks. This paper reports on the correlations found between selected parameters in a QH-mode database developed from several hundred DIII-D counter injected discharges. Time traces of key plasma parameters from a QH-mode discharge are shown. On DIII-D the negative going plasma current (a) indicates that the beam injection direction is counter to the plasma current direction, a common feature of all QH-modes. The D{sub {alpha}} time behavior (c) shows that soon after high powered beam heating (b) is applied, the discharge makes a transition to ELMing H-mode, then the ELMs disappear, indicating the start of the QH period that lasts for the remainder of the high power beam heating (3.5 s). Previously published work showing density and temperature profiles indicates that long-pulse, high-triangularity QH discharges develop an internal transport barrier in combination with the QH edge barrier. These discharges aremore » known as quiescent, double-barrier discharges (QDB). The H-factor (d) and stored energy (c) rise then saturate at a constant level and the measured axial and minimum safety factors remain above 1.0 for the entire QH duration. During QDB operation the performance of the plasma can be very good, with {beta}{sub N}*H{sub 89L} product reaching 7 for > 10 energy confinement times. These discharges show promise that a stationary state can be achieved.« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
GENERAL ATOMICS (US)
Sponsoring Org.:
(US)
OSTI Identifier:
821591
DOE Contract Number:  
AC03-99ER54463
Resource Type:
Conference
Resource Relation:
Conference: 30TH EUROPEAN PHYSICAL SOCIETY CONFERENCE ON CONTROLLED FUSION AND PLASMA PHYSICS, ST PETERSBURG (RU), 07/07/2003--07/11/2003; Other Information: PBD: 1 Aug 2003
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BEAM INJECTION; CONFINEMENT; CONFINEMENT TIME; DIVERTORS; DOUBLET-3 DEVICE; EDGE LOCALIZED MODES; ELECTRIC CURRENTS; HEATING; PERFORMANCE; PHYSICS; PLASMA; SAFETY; STORED ENERGY; TRANSPORT

Citation Formats

WEST, WP, BURRELL, KH, deGRASSIE, JS, DOYLE, EJ, GREENFIELD, CM, LASNIER, CJ, SNYDER, PB, and ZENG, L. QUIESCENT H-MODE, AN ELM-FREE HIGH-CONFINEMENT MODE ON DIII-D WITH POTENTIAL FOR STATIONARY STATE OPERATION. United States: N. p., 2003. Web.
WEST, WP, BURRELL, KH, deGRASSIE, JS, DOYLE, EJ, GREENFIELD, CM, LASNIER, CJ, SNYDER, PB, & ZENG, L. QUIESCENT H-MODE, AN ELM-FREE HIGH-CONFINEMENT MODE ON DIII-D WITH POTENTIAL FOR STATIONARY STATE OPERATION. United States.
WEST, WP, BURRELL, KH, deGRASSIE, JS, DOYLE, EJ, GREENFIELD, CM, LASNIER, CJ, SNYDER, PB, and ZENG, L. Fri . "QUIESCENT H-MODE, AN ELM-FREE HIGH-CONFINEMENT MODE ON DIII-D WITH POTENTIAL FOR STATIONARY STATE OPERATION". United States. https://www.osti.gov/servlets/purl/821591.
@article{osti_821591,
title = {QUIESCENT H-MODE, AN ELM-FREE HIGH-CONFINEMENT MODE ON DIII-D WITH POTENTIAL FOR STATIONARY STATE OPERATION},
author = {WEST, WP and BURRELL, KH and deGRASSIE, JS and DOYLE, EJ and GREENFIELD, CM and LASNIER, CJ and SNYDER, PB and ZENG, L},
abstractNote = {OAK-B135 The quiescent H-mode (QH-mode) is an ELM-free and stationary state mode of operation discovered on DIII-D. This mode achieves H-mode levels of confinement and pedestal pressure while maintaining constant density and radiated power. The elimination of edge localized modes (ELMs) and their large divertor loads while maintaining good confinement and good density control is of interest to next generation tokamaks. This paper reports on the correlations found between selected parameters in a QH-mode database developed from several hundred DIII-D counter injected discharges. Time traces of key plasma parameters from a QH-mode discharge are shown. On DIII-D the negative going plasma current (a) indicates that the beam injection direction is counter to the plasma current direction, a common feature of all QH-modes. The D{sub {alpha}} time behavior (c) shows that soon after high powered beam heating (b) is applied, the discharge makes a transition to ELMing H-mode, then the ELMs disappear, indicating the start of the QH period that lasts for the remainder of the high power beam heating (3.5 s). Previously published work showing density and temperature profiles indicates that long-pulse, high-triangularity QH discharges develop an internal transport barrier in combination with the QH edge barrier. These discharges are known as quiescent, double-barrier discharges (QDB). The H-factor (d) and stored energy (c) rise then saturate at a constant level and the measured axial and minimum safety factors remain above 1.0 for the entire QH duration. During QDB operation the performance of the plasma can be very good, with {beta}{sub N}*H{sub 89L} product reaching 7 for > 10 energy confinement times. These discharges show promise that a stationary state can be achieved.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2003},
month = {8}
}

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