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Title: Intrinsic rotation in DIII-D

Abstract

In the absence of any auxiliary torque input, the DIII-D plasma consists of nonzero toroidal angular momentum, in other words, it rotates. This effect is commonly observed in tokamaks, being referred to as intrinsic rotation. Measurements of intrinsic rotation profiles have been made in DIII-D [J. Luxon, Nucl. Fusion 42, 614 (2002)] H-mode discharges, with both Ohmic heating (OH) and electron cyclotron heating (ECH) in which there is no auxiliary torque. Recently, the H-mode data set has been extended with the newly configured DIII-D simultaneous co- and counter-directed neutral beam injection (NBI) capability resulting in control of the local torque deposition, where co and counter refer to the direction relative to the toroidal plasma current. Understanding intrinsic rotation is important for projection toward burning plasma performance where any NBI torque will be relatively small. The toroidal velocity is recognizably important regarding issues of stability and confinement. In DIII-D ECH H-modes the rotation profile is hollow, co-directed at large minor radius and depressed, or actually counter-directed, nearer the magnetic axis. This profile varies with the ECH power deposition profile to some extent. In contrast, OH H-modes have a relatively flat co-directed rotation profile. There is a scaling of the DIII-D intrinsicmore » toroidal velocity with W/I{sub p}, as seen in intrinsic rotation in Alcator C-Mod [J. Rice, Nucl. Fusion 39, 1175 (1999)], where W is the total plasma thermal energy and I{sub p} is the magnitude of the toroidal plasma current. This common scaling resulted in a dimensionless similarity experiment between DIII-D and Alcator C-Mod on intrinsic rotation, obtaining a single spatial point match in the toroidal velocity normalized to the ion thermal velocity. The balanced NBI capability in DIII-D is a useful tool to push scaling studies to higher values of the plasma normalized energy, notwithstanding the details of torque deposition for co-NBI versus counter-NBI. There are theories which address intrinsic rotation, both extensions of neoclassical theory and related to turbulent transport. At this time, the comparisons with theory are qualitative.« less

Authors:
; ; ; ;  [1];  [2];  [2];  [2]
  1. General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20975053
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 5; Other Information: DOI: 10.1063/1.2539055; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ALCATOR DEVICE; ANGULAR MOMENTUM; COMPARATIVE EVALUATIONS; CONTROL; DOUBLET-3 DEVICE; ECR HEATING; ELECTRIC CURRENTS; H-MODE PLASMA CONFINEMENT; IONS; NEOCLASSICAL TRANSPORT THEORY; PLASMA; PLASMA BEAM INJECTION; RF SYSTEMS; ROTATION; SCALING; VELOCITY

Citation Formats

DeGrassie, J. S., Rice, J. E., Burrell, K. H., Groebner, R. J., Solomon, W. M., Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, General Atomics, P.O. Box 85608, San Diego, California 92186-5608, and Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451. Intrinsic rotation in DIII-D. United States: N. p., 2007. Web. doi:10.1063/1.2539055.
DeGrassie, J. S., Rice, J. E., Burrell, K. H., Groebner, R. J., Solomon, W. M., Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, General Atomics, P.O. Box 85608, San Diego, California 92186-5608, & Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451. Intrinsic rotation in DIII-D. United States. doi:10.1063/1.2539055.
DeGrassie, J. S., Rice, J. E., Burrell, K. H., Groebner, R. J., Solomon, W. M., Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, General Atomics, P.O. Box 85608, San Diego, California 92186-5608, and Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451. Tue . "Intrinsic rotation in DIII-D". United States. doi:10.1063/1.2539055.
@article{osti_20975053,
title = {Intrinsic rotation in DIII-D},
author = {DeGrassie, J. S. and Rice, J. E. and Burrell, K. H. and Groebner, R. J. and Solomon, W. M. and Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307 and General Atomics, P.O. Box 85608, San Diego, California 92186-5608 and Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451},
abstractNote = {In the absence of any auxiliary torque input, the DIII-D plasma consists of nonzero toroidal angular momentum, in other words, it rotates. This effect is commonly observed in tokamaks, being referred to as intrinsic rotation. Measurements of intrinsic rotation profiles have been made in DIII-D [J. Luxon, Nucl. Fusion 42, 614 (2002)] H-mode discharges, with both Ohmic heating (OH) and electron cyclotron heating (ECH) in which there is no auxiliary torque. Recently, the H-mode data set has been extended with the newly configured DIII-D simultaneous co- and counter-directed neutral beam injection (NBI) capability resulting in control of the local torque deposition, where co and counter refer to the direction relative to the toroidal plasma current. Understanding intrinsic rotation is important for projection toward burning plasma performance where any NBI torque will be relatively small. The toroidal velocity is recognizably important regarding issues of stability and confinement. In DIII-D ECH H-modes the rotation profile is hollow, co-directed at large minor radius and depressed, or actually counter-directed, nearer the magnetic axis. This profile varies with the ECH power deposition profile to some extent. In contrast, OH H-modes have a relatively flat co-directed rotation profile. There is a scaling of the DIII-D intrinsic toroidal velocity with W/I{sub p}, as seen in intrinsic rotation in Alcator C-Mod [J. Rice, Nucl. Fusion 39, 1175 (1999)], where W is the total plasma thermal energy and I{sub p} is the magnitude of the toroidal plasma current. This common scaling resulted in a dimensionless similarity experiment between DIII-D and Alcator C-Mod on intrinsic rotation, obtaining a single spatial point match in the toroidal velocity normalized to the ion thermal velocity. The balanced NBI capability in DIII-D is a useful tool to push scaling studies to higher values of the plasma normalized energy, notwithstanding the details of torque deposition for co-NBI versus counter-NBI. There are theories which address intrinsic rotation, both extensions of neoclassical theory and related to turbulent transport. At this time, the comparisons with theory are qualitative.},
doi = {10.1063/1.2539055},
journal = {Physics of Plasmas},
number = 5,
volume = 14,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}