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Title: Intrinsic rotation and electric field shear

Abstract

A novel mechanism for the generation and amplification of intrinsic rotation at the low-mode to high-mode transition is presented. The mechanism is one where the net parallel flow is accelerated by turbulence. A preferential direction of acceleration results from the breaking of k{sub parallel}{yields}-k{sub parallel} symmetry by sheared ExB flow. It is shown that the equilibrium pressure gradient contributes a piece of the parallel Reynolds stress, which is nonzero for vanishing parallel flow, and so can accelerate the plasma, driving net intrinsic rotation. Rotation drive, transport, and fluctuation dynamics are treated self-consistently.

Authors:
; ; ;  [1];  [2];  [3]
  1. Center for Astrophysics and Space Sciences, University of California, San Diego, La Jolla, California 92093-0424 (United States)
  2. (United States)
  3. (India)
Publication Date:
OSTI Identifier:
20974927
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 4; Other Information: DOI: 10.1063/1.2717891; (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; ACCELERATION; AMPLIFICATION; ELECTRIC FIELDS; ELECTROMAGNETIC FIELDS; EQUILIBRIUM; PLASMA PRESSURE; PRESSURE GRADIENTS; REYNOLDS NUMBER; ROTATING PLASMA; SHEAR; STRESSES; TURBULENCE

Citation Formats

Guercan, Oe. D., Diamond, P. H., Hahm, T. S., Singh, R., Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451, and Institute for Plasma Research, Bhat, Gandhinagar-382 428. Intrinsic rotation and electric field shear. United States: N. p., 2007. Web. doi:10.1063/1.2717891.
Guercan, Oe. D., Diamond, P. H., Hahm, T. S., Singh, R., Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451, & Institute for Plasma Research, Bhat, Gandhinagar-382 428. Intrinsic rotation and electric field shear. United States. doi:10.1063/1.2717891.
Guercan, Oe. D., Diamond, P. H., Hahm, T. S., Singh, R., Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451, and Institute for Plasma Research, Bhat, Gandhinagar-382 428. Sun . "Intrinsic rotation and electric field shear". United States. doi:10.1063/1.2717891.
@article{osti_20974927,
title = {Intrinsic rotation and electric field shear},
author = {Guercan, Oe. D. and Diamond, P. H. and Hahm, T. S. and Singh, R. and Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451 and Institute for Plasma Research, Bhat, Gandhinagar-382 428},
abstractNote = {A novel mechanism for the generation and amplification of intrinsic rotation at the low-mode to high-mode transition is presented. The mechanism is one where the net parallel flow is accelerated by turbulence. A preferential direction of acceleration results from the breaking of k{sub parallel}{yields}-k{sub parallel} symmetry by sheared ExB flow. It is shown that the equilibrium pressure gradient contributes a piece of the parallel Reynolds stress, which is nonzero for vanishing parallel flow, and so can accelerate the plasma, driving net intrinsic rotation. Rotation drive, transport, and fluctuation dynamics are treated self-consistently.},
doi = {10.1063/1.2717891},
journal = {Physics of Plasmas},
number = 4,
volume = 14,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}
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  • Using the unique capability of JET to monotonically change the amplitude of the magnetic field ripple, without modifying other relevant equilibrium conditions, the effect of the ripple on the angular rotation frequency of the plasma column was investigated under the conditions of no external momentum input. The ripple amplitude was varied from 0.08% to 1.5% in Ohmic and ion-cyclotron radio-frequency (ICRF) heated plasmas. In both cases the ripple causes counterrotation, indicating a strong torque due to nonambipolar transport of thermal ions and in the case of ICRF also fast ions.
  • The relaxation of core transport barriers in TFTR enhanced reversed shear plasmas has been studied by varying the radial electric field using different applied torques from neutral beam injection. Transport rates and fluctuations remain low over a wide range of radial electric field shear, but increase when the local {bold E}{times}{bold B} shearing rates are driven below a threshold comparable to the fastest linear growth rates of the dominant instabilities. Shafranov-shift-induced stabilization alone is not able to sustain enhanced confinement. {copyright} {ital 1997} {ital The American Physical Society}
  • We present an experimental and numerical study of hydrodynamic and magnetohydrodynamic free shear layers and their stability. We first examine the experimental measurement of globally unstable hydrodynamic shear layers in the presence of rotation and their range of instability. These are compared to numerical simulations, which are used to explain the modification of the shear layer, and thus the critical Rossby number for stability. Magnetic fields are then applied to these scenarios and globally unstable magnetohydrodynamic shear layers generated. These too are compared to numerical simulations showing behavior consistent with the hydrodynamic case and previously reported measurements.