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Title: A Model of Plasma Rotation in the Livermore Spheromak for the Regimes of Large Connection Lengths

Abstract

A model is suggested that predicts the velocity and geometrical characteristics of the plasma rotation in the Livermore spheromak. The model addresses the ''good confinement'' regimes in this device, where the typical length of magnetic field lines before their intersection with the wall (this length is called ''connection length'' below) becomes large enough to make the parallel heat loss insignificant. In such regimes, the heat flux is determined by the transport across toroidally-averaged flux surfaces. The model is based on the assumption that, entering the good confinement regime, does not automatically mean that the connection length becomes infinite, and perfect flux surfaces are established. It is hypothesized that connection length remains finite, albeit large in regard to the parallel heat loss. The field lines are threading the whole plasma volume, although it takes a long distance for them to get from one toroidally-averaged flux surface to another. The parallel electron momentum balance then uniquely determines the distribution of the electrostatic potential between these surfaces. An analysis of viscous stresses shows that the toroidal flow is much faster than the poloidal flow. It is shown that the rotation shear usually exceeds by a factor of a few the characteristic growth ratemore » of drift waves, meaning that suppression of the transport caused by the drift turbulence may occur, and a transport barrier with respect to this transport mechanism may be formed. The model may be useful for assessing the plasma rotation in other spheromaks and, possibly, reversed-field pinches and field-reversed configurations provided a certain set of applicability conditions (Sec. II) is fulfilled.« less

Authors:
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
908132
Report Number(s):
UCRL-JRNL-227066
Journal ID: ISSN 1070-664X; PHPAEN; TRN: US0703642
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas, vol. 14, no. 02, February 23, 2007, pp. 022506; Journal Volume: 14, no.; Journal Issue: 02
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION; DISTRIBUTION; ELECTRONS; ELECTROSTATICS; HEAT FLUX; MAGNETIC FIELDS; MAGNETIC SURFACES; PLASMA; ROTATION; SHEAR; STRESSES; TRANSPORT; TURBULENCE; VELOCITY; TOKAMAK DEVICES; TOKAMAK TYPE REACTORS

Citation Formats

Ryutov, D. A Model of Plasma Rotation in the Livermore Spheromak for the Regimes of Large Connection Lengths. United States: N. p., 2007. Web. doi:10.1063/1.2435705.
Ryutov, D. A Model of Plasma Rotation in the Livermore Spheromak for the Regimes of Large Connection Lengths. United States. doi:10.1063/1.2435705.
Ryutov, D. Wed . "A Model of Plasma Rotation in the Livermore Spheromak for the Regimes of Large Connection Lengths". United States. doi:10.1063/1.2435705. https://www.osti.gov/servlets/purl/908132.
@article{osti_908132,
title = {A Model of Plasma Rotation in the Livermore Spheromak for the Regimes of Large Connection Lengths},
author = {Ryutov, D},
abstractNote = {A model is suggested that predicts the velocity and geometrical characteristics of the plasma rotation in the Livermore spheromak. The model addresses the ''good confinement'' regimes in this device, where the typical length of magnetic field lines before their intersection with the wall (this length is called ''connection length'' below) becomes large enough to make the parallel heat loss insignificant. In such regimes, the heat flux is determined by the transport across toroidally-averaged flux surfaces. The model is based on the assumption that, entering the good confinement regime, does not automatically mean that the connection length becomes infinite, and perfect flux surfaces are established. It is hypothesized that connection length remains finite, albeit large in regard to the parallel heat loss. The field lines are threading the whole plasma volume, although it takes a long distance for them to get from one toroidally-averaged flux surface to another. The parallel electron momentum balance then uniquely determines the distribution of the electrostatic potential between these surfaces. An analysis of viscous stresses shows that the toroidal flow is much faster than the poloidal flow. It is shown that the rotation shear usually exceeds by a factor of a few the characteristic growth rate of drift waves, meaning that suppression of the transport caused by the drift turbulence may occur, and a transport barrier with respect to this transport mechanism may be formed. The model may be useful for assessing the plasma rotation in other spheromaks and, possibly, reversed-field pinches and field-reversed configurations provided a certain set of applicability conditions (Sec. II) is fulfilled.},
doi = {10.1063/1.2435705},
journal = {Physics of Plasmas, vol. 14, no. 02, February 23, 2007, pp. 022506},
number = 02,
volume = 14, no.,
place = {United States},
year = {Wed Jan 03 00:00:00 EST 2007},
month = {Wed Jan 03 00:00:00 EST 2007}
}