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Title: Effects of ExB Velocity Shear and Magnetic Shear in the Formation of Core Transport Barriers in the DIII-D Tokamak

Abstract

Core transport barriers can be reliably formed in DIII-D by tailoring the evolution of the current density profile. This paper reports studies of the relative role of magnetic and ExB shear in creating core transport barriers in the DIII-D tokamak and considers the detailed dynamics of the barrier formation. The core barriers seen in DIII-D negative shear discharges form in a stepwise fashion during the initial current ramp. The reasons for the stepwise formation is not known; these steps do not correlate with integer values of q(O) or minimum q. The data from DIII-D is consistent with previous results that negative magnetic shear facilitates the formation of core transport barriers in the ion channel but is not necessary. However, strongly negative magnetic shear does allow formation of transport barriers in particle, electron thermal, ion thermal and angular momentum transport channels. Shots with strong negative magnetic shear have produced the steepest ion temperature and toroidal rotation profiles seen yet in DIII-D. In addition, the ExB shearing rates seen in these shots exceed the previous DIII-D record value by a factor of four.

Authors:
; ; ;  [1];  [2]; ;  [3]
  1. General Atomics, San Diego, CA (United States)
  2. Texas University, Austin, TX (United States)
  3. Lawrence Livermore National Lab., CA (United States)
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States); USDOE Office of Energy Research, Washington, DC (United States)
OSTI Identifier:
629302
Report Number(s):
GA-A22715; CONF-9709100-
ON: DE98001906; TRN: 98:009734
DOE Contract Number:  
AC03-89ER51114; FG03-97ER54415; W-7405-ENG-48
Resource Type:
Technical Report
Resource Relation:
Conference: US/Japan workshop on H-mode physics and 6th H-mode workshop, Kloster Seeon (Germany), 22-24 Sep 1997; Other Information: PBD: [Dec 1997]
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION; IONS; ELECTRON DENSITY; CHARGED-PARTICLE TRANSPORT; CURRENT DENSITY; ELECTRONS; ANGULAR MOMENTUM; ION DENSITY; MOMENTUM TRANSFER; DOUBLET-3 DEVICE; MAGNETIC CONFINEMENT; SHEAR; ELECTROMAGNETIC FIELDS; EXPERIMENTAL DATA; magnetic shear; core transport barriers

Citation Formats

Burrell, K.H., Greenfield, C.M., Lao, L.L., Staebler, G.M., Austin, M.E., Rice, B.W., and Stallard, B.W.. Effects of ExB Velocity Shear and Magnetic Shear in the Formation of Core Transport Barriers in the DIII-D Tokamak. United States: N. p., 1997. Web. doi:10.2172/629302.
Burrell, K.H., Greenfield, C.M., Lao, L.L., Staebler, G.M., Austin, M.E., Rice, B.W., & Stallard, B.W.. Effects of ExB Velocity Shear and Magnetic Shear in the Formation of Core Transport Barriers in the DIII-D Tokamak. United States. doi:10.2172/629302.
Burrell, K.H., Greenfield, C.M., Lao, L.L., Staebler, G.M., Austin, M.E., Rice, B.W., and Stallard, B.W.. Wed . "Effects of ExB Velocity Shear and Magnetic Shear in the Formation of Core Transport Barriers in the DIII-D Tokamak". United States. doi:10.2172/629302. https://www.osti.gov/servlets/purl/629302.
@article{osti_629302,
title = {Effects of ExB Velocity Shear and Magnetic Shear in the Formation of Core Transport Barriers in the DIII-D Tokamak},
author = {Burrell, K.H. and Greenfield, C.M. and Lao, L.L. and Staebler, G.M. and Austin, M.E. and Rice, B.W. and Stallard, B.W.},
abstractNote = {Core transport barriers can be reliably formed in DIII-D by tailoring the evolution of the current density profile. This paper reports studies of the relative role of magnetic and ExB shear in creating core transport barriers in the DIII-D tokamak and considers the detailed dynamics of the barrier formation. The core barriers seen in DIII-D negative shear discharges form in a stepwise fashion during the initial current ramp. The reasons for the stepwise formation is not known; these steps do not correlate with integer values of q(O) or minimum q. The data from DIII-D is consistent with previous results that negative magnetic shear facilitates the formation of core transport barriers in the ion channel but is not necessary. However, strongly negative magnetic shear does allow formation of transport barriers in particle, electron thermal, ion thermal and angular momentum transport channels. Shots with strong negative magnetic shear have produced the steepest ion temperature and toroidal rotation profiles seen yet in DIII-D. In addition, the ExB shearing rates seen in these shots exceed the previous DIII-D record value by a factor of four.},
doi = {10.2172/629302},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Dec 31 00:00:00 EST 1997},
month = {Wed Dec 31 00:00:00 EST 1997}
}

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