skip to main content

SciTech ConnectSciTech Connect

Title: Progress toward fully noninductive discharge operation in DIII-D using off-axis neutral beam injection

The initial experiments on off-axis neutral beam injection into high noninductive current fraction (f{sub NI}), high normalized pressure (β{sub N}) discharges in DIII-D [J. L. Luxon, Fusion Sci. Technol. 48, 828 (2005)] have demonstrated changes in the plasma profiles that increase the limits to plasma pressure from ideal low-n instabilities. The current profile is broadened and the minimum value of the safety factor (q{sub min}) can be maintained above 2 where the profile of the thermal component of the plasma pressure is found to be broader. The off-axis neutral beam injection results in a broadening of the fast-ion pressure profile. Confinement of the thermal component of the plasma is consistent with the IPB98(y,2) scaling, but global confinement with q{sub min}>2 is below the ITER-89P scaling, apparently as a result of enhanced transport of fast ions. A 0-D model is used to examine the parameter space for f{sub NI}=1 operation and project the requirements for high performance steady-state discharges. Fully noninductive solutions are found with 4<β{sub N}<5 and bootstrap current fraction near 0.5 for a weak shear safety factor profile. A 1-D model is used to show that a f{sub NI}=1 discharge at the top of this range of β{sub N}more » that is predicted stable to n=1, 2, and 3 ideal MHD instabilities is accessible through further broadening of the current and pressure profiles with off-axis neutral beam injection and electron cyclotron current drive.« less
Authors:
; ; ; ; ; ; ;  [1] ;  [2] ;  [3] ; ;  [4] ;  [5] ; ;  [6] ;  [7] ;  [8]
  1. General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States)
  2. Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, California 94550-9234 (United States)
  3. Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)
  4. Columbia University, 116th St and Broadway, New York, New York 10027 (United States)
  5. University of California, Irvine, University Dr., Irvine, California 92697 (United States)
  6. University of California, Los Angeles, PO Box 957099, Los Angeles, California 90095-7099 (United States)
  7. FAR-TECH, Inc., 10350 Science Center Dr., San Diego, California 92121-1136 (United States)
  8. Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543-0451 (United States)
Publication Date:
OSTI Identifier:
22220605
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 20; Journal Issue: 9; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BOOTSTRAP CURRENT; DOUBLET-3 DEVICE; ECR CURRENT DRIVE; ELECTRIC DISCHARGES; IONS; ITER TOKAMAK; MAGNETOHYDRODYNAMICS; PLASMA BEAM INJECTION; PLASMA CONFINEMENT; PLASMA INSTABILITY; PLASMA PRESSURE; PLASMA RADIAL PROFILES; SOLUTIONS