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Your search keyword '"null R. Maingi"' showing total 6 results
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6 results on '"null R. Maingi"'

1. Recent Liquid Lithium Limiter Experiments in CDX-U

Author

null R. Majeski, null S. Jardin, null R. Kaita, null T. Gray, null P. Marfuta, null J. Spaleta, null J. Timberlake, null L. Zakharov, null G. Antar, null R. Doerner, null S. Luckhardt, null R. Seraydarian, null V. Soukhanovskii, null R. Maingi, null M. Finkenthal, null D. Stutman, null D. Rodgers, and null S. Angelini

Published
2005

2. The H-mode Pedestal and Edge Localized Modes in NSTX

Author

null R. Maingi, null E.D. Fredrickson, null J.E. Menard, null N. Nishino, null A.L. Roquemore, null S.A. Sabbagh, null K. Tritz, and null the NSTX Team

Subjects
Physics, Tokamak, Pedestal, law, Beta (plasma physics), Magnetic confinement fusion, Pulse duration, Atomic physics, Edge (geometry), Instability, Aspect ratio (image), law.invention, Computational physics
Abstract

The research program of the National Spherical Torus Experiment (NSTX) routinely utilizes the H-mode confinement regime to test and extend beta and pulse length limits. As in conventional aspect ratio tokamaks, NSTX observes a variety of edge localized modes (ELMs) in H-mode. Hence a significant part of the research program is dedicated to ELMs studies.

Published
2004

3. Effect of Gas Fueling Location on H-mode Access in NSTX

Author

null R. Maingi, null M. Bell, null R. Bell, null T. Biewer, null C. Bush, null C.S. Chang, null D. Gates, null S. Kaye, null H. Kugel, null B. LeBlanc, null R. Maqueda, null J. Menard, null D. Mueller, null R. Raman, null S. Sabbagh, null V. Soukhanovskii, and null the NSTX Team

Subjects
Physics, Toroid, Stack (abstract data type), Monte Carlo method, Mode (statistics), Edge (geometry), Electric current, Atomic physics, Rotation, Power (physics), Computational physics
Abstract

The dependence of H-mode access on the poloidal location of the gas injection source has been investigated in the National Spherical Torus Experiment (NSTX). We find that gas fueling from the center stack midplane area produces the most reproducible H-mode access with generally the lowest L-H threshold power in lower single-null configuration. The edge toroidal rotation velocity is largest (in direction of the plasma current) just before the L-H transition with center stack midplane fueling, and then reverses direction after the L-H transition. Simulation of these results with a 2-D guiding-center Monte Carlo neoclassical transport code is qualitatively consistent with the trends in the measured velocities. Double-null discharges exhibit H-mode access with gas fueling from either the center stack midplane or center stack top locations, indicating a reduced sensitivity of H-mode access on fueling location in that shape.

Published
2003

4. High-Harmonic Fast Wave Driven H-mode Plasmas on NSTX

Author

null B.P. LeBlanc, null R.E. Bell, null S.I. Bernabei, null K. Indireshkumar, null S.M. Kaye, null R. Maingi, null T.K. Mau, null D.W. Swain, null G. Taylor, null P.M. Ryan, null J.B Wilgen, and null J.R. Wilson

Published
2003

5. Results of NSTX Heating Experiments

Author

null D. Mueller, null M. Ono, null M.G. Bell, null R.E. Bell, null M. Bitter, null C. Bourdelle, null D.S. Darrow, null P.C. Efthimion, null E.D. Fredrickson, null D.A Gates, null R.J. Goldston, null L.R. Grisham, null R.J. Hawryluk, null K.W. Hill, null J.C. Hosea, null S.C. Jardin, null H. Ji, null S.M. Kaye, null R. Kaita, null H.W. Kugel, null D.W. Johnson, null B.P. LeBlanc, null R. Majeski, null E. Mazzucato, null S.S. Medley, null J.E. Menard, null H.K. Park, null S.F. Paul, null C.K. Phillips, null M.H. Redi, null A.L. Rosenberg, null C.H. Skinner, null V.A. Soukhanovskii, null B. Stratton, null E.J Synakowski, null G. Taylor, null J.R. Wilson, null S.J. Zweben, null Y-K.M. Peng, null R. Barry, null T. Bigelow, null C.E. Bush, null M. Carter, null R. Maingi, null M. Menon, null P.M. Ryan, null D.W. Swain, null J. Wilgen, and null 37 additional authors

Subjects
Physics, Toroid, Physics::Plasma Physics, Beta (plasma physics), Torus, Plasma, Magnetohydrodynamics, Atomic physics, Scaling, Neutral beam injection, Bootstrap current
Abstract

The National Spherical Torus Experiment (NSTX) at Princeton is designed to assess the potential of the low-aspect-ratio spherical torus concept for magnetic plasma confinement. The plasma has been heated by up to 5 MW of neutral beam injection, NBI, at an injection energy of 90 keV and up to 6 MW of high harmonic fast wave, HHFW, at 30 MHz. NSTX has achieved beta T of 32%. A variety of MHD phenomena have been observed to limit eta. NSTX has now begun addressing E scaling, eta limits and current drive issues. During the NBI heating experiments, a broad Ti profile with Ti up to 2 keV, Ti > Te and a large toroidal rotation. Transport analysis suggests that the impurity ions have diffusivities approaching neoclassical. For L-Mode plasmas, E is up to two times the ITER-89P L-Mode scaling and exceeds the ITER-98pby2 H-Mode scaling in some cases. Transitions to H-Mode have been observed which result in an approximate doubling of tE. after the transition in some conditions. During HH FW heating, Te > Ti and Te up to 3.5 keV were observed. Current drive has been studied using coaxial helicity injection (CHI), which has produced 390 kA of toroidal current and HHFW, which has produced H-modes with significant bootstrap current fraction at low Ip, high q and high{sub etap}.

Published
2002

6. Stability and Confinement Properties of Auxiliary Heated NSTX Discharges

Author

null J.E. Menard, null R.E.Bell, null C. Bourdelle, null D.S. Darrow, null E.D. Fredrickson, null D.A. Gates, null L.R. Grisham, null S.M. Kaye, null B.P. LeBlanc, null R. Maingi, null S.S. Medley, null D. Mueller, null F. Paoletti, null S.A. Sabbagh, null D. Stutman, null D.W. Swain, null J.R. Wilson, null M.G. Bell, null J.M. Bialek, null C.E.Bush, null J.C. Hosea, null D.W. Johnson, null R. Kaita, null H.W. Kugel, null R.J. Maqueda, null M. Ono, null Y-K.M. Peng, null C.H. Skinner, null V.A. Soukhanovskii, null E.J. Synakowski, null G. Taylor, null G.A. Wurden, and null and S.J. Zweben

Subjects
Electron density, Chemistry, Thomson scattering, Electron temperature, Radius, Plasma, Atomic physics, Spherical tokamak, Energy source, Dimensionless quantity
Abstract

The National Spherical Torus Experiment (NSTX) is a spherical tokamak with nominal plasma major radius R(subscript ''0'') = 0.85 m, minor radius a = 0.66 m, and aspect ratio A > 1.28. Typical discharge parameters are plasma current I (subscript ''p'') = 0.7-1.4 MA, toroidal magnetic field B(subscript ''t0'') = 0.25-0.45 Tesla at major radius R(subscript ''0''), elongation = 1.7-2.2, triangularity 0.3-0.5, line-average electron density = 2-5 x 10(superscript ''19'') m(superscript ''-3''), electron temperature T(subscript ''e'')(0) = 0.5-1.5 keV, and ion temperature T(subscript ''i'')(0) = 0.5-2 keV. The NSTX auxiliary heating systems can routinely deliver 4.5 MW of 80-keV deuterium neutral beams and 3 MW of 30-MHz high-harmonic fast-wave power. Kinetic profile diagnostics presently include a 10-channel, 30-Hz multipulse Thomson scattering system (MPTS), a 17-channel charge-exchange recombination spectroscopy (CHERS) system, a 48-chord ultra-soft X-ray (USXR) array, and a 15-chord bolometry array. Initial experiments utilizing auxiliary heating on NSTX have focused on MHD stability limits, confinement trends, studying H-mode characteristics, and performing initial power balance calculations.

Published
2001

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