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6 results on '"null R. Kaita"'

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. 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

3. NSTX Overview

Author

null M. Ono, null M. Bell, null R.E. Bell, null M. Bitter, null C. Bourdelle, null D. Darrow, null D. Gates, null J. Hosea, null S.M. Kaye, null R. Kaita, null H. Kugel, null D. Johnson, null B. LeBlanc, null S. Medley, and null et al.

Published
2001

4. 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

5. Diagnostic Development on NSTX

Author

null A.L. Roquemore, null D. Johnson, null R. Kaita, and null et al

Subjects
Engineering, Aspect ratio, business.industry, Toroidal field, Electrical engineering, Mechanical engineering, business
Abstract

Diagnostics are described which are currently installed or under active development for the newly commissioned NSTX device. The low aspect ratio (R/a less than or equal to 1.3) and low toroidal field (0.1-0.3T) used in this device dictate adaptations in many standard diagnostic techniques. Technical summaries of each diagnostic are given, and adaptations, where significant, are highlighted.

Published
1999

6. NSTX High Temperature Sensor Systems

Author

null B.McCormack, null H.W. Kugel, null P. Goranson, null R. Kaita, and null et al

Subjects
Engineering, business.industry, Divertor, Nuclear engineering, Electrical engineering, Plasma, Fusion power, symbols.namesake, Stack (abstract data type), Thermocouple, visual_art, symbols, visual_art.visual_art_medium, Langmuir probe, Tile, business, Rogowski coil
Abstract

The design of the more than 300 in-vessel sensor systems for the National Spherical Torus Experiment (NSTX) has encountered several challenging fusion reactor diagnostic issues involving high temperatures and space constraints. This has resulted in unique miniature, high temperature in-vessel sensor systems mounted in small spaces behind plasma facing armor tiles, and they are prototypical of possible high power reactor first-wall applications. In the Center Stack, Divertor, Passive Plate, and vessel wall regions, the small magnetic sensors, large magnetic sensors, flux loops, Rogowski Coils, thermocouples, and Langmuir Probes are qualified for 600 degrees C operation. This rating will accommodate both peak rear-face graphite tile temperatures during operations and the 350 degrees C bake-out conditions. Similar sensor systems including flux loops, on other vacuum vessel regions are qualified for 350 degrees C operation. Cabling from the sensors embedded in the graphite tiles follows narrow routes to exit the vessel. The detailed sensor design and installation methods of these diagnostic systems developed for high-powered ST operation are discussed.

Published
1999

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