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in creator/contributor: "WURDEN, G. A."  
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Harmonic launching of ion Bernstein waves via mode transformation

Description: Ion Bernstein wave excitation and propagation via finite ion-Larmor-radium mode-transformation are investigated theoretically and experimentally. It is shown that in the ion cyclotron range of frequencies omega less than or equal to 4..cap omega../sub i/, with modest ion temperatures (T/sub i/ less than or equal to 10 eV), the finite-Larmor-radius effect removes the wave singularity at lower-hybrid resonance layer, enabling an externally initiated electron plasma wave to transform continuously … more
Date: June 1, 1982
Creator: Ono, M.; Wong, K. L. & Wurden, G. A.
Partner: UNT Libraries Government Documents Department
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Ion Bernstein-wave excitation via finite-Larmor-radius mode-transformation process

Description: It is shown that in the ion cyclotron range of frequency ..omega.. less than or equal to 2 ..cap omega../sub i/, the finite-Larmor-radius effect removes the wave singularity at the lower-hybrid resonance layer, enabling an externally initiated electron plasma wave to propagate freely through the resonance layer, transforming continuously into an ion Bernstein wave. In an ACT-1 hydrogen plasma (T/sub e/ approx. = 2.5 eV, T/sub i/ approx. = 1.5 eV), linear excitation of ion Bernstein waves has be… more
Date: July 1, 1981
Creator: Ono, M.; Wong, K. L. & Wurden, G. A.
Partner: UNT Libraries Government Documents Department
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Ion temperature via laser scattering on ion Bernstein waves

Description: Hydrogen ion temperature has been measured in a warm toroidal plasma with externally launched ion Bernstein waves detected by heterodyne CO/sub 2/ laser scattering. Radial scanning of the laser beam allows precise determination of k/sub perpendicular to/ for the finite ion Larmor radius wave (..omega.. approx. less than or equal to 2..cap omega../sub i/). Knowledge of the magnetic field strength and ion concentration then give a radially resolved ion temperature from the dispersion relation. Pr… more
Date: October 1, 1981
Creator: Wurden, G. A.; Ono, M. & Wong, K. L.
Partner: UNT Libraries Government Documents Department
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Observation of magnetized-ion thermal effects on lower-hybrid waves

Description: Finite ion Larmor radius modification of lower-hybrid waves in the ACT-1 toroidal plasma at frequencies ..omega.. approx. = 4 to 8 ..omega../sub ci/, close to the lower-hybrid resonance layer, is observed experimentally. Probe and CO/sub 2/ laser scans of the wave amplitude show interference patterns at frequencies above each ion cyclotron harmonic. Modeling with a hot-ion, electrostatic ray tracing code and Fourier reconstruction of the waveform suggests that linear mode conversion to hot plas… more
Date: February 1, 1983
Creator: Wurden, G. A.; Wong, K. L.; Skiff, F. & Ono, M.
Partner: UNT Libraries Government Documents Department
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Efficient ion heating via finite-Larmor-radius ICRF

Description: Ion heating by externally launched ion Bernstein waves is investigated in the ACT-1 hydrogen plasma. Detailed measurements of wave absorption and of the ion temperature profiles have clearly identified various heating layers near the ion cyclotron harmonics of deuterium-like and tritium-like ions. The observed heating of 10 eV/WATT/10/sup 10/ cm/sup -3/ and the power-balance estimates suggest excellent overall efficiency for FLR-ICRF heating.
Date: March 1, 1983
Creator: Ono, M.; Wurden, G. A. & Wong, K. L.
Partner: UNT Libraries Government Documents Department
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A scintillating-fiber 14-MeV neutron detector on TFTR during DT operation

Description: A compact 14-MeV neutron detector using an array of scintillating fibers has been tested on the TFTR tokamak under conditions of a high gamma background. This detector uses a fiber-matrix geometry, a magnetic field-insensitive phototube with an active HV base and pulse-height discrimination to reject low-level pulses from 2.5 MeV neutron and intense gammas. Laboratory calibrations have been performed at EG&G Las Vegas using a pulsed DT neutron generator and a 30 kCi {sup 60}Co source as backgro… more
Date: July 1, 1994
Creator: Wurden, G. A.; Chrien, R. E.; Barnes, C. W.; Sailor, W. C.; Roquemore, A. L.; Lavelle, M. J. et al.
Partner: UNT Libraries Government Documents Department
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The National Spherical Torus Experiment (NSTX) Research Program and Progress Towards High Beta, Long Pulse Operating Scenarios

Description: A major research goal of the National Spherical Torus Experiment is establishing long-pulse, high-beta, high-confinement operation and its physics basis. This research has been enabled by facility capabilities developed over the last two years, including neutral-beam (up to 7 MW) and high-harmonic fast-wave heating (up to 6 MW), toroidal fields up to 6 kG, plasma currents up to 1.5 MA, flexible shape control, and wall preparation techniques. These capabilities have enabled the generation of pla… more
Date: October 15, 2002
Creator: Synakowski, E. J.; Bell, M. G.; Bell, R. E.; Bigelow, T.; Bitter, M.; Blanchard, W. et al.
Partner: UNT Libraries Government Documents Department
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Recent Progress on the National Spherical Torus Experiment (NSTX)

Description: Recent upgrades to the NSTX facility have led to improved plasma performance. Using 5MW of neutral beam injection, plasmas with toroidal {beta}{sub T} (= 2{micro}{sub 0}<p>/B{sub T}{sup 2} where B{sub T} is the vacuum toroidal field at the plasma geometric center) > 30% have been achieved with normalized {beta}{sub N} (= {beta}{sub T}aB{sub I}/I{sub p}) {approx} 6% {center_dot} m {center_dot} T/MA.. The highest {beta} discharge exceeded the calculated no-wall {beta} limit for several w… more
Date: July 2, 2002
Creator: Gates, D. A.; Bell, M. G.; Bell, R. E.; Bialek, J.; Bigelow, T.; Bitter, M. et al.
Partner: UNT Libraries Government Documents Department
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Operational Regimes of the National Spherical Torus Experiment

Description: The National Spherical Torus Experiment (NSTX) is a proof-of-principle experiment designed to study the physics of Spherical Tori (ST), i.e., low-aspect-ratio toroidal plasmas. Important issues for ST research are whether the high-eta stability and reduced transport theoretically predicted for this configuration can be realized experimentally. In NSTX, the commissioning of a digital real-time plasma control system, the provision of flexible heating systems, and the application of wall condition… more
Date: June 3, 2002
Creator: Mueller, D.; Bell, M. G.; Bell, R. E.; Bitter, M.; Bigelow, T.; Bonoli, P. et al.
Partner: UNT Libraries Government Documents Department
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Progress Towards High Performance, Steady-state Spherical Torus

Description: Research on the Spherical Torus (or Spherical Tokamak) is being pursued to explore the scientific benefits of modifying the field line structure from that in more moderate aspect-ratio devices, such as the conventional tokamak. The Spherical Tours (ST) experiments are being conducted in various U.S. research facilities including the MA-class National Spherical Torus Experiment (NSTX) at Princeton, and three medium-size ST research facilities: Pegasus at University of Wisconsin, HIT-II at Univer… more
Date: October 2, 2003
Creator: Ono, M.; Bell, M. G.; Bell, R. E.; Bigelow, T.; Bitter, M.; Blanchard, W. et al.
Partner: UNT Libraries Government Documents Department
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Tokamak physics experiment: Diagnostic windows study

Description: We detail the study of diagnostic windows and window thermal stress remediation in the long-pulse, high-power Tokamak Physics Experiment (TPX) operation. The operating environment of the TPX diagnostic windows is reviewed, thermal loads on the windows estimated, and cooling requirements for the windows considered. Applicable window-cooling technology from other fields is reviewed and its application to the TPX windows considered. Methods for TPX window thermal conditioning are recommended, with… more
Date: November 1, 1995
Creator: Merrigan, M. & Wurden, G. A.
Partner: UNT Libraries Government Documents Department
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Lower hybrid wave resonance cone detection via CO/sub 2/ laser scattering

Description: Lower hybrid waves are studied in the Princeton ACT-I steady-state toroidal plasma device using a radially scanning CO/sub 2/ laser scattering system with both amplitude and phase sensitive detection techniques. Clearly defined resonance cones launched from external electrostatic antennas are seen to disappear as the plasma density is raised. Scaling of LHW laser signal with RF power in the presence of resonance cones shows nonlinearities associated with RF induced changes in the effective lase… more
Date: April 1, 1984
Creator: Wurden, G. A.; Wong, K. L. & Ono, M.
Partner: UNT Libraries Government Documents Department
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Status and Plans for the National Spherical Torus Experimental Research Facility

Description: An overview of the research capabilities and the future plans on the MA-class National Spherical Torus Experiment (NSTX) at Princeton is presented. NSTX research is exploring the scientific benefits of modifying the field line structure from that in more conventional aspect ratio devices, such as the tokamak. The relevant scientific issues pursued on NSTX include energy confinement, MHD stability at high beta, non-inductive sustainment, solenoid-free start-up, and power and particle handling. I… more
Date: July 27, 2005
Creator: Columbia University
Partner: UNT Libraries Government Documents Department
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High Performance Plasmas on the National Spherical Torus Experiment

Description: The National Spherical Torus Experiment (NSTX) has produced toroidal plasmas at low aspect ratio (A = R/a = 0.86 m/0.68 m approximately equal to 1.3, where R is the major radius and a is the minor radius of the torus) with plasma currents of 1.4 MA. The rapid development of the machine has led to very exciting physics results during the first full year of physics operation. Pulse lengths in excess of 0.5 sec have been obtained with inductive current drive. Up to 4 MW of High Harmonic Fast Wave … more
Date: July 10, 2001
Creator: Gates, D. A.; Bell, M. G.; Bell, R. E.; Bialek, J.; Bigelow, T.; Bitter, M. et al.
Partner: UNT Libraries Government Documents Department
open access

Stability and Confinement Properties of Auxiliary Heated NSTX Discharges

Description: 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''), ele… more
Date: July 5, 2001
Creator: Menard, J. E.; Bell, R. E.; Bourdelle, C.; Darrow, D. S.; Fredrickson, E. D.; Gates, D. A. et al.
Partner: UNT Libraries Government Documents Department
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