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Absorption of ion Bernstein waves by impurity cyclotron harmonics

Description: This paper analyzes the damping of externally-launched ion Bernstein waves by absorption at the cyclotron harmonics of the impurity ions. The inclusion of the non-magnetic energy flux term reduces the damping rate by nearly two orders of magnitude from the previous calculation. Excessive impurity damping can be avoided by launching ion Bernstein waves at a frequency just below the second (or higher) cyclotron harmonic of hydrogen.
Date: May 1, 1982
Creator: Ono, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Effect of low-frequency density fluctuations on ion-cyclotron waves

Description: Scattering of waves in the ion cyclotron range of frequencies by low-frequency fluctuations is analyzed in the weak turbulence approximation. Finite-ion-Larmor radius, multi-ion-species, ion-drift-motion, and electromagnetic terms are included in the wave kinetic equation. Conditions for significant scattering have been identified for the fast wave as well as for externally launched ion Bernstein waves. Implications for ICRF heating in tokamak plasmas are discussed.
Date: October 1, 1981
Creator: Ono, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Plasma heating by externally launched ion Bernstein waves

Description: Externally launched ion Bernstein waves are shown to provide highly effective means for heating reactor plasmas. In a high density plasma (n/sub 0/ greater than or equal to 10/sup 14/cm/sup -3/), an ion Bernstein wave with a parallel index of refraction n/sub parallel/ = O (1) is mode-transformed into a high-density ion Bernstein wave with electron Landau damping several orders of magnitude smaller than that of the original ion Bernstein wave. Because of this reduced damping, an externally laun… more
Date: October 1, 1979
Creator: Ono, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Cold electrostatic ion cyclotron waves and ion--ion hybrid resonances

Description: By utilizing a singly phased external ring structure, the existence of the cold low frequency resonance cone is verified for ..omega.. < ..cap omega../sub i/ and ..omega../k/sub parallel parallel/ > V/sub Te/. Then with a slow wave structure, the dispersion relations of the cold electrostatic ion cyclotron waves are measured in both single and two-ion-species plasmas. In a two-ion-species plasma, a resonance near the ion-ion hybrid frequency is observed.
Date: December 1, 1978
Creator: Ono, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Characteristics of ion Bernstein wave heating in JIPPT-II-U tokamak

Description: Using a transport code combined with an ion Bernstein wave tokamak ray tracing code, a modelling code for the ion Bernstein wave heating has been developed. Using this code, the ion Bernstein wave heating experiment on the JIPPT-II-U tokamak has been analyzed. It is assumed that the resonance layer is formed by the third harmonic of deuterium-like ions, such as fully ionized carbon, and oxygen ions near the plasma center. For wave absorption mechanisms, electron Landau damping, ion cyclotron ha… more
Date: November 1, 1985
Creator: Okamoto, M. & Ono, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Externally launched ion Berstein wave in the ACT-1 toroidal device

Description: In a hydrogen plasma (T/sub e/ = 2.5 eV, T/sub i/ = 1.5 eV), excitation of ion Bernstein waves by an externally placed electrostatic antenna has been investigated for ..omega.. approx. = 2 ..cap omega../sub i/. Mode transformation of the electron plasma wave at ..omega.. approx. = ..omega../sub pi/ without observable reflection was observed, followed by strong excitation of the ion Bernstein wave. Detailed measurements of k/sub perpendicular to/(..omega..,k/sub parallel/) and of the wave packet… more
Date: June 1, 1980
Creator: Ono, M. & Wong, K. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Viscous current drive

Description: It is suggested that electron viscosity associated with magnetic turbulence be used to control the current profile or to drive steady-state current in a tokamak. Due to the strongly asymmetric character of the onset condition for an instability such as the double-tearing mode, rapid radial penetration will occur only for properly directed incremental current. This penetration can be modelled by adding a new term to Ohm's law, one which represents the mean-field behavior of the instability-assoc… more
Date: April 1, 1985
Creator: Stix, T.H. & Ono, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Effects of ion cyclotron harmonic damping on current drive in the lower hybrid frequency range

Description: We investigate the ion cyclotron harmonic damping effects on slow and fast waves in the lower hybrid frequency range for tokamak reactor parameters. Inclusion of the higher order terms in the hot plasma dielectric tensor introduces ion cyclotron harmonic damping; these terms also contribute to the real part of the dispersion relation and affect the wave trajectories. However, wave absorption by 15 keV deuterium and tritium ions can be avoided by choosing the slow wave frequency above the lower … more
Date: November 1, 1983
Creator: Wong, K. L. & Ono, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Radio-frequency wave trajectories for current drive in tokamak reactors

Description: Detailed ray tracing calculations were carried out for three modes of waveguide-launched radio-frequency waves for tokamak reactor parameters to evaluate their applicability for steady state current drive. The merits and demerits of each mode are discussed.
Date: December 1, 1982
Creator: Wong, K. L. & Ono, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Non-resonant parametric decay of lower-hybrid waves in the ACT-1 toroidal device

Description: Non-resonant parametric decay of lower-hybrid waves, observed in a number of high-power tokamak rf heating experiments, is positively identified as a decay into ion-cyclotron quasi-modes. The decay-wave spectrum, wavelength and amplitude profile are measured inside a toroidal plasma with pump frequency f/sub 0/ approx. 3.5 f/sub ..pi../ approx. 25 f/sub ci/.
Date: February 1, 1981
Creator: Wong, K. L. & Ono, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Ion Bernstein wave heating on the Compact Ignition Tokamak (CIT)

Description: In the present plan, CIT is to be heated by power in the ion cyclotron range of frequencies (ICRF), and electron cyclotron heating (ECH) may be used if suitable rf sources can be developed. We consider the option of ion Bernstein wave heating (IBWH). The key points are that a simple vacuum waveguide launcher can be well- removed from high fluxes of heat and particles and that the development of a suitable source is straightforward. A practical point is that an IBWH waveguide launcher, including… more
Date: February 1, 1989
Creator: Ignat, D. W. & Ono, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Parametric excitation of ion Bernstein waves by a fast wave antenna in the ion cyclotron frequency range

Description: Parametric excitation of ion Bernstein waves is observed with an ICRF fast wave induction loop antenna in the ion cyclotron frequency range (..omega../sub o/ approx. 2..cap omega../sub i/ - 4..cap omega../sub i/). Important features of the decay process are investigated and discussed.
Date: November 1, 1983
Creator: Skiff, F.; Ono, M. & Wong, K. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Boxcar photography

Description: A simple, inexpensive diagnostic has been developed for time-resolved imaging of repetitive self-luminescent phenomena. An electro-optic birefringent ceramic shutter is employed to perform photographic sampling and yields time resolution of 100 ..mu..sec. Methods of image enhancement in the presence of background light from a finite-contrast shutter are discussed. The system has been applied to the study of plasma evolution in the CDX device. 21 refs., 4 figs.
Date: July 1, 1987
Creator: Greene, G. J.; Cutsogeorge, G. & Ono, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Echo phenomenon associated with lower-hybrid-wave launching

Description: Lower hybrid waves at two different frequencies f/sub 1/ and f/sub 2/ are launched simultaneously from two localized antennas, and a third wave is observed to arise near the plasma edge at the frequency f = f/sub 2/ - f/sub 1/. This phenomenon can be explained by an echo effect near the plasma surface.
Date: June 1, 1983
Creator: Wong, K. L.; Skiff, F. & Ono, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Anomalous electron diffusion across a magnetic field in a beam-plasma system

Description: The diffusion of electrons across a magnetic field in the presence of a beam-plasma instability has been studied by means of two-dimensional numerical simulations. It is found that the beam electrons can diffuse much faster across the magnetic field than the thermal electrons. This can be explained by the fact that the electrons in the beam are in resonance with the waves excited by the beam-plasma instability so that they experience a nearly dc electric field, causing large cE x B/B/sup 2/ exc… more
Date: October 1, 1987
Creator: Okuda, H.; Ono, M. & Armstrong, R.J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Observation of the backward electrostatic ion cyclotron wave

Description: The backward branch of the electrostatic ion cyclotron wave has been observed, we believe, for the first time. The wave, which was driven by a phased antenna structure inserted in a neon plasma, exists in the parameter ranges 2T/sub i//m/sub i/ << (..omega../k/sub parallel/)/sup 2/ << 2T/sub e//m/sub e/, n..cap omega../sub i/ < ..omega.. < (n+1)..cap omega../sub i/, T/sub e/ greater than or equal to T/sub i/, and ..omega../sub pi/ > ..cap omega../sub i/. Double-tip probe interferomety data agre… more
Date: December 1, 1984
Creator: Goree, J.; Ono, M. & Wong, K. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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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.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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NSTX: Facility/Research Highlights and Near Term Facility Plans

Description: The National Spherical Torus Experiment (NSTX) is a collaborative mega-ampere-class spherical torus research facility with high power heating and current drive systems and the state-of-the-art comprehensive diagnostics. For the 2008 experimental campaign, the high harmonic fast wave (HHFW) heating efficiency in deuterium improved significantly with lithium evaporation and produced a record central Te of 5 keV. The HHFW heating of NBI-heated discharges was also demonstrated for the first time wi… more
Date: November 19, 2008
Creator: Ono, M.
Item Type: Refine your search to only Article
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.
Item Type: Refine your search to only Report
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.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Parametric decay into ion cyclotron waves and drift waves in multi-ion-species plasma

Description: Parametric decay processes near the ion cyclotron frequency are investigated experimentally and theoretically in multi-ion species plasmas. The relevant theoretical dispersion relation of the parametric coupling is derived, including the ion drift motion. Experiment data obtained in the Princeton L-4 device verifies these theoretical predictions in some detail. In a helium-neon plasma, the relative ion drift motion excites electrostatic ion cyclotron waves (the kinetic ion-ion hybrid mode) when… more
Date: October 1, 1979
Creator: Ono, M.; Porkolab, M. & Chang, R. P. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Harmonic generation and parametric decay in the ion cyclotron frequency range

Description: Harmonic generation and parametric decay are examined in a toroidal ACT-I plasma using electrostatic plate antennas. The harmonic generation, which is consistent with sheath rectification, is sufficiently strong that the nonlinearly generated harmonic modes themselves decay parametrically. Resonant and nonresonant parametric decay of the second harmonic are observed and compared with uniform pump theory. Resonant decay of lower hybrid waves into lower hybrid waves and slow ion cyclotron waves i… more
Date: June 1, 1984
Creator: Skiff, F. N.; Wong, K. L. & Ono, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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