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Leakage of runaway electrons from tokamaks

Description: Runaway electron orbits are calculated in a tokamak magnetic field. It is shown that these electrons tend to drift towards a larger major radius with a velocity v Vector/sub R/ = qcE/B/sub 0/ R. This effect may be relevant to some recent experimental observations in tokamaks.
Date: February 1, 1982
Creator: Wong, K. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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An alpha particle diagnostic based on measurements of lower hybrid wave fluctuations

Description: It is shown that the one-dimensional alpha particle velocity distribution function can be determined from the fluctuation- dissipation theorem based on measurements of lower hybrid wave fluctuations in an equilibrium plasma. This method uses collective Thomson scattering data with large signal-to-noise ratio, but it is applicable only when the alpha particles have an isotropic velocity distribution. 16 refs., 1 fig.
Date: July 1, 1989
Creator: Wong, K. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Experimental observation of current generation by unidirectional electron plasma waves

Description: A slow wave structure was used to launch electron plasma waves traveling preferentially in one direction. The current generated by the waves was observed. The magnitude of the current can be estimated from momentum conservation in the wave-particle interaction process.
Date: August 1, 1978
Creator: Wong, K. L.
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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Assessment of eddy current effects on compression experiments in the TFTR tokamak

Description: The eddy current induced on the TFTR vacuum vessel during compression experiments is estimated based on a cylindrical model. It produces an error magnetic field that generates magnetic islands at the rational magnetic surfaces. The widths of these islands are calculated and found to have some effect on electron energy confinement. However, resistive MHD simulation results indicate that the island formation process can be slowed down by plasma rotation.
Date: May 1, 1986
Creator: Wong, K. L. & Park, W.
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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Excitation of drift waves by lower hybrid waves

Description: The excitation of low frequency oscillations by lower hybrid waves at electric fields lower than the thresholds of other parametric decay processes is reported. The frequencies and wavelengths of these oscillations agree with the collisional drift wave dispersion relation. The excitation is localized deep inside the plasma density gradient. The excited drift waves change the density profile and the lower hybrid wave trajectory.
Date: March 1, 1977
Creator: Wong, K. L. & Bellan, P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Suppression of lower hybrid wave coupling due to the ponderomotive force

Description: The coupling efficiency from a slow-wave structure to lower hybrid waves is investigated experimentally. At moderate electric field strengths large edge density changes are observed. Wave trajectory modifications and departure from linear coupling are observed consistent with these changes and in good agreement with a simple nonlinear theory that includes the ponderomotive force.
Date: April 1, 1980
Creator: Wilson, J. R. & Wong, K. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Neoclassical diffusion of heavy impurities in a rotating tokamak plasma

Description: Particle orbits in a rotating tokamak plasma are calculated from the equation of motion in the frame that rotates with the plasma. It is found that heavy particles in a rotating plasma can drift away from magnetic surfaces significantly faster, resulting in a diffusion coefficient much larger than that for a stationary plasma. Particle simulation is carried out and the results offer a qualitative explanation for some experimental data from the Tokamak Test Reactor (TFTR). 13 refs., 2 figs.
Date: August 1, 1987
Creator: Wong, K. L. & Cheng, C. Z.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Non-linear converging resonance cones

Description: The trajectory modification of a focused resonance cone due to ponderomotive force effects was investigated in the Princeton L-3 device. A single ring pulsed at f/sub 0/ approx. 50 MHZ (f/sub 1h/ much less than f/sub 0/ much less than f/sub pe/, f/sub ce/) launches a converging resonance cone in an argon plasma with n/sub e/ approx. 10/sup 9/ to 10/sup 10/, B approx. 400G to 1kG, T/sub e/ approx. 1 to 3 eV. At high driving power the strong localized electric fields modify the density through th… more
Date: July 1, 1979
Creator: Wilson, J. R. & Wong, K. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Orbit effects on impurity transport in a rotating tokamak plasma

Description: Particle orbits in a rotating tokamak plasma are calculated from the equation of motion in the frame that rotates with the plasma. It is found that heavy particles in a rotating plasma can drift away from magnetic surfaces significantly faster with a higher bounce frequency, resulting in a diffusion coefficient much larger than that for a stationary plasma. Particle orbits near the surface of a rotating tokamak are also analyzed. Orbit effects indicate that more impurities can penetrate into a … more
Date: May 1, 1988
Creator: Wong, K. L. & Cheng, C. Z.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Effect of density fluctuations of lower hybrid resonance cone propagation

Description: Experimental measurements show that coherent, azimuthal density fluctuations (1) focus lower hybrid resonance cones azimuthally, and (2) modulate the radial location of the resonance cones. A simple theory based on wave refraction is presented; this theory is in good agreement with the experimental observations. The theory is extended to give a physical description of wave propagation through turbulent, isotropic (perpendicular to B) noise such as has been observed in tokamaks; it is found that… more
Date: April 1, 1977
Creator: Bellan, P. M. & Wong, K. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Resonant decay of finite extent cold electron plasma waves

Description: The parametric decay of a finite extent cold electron plasma wave (slow wave) was studied experimentally. Using a frequency of ..omega../sub 0/ approximately greater than 10..omega../sub pi/, it was found that the decay waves propagated along the pump wave rather than in the Vector E/sub 0/ x Vector B direction. This is in agreement with the recent theoretical predictions of finite length stabilization.
Date: February 1, 1978
Creator: Wong, K. L.; Bellan, P. & Porkolab, 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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Summary and review of hydrogen theoretical equation-of-state models at Lawrence Livermore Laboratory

Description: A review and analysis of the hydrogen equations of state (EOS) at use at Lawrence Livermore Laboratory (LLL) are presented. Careful comparisons to experimental data and among EOS's are performed and evaluated. The new LLL hydrogen EOS (EOS95) and its representations produce the best agreement with experimental data and hydrodynamic simulation studies.
Date: February 1, 1980
Creator: Graboske, H. C. Jr. & Wong, K. L.
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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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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Vacuum vessel eddy current modeling for TFTR adiabatic compression experiments

Description: A relatively simple current filament model of the TFTR vacuum vessel is described. It is used to estimate the three-dimensional structure of magnetic field perturbations in the vicinity of the plasma that arise from vacuum vessel eddy currents induced during adiabatic compression. Eddy currents are calculated self-consistently with the plasma motion. The Shafranov formula and adiabatic scaling laws are used to model the plasma. Although the specific application is to TFTR, the present model is … more
Date: July 1, 1985
Creator: DeLucia, J.; Bell, 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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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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