A5049489470- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Ionosphere and magnetosphere dynamics
- Laser-induced spectroscopy and plasma
- Laser-Plasma Interactions and Diagnostics
- Particle accelerators and beam dynamics
- Atomic and Molecular Physics
- Solar and Space Plasma Dynamics
- Electrohydrodynamics and Fluid Dynamics
- Fusion materials and technologies
- Superconducting Materials and Applications
- Mass Spectrometry Techniques and Applications
- Plasma Applications and Diagnostics
- Laser Design and Applications
- Dust and Plasma Wave Phenomena
- Spectroscopy and Laser Applications
- Gas Dynamics and Kinetic Theory
- Vacuum and Plasma Arcs
- Atomic and Subatomic Physics Research
- Metal and Thin Film Mechanics
- Advanced Chemical Physics Studies
- Silicon and Solar Cell Technologies
- Nuclear reactor physics and engineering
- Laser-Matter Interactions and Applications
- Gyrotron and Vacuum Electronics Research
The University of Texas at Austin
2010-2021
Sandia National Laboratories
2011-2021
Lawrence Livermore National Laboratory
2021
National Technical Information Service
2011
Office of Scientific and Technical Information
2011
Fusion Academy
1988-2009
Fusion (United States)
1995-2009
University of Michigan–Ann Arbor
2009
Marshall Space Flight Center
2009
University of Alabama in Huntsville
2009
A reversal has been observed in the mean phase velocity of turbulent fluctuations edge plasma TEXT tokamak. The observations can be described by a model which wave lab frame is dominated nonuniform Er×B and gradient driven drift. measurements also exhibit localized instability occurs region maximum shear.
The results of a study the statistical space/time properties turbulence observed in edge region Pretext tokamak are reported. A local estimate wavenumber frequency spectra S(κ,ω) for poloidal (ky)an d toroidal (kz) wavenumbers is determined range 0.5 cm−1 < k 7.5 cm−1, both potential and density fluctuations obtained from spatially fixed Langmuir probe pairs. S(ky, ω) aredominated by low frequencies ( 200 kHz) small (< 3 cm−1) appear broadened about an approximately linear dispersion...
A quantitative comparison of the fluctuation-induced energy flux with total has been made in edge region TEXT tokamak using fluctuation measurements from Langmuir, heavy-ion-beam, and magnetic probes. At all but lowest densities convected due to electrostatic fluctuations dominates losses caused by plasma transport. Energy loss through is insignificant region.
The nonlinear coupling coefficient and the energy transfer associated with three-wave interactions are computed from measured data of turbulent edge plasma Texas Experimental Tokamak(TEXT) [Nucl. Technol. Fusion 1, 479 (1981)]. results show presence interactions. cause to cascade away dominant waves spectrum primarily toward lower, but also higher frequencies. obtained a new digital spectral analysis technique based on estimation higher-order cumulants. method is discussed tested simulation...
This article reviews digital spectral analysis techniques that yield experimental insight into plasma turbulence. Methods to quantify the statistical properties of fluctuations and measure particle heat flux caused by electrostatic are presented. Furthermore, study nonlinear coupling process turbulence redistribution energy among different modes discussed. The impact on fusion research is demonstrated with results collected Langmuir probes, heavy-ion beam laser scattering in tokamak TEXT....
Externally applied magnetic fields are used on the Texas Experimental Tokamak (TEXT) to study possibility of controlling particle, impurity and heat fluxes at plasma edge. Fields with toroidal mode number n = 2 or 3 multiple poloidal numbers m (dominantly 7) used, a poloidally toroidally averaged ratio radial field components 〈|br/Bø〉 ≅0. 1%. Calculations show that it is possible produce mixed islands stochastic regions edge (r/a ≥ 0.8) without affecting interior. The expected structure...
The spectra, magnitude and spatial distribution of low-frequency (ω ≪ ωci) density fluctuation have been measured by two independent experimental methods in the edge plasma TEXT tokamak. Good agreement between far-infrared laser scattering Langmuir probe measurements has achieved strengths each technique are evaluated. probes used to directly determine particle flux induced fluctuations (Γ ∝ ⟨ñ×B⟩) collective Thomson permits an extension these observations interior. Results presented for...
Particle transport in an ohmically heated tokamak plasma was investigated the Texas Experimental Tokamak (TEXT). Spectroscopic measurements of electron source were used with density to derive particle confinement times from continuity equation. Scalings developed for time density, current, toroidal field, and positioning. Simultaneous measurement electrostatic fluctuations Langmuir probes may suggest a correlation between edge TEXT turbulence. In addition, two major features isolated. First,...
Absolute transition probabilities of the stronger Xe I and II lines between 3800 8400 \AA{} are measured in emission. State variables shock-tube plasmas determined by several independent methods. Accuracies for 25 neutral 128 ionic $A$ values estimated to be (22-50)%. Experimental line strengths compared with theoretical predictions. The results examined conformity quantum-mechanical sum rules lifetime data from literature.
A new scheme to extend the triple Langmuir probe technique for measurement of electron temperature fluctuations and fluctuation-driven transport has been developed. The extension is aimed at reducing phase delay error introduced by finite tip separations in standard triple-probe method. modified provides a more reliable proper interpretation density potential from data. New results on have obtained Phaedrus-T TEXT-U tokamaks.
Widths and shifts of Stark-broadened, neutral atomic lines have been measured using a gas-driven shock tube. Stark widths are given for 35 isolated or blended multiplets carbon, oxygen, neon, silicon, phosphorus, sulphur, chlorine, argon. Shift data presented 15 these features. Electron densities determined from both ${\mathrm{H}}_{\ensuremath{\beta}}$ profiles pressure-temperature data. Estimated accuracy is 8-25% the 15-40% shifts. Results compared with theoretical predictions other measurements.
Using the technique first described by Robinson and Rusbridge [Plasma Phys. 11, 73 (1969)] electron temperature fluctuations have been measured in scrape-off layer of TEXT tokamak [Nucl. Technol. Fusion 1, 479 (1981)] to be T̃e/Te ≂0.4ñe/ne. Particle energy transport were estimated from 〈ñe Ẽθ〉 〈T̃e correlations. The fluctuation-driven particle was consistent with earlier measurements global confinement. A high correlation electric field a low but positive between density observed.
High-powered electric propulsion thrusters utilizing a magnetized plasma require that exhaust detach from the applied magnetic field in order to produce thrust. This paper presents experimental results demonstrating sufficiently energetic and flowing can indeed nozzle. Microwave interferometer probe measurements provide plume density, electron temperature, ion flux nozzle region. Measurements of show low-beta which follows lines until kinetic pressure reaches high-beta expanding...
Experimental profiles, theoretical Stark-broadened line and the asymptotic wing approximation of hydrogen Balmer lines ${\mathrm{H}}_{6}$-${\mathrm{H}}_{12}$ are compared at an electron density 1.2\ifmmode\times\else\texttimes\fi{}${10}^{13}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ a temperature 1850\ifmmode^\circ\else\textdegree\fi{}K. Theoretical profiles calculated using impact for electrons quasistatic ions. The half-widths $\frac{1}{10}$ widths agree to within mutual tolerances, over-all...
Measured thermodynamic conditions behind reflected shocks in a gas-driven diaphragm shock tube are compared to Rankine-Hugoniot predictions. Pressures of the shock-heated neon, which contained small concentrations spectroscopic additives, were measured by quartz transducers. Temperatures (9000-13 000°K) simultaneously spectroscopically line reversal and absolute emission techniques, while electron densities broadening Balmer Hβ. The temperature has been an accuracy ±1.5%, have determined...
Helicon discharges produce plasmas with a density gradient across the confining magnetic field. Such can create radial potential well for nonaxisymmetric whistlers, allowing radially localized helicon (RLH) waves. This work presents new evidence that RLH waves play significant role in plasma sources. An experimentally measured profile an argon discharge is used to calculate rf field structure. The calculations are performed using two–dimensional solver under assumption axisymmetric. It found...
Links between turbulent fluctuations and transport processes in tokamaks, particularly TEXT, are discussed. In the plasma edge probes allow detailed measurements of quantities required to directly determine fluctuation driven fluxes. The total flux particles is well explained by measured electrostatic flux. However, a satisfactory model explain origin has not been identified. responsible for determining electron heat less clear. confinement region experimental observations restricted density...
The Texas turbulent torus is a device to turbulently heat plasma and maintain the heating current confine in tokamak configuration. Initial results show penetration of at densities up 1013 cm−3, electrons temperatures order 10 keV, fraction ions several keV.
Absolute transition probabilities in the visible and near-infrared spectra of FI, ClI, ClII, BrI have been measured using a gas-driven shock tube. Thermodynamic conditions source were overdetermined by line intensity, pressure, electron-density data. $A$ values obtained spectroscopic techniques which reduced errors due to residual uncertainties conditions. Measured are compared with theoretical calculations other experimental values.
Measurements of the radio frequency (rf) field structure, plasma density, and electron temperature are presented for a 1 kW argon helicon source. The measured profiles change considerably when equilibrium magnetic is reversed. rf fields identified as radially localized waves, which propagate in axial direction. structure compared to results two-dimensional cold full-wave simulations density profiles. Electron collision adjusted match simulated resulting anomalously high, attributed...
Two techniques are applied and the results compared in edge plasma of TEXT-U to estimate temperature fluctuations. The first technique fits measured current fluctuations from a double probe as function bias with several fitting functions provide density, but no spectral information. second method uses triple-probe measure temperature, floating potential time. two agreement within estimated error limits find T̃/T≊0.4–0.5 ñ/n both scrape-off layer main body plasma.
We present the first direct observation of structure a driven global Alfvén eigenmode in tokamak plasma using CO2 laser interferometry.Received 30 April 1984DOI:https://doi.org/10.1103/PhysRevLett.53.1743©1984 American Physical Society
Strengths and Stark-effect widths of the Sni Snii lines prominent between 3200 7900 \AA{} are measured with a spectroscopic shock tube. Absolute strengths 17 ionic obtained estimated (22-50)% accuracy conform to appropriate quantum-mechanical sum rules. Relative transition probabilities for nine neutral tin lines, normalized radiative-lifetime data, compared other experiments theoretical predictions. Parameters broadening over range plasma electron densities. Broadening data [with accuracies...