Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 2026-2028 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present ion temperature profiles for the outer half of the TEXT plasma using the Doppler broadened far line wings of the Hα line profile. The technique depends on the assumption that the hydrogen neutrals have equilibrated with the ions through charge-exchange collisions. Data reduction depends upon going far enough out on the line wing that the remaining intensity in the profile originates in the hottest portion of the line of sight, thus removing the need for an inversion procedure. A scanning Fabry–Perot interferometer is used to measure the line profiles because of its superior instrumental profile. This technique and its results will be compared with the charge-exchange technique and impurity Doppler broadening results. The application to ion temperature measurements using a diagnostic neutral beam will also be discussed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 1989-1991 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The objective of this paper is to describe the principles of digital complex demodulation, and to summarize its advantages with respect to rapid time response and insensitivity to noise. These advantages are demonstrated by application to interferometry data collected on the Texas experimental tokamak (TEXT).
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1494-1496 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Neutral density profiles are measured in the outer third of the plasma of the TEXT tokamak in conjunction with ion temperature measurements using the far line wings of a Hα profile. The advantage of this technique is that it does not require a radial inversion of the data to obtain a measure of the local neutral density. The ion temperature profiles are compared with the results from a neutral particle analyzer, and the neutral profiles with the results of a numerical code which solves a system of coupled linear equations describing particle transport from a neutral source.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using active feedback, the turbulent fluctuation levels have been reduced by as much as a factor of 2 in the edge of the Texas Experimental Tokamak (TEXT) [K. W. Gentle, Nucl. Fusion Technol. 1, 479 (1981)]. A probe system was used to drive a suppressor wave in the TEXT limiter shadow. A decrease in the local turbulence-induced particle flux has been seen, but a global change in the particle transport at the present time has not been observed. By changing the phase shift and gain of the feedback network, the amplitude of the turbulence was increased by a factor of 10.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 5 (1998), S. 752-762 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experiments in the edge plasma of TEXT-U (the Texas Experimental Tokamak-Upgrade) [K. W. Gentle, Nucl. Technol. Fusion 1, 479 (1981)] have used a positively biased Langmuir probe in conjunction with two triple probes to examine the "wake" or disturbance in the plasma caused by the electron current collected by the driven probe. Spatial measurements of the disturbed volume have been made in the radial and poloidal directions at two points along the disturbed flux tube, at 12 meters and 28 meters away from the driven probe. Both non-time dependent and time-dependent experiments are used to determine the dispersion of the driven wave. A classical collisional two-fluid model of electron collection by a biased surface, which accounts for electric potential perturbations and the associated currents only, successfully predicts many of the qualitative features of the disturbance. The magnitudes of the collision rates, however, have to be increased beyond the best estimates in order to achieve quantitative agreement, indicating the possible involvement of anomalous cross-field current transport processes. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 4 (1997), S. 2928-2932 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Shear viscosity [η≡α×(mass density)×(diffusivity)] and parallel flow velocity [M∞×(Te+Ti)/mi] of tokamak edge plasma were simultaneously measured in the Texas Experimental Tokamak-Upgrade (TEXT-U) tokamak by using a "Visco-Mach" probe with the iteration method (VMPI) [K-S. Chung, Nucl. Fusion 34, 1213 (1994)]. The VMPI was composed of two Mach probes measuring two ratios of ion saturation current densities, with the small Mach probe located within the free presheath generated by the large Mach probe (LMP). Radial variations of the normalized shear viscosity, α, and parallel Mach number, M∞, for typical discharges were deduced from two measured ratios of ion saturation current densities, and plasma density from ion saturation currents by LMP. Here α varied from 0.7 to 1.3 with an estimated error of ±40%, and M∞ from 0 to 0.2 for 0〈r−rl〈4.5 cm, where rl=27 cm is the limiter radius. Also, α and M∞ increased with the radial direction, while cross-field diffusivity (D⊥) was approximately constant. Here D⊥ is obtained as ∼3DB, where a typical Bohm diffusivity (DB) is ∼1 m2/s. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 4586-4588 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A fast bolometer was used for direct measurements of parallel electron energy flux in the edge of the Texas Experimental Tokamak (TEXT-U) [K. W. Gentle, Nucl. Technol. Fusion 1, 479 (1981)]. The fluctuating component of the parallel electron energy flux, combined with a measurement of magnetic fluctuations, provides an upper limit to the perpendicular electron flux. This magnetically driven energy flux cannot account for the observed energy flux. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 3250-3261 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The low-frequency E×B turbulence driven by the shear in the mass flow velocity parallel to the magnetic field is studied using the fluid theory in a slab configuration with magnetic shear. Ion temperature gradient effects are taken into account. The eigenfunctions of the linear instability are asymmetric about the mode rational surfaces. Quasilinear Reynolds stress induced by such asymmetric fluctuations produces momentum and energy transport across the magnetic field. Analytic formulas for the parallel and perpendicular Reynolds stress, viscosity, and energy transport coefficients are given. Experimental observations of the parallel and poloidal plasma flows on the Texas Experimental Tokamak Upgrade (TEXT-U) are presented and compared with the theoretical models.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 2092-2097 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Recent experimental and theoretical results are combined to explore the energy dependence of runaway and suprathermal electron diffusion. It is shown that a quasilinear theory containing both magnetic and electrostatic E×B-driven radial transport is consistent with the available experimental data, and supports the notion that magnetic turbulence dominates runaway diffusion but electrostatic turbulence dominates thermal diffusion in the edge plasma of the Texas Experimental Tokamak (TEXT) [Nucl. Technol./Fusion 1, 479 (1981)]. These observations further expand the possibilities for employing runaway or suprathermal electrons as a diagnostic of the underlying transport mechanisms in a tokamak plasma.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 125-137 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Convenient mathematical models appropriate for simultaneously measuring the thermal and energetic electron diffusivities by their responses to internal disruptions are presented and compared to simultaneous soft and hard x-ray sawtooth data from the Texas Experimental Tokamak (TEXT) [Nucl. Technol./Fusion 1, 479 (1981)]. The eigenfunction expansion technique employed is first illustrated on a constant diffusivity, single sawtooth crash model that is unable to give a satisfactory fit to the TEXT soft x-ray data at disparate radii for an initial condition of a flattened temperature profile out to the mixing radius. A more sophisticated single crash model having a parabolic radial dependence for the thermal diffusivity and a flattened profile initial condition substantially improves the fit to the TEXT soft x-ray data. Simultaneous measurements of the sawtooth oscillations on the hard x-ray signal caused by runaway electrons hitting the limiter are interpreted to obtain a measure of the diffusivity of the energetic electrons in TEXT following the same crash used to measure the thermal diffusivity. A single sawtooth crash model is no longer adequate because the diffusivity of the energetic electrons may be substantially less than the thermal value. Therefore the eigenfunction expansion technique is extended to a periodic sawtooth crash model. Measurements of diffusivities far smaller than those that can be measured by a single crash model are possible and more than one value of diffusivity can fit the simultaneous TEXT hard x-ray data. The lower values of diffusivity could not have been obtained by a single crash model. Additional hard x-ray measurements having differing sawtooth periods are needed to remove the ambiguity. As more extensive hard x-ray data become available on TEXT, it may become possible to simultaneously and unambiguously measure the thermal and energetic electron diffusivities during the same crash.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...