TITLE

Extraction of large-scale coherent structure from plasma turbulence using rake probe and wavelet analysis in a tokamak

AUTHOR(S)
Xu, G. S.; Wan, B. N.; Zhang, W.
PUB. DATE
June 2006
SOURCE
Review of Scientific Instruments;Jun2006, Vol. 77 Issue 6, p063505
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
In fusion plasmas, intermittently occurring large-scale coherent structures in electrostatic turbulence sometimes contribute more than 50% of total transport, so the investigation on these coherent structures is important for understanding plasma confinement. New experimental techniques are required to extract these coherent structures from fluctuating signals. In this work a 12-tip poloidal rake probe was used on the HT-7 superconducting tokamak to measure plasma turbulence in the plasma edge region. Several signal analysis methods based on a biorthogonal wavelet were developed and applied to the probe data. Since the structure of the selected wavelet is every similar to that of the turbulence wave packet, information about large-scale coherent structures can be selectively extracted from the ambient turbulence. The spatiotemporal patterns of the large-scale coherent structures were reconstructed using the selected wavelets as well as those of small-scale details. These wavelet-based techniques can be applied to all kinds of plasma fluctuation diagnostics, so they possibly present a new opportunity for uncovering the mechanism underlying plasma turbulent transport.
ACCESSION #
22567749

 

Related Articles

  • Point-to-point analysis of MSE data for plasma diagnostics and control. Giannella, R.; Hawkes, N. C.; Jayakumar, R.; Makowski, M.; Zabeo, L. // Review of Scientific Instruments;Oct2004 Part I & II, Vol. 75 Issue 10, p4247 

    A local analysis technique is presented for the analysis of MSE data to deduce the safety factor q in tokamak discharges. The technique preserves as much as possible the individuality of every single measure by a simple rule of translation of magnetic field pitch angle measurements into...

  • The origin of convective structures in the scrape-off layer of linear magnetic fusion devices investigated by fast imaging. Antar, G. Y.; Yu, J. H.; Tynan, G. // Physics of Plasmas;Feb2007, Vol. 14 Issue 2, p022702 

    A fast imaging camera is used to unveil the spatio-temporal properties of radially convective events in the CSDX linear plasma device [M. J. Burin et al., Phys. Plasmas, 12, 052320 (2005)]. The exposure time is set to 1 μs and the time between frames to 10 μs. The time series from a...

  • Low to high confinement transition theory of finite-beta drift-wave driven shear flow and its comparison with data from DIII-D. Guzdar, P.N.; Kleva, R.G.; Groebner, R.J.; Gohil, P. // Physics of Plasmas;Mar2004, Vol. 11 Issue 3, p1109 

    Shear flow stabilization of edge turbulence in tokamaks has been the accepted paradigm for the improvement in confinement observed in high (H) confinement mode plasmas. Results on the generation of zonal flow and fields in finite β plasmas are presented. This theory yields a criterion for...

  • Monte Carlo Simulation of Initial Breakdown Phase for Magnetised Toroidal ICRF Discharges. Tripský, M.; Wauters, T.; Lyssoivan, A.; Koch, R.; Bobkov, V.; Vervier, M.; Van Oost, G.; Van Schoor, M. // AIP Conference Proceedings;2014, Vol. 1580, p334 

    The radio-frequency (RF) plasma production technique in the ion cyclotron range of frequency (ICRF) attracts growing attention among fusion experts because of its high potential for solving several basic problems of reactor-oriented superconducting fusion machines, such as ICRF wall conditioning...

  • Measurement of plasma rotation velocities with electrode biasing in the Saskatchewan... Xiao, C.; Jain, K.K.; Zhang, W.; Hirose, A. // Physics of Plasmas;Jul94, Vol. 1 Issue 7, p2291 

    Presents the physical mechanism responsible for improved confinement, radial profile of the electric field, density and plasma rotation velocity in the Saskatchewan Torus-Modified (STOR-M) tokamak. Description of the STOR-M tokamak; Time evolution and edge profile of various plasma parameters.

  • A Change in the Characteristics of Fluctuations of the Boundary Plasma Parameters in the FT-2 Tokamak upon Transition to the Improved Plasma Conf inement Regime. Vekshina, E. O.; Goncharov, P. R.; Shatalin, S. V.; Budnikov, V. N.; Esipov, L. A.; Its, E. R.; Lashkul, S. I. // Technical Physics Letters;Oct2000, Vol. 26 Issue 10, p873 

    Processes in the boundary (near-wall) plasma of the FT-2 tokamak upon transition into an improved plasma confinement regime under the action of lower hybrid heating were studied by a refined plasma diagnostic method using multielectrode Langmuir probes. The experimental data show evidence of...

  • Deuterium-tritium plasmas in novel regimes in the Tokamak Fusion Test Reactor. Bell, M.G.; Batha, S.; Beer, M.; Bell, R.E.; Below, A.; Berk, H.; Bernabei, S.; Bitter, M.; Breizman, B.; Bretz, N.L.; Budny, R.; Bush, C.E.; Callen, J.; Cauffman, S.; Chang, C.S.; Chang, Z.; Cheng, C.Z.; Darrow, D.S. // Physics of Plasmas;May97, Vol. 4 Issue 5, p1714 

    Investigates the physics of deuterium-tritium plasmas (D-T) in novel regimes in the Tokamak Fusion Test Reactor. Novel regimes of improved tokamak confinement in D-T plasmas; Modification of the plasma-limiter interaction through in situ deposition of lithium; Transitions to enhanced...

  • Deuterium-tritium high confinement (H-mode) studies in the Tokamak Fusion Test Reactor. Bush, C.E.; Sabbagh, S.A.; Zweben, S.J.; Bell, R.E.; Synakowski, E.J.; Taylor, G.; Batha, S.; Bell, M.; Bitter, M.; Bretz, N.L.; Budny, R.; Chang, Z.; Darrow, D.S.; Efthimion, P.C.; Ernst, D.; Fredrickson, E.; Hanson, G.R.; Johnson, L.C.; Kesner, J. // Physics of Plasmas;Jun95, Vol. 2 Issue 6, p2366 

    Discusses the creation of deuterium-tritium (DT)-fueled, high confinement plasmas in a circular limiter configuration in the Tokamak Fusion Test Reactor. Isotope effects due to the presence of helium; Edge localized magnetohydrodynamic modes; Threshold power for the H-mode transition.

  • Improved particle control for high integrated plasma performance in Japan Atomic Energy Research Institute Tokamak-60 Upgrade. Takenaga, H. // Physics of Plasmas;May2001, Vol. 8 Issue 5, p2217 

    Pellet fueling and impurity transport have been investigated in high poloidal-beta (β[sub p]) and reversed shear (RS) plasmas. It is observed that pellet injection from the high-field side at the top is more effective for density increase in the neutral-beam-heated plasma compared with pellet...

Share

Read the Article

Courtesy of THE LIBRARY OF VIRGINIA

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics