Session BO4: NSTX and Spherical Torus

9:30 AM–12:30 PM, Monday, November 14, 2011
Room: Ballroom E

Chair: Ted Biewer, Oak Ridge National Laboratory

Abstract ID: BAPS.2011.DPP.BO4.2

Abstract: BO4.00002 : Measurements of low-wavenumber turbulence in NSTX H-mode plasmas

9:42 AM–9:54 AM

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Authors:

  David R. Smith
    (University of Wisconsin-Madison)

  R.J. Fonck
    (University of Wisconsin-Madison)

  G.R. McKee
    (University of Wisconsin-Madison)

  D.S. Thompson
    (University of Wisconsin-Madison)

  I.U. Uzun-Kaymak
    (University of Wisconsin-Madison)

New Beam Emission Spectroscopy (BES) measurements provide the first radially and poloidally-resolved measurements of low-k turbulence in a fusion-grade spherical torus plasma in the National Spherical Torus Experiment (NSTX). Measured broadband turbulence with k$_{\bot }\rho _{i}$ $\mathbin{\lower.3ex\hbox{$\buildrel<\over {\smash{\scriptstyle\sim}\vphantom{_x}}$}}$ 1 and frequencies up to 100 kHz is qualitatively similar to higher-field tokamak turbulence. Multi-point correlation analysis indicates poloidal and radial correlation lengths are on the order of 10 cm at r/a$\sim $0.85. The correlation lengths are larger than those in higher-field tokamaks, but consistent with a rho-star scaling of turbulence. In stationary H-mode phases, longer poloidal correlation lengths correlate with higher density, density gradient, and electron temperature, suggesting a connection to instability drive mechanisms. Eddy poloidal velocities are about 10 km/s, consistent with equilibrium E$\times $B dominated flow. Poloidal flow fluctuations from time-delay estimation calculations will be discussed. The measurements and calculations motivate the inclusion of low-k turbulence in transport models of spherical torus plasmas.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2011.DPP.BO4.2