Detection of zonal flow spectra in DIII-D by a dual-channel Doppler backscattering system

Schmitz, L.; Wang, G.; Hillesheim, J. C.; Rhodes, T. L.; Peebles, W. A.; White, A. E.; Zeng, L.; Carter, T. A.; Solomon, W.
October 2008
Review of Scientific Instruments;Oct2008, Vol. 79 Issue 10, p10F113
Academic Journal
Doppler backscattering (DBS) has been successfully used to measure the E×B flow velocity and local intermediate wavenumber density fluctuation levels in the DIII-D tokamak. Depending on the launch angle and the frequency of the probing beam, the signal backscattered from the plasma cut-off layer is sensitive to density fluctuations at a specific perpendicular wavenumber (1<=k⊥ρs<=4). Due to the localization and high time resolution for poloidal flow measurements, DBS is well suited to detect stationary and time-dependent shear flows [zonal flows (ZFs)]. We present a novel scheme to measure ZF spectra using a dual-channel DBS system capable of simultaneously probing two minor radii separated by a distance of 0.2 cm<Δr<3 cm. Frequency spectra of geodesic acoustic modes and low frequency ZFs (f<=10 kHz) have been obtained for 0.6


Related Articles

  • Shear flow reduction by the geodesic transfer mechanism in tokamak edge turbulence. Kendl, A.; Scott, B. D. // Physics of Plasmas;Jun2005, Vol. 12 Issue 6, p064506 

    The geodesic transfer mechanism in tokamak edge plasmas, which serves as an important saturation mechanism for the self-generation of zonal flows by E-cross-B turbulence, is analyzed and quantified. Modification of the geodesic curvature is shown to influence the transport reduction by...

  • Experimental investigation of geodesic acoustic mode spatial structure, intermittency, and interaction with turbulence in the DIII-D tokamak. Hillesheim, J. C.; Peebles, W. A.; Carter, T. A.; Schmitz, L.; Rhodes, T. L. // Physics of Plasmas;Feb2012, Vol. 19 Issue 2, p022301 

    Geodesic acoustic modes (GAMs) and zonal flows are nonlinearly driven, axisymmetric (m=0andn=0) E×B flows, which are thought to play an important role in establishing the saturated level of turbulence in tokamaks. Results are presented showing the GAM's observed spatial scales, temporal...

  • Fast reciprocating Langmuir probe for the DIII-D divertor Watkins, J. G.; Hunter, J.; Tafoya, B.; Ulrickson, M.; Watson, R. D.; Moyer, R. A.; Cuthbertson, J. W.; Gunner, G.; Lehmer, R.; Luong, P.; Hill, D. N.; Mascaro, M.; Robinson, J. I.; Snider, R.; Stambaugh, R. // Review of Scientific Instruments;Jan1997, Vol. 68 Issue 1, p373 

    Details how a reciprocating Langmuir probe was used to measure density and temperature profiles, ion flow, and potential fluctuation levels from the lower divertor floor up to the X point on the DIII-D Tokamak. Mechanical design of the probe; Probe tip design; Measurements of physical...

  • Operation of flush-mounted probes in the TdeV tokamak Gunn, J.P.; Boucher, C.; Desroches, D.; Robert, A. // Review of Scientific Instruments;Jan1997, Vol. 68 Issue 1, p404 

    Describes the installation of an array of 16 flush-mounted probes in the outboard divertor plate of the TdeV tokamak, giving a radial resolution of 3.3 millimeters at the plasma strike point. Analysis of the I-V characteristic of a flush-mounted probe; Effect of probe recession.

  • Heavy ion beam probe diagnostic system on JFT-2M. Ido, T.; Hamada, Y.; Nishizawa, A.; Kawasumi, Y.; Miura, Y.; Kamiya, K. // Review of Scientific Instruments;Jan1999, Vol. 70 Issue 1, p955 

    Describes the installation of a heavy ion beam probe on JFT-2M tokamak. Use of two sets of poloidal and toroidal sweepers; Measurement of the plasma potential profile from the edge to the core of the plasma; Significance of calibrating the required voltages on the sweeper electrodes for...

  • Sweep system design for a heavy ion beam probe on Madison Symmetric Torus. Lei, J.; Crowley, T.P.; Shah, U.; Schoch, P.M.; Connor, K.A.; Schatz, J. // Review of Scientific Instruments;Jan1999, Vol. 70 Issue 1, p967 

    Describes the sweep system for the heavy ion beam probe on the Madison Symmetric Torus. Two components of the system; Key issued in the sweep system design; Active trajectory control; Plasma/ultraviolet loading effects and mitigation techniques.

  • Flush-mounted probes in the divertor plates of Tokamak de Varennes. Gunn, James P.; Boucher, Claude; Stansfield, Barry L.; Savoie, Sylvio // Review of Scientific Instruments;Jan1995, Vol. 66 Issue 1, p154 

    Describes the installation of arrays of 12 flush-mounted Langmuir plasma probes in the upper and lower outboard divertor plates of Tokamak de Varennes (TdeV). Measurement of electron temperature and density; Validation of the technique by comparing measurements from a cylindrical and a flush...

  • Transport by intermittent convection in the boundary of the DIII-D tokamak. Boedo, J. A.; Rudakov, D.; Moyer, R.; Krasheninnikov, S.; Whyte, D.; McKee, G.; Tynan, G.; Schaffer, M.; Stangeby, P.; West, P.; Allen, S.; Evans, T.; Fonck, R.; Hollmann, E.; Leonard, A.; Mahdavi, A.; Porter, G.; Tillack, M.; Antar, G. // Physics of Plasmas;Nov2001, Vol. 8 Issue 11, p4826 

    Intermittent plasma objects (IPOs) featuring higher pressure than the surrounding plasma, and responsible for ∼50% of the E×B[sub T] radial transport, are observed in the scrape off layer (SOL) and edge of the DIII-D tokamak [J. Watkins et al., Rev. Sci. Instrum. 63, 4728 (1992)]....

  • Reply to ��Comment on �Peeling of convection cells and the generation of sheared flow� [Phys. Fluids B 4, 488 (1992)]��. Drake, J. F.; Finn, J. M.; Guzdar, P. N.; Shapiro, V.; Shevchenko, V.; Waelbroeck, F.; Hassam, A. B.; Liu, C. S.; Sagdeev, R. // Physics of Fluids B: Plasma Physics;Feb93, Vol. 5 Issue 2, p658 

    The comments of Montgomery and Matthaeus on the authors� paper1, have been answered. The results do not contradict those of Montgomery and Matthaeus but for simple case considered, transition to shear flow state and shape of initial vortices is explained. (AIP)


Read the Article


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

Try another library?
Sign out of this library

Other Topics