Equilibrium Plasma Parameters Turbulent Wave Number Spectra Microscopic Structure of Turbulence in the Torsatron TJ-K Carsten Lechte, HSX Plasma Laboratory, University of Wisconsin-Madison, USA Mirko Ramisch, Navid Mahdizadeh, Ulrich Stroth, IEAP, University Kiel, Germany Email: stroth@physik.uni-kiel.de Motivation Equilibrium Plasma Parameters Turbulent Wave Number Spectra Spectral Index Energy Cascade in Fluids (3D) Energy entered at large scales (Injection) Total energy locally transferred to smaller scales by shearing (Inertial region) Energy totally dissipated at smallest scales  Power Spectrum ~ k-5/3 Spectrum of 2D-Turbulence Kraichnan, Phys. Fluids, 1967 Enstrophy (conserved) log( 1 / structure size) log( energy density) Injection Floating potential (V) Ion saturation current (mA) Radial Tranport Profile Motivation: turbulent transport in fusion plasmas The experiment TJ-K: powerful turbulence diagnostics Form and propagation of turbulent events Spatial scales of fluctuations and transport 31 mm 3 mm The Torsatron TJ-K Krause, Lechte et. al., Rev. Sci. Instr. 2002 R = 0.6 m, a = 0.1 m B < 0.25 T, Te < 30 eV, ne < 51018 m-3 Heating: 2 kW Helicon (rf) or Up to 6 kW ECRH (microwave) Discharges up to 60 min in H, He, Ar (variation of rs) Langmuir probes employable Everywhere Formerly: TJ-IU, CIEMAT, Madrid Conditional Averaging TJ-K Spectra display broadband turbulence Argon, rs = 31mm Spectra shifted according to rs spectral index -3  Enstrophy cascade No space left for inverse energy cascade Isat rs-Scaling of Structure Sizes Ffloat Correlation length Lcorr calculated by Fourier transform, averaged over poloidal Circumference increases with drift scale Turbulent Transport Scales Power Spectrum Probe Diagnostics Isat Argon 72 mT rs = 31 mm Helium 89 mT rs = 10 mm Hydrogen 96 mT rs = 3 mm Large quasi-coherent m=2 mode (2/7 rational), cross phase zero Little radial propagation, mode appears in spectrum Poloidal propagation determined by EB and diamagnetic drift 2D Movement Stage for Probes Equilibrium quantities Correlation measurment: Structures Transport G = n Eq / B Helium, rs = 10mm Lcorr Lcorr Lcorr References and Acknowlegements 64 probes on flux surface: kq Tilted view from above Isat [1] Lechte, C., Mahdizadeh, N., Ramisch, M., Stroth, U., Phys. Rev. Lett., submitted 2003 [2] C. Lechte, S. Niedner, and U. Stroth, New J. Phys. 4, 34 (2002). [3] Krause, N., Lechte, C., Niedner, S., Westphal, R., Stroth, U., Rev. Sci. Instrum. 73, 3474 (2002). [4] S. Niedner, B. D. Scott, and U. Stroth, Plasma Phys. Controll. Fusion 44, 397 (2002). [5] B. Scott, Plasma Phys. Controll. Fusion 39, 1635 (1997). We acknowledge financial support form Max-Planck Institut fuer Plasmaphysik. The TJ-K device was prodvided by CIEMAT, Madrid. We acknowledge A. Piel for support with the DAQ system. Ffloat H, He, Ar similar, Kolmogorov-like, Transport maximum at correlation length of fluctuations DAQ: A. Piel Little radial propagation, cross phase zero, mode not in spectrum Dipole structure, smaller than Argon Cross Phases  0: Drift Waves in TJ-K Measurement of all spatial scales at the same time First time simultaneous n, F, G in fusion geometry Argon Hydrogen Helium Simulation with DALF3 MHD+Drift-Alfvén code Highpass filtered data: smaller structures Power Spectrum Requests for Reprints Ffloat (V) Isat (mA) Turbulent Mean EB Transport Isat + - Cross phase g governs mean transport