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Recent experiments in the STOR-M Tokamak* Akira Hirose In collaboration with: C. Boucher (INRS-EMT), G. St. Germaine D. Liu, S. Livingstone, A. Singh,

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Presentation on theme: "Recent experiments in the STOR-M Tokamak* Akira Hirose In collaboration with: C. Boucher (INRS-EMT), G. St. Germaine D. Liu, S. Livingstone, A. Singh,"— Presentation transcript:

1 Recent experiments in the STOR-M Tokamak* Akira Hirose In collaboration with: C. Boucher (INRS-EMT), G. St. Germaine D. Liu, S. Livingstone, A. Singh, C. Xiao Plasma Physics Laboratory University of Saskatchewan Saskatoon, Saskatchewan, Canada *Supported by NSERC, CRC

2 PPL, Univ. of Sask.Department of Physics & Engineering Physics Outline Edge plasma flow measurements with Mach probes Low frequency edge density and potential fluctuation measurements with Langmuir probes (GAM) Skin size ballooning mode (theory) Density fluctuation measurements with 2 mm microwave scattering (search for ETG and skin size mode) Vertical CT (compact torus) injection Future plan

3 PPL, Univ. of Sask.Department of Physics & Engineering Physics STOR-M top view

4 PPL, Univ. of Sask.Department of Physics & Engineering Physics STOR-M side view

5 PPL, Univ. of Sask.Department of Physics & Engineering Physics 4-Pair Mach (Gundestrup) Probes

6 PPL, Univ. of Sask.Department of Physics & Engineering Physics Ohmic discharge (I p Ohmic discharge (I p counter to B t ) Flow is predominantly along the magnetic field.

7 PPL, Univ. of Sask.Department of Physics & Engineering Physics Parallel flow in the direction of current. t=17 ms r=10.5 cm BtBt IpIp

8 PPL, Univ. of Sask.Department of Physics & Engineering Physics When the current is reversed, so is the flow. BtBt IpIp t=17 ms r=12 cm

9 PPL, Univ. of Sask.Department of Physics & Engineering Physics Neoclassical theory In an axisymmetric plasma, Toroidal flow Poloidal flow may depend on collisionality

10 PPL, Univ. of Sask.Department of Physics & Engineering Physics Electrode Biasing

11 PPL, Univ. of Sask.Department of Physics & Engineering Physics GAM (Geodesic Acoustic Mode) GAM frequency In GAM, the potential is symmetric but density perturbation is not, Excitation mechanism? Its roles? poloidal angle

12 PPL, Univ. of Sask.Department of Physics & Engineering Physics Probes and locations

13 PPL, Univ. of Sask.Department of Physics & Engineering Physics Observation Potential fluctuations have a peak at f ~ 12-15 kHz at all positions Density fluctuation has this peak except at the outer mid plane  where it is small. Unclear what role is played by GAM in transport.

14 PPL, Univ. of Sask.Department of Physics & Engineering Physics Power spectra of potential and density fluctuations Density at -90 degrees (bottom) Potential at 0 degree Density at 0 degree

15 PPL, Univ. of Sask.Department of Physics & Engineering Physics Skin size ballooning mode Skin size plasma turbulence has long been speculated. Such turbulence would explain Ohkawa diffusivity and thus Alcator scaling Earlier this year, a novel short wavelength ballooning mode was predicted in the regime

16 PPL, Univ. of Sask.Department of Physics & Engineering Physics Electron thermal diffusivity in units of gyro-Bohm

17 PPL, Univ. of Sask.Department of Physics & Engineering Physics Klystron Directional Coupler 20dB Two Attenuators Phase Shifter Detector 2 Over-moded (WR-28) waveguidesections GOLA Horn Standard Gain Horn Mixer Isolator Detector 1 Transmitted signal Received signal Power supply and cooling system ScatteringVolume Lowermirror Uppermirror Plasma Reference Arm E-H Tuner Quartz windows Vertical ports onSTOR-M chamber 2 mm microwave scattering: experimental setup Isolator Directional Coupler

18 PPL, Univ. of Sask.Department of Physics & Engineering Physics Dispersion relation The solid line indicates the ion drift mode. The observed normalized frequency tends to be constant at high k.

19 PPL, Univ. of Sask.Department of Physics & Engineering Physics Fueling Large Tokamak A.J.H. Donne et al. Fusion Sci. &Tech., January 2006 issue: “In the field of density control it has been concluded that there is not much flexibility in the fueling of ITER.” As part of their recommendations, they further state: “New fueling techniques should be tested on present devices. Given the prospects of CT (compact torus) injection, a test on a relatively large device is highly desirable.” [Summary of 2005 IEA Workshop on Burning Plasma Physics and Simulations, Tarragona, Spain]

20 PPL, Univ. of Sask.Department of Physics & Engineering Physics Compact Torus (CT) injection Horizontal vs. vertical

21 PPL, Univ. of Sask.Department of Physics & Engineering Physics USCTI with deflector

22 PPL, Univ. of Sask.Department of Physics & Engineering Physics Effects of vertical CT injection (preliminary)

23 PPL, Univ. of Sask.Department of Physics & Engineering Physics Vertical CT injection (cont.)

24 PPL, Univ. of Sask.Department of Physics & Engineering Physics Future plan Plasma flow: more complete plasma data are needed for comparison with the neoclassical theory Repetitive CT injection Heterodyne 2 mm microwave scattering Numerical simulations of the skin size ballooning mode


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