Edge transport and fluctuation induced turbulence characteristics in early SST-1 plasma

•Anomalous particle transport during the high MHD activity at SST-1.•Electrostatic turbulence is modulated by MHD activity at SST-1 tokamak.•Edge floating potential fluctuations shows poloidal long-range cross correlation. Plasma edge transport characteristics are known to be heavily influenced by t...

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Bibliographic Details
Published in:Fusion engineering and design 2017-02, Vol.115, p.85-92
Main Authors: Kakati, B., Pradhan, S., Dhongde, J., Semwal, P., Yohan, K., Banaudha, M.
Format: Article
Language:English
Subjects:
Bispectral analysis
Coils
Columns (structural)
Cross correlation
Floating structures
Magnetic variations
Magnetohydrodynamic turbulence
MHD
Nonlinear analysis
Particle transport
Plasma
Plasma confinement
Plasma diagnostics
Tokamak devices
Tokamak plasma
Transport
Turbulence
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Summary:•Anomalous particle transport during the high MHD activity at SST-1.•Electrostatic turbulence is modulated by MHD activity at SST-1 tokamak.•Edge floating potential fluctuations shows poloidal long-range cross correlation. Plasma edge transport characteristics are known to be heavily influenced by the edge fluctuation induced turbulences. These characteristics play a critical role towards the confinement of plasma column in a Tokamak. The edge magnetic fluctuations and its subsequent effect on electrostatic fluctuations have been experimentally investigated for the first time at the edge of the SST-1 plasma column. This paper reports the correlations that exist and is experimentally been observed between the edge densities and floating potential fluctuations with the magnetic fluctuations. The edge density and floating potential fluctuations have been measured with the help of poloidally separated Langmuir probes, whereas the magnetic fluctuations have been measured with poloidally spaced Mirnov coils. Increase in magnetic fluctuations associated with enhanced MHD activities has been found to increase the floating potential and ion saturation current. These observations indicate electrostatic turbulence getting influenced with the MHD activities and reveal the edge anomalous particle transport during SST-1 tokamak discharge. Large-scale coherent structures have been observed in the floating potential fluctuations, indicating long-distance cross correlation in the poloidal directions. From bispectral analysis, a strong nonlinear coupling among the floating potential fluctuations is observed in the low-frequency range about 0–15kHz.
ISSN:0920-3796
1873-7196
DOI:10.1016/j.fusengdes.2016.12.041