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arXiv · 1211.2883

Local dependence of ion temperature gradient on magnetic configuration, rotational shear and turbulent heat flux in MAST

Y. -c. Ghim·A. R. Field·A. A. Schekochihin·E. G. Highcock·C. Michael·the MAST Team
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Abstract

Experimental data from the Mega Amp Spherical Tokamak (MAST) is used to show that the inverse gradient scale length of the ion temperature R/LTi (normalized to the major radius R) has its strongest local correlation with the rotational shear and the pitch angle of the magnetic field (or, equivalently, an inverse correlation with q/ε, the safety factor/the inverse aspect ratio). Furthermore, R/LTi is found to be inversely correlated with the gyro-Bohm-normalized local turbulent heat flux estimated from the density fluctuation level measured using a 2D Beam Emission Spectroscopy (BES) diagnostic. These results can be explained in terms of the conjecture that the turbulent system adjusts to keep R/LTi close to a certain critical value (marginal for the excitation of turbulence) determined by local equilibrium parameters (although not necessarily by linear stability).

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Y. -c. Ghim, A. R. Field, A. A. Schekochihin, E. G. Highcock, C. Michael, the MAST Team. 2012-11-13. Local dependence of ion temperature gradient on magnetic configuration, rotational shear and turbulent heat flux in MAST. https://arxiv.org/abs/1211.2883

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