Turbulent Equipartition Pinch of Toroidal Momentum in Spherical Torus
نویسندگان
چکیده
We present a new analytic expression for turbulent equipartition (TEP) pinch of toroidal angular momentum originating from magnetic field inhomogeneity of spherical torus (ST) plasmas. Starting from a conservative modern nonlinear gyrokinetic equation [Hahm et al., 1988 Phys. Fluids 31, 2670], we derive an expression for pinch to momentum diffusivity ratio without using a usual tokamak approximation of B ∝ 1/R which has been previously employed for TEP momentum pinch derivation in tokamaks [Hahm et al., 2007 Phys. Plasmas 14, 072302]. Our new formula is evaluated for model equilibria of National Spherical Torus eXperiment (NSTX) [M.Ono et al., 2001 Nuclear Fusion 41, 1435] and Versatile Experiment Spherical Torus (VEST) [K.J. Chung et al., 2013 Plasma Sci. Technol. 15, 244] plasmas. Our result predicts stronger inward pinch for both cases, as compared to the prediction based on the tokamak formula.
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Turbulent equipartition and homogenization of plasma angular momentum.
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