Intrinsic rotation driven by non-Maxwellian equilibria in Tokamak plasmas.
Physical review letters 111:5 (2013) 055005
Abstract:
The effect of small deviations from a Maxwellian equilibrium on turbulent momentum transport in tokamak plasmas is considered. These non-Maxwellian features, arising from diamagnetic effects, introduce a strong dependence of the radial flux of cocurrent toroidal angular momentum on collisionality: As the plasma goes from nearly collisionless to weakly collisional, the flux reverses direction from radially inward to outward. This indicates a collisionality-dependent transition from peaked to hollow rotation profiles, consistent with experimental observations of intrinsic rotation.Corrigendum to “AstroGK: Astrophysical gyrokinetics code” [J. Comput. Phys. 229 (2010) 9347–9372]
Journal of Computational Physics Elsevier 245 (2013) 493-494
Multi-channel transport experiments at Alcator C-Mod and comparison with gyrokinetic simulationsa)
Physics of Plasmas AIP Publishing 20:5 (2013) 056106
Experimental signatures of critically balanced turbulence in MAST.
Physical review letters 110:14 (2013) 145002
Abstract:
Beam emission spectroscopy (BES) measurements of ion-scale density fluctuations in the MAST tokamak are used to show that the turbulence correlation time, the drift time associated with ion temperature or density gradients, the particle (ion) streaming time along the magnetic field, and the magnetic drift time are consistently comparable, suggesting a "critically balanced" turbulence determined by the local equilibrium. The resulting scalings of the poloidal and radial correlation lengths are derived and tested. The nonlinear time inferred from the density fluctuations is longer than the other times; its ratio to the correlation time scales as ν(*i)(-0.8 ± 0.1), where ν(*i) = ion collision rate/streaming rate. This is consistent with turbulent decorrelation being controlled by a zonal component, invisible to the BES, with an amplitude exceeding those of the drift waves by ∼ ν(*i)(-0.8).Electron flow driven instability in finite beta plasmas
40th EPS Conference on Plasma Physics, EPS 2013 2 (2013) 1098-1101