Collisionality Scaling of Main-ion Toroidal and Poloidal Rotation in Low Torque DIII-D Plasmas
Authors: B.A. Grierson,. K.H. Burrell, W.M. Solomon, R.V. Budny and J. Candy
Abstract:
In tokamak plasmas with low levels of toroidal rotation, the radial
electric fi eld Er is a combination of pressure gradient and toroidal and poloidal
rotation components, all having similar magnitudes. In order to assess the validity of
neoclassical poloidal rotation theory for determining the poloidal rotation contribution
to Er , Dα emission from neutral beam heated tokamak discharges in DIII-D [J.L.
Luxon, Nucl. Fusion 42 , 614 (2002)] has been evaluated in a sequence of low torque
(electron cyclotron resonance heating and balanced diagnostic neutral beam pulse)
discharges to determine the local deuterium toroidal rotation velocity. By invoking
the radial force balance relation the deuterium poloidal rotation can be inferred. It is
found that the deuterium poloidal low exceeds the neoclassical value in plasmas with
collisionality νi < 0: 1, being more ion diamagnetic, and with a stronger dependence on
collisionality than neoclassical theory predicts. At low toroidal rotation, the poloidal
rotation contribution to the radial electric fi eld and its shear is signi cant. The eff ect
of anomalous levels of poloidal rotation on the radial electric fi eld and cross fi eld heat
transport is investigated for ITER parameters.
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Submitted to: Nuclear Fusion (March, 2013)
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