A novel mechanism for exciting intrinsic toroidal rotation
- Department of Physics and Center for Astrophysics and Space Sciences, University of California San Diego, La Jolla, California 92093-0424 (United States)
- CEA Cadarache, 13108 St. Paul Lez Durance (France)
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543-0451 (United States)
Beginning from a phase space conserving gyrokinetic formulation, a systematic derivation of parallel momentum conservation uncovers two physically distinct mechanisms by which microturbulence may drive intrinsic rotation. The first mechanism, which emanates from ExB convection of parallel momentum, has already been analyzed [O. D. Gurcan et al., Phys. Plasmas 14, 042306 (2007); R. R. Dominguez and G. M. Staebler, Phys. Fluids B 5, 3876 (1993)] and was shown to follow from radial electric field shear induced symmetry breaking of the spectrally averaged parallel wave number. Thus, this mechanism is most likely active in regions with steep pressure gradients or strong poloidal flow shear. The second mechanism uncovered, which appears in the gyrokinetic formulation through the parallel nonlinearity, emerges due to charge separation induced by the polarization drift. This novel means of driving intrinsic rotation, while nominally higher order in an expansion of the mode frequency divided by the ion cyclotron frequency, does not depend on radial electric field shear. Thus, while the magnitude of the former mechanism is strongly reduced in regions of weak radial electric field shear, this mechanism remains unabated and is thus likely relevant in complementary regimes.
- OSTI ID:
- 21277076
- Journal Information:
- Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 16; ISSN PHPAEN; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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