Recent developments in plasma turbulence and turbulent transport
- Univ. of Wisconsin, Madison, WI (United States)
This report contains viewgraphs of recent developments in plasma turbulence and turbulent transport. Localized nonlinear structures occur under a variety of circumstances in turbulent, magnetically confined plasmas, arising in both kinetic and fluid descriptions, i.e., in either wave-particle or three-wave coupling interactions. These structures are non wavelike. They cannot be incorporated in the collective wave response, but interact with collective modes through their shielding by the plasma dielectric. These structures are predicted to modify turbulence-driven transport in a way that in consistent with, or in some cases are confirmed by recent experimental observations. In kinetic theory, non wavelike structures are localized perturbations of phase space density. There are two types of structures. Holes are self-trapped, while clumps have a self-potential that is too weak to resist deformation and mixing by ambient potential fluctuations. Clumps remain correlated in turbulence if their spatial extent is smaller than the correlation length of the scattering fields. In magnetic turbulence, clumps travel along stochastic magnetic fields, shielded by the plasma dielectric. A drag on the clump macro-particle is exerted by the shielding, inducing emission into the collective response. The emission in turn damps back on the particle distribution via Landau dampling. The exchange of energy between clumps and particles, as mediated by the collective mode, imposes constraints on transport. For a turbulent spectrum whose mean wavenumber along the equilibrium magnetic field is nonzero, the electron thermal flux is proportional to the ion thermal velocity. Conventional predictions (which account only for collective modes) are larger by the square root of the ion to electron mass ratio. Recent measurements are consistent with the small flux. In fluid plasma,s localized coherent structures can occur as intense vortices.
- Research Organization:
- Associated Universities, Inc., Upton, NY (United States)
- OSTI ID:
- 605664
- Report Number(s):
- BNL-64912-Vol.4; CONF-9709192-Vol.4; ON: DE98001892; TRN: 98:009649
- Resource Relation:
- Conference: RIKEN BNL Research Center workshop on non-equilibrium many body dynamics, Upton, NY (United States), 23-25 Sep 1997; Other Information: PBD: 22 Sep 1997; Related Information: Is Part Of Non-equilibrium many body dynamics; Creutz, M.; Gyulassy, M.; PB: 247 p.
- Country of Publication:
- United States
- Language:
- English
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