Granular fluctuations in plasma turbulence and their role in transport
Three general types of granular or discrete fluctuations in plasma turbulence are reviewed, with emphasis placed on their unique role in fluctuation-induced transport. These fluctuations are clumps, holes, and vortices, and represent structures that are not part of the normal mode response, the basis of conventional descriptions of plasma turbulence and transport. These fluctuations interact with the normal mode response to produce profound modifications of transport. The self-consistent linking of fields and particle distributions through quasineutrality and Ampere`s law is shown to be crucial in calculating these modifications. In particular, it is pointed out that collisionless electron motion along perturbed magnetic fields produces almost no transport of field aligned current across equilibrium surfaces. It is also shown that clumps are granular structures which are turbulently mixed, whereas holes and vortices avoid mixing and relaxation through strong self-binding effects. The distinction between structures that are mixed and those that are persistent is probed in an analysis of the interaction of an intense vortex and ambient turbulent fluctuations. It is shown that, above a critical amplitude, the shearing of eddies due to the differential rotation of the vortex suppresses the fluctuations that mix its vorticity, allowing it to achieve a lifetime greatly in excess of the turbulent interaction time scale.
- Research Organization:
- Wisconsin Univ., Madison, WI (United States). Plasma Physics Research
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-89ER53291
- OSTI ID:
- 10157437
- Report Number(s):
- DOE/ER/53291-217; CONF-9302117-1; ON: DE93013465; TRN: 93:020826
- Resource Relation:
- Conference: Interdisciplinary workshop on statistical description of transport in astro- and nuclear physics,Les Houches (France),2-11 Feb 1993; Other Information: PBD: Apr 1993
- Country of Publication:
- United States
- Language:
- English
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