Neoclassical polarization

Sheared zonal flow is known to be the predominant saturation mechanism of plasma turbulence. Rosenbluth and Hinton(R-H) have shown that the zonal flow level is inversely proportional to the plasma radial polarizability due to magnetic drift departure from a flux surface. In another calculation, Hinton and Rosenbluth (H-R) considered the weakly collisional case in the banana regime and calculated the neoclassical polarization and associated zonal flow damping in the high frequency and low frequency limits. The work presented here extends R-H's calculation in several aspects. We calculate the neoclassical polarization for arbitrary radial wavelength zonal flows so that finite ion banana width and ion gyroradius are retained. We also add plasma shape effects into the R-H collisionless calculation and find the influence of elongation and triangularity on neoclassical polarization and zonal flow damping. In addition, we extend the H-R collisional calculation using an exact eigenfunction expansion of the collision operator to calculate neoclassical polarization for the entire range of frequencies. A semi-analytical fit of the exact results is obtained that gives the polarization to within 15% and allows the collisional zonal flow damping rate to be evaluated for arbitrary collisionality.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Nuclear Science and Engineering

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2006

Author dc:creator

• Xiao, Yong

Advisor dc:contributor.advisor

• Peter J. Catto and Kim Molvig.

• Nuclear Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/41275

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/41275