Magnetic reconnection in high-temperature plasmas : excitation of the drift-tearing mode and the transport of electron thermal energy

The problem of excitation of the drift-tearing mode (Coppi, 1964) in high-temperature plasmas is considered. Existing theories predict that under the conditions typical of modern toroidal experiments on nuclear fusion, the mode is linearly stable in both collisionless (Coppi et al., 1979), and in a weakly collisional (Antonsen and Drake, 1983) regimes. We propose that the presence of a spectrum of background microscopic modes leads to destabilization of the drift-tearing mode by significantly altering the electron thermal energy transport. Two phenomenological models that illustrate this possibility are considered. In particular, we demonstrate that a localized reduction in parallel electron thermal conductivity, or a localized depression in the electron temperature gradient cause a significant reduction of the mode excitation threshold, as measured by Acrit, the jump of the first derivative of the magnetic field across the reconnection layer. Both experimental observations and theoretical considerations indicate that in the regimes of interest the values of the perpendicular thermal diffusivity D are significantly higher than the corresponding collisional estimates. Therefore the influence of the perpendicular heat flux on the excitation properties of the drift-tearing mode must be analyzed.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Physics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2007

Author dc:creator

• Roytershteyn, Vadim

Advisor dc:contributor.advisor

• Bruno Coppi.

• Physics.

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/1721.1/39291

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/39291