Structures generated in a temperature filament due to drift-wave convection

Shi, M.; Pace, D. C.; Morales, G. J.; Maggs, J. E.; Carter, T. A.
June 2009
Physics of Plasmas;Jun2009, Vol. 16 Issue 6, p062306
Academic Journal
A simplified numerical study is made of the structures that are formed in a magnetized temperature filament due to oscillatory convection from large amplitude drift waves. This study is motivated by a recent experiment [D. C. Pace, M. Shi, J. E. Maggs et al., Phys. Plasmas 15, 122304 (2008)] in which Lorentzian-shaped temporal pulses are observed. These pulses produce a broadband, exponential frequency power spectrum. The model consists of an electron heat transport equation in which plasma convection arising from pressure-gradient driven drift-waves is included. It is found that above a critical wave amplitude, spatially complex structures are formed, which give rise to temporal pulses having positive and negative polarities at different radial positions. The temporal shape of the pulses can be fit by a Lorentzian function. The associated spatial structures exhibit temporally oscillatory heat plumes (positive polarity) and cold channels (negative polarity). The idealized effect of a static flow on these structures is explored. Depending on the flow direction (relative to the azimuthal propagation of the drift waves), the temporal Lorentzian pulses can be suppressed.


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