Sherwood 2015

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Stability Analysis on Electromagnetic Drift-Kinetic Equation for Arbitrarily Collisional Plasma Blobs

Author: Wonjae Lee
Requested Type: Poster Only
Submitted: 2015-01-12 16:46:27

Co-authors: J.R. Angus, S.I. Krasheninnikov

Contact Info:
University of California, San Diego
9500 Gilman Drive
La Jolla, California   92093

Abstract Text:
Plasma blobs are meso-scale turbulent structures usually observed in the scrape-off layer (SOL) of magnetic confinement devices. It has been shown that the coherency of the blob can be substantially limited by the onset of the electrostatic resistive drift wave instability (Angus et al., Physics of Plasmas 19, 082312 (2012)). Moreover, a kinetic description to describe the secondary instability within the blob is necessary in the parameter regime where the validity of fluid equations is only marginally satisfied (Angus et al., Physics of Plasmas 19, 052504 (2012)). In addition to the kinetic description, electromagnetic effects become important in the case of increased plasma beta.
In this work, we use standard local linear analysis to derive a general form of wave dispersion relation for the electromagnetic and arbitrarily collisional plasmas. The electron dynamics in the plasmas is expressed by an electromagnetic drift-kinetic equation with a BGK-like collision operator. The growth rates from the general form of dispersion relation are compared with growth rates from dispersion relations with collisionless/collisional limits and electrostatic approximation. The electromagnetic dispersion relation from the kinetic equations returns to the electrostatic approximation as plasma beta decreases. However, there are significant differences in the growth rates between the electromagnetic and electrostatic fluid limits in the low collisional plasmas. We demonstrate that the plasma with low-moderate collisionality regime can only be described properly by the general form of electromagnetic-kinetic dispersion relation. The comparisons between different limits with various parameter scans and their physical implications will be discussed.


March 16-18, 2015
The Courant Institute, New York University