Sherwood 2015

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approvedadityaks_sherwood15_abstr.pdf2015-01-19 21:40:18Aditya Krishna Swamy

Gyrokinetic Global Linear Aspects of Microtearing Modes in Large Aspect Ratio Tokamaks

Author: Aditya Krishna Swamy
Requested Type: Consider for Invited
Submitted: 2015-01-19 03:37:06

Co-authors: R. Ganesh, J. Chowdhury, S. Brunner, J. Vaclavik, L. Villard

Contact Info:
Institute for Plasma Research
Gandhinagar, Gujarat   382428

Abstract Text:
Microtearing modes (MTMs) are low frequency, high-n electromagnetic microinstabilities envisaged to open up an important, additional electron channel of transport in tokamak plasmas. The mode draws free energy from the equilibrium electron temperature gradient and is identified by the tearing parity of fluctuations, i.e. odd parity in the electrostatic potential
and even parity in the parallel magnetic vector potential. Until recently, collisionless MTMs were expected to be stable in modern hot tokamaks, but have been found to be unstable in numerical simulations for spherical as well as large aspect ratio tokamaks [1,2]. In the absence of collisions, in spherical tokamak plasmas, the drive comes mainly from the drift resonance of trapped electrons. In the context of large aspect ratio tokamaks, the mode has been found to be driven by the magnetic drift resonance of passing electrons. Fundamental aspects of collisionless MTMs in large aspect ratio tokamaks, such as the role of trapped electron population dynamics, effect of Shafranov shift of equilibrium flux surfaces, effect of parallel magnetic field fluctuations and role of equilibrium flows will be presented.

[1] D. Dickinson, C. M. Roach,, Plasma Phys. Control. Fusion 55, 074006 (2013).
[2] Aditya K. Swamy, R Ganesh, Phys. Plasmas 21, 082513 (2014)


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