Optimized up–down asymmetry to drive fast intrinsic rotation in tokamaks. (19th December 2017)

• Record Type: Journal Article
• Authors: Ball, Justin; Parra, Felix I.; Landreman, Matt; Barnes, Michael
• Is Part Of: Nuclear fusion. Volume 58:Number 2(2018:Feb.)
• Publication Date: 2017-12-19
• Subjects: gyrokinetics -- magnetohydrodynamics -- tokamaks -- plasma turbulence -- transport properties -- nonlinear simulations; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/1741-4326/aa9a50
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: Breaking the up–down symmetry of the tokamak poloidal cross-section can significantly increase the spontaneous rotation due to turbulent momentum transport. In this work, we optimize the shape of flux surfaces with both tilted elongation and tilted triangularity in order to maximize this drive of intrinsic rotation. Nonlinear gyrokinetic simulations demonstrate that adding optimally-tilted triangularity can double the momentum transport of a tilted elliptical shape. This work indicates that tilting the elongation and triangularity in an ITER-like device can reduce the energy transport and drive intrinsic rotation with an Alfvén Mach number of roughly 1 % . This rotation is four times larger than the rotation expected in ITER and is approximately what is needed to stabilize MHD instabilities. It is shown that this optimal shape can be created using the shaping coils of several present-day experiments.