Transport barriers with Gysela
A transport barrier creation was successfully simulated with the Gysela code. We developed a very innovative method to mimic in our simulations the external polarization of the plasma by Ion Bernstein Waves observed in experiments. The associated sheared flow allowed us to simulate for the very first time the creation of a transport barrier using a flux-driven, so called full-f gyrokinetic (5D) model.
In addition, we discovered that those barriers could be destabilized by a secondary instability, linked to the temperature anisotropy which is naturally associated to the induced polarization. These results promote a renewed interest in externally induced transport barriers.
Details concerning those results can be found in Strugarek et al., PPCF, 55 (7), pp. 074013 (2013)
You can also download the video.
This video shows two successive formation and destabilizations of a transport barrier. The color contours represent the positive (yellow-orange) and negative (blue) electric potential. The heat flows outwards along those contours. When a transport barrier is created, the turbulent cells disappear on a annulus and the associated outward heat flux is stopped. As a result, the confinement of energy in the tokamak plasma is improved.