59th Annual Meeting of the APS Division of Plasma Physics
Volume 62, Number 12
Monday–Friday, October 23–27, 2017;
Milwaukee, Wisconsin
Session BI3: Gyrokinetics and Plasma Turbulence
9:30 AM–12:30 PM,
Monday, October 23, 2017
Room: 103ABC
Chair: Christopher Holland, University of California, San Diego
Abstract ID: BAPS.2017.DPP.BI3.3
Abstract: BI3.00003 : Non-linear isotope and fast ions effects: routes for low turbulence in DT plasmas
10:30 AM–11:00 AM
Preview Abstract
Abstract
Author:
Jeronimo Garcia
(CEA)
The isotope effect, i.e. the fact that heat and particle fluxes do not
follow the expected Gyro-Bohm estimate for turbulent transport when the
plasma mass is changed, is one of the main challenges in plasma theory. Of
particular interest is the isotope exchange between the fusion of deuterium
(DD) and deuterium-tritium (DT) nuclei as there are no clear indications of
what kind of transport difference can be expected in burning plasmas.
The GENE code [1] is therefore used for computing DD vs DT linear and
nonlinear microturbulence characteristics in the core plasma region of a
previously ITER hybrid scenario at high beta obtained in the framework of
simplified integrated modelling. Scans on common turbulence related
quantitates as external ExB flow shear, Parallel Velocity Gradient (PVG),
plasma beta, colisionality or the number of ion species have been performed.
Additionally, the role of energetic particles, known to reduce Ion
Temperature Gradient (ITG) turbulence has been also addressed [2,3].
It is obtained that the ITER operational point will be close to threshold
and in these conditions turbulence is dominated by ITG modes. A purely weak
non-linear isotope effect, absent in linear scans, can be found when
separately adding moderate ExB flow shear or electromagnetic effects,
whereas collisionality just modulates the intensity. The isotope effect, on
the other hand, becomes very strong in conditions with simultaneously
moderate ExB flow shear, beta and low q profile with significant reductions
of ion heat transport from DD to DT [3]. By analyzing the radial structure
of the two point electrostatic potential correlation function it has been
found that the inherent Gyro-Bohm scaling for plasma microturbulence, which
increases the radial correlation length at short scales form DD to DT, is
counteracted by the concomitant appearance of a complex nonlinear multiscale
space interaction involving external ExB flow shear, zonal flow activity,
magnetic geometry and electromagnetic effects. The number of ion species and
the fast ion population is also found to play a role in this non-linear
process whereas a symmetry breaking between D and T, with systematic reduced
heat and particle transport for T, is always obtained.
[1] F. Jenko, W. Dorland, M. Kotschenreuther and B.N. Rogers, Phys. Plasmas
7, 1904 (2000).
[2] J. Citrin et al., Phys. Rev. Lett. 111, 155001 (2013). J. Garcia et al.,
Nucl. Fusion 55, 053007 (2015).
[3] J. Garcia et al., Nucl. Fusion 57, 014007 (2017)
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2017.DPP.BI3.3