Speaker
Simon James Freethy
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/O4.109.pdf
Turbulence measurements and gyrokinetic validation at ASDEX Upgrade
S.J. Freethy1,2 , T. Happel1 , G.D. Conway1 , A. Creely2 , T. Görler1 , P. Hennequin3 ,C. Lechte 4 ,
J. Pinzon1,5 , D. Prisiazhniuk1,5 , U. Stroth1,5 , A.E. White2 and the ASDEX Upgrade Team1
1 Max Planck Institute for Plasma Physics, 85748 Garching, Germany
2 MIT Plasma Science and Fusion Center, Cambridge, MA, USA.
3 Laboratoire de Physique des Plasmas, Ecole Polytechnique, 91128, Palaiseau cedex, France
4 IGVP, Universit at Stuttgart, Pfaffenwaldring 31, D-70569 Stuttgart, Germany
5 Physik-Department E28, Technische Universität München, Garching, Germany
Quantitative comparison of gyrokinetic (GK) models of plasma turbulence to experimental
measurements of fluctuating quantities is essential to provide stringent tests of the theory. Re-
cently, the development in the fidelity of GK simulations, new experimental diagnostics and ad-
vanced synthetic diagnostics for qunatitative comparison, means that GK models can be tested
more thoroughly than ever. At ASDEX Upgrade (AUG), using a recently developed 30 channel
Correlation Electron Cyclotron Emission (CECE) radiometer, measurements of the fluctuation
amplitude, δ Te⊥ , radial correlation length, Lr (Te ), and ne -Te cross-phase, αne Te , have been ob-
tained simultaneously in an L-mode plasma and are quantitatively compared to non-linear ion-
scale GK simulations in an extensive validation study [1]. Additionally, eddy tilt angles have
been measured for the first time at AUG using Radial Correlation Doppler Reflectometry and
are found to be different for ITG and TEM dominated turbulence [2]. The results are interpreted
through the use of extensive full wave simulations and compared directly to theoretical values.
Doppler Reflectometry (DR) was recently used in the AUG core plasma to measure the electron
density k⊥ spectrum in the range 0.4 < k⊥ ρs < 3 [3]. Discrepancies between O and X mode
measurements are found to be explained by a combination of non-linear saturation at low-k and
an enhanced power response at high-k [4]. O-mode results are in reasonable agreement with
GK simulations. Furthermore, measurements of the eddy dissipation time and perpendicular
correlation length of ne fluctuations have been made using Poloidal Correlation Reflectome-
try [5] and compared to GK values. Experiments were recently performed to bring together as
many simultaneous, spatially overlapping turbulence measurements as possible for quantitative
comparisons to non-linear GK simulations. The measurements and progress in their quantitative
comparison to GK simulations will be discussed.
References
[1] S.J. Freethy et al. Phys. Plasmas, in preparation.
[2] J.R. Pinzon et al. Phys. Rev. Lett., in preparation.
[3] T. Happel et al. Plasma Phys. Control. Fusion, 59(054009), 2017.
[4] J.R. Pinzon et al. Plasma Phys. Control. Fusion, 59(035005), 2017.
[5] D. Prisiazhniuk et al. Plasma Phys. Control. Fusion, 59(025013), 2017.
