Speaker
Christopher Georg Albert
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P2.1046.pdf
Kinetic modeling of plasma response to RMPs for a tokamak in full
toroidal geometry
C. G. Albert1 , M. F. Heyn1 , S. V. Kasilov1,2 , W. Kernbichler1 , the EUROfusion MST1 Team∗
1 Fusion@ÖAW, Institut für Theoretische Physik - Computational Physics,
TU Graz, Petersgasse 16, A–8010 Graz, Austria
2 Institute of Plasma Physics, National Science Center “Kharkov Institute of Physics and
Technology”, Akademicheskaya Str. 1, 61108 Kharkov, Ukraine
∗ See the author list “H. Meyer et al 2017 Nucl. Fusion 57 102014”
The successful application of external non-axisymmetric magnetic perturbations (resonant
magnetic perturbations or RMPs) for the mitigation and suppression of edge-localized modes
in medium-sized tokamaks [1] has left a number of open questions with regard to models that
include plasma response currents in a 3D equilibrium. Kinetic modeling in straight cylindrical
geometry [2] shows a collisionality-dependent difference of plasma response currents compared
to predictions of commonly used MHD models, in particular a shift of electron fluid resonances
depending on the temperature gradient. Therefore a predictive model should include kinetic
effects. Because cylindrical geometry cannot account for poloidal mode coupling and guiding-
center orbit effects pertinent to a toroidal configuration, a model in full toroidal geometry is
necessary. Since resonant plasma response localized around resonant flux surfaces and non-
resonant (NTV) response in the whole plasma volume cannot be decoupled, a predictive model
should take both of them into account. Here results from a kinetic Monte-Carlo model in full
toroidal geometry and with realistic magnetic perturbations [3] are presented for the case of
ASDEX Upgrade with ELM mitigation coils. Namely the perturbed pressure tensor and current
density are compared to results from a corresponding MHD model. It is shown that the pressure
perturbation is strongly anisotropic not only in vicinity of resonant surfaces, but in the whole
plasma volume. While parallel pressure agrees well with ideal MHD predictions, perpendicular
pressure might be affected by orbital resonances, which are usually important for ion NTV at
low-collisional reactor-relevant conditions [4, 5]. This means that perturbations of diamagnetic
currents caused by external non-axisymmetric perturbations cannot always be described by ideal
MHD theory, and kinetic modeling may be required for the calculation of perturbed plasma
equilibria even in absence of resonant flux surfaces.
References
[1] A. Kirk, W. Suttrop, et al., Nucl. Fusion 55, 043011 (2015)
[2] M. F. Heyn et al., Nucl. Fusion 54, 064005 (2014)
[3] C. G. Albert et al., Varenna-Lausanne Workshop, J. Phys. Conf. Ser. 75, 012001 (2016)
[4] K. C. Shaing et al., Nucl. Fusion 55 125001 (2015)
[5] A. F. Martitsch et al., Plasma Phys. Contr. Fusion 58, 074007 (2016)
