Speaker
Shuai Xu
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P1.1032.pdf
Three-dimensional simulations of edge plasma transport with
LHW-induced magnetic perturbations on EAST
S. Xu1,2 , M. Rack1 , Y. Liang1,2 , J. Huang1 , M. Jia1,2 , Y. Feng3 , J. Cosfeld1 , H. Zhang2 ,
S. Liu2 , Y. Gao1 , K. Gan2 , W. Feng2 , L. Wang2 , W. Zholobenko1 , D. Reiter1
1 Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung-Plasmaphysik,
Partner of the Trilateral Euregio Cluster (TEC), 52425 Jülich, Germany
2 Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People’s Republic
of China
3 Max-Planck-Institute für Plasmaphysik, 17491 Greifswald / 85748 Garching, Germany
Recent experiments from the Experimental Advanced Superconducting Tokamak (EAST)
show that lower hybrid waves (LHWs) can profoundly change the magnetic topology by induc-
ing helical current filaments flowing along magnetic field lines in the scrape-off layer [1, 2].
The spectrum of LHW-induced perturbation fields automatically adjusts to the edge-safety-
factor, because the helicity of current filaments closely fits the pitch of the edge field line. It has
been proved in the experiments that such flexible magnetic perturbations have powerful abilities
in controlling heat load on divertor targets, controlling impurities, as well as mitigating Edge-
Localized Modes (ELMs). However, the underlying physical mechanisms are still unclear. To
better understand the physics behind, here it is investigated how these magnetic perturbations
caused by LHWs affect the edge plasma transport utilizing the 3D Monte Carlo code EMC3-
EIRENE. The 3D magnetic topology structure is reflected in the plasma properties, due to much
stronger parallel field transport compared with cross field diffusion. Good quantitative agree-
ments between simulations and experiments demonstrate that the EMC3-EIRENE code now is
capable of taking into account the LHW-induced magnetic perturbation fields with both phys-
ical and geometrical effects being considered. The larger current of filaments caused by the
increased LHWs input power can further deepen the penetration depth of the additional trans-
port channel by extending the stochastic edge layer, and influence the ratio of heat (or particle)
flux between split striated and original strike line on divertor targets. The 3D simulation results
also indicate that the additional plasma transport channel induced by LHWs can significantly
cause the redistribution of heat load between inner and outer divertor targets, which could not
be found by the field line tracing method in previous works [3, 4].
References [2] Y. Liang et al., Phys. Rev. Lett. 110 235002 (2013)
[3] M. Rack et al., Nucl. Fusion 54 064016 (2014)
[1] J. Li et al., Nat. Phys. 9 817-821 (2013) [4] W. Feng et al., Nucl. Fusion 57 126054 (2017)
