1. (TH/8-1, Jae-Min Kwon et al
(TH/8-1, Jae-Min Kwon et al.) Gyrokinetic XGC1 Study of Magnetic Island Effect on Neoclassical and Turbulence Physics in a KSTAR Plasma
Full-f gyrokinetic study has been performed, for the first time, to study neoclassical and turbulence physics in a given (2,1) 3D magnetic island structure
Mean potential, plasma profile and flow evolve to 3D structure
Turbulence penetrates through the X-point, followed by propagation to O-area
(a)
Turbulence evolution near X-point of magnetic island.
Black dashed line represents magnetic island separatrix.
Kinetic ion orbits and turbulence make the density inside the island non-flat across the O-point radius
The island effect on bootstrap current flattening is not as dramatic as previously assumed
Discontinuity in the magnetic topology makes a double δϕ layer across the magnetic islands [figure (b)]
Strongly sheared ExB layer formed across the magnetic island
Weakening of ambient ITG-TEM turbulence
Consistent with experimental observation in KSTAR1
Conclusion: Existence of magnetic island does not have to flatten the local boostrap current or degrade the plasma confinement, as seen in KSTAR experiment1
(b)
Perturbed mean potential
1 M.J. Choi et al, Nucl. Fusion Lett. 57, (2017); Jae-Min Kwon et al, Phys. Plasmas 25, (2018)