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J. -M. Kwon

Publications and source records attributed to J. -M. Kwon.

2 recordsLinked to original sources
arXiv2019

Experimental evidence of the non-diffusive avalanche-like electron heat transport events and their dynamical interaction with the shear flow structure

We present experimental observations suggesting that the non-diffusive avalanche-like events are a prevalent and universal process of the electron turbulent heat transport in tokamak core plasmas. They are observed in the low confinement mode and the weak internal transport barrier tokamak plasmas in the absence of magnetohydrodynamic instabilities. In addition, the electron temperature profile corrugation, which indicates the existence of the $E \times B$ shear flow layers, is clearly demonstrated as well as their dynamical interaction with the avalanche-like events. The measured width of the profile corrugation is around $45ρ_i$, which implies the mesoscale nature of the structure.

physics.plasm-ph↗
arXiv2017

Multiscale interaction between a large scale magnetic island and small scale turbulence

Multiscale interaction between the magnetic island and turbulence has been demonstrated through simultaneous two-dimensional measurements of turbulence and temperature and flow profiles. The magnetic island and turbulence mutually interact via the coupling between the electron temperature ($T_e$) gradient, the $T_e$ turbulence, and the poloidal flow. The $T_e$ gradient altered by the magnetic island is peaked outside and flattened inside the island. The $T_e$ turbulence can appear in the increased $T_e$ gradient regions. The combined effects of the $T_e$ gradient and the the poloidal flow shear determine two-dimensional distribution of the $T_e$ turbulence. When the reversed poloidal flow forms, it can maintain the steepest $T_e$ gradient and the magnetic island acts more like a electron heat transport barrier. Interestingly, when the $T_e$ gradient, the $T_e$ turbulence, and the flow shear increase beyond critical levels, the magnetic island turns into a fast electron heat transport channel, which directly leads to the minor disruption.

physics.plasm-ph↗