957 / 2019-10-27 10:02:34

Analytical model of plasma response to external magnetic perturbation in absence of no-slip condition

全体主题 > 磁约束核聚变理论与模拟

Recent simulation and experimental results suggest that the magnetic island and flow
on resonant surface often do not satisfy the ``no-slip" condition in the steady state. A new theory
model on nonlinear plasma response to external magnetic perturbation in absence of no-slip
condition is proposed. The model is composed of the equations for the evolution of both width
and phase of magnetic island due to forced reconnection driven by the external magnetic
perturbation, and the force-balance equation for the plasma flow. When the island width is much
less than the resistive layer width, the island growth is governed by the linear
Hahm-Kulsrud-Taylor solution in presence of time-dependent plasma flow. In the other regime
when the island width is much larger than the resistive layer width, the evolution of both island
width and phase can be described using the Rutherford theory. The island solution is used to
construct the quasi-linear electromagnetic force, which together with viscous one, contributes to
the nonlinear variation in plasma flow. The no-slip condition assumed in the conventional error
field theory is not imposed here, where the island oscillation frequency depends on but does not
necessarily equal to the plasma flow frequency at the rational surface.