5 papers
Functional perturbation theory under axisymmetry: Simplified formulae and their uses for tokamaks
Wenyin Wei, Liang Liao, Alexander Knieps +3
In strictly axisymmetric configurations of tokamaks, field-line tracing reduces from a three-dimensional ODE system to a two-dimensional one, where Poincaré-Bendixson theorem appli…
Observation and characterisation of trapped electron modes in Wendelstein 7-X
A. Krämer-Flecken, J. H. E. Proll, G. Weir +17
In the past, quasi coherent modes were reported for nearly all tokamaks. The general definition describes modes as quasi coherent when the magnitude squared coherence is in the ran…
On the shifts of stable and unstable manifolds of a hyperbolic cycle under perturbation
Wenyin Wei, Jiankun Hua, Alexander Knieps +1
Stable and unstable manifolds, originating from hyperbolic cycles, fundamentally characterize the behaviour of dynamical systems in chaotic regions. This letter demonstrates that t…
On the shifts of orbits and periodic orbits under perturbation and the change of Poincaré map Jacobian of periodic orbits
Wenyin Wei, Alexander Knieps, Yunfeng Liang
Periodic orbits and cycles, respectively, play a significant role in discrete- and continuous-time dynamical systems (i.e. maps and flows). To succinctly describe their shifts when…
Deformation of invariant tori under perturbation
Wenyin Wei, Jiankun Hua, Alexander Knieps +1
This study extends the functional perturbation theory~(FPT) of dynamical systems, which was initially developed for investigating the shifts of magnetic field line trajectories wit…