2018/11/29 by Lei Chang · 1 citation
Physics and Astronomy · #Atomic physics #Computational physics #Condensed matter physics #Dispersion relation #Dust and Plasma Wave Phenomena #Instability #Ionosphere and magnetosphere dynamics #Magnetic confinement fusion research #Magnetic field #Mechanics #Normal mode #Optics #Physics #Plasma #Quantum mechanics #Vibration #Wavelength #physics.plasm-ph
paper · pdf · doi:10.1063/1.5066047
published in Physics of Plasmas 25(12) (American Institute of Physics)
arxiv created 2018/11/29 · openalex publication_date 2018/12/01 · arxiv updated 2021/12/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
To guide the experimental design of a linear plasma device for studying the interaction between energetic ions and Alfvénic gap eigenmode (AGE), this work computes AGE referring to fusion conditions in an ultra-long large plasma cylinder ended with strong magnetic throats for axial confinement of charged particles. It is shown that (i) for uniform equilibrium field between the ending throats, the dispersion relation of the computed wave field agrees well with a simple analytical model for the shear Alfvénic mode and (ii) for periodic equilibrium field with local defect, clear AGE is formed inside the spectral gap for both low and high depths of magnetic throats, although lower depth yields easier observation. The strongest AGE can be on the order of 3.1 × 10−4 to equilibrium field, making it conveniently measurable in experiment. The AGE is a standing wave localized around the defect which is introduced to break the system's periodicity, and its wavelength is twice the system's period, consistent with Bragg's law. The parameter scan reveals that the AGE remains nearly the same when the number of magnetic ripples is reduced from 18 to 8; however, there occurs an upward frequency shift when the depth of magnetic ripples drops from 0.5 to 0.1, possibly due to a flute-like effect: shrinking resonant cavity of the spectral gap.