The co-excitation of electrostatic ion-cyclotron wave and ion-Bernstein-like wave launched from a grid

【摘要】 Electrostatic ion-cyclotron wave（EICW） and ion-Bernstein wave（IBW） are two typical normal modes of plasma propagating vertically to a magnetic field. These modes satisfy the extreme conditions ω ? k_∥v_te and ω ? k_∥v_te, where ω,k_∥, and v_te are the wave angular frequency, wave number parallel to the magnetic field, and the electron thermal speed. Between these extremities,there exist IBW-like waves that have not been studied. In this paper, the co-excitation of the EICW and IBW-like wave in an experiment is presented. It is shown that, in an argon（Ar）discharge, the EICW appears in the fundamental and second harmonic frequency bands of the ioncyclotron frequency. In contrast, the IBW-like wave appears in the higher harmonic frequency bands and in the case of a relatively strong magnetic field. In a helium（He） discharge, the IBW-like wave is excited in the fundamental frequency band, but the wave behaviour becomes complicated in the harmonic frequency bands. The measured dispersion relations of the excited EICW are in agreement with the results of the fluid and kinetic models in some range of frequencies,but those of the excited IBW-like wave are only in qualitative agreement with the kinetic model of the IBW. This study is important for identifying the IBW-like mode that may have potential application in plasma heating via Landau damping.更多还原

【Abstract】 Electrostatic ion-cyclotron wave（EICW） and ion-Bernstein wave（IBW） are two typical normal modes of plasma propagating vertically to a magnetic field. These modes satisfy the extreme conditions ω ? k_∥v_te and ω ? k_∥v_te, where ω,k_∥, and v_te are the wave angular frequency, wave number parallel to the magnetic field, and the electron thermal speed. Between these extremities,there exist IBW-like waves that have not been studied. In this paper, the co-excitation of the EICW and IBW-like wave in an experiment is presented. It is shown that, in an argon（Ar）discharge, the EICW appears in the fundamental and second harmonic frequency bands of the ioncyclotron frequency. In contrast, the IBW-like wave appears in the higher harmonic frequency bands and in the case of a relatively strong magnetic field. In a helium（He） discharge, the IBW-like wave is excited in the fundamental frequency band, but the wave behaviour becomes complicated in the harmonic frequency bands. The measured dispersion relations of the excited EICW are in agreement with the results of the fluid and kinetic models in some range of frequencies,but those of the excited IBW-like wave are only in qualitative agreement with the kinetic model of the IBW. This study is important for identifying the IBW-like mode that may have potential application in plasma heating via Landau damping.更多还原