Warm electromagnetic lower hybrid wave dispersion relation

Abstract

Lower hybrid (LH) waves can interact resonantly with both electrons and ions transferring energy between the species. For this reason the properties of LH waves are of interest. Most treatments of LH waves include either electromagnetic (EM) or warm plasma effects but not both. Here a new analytic dispersion relation for LH waves, including both EM and warm plasma effects, is derived and shown to be more consistent than the previous analytic dispersion relations with numerical results. These comparisons show a very good agreement of the real part of the frequency and reasonable agreement of the imaginary part for a wide range of parameters. It is found that ion magnetization effects, which have been neglected in all previous analytic treatments of LH waves, are surprisingly important. When ion magnetization effects become important the continuous LH mode breaks up into a series of segments of ion Bernstein modes.

Parametric decay instability near the upper hybrid resonance in magnetically confined fusion plasmas

“…which describes so-called warm LH waves. The above dispersion relation was obtained in [1] and is similar to the one used by [2] for ω 2 pe ω 2 ce and the electrostatic version given by [52] for ω 2 pe ω 2…”

“…The present paper is mainly concerned with highorder pure ion Bernstein waves, leading to frequency shifts on the order of ω pi (∼ 1 GHz in the ASDEX Upgrade main plasma), where χ i (k, ω) may be evaluated in the limit of Re(ω) ω ci and b i 1; remember that ω 2 pi /ω 2 ci = [m i /(Z i m e )]ω 2 pe /ω 2 ce in a simple plasma, so ω ci ω pi for ω pe ∼ |ω ce |. Here, the basic behaviour can be obtained by considering the ions to be unmagnetised, since their trajectories are essentially straight lines on the relevant temporal and spatial scales (respectively, 1/ω 1 ∼ 1/ω pi ∼ 200 ps and 1/k ⊥ ∼ r Le / √ b e ∼ 30 µm near the UHR in the considered ASDEX Upgrade discharge), although the details at integer values of ω ci and interpretation of the Landau damping involve some subtleties [51,52]. For unmagnetised ions we may insert χ σ (k, ω) from (10) with ν σ ≈ 0, and find…”

The multi-scale nature of the solar wind

“…In the highly-oblique limit (cos 2 θ m e /m p ), the FM/W wave corresponds to the lower-hybrid wave. A useful approximation for its linear dispersion relation in the cold-plasma limit is (Verdon et al, 2009)…”

Physical Interpretation of the Angle-Dependent Magnetic Helicity Spectrum in the Solar Wind: The Nature of Turbulent Fluctuations Near the Proton Gyroradius Scale

“…The Alfvén wave transitions to the ion cyclotron wave (ICW) in the limit of small parallel scales k d i 1 and to the kinetic Alfvén wave (KAW) in the anisotropic limit of small perpendicular scales k ⊥ ρ i 1 and k ⊥ ≫ k . The kinetic fast wave transitions to the whistler wave in the limit of small parallel scales k d i 1 and to the ion Bernstein wave in the limit of small perpendicular scales k ⊥ ρ i 1 and k ⊥ ≫ k (Howes 2009;Verdon et al 2009). In this study we focus on the magnetic helicity signatures of the kinetic Alfvén wave, ion cyclotron wave, and whistler wave.…”