Simulation study of Bernstein modes

Kamimura, Tomohiko; Wagner, Tino; Dawson, J. M.

doi:10.1063/1.862354

Cited by 35 publications

(13 citation statements)

References 22 publications

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“…The waves in those bands with ω < ω uh start at frequencies ω ≃ ( n + 1)Ω e at long wavelengths (i.e., small λ e = k ⊥ 2 ρ e 2 /2) and descend to ω ≃ n Ω e when λ e ≫ n . Those waves with ω > ω uh start at ω ≃ n Ω e ascend to a peak near λ e ∝ n , or similarly k ⊥ ρ e ∝ , and then return to ω ≃ n Ω e for λ e ≫ n [ Kamimura et al , 1978]. In these high‐frequency harmonic bands, the modes have a zero group velocity ( v g = ∂ω/∂ k = 0) for λ e ∝ n , and therefore there is a neighboring range of λ e for which the group velocity is small.…”

Section: Introductionmentioning

confidence: 99%

Dispersion characteristics for plasma resonances of Maxwellian and Kappa distribution plasmas and their comparisons to the IMAGE/RPI observations

Viñas

2005

J. Geophys. Res.

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[1] The Radio Plasma Imager (RPI) on the IMAGE satellite stimulates short-range plasma wave echoes and plasma emissions, known as plasma resonances, which are then displayed on plasmagrams. These resonances are used to provide measurements of the local electron density n e and magnetic field strength jBj. The RPI-stimulated resonances are the magnetospheric analog of plasma resonances stimulated by topside ionospheric sounders. These resonances are stimulated at the harmonic of the electron cyclotron frequency f ce , the electron plasma frequency f pe , and the upper-hybrid frequency f uh (where f uh 2 = f pe 2 + f ce 2 ). They are also observed between the harmonics of f ce (i.e., nf ce ) both above and below f pe , where they are known as Qn and Dn resonances, respectively. Calculations of the Qn resonances in the ionospheric environment, based upon a thermal Maxwellian plasma model, provided confidence in the resonance identification between the observations and the estimated values within the experimental errors. However, there is often an apparent difference between these resonances in the magnetospheric environment and those predicted by calculations based on a Maxwellian plasma model. For example, the Qns are often (and perhaps consistently) observed at frequencies slightly lower than expected for a Maxwellian plasma. We present a new set of resonance calculations using the dispersion characteristics of these resonances based upon a nonthermal kappa distribution. We then compare these calculations and those based on a traditional Maxwellian thermal plasma model with the IMAGE/RPI observations. The calculations based on the kappa distribution model appear to resolve the aforementioned frequency discrepancy. In addition, the results also provide insights into the nature of the electron distribution function in the magnetosphere.

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Section: Introductionmentioning

confidence: 99%

Dispersion characteristics for plasma resonances of Maxwellian and Kappa distribution plasmas and their comparisons to the IMAGE/RPI observations

Viñas

2005

J. Geophys. Res.

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“…The neglect of electromagnetic effects in (3.4) is well ,justified for the parameter range of interest [Lampe et al, 19721. Because of the strong Landau damping of Bernstein waves propagating at 8^0, the unstable waves are similarly confined to angles eca e /(2nwe k I X e ) [Kamimura et al, 1978]. At 1 AU, w e /ne =170, so that 0<1 0 for kx e =0.1.…”

Section: Forward and Reverse Shocksmentioning

confidence: 99%

Microscale instabilities in stream interaction regions

Eviatar¹,

Goldstein²

1980

J. Geophys. Res.

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A theoretical investigation of the microstructure of solar wind stream interaction regions is presented. We discuss the role of several electrostatic kinetic instabilities which may be important within the stream interface and the compression region. Inside of 1 AU the interface is likely to be stable against the electrostatic streaming instabilities considered. Between 1 and 2 AU we argue that the interface will excite the magnetized ion‐ion instability. The compression region is also found to be unstable beyond 1 AU, where the modified two‐stream instability, beam‐cyclotron instability, and ion‐acoustic instability will be important in determining the structure of the compressive pulses as they evolve into forward and reverse shocks. We conclude that the modified two‐stream instability and beam‐cyclotron instability predominately play a role in heating the electrons to the threshold for the ion‐acoustic instability. Various electrostatic plasma waves, ranging in frequency from the lower‐hybrid to harmonics of the electron cyclotron frequency, would be produced by these instabilities. Their signature should also be seen by high time resolution measurements of the temperature of the various plasma species.

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“…39 Also evident from the plots of the ion Bernstein wave spectrum was the zero-frequency mode, which is not predicted by linear theory, but has been observed in particle simulations of the electrostatic Bernstein wave. 57 The fluctuation spectrum produced during each simulation was analysed. Both the simulations with kappa velocity distributions as well as the one with the Maxwellian velocity distribution showed good agreement between the measured fluctuation spectrum and the theoretical prediction.…”

Section: Discussionmentioning

confidence: 99%

“…This is known as the zero-frequency mode and is not predicted by linear theory. 57 The zero-frequency mode was observed in the simulations of Kamimura et al 57 for Maxwellian plasmas and is believed to cause particle diffusion in the plasma. 58 Figure 9 shows the low frequency range of electric field intensities for the j e ¼ j i ¼ 4 simulation, whose upper frequency range fluctuations are shown in Figure 4.…”

Section: B Ion Bernstein Wavesmentioning

confidence: 93%

One-dimensional particle-in-cell simulations of electrostatic Bernstein waves in plasmas with kappa velocity distributions

Abdul

Mace

2015

Physics of Plasmas

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Electrostatic Bernstein waves that propagate exactly perpendicularly to a static magnetic field in an electron-ion plasma are investigated using one-and-two-halves dimensional particle-in-cell simulations. An ion-to-electron mass ratio of m i /m e ¼ 100 is used, allowing sufficient separation of the electron and ion time scales while still accounting for the ion dynamics without resorting to exceptionally long simulation run times. As a consequence of the mass ratio used, both the high frequency electron Bernstein wave and the lower frequency ion Bernstein wave are resolved within a single simulation run. The simulations presented here use isotropic three-dimensional kappa velocity distributions as well as the widely used Maxwellian velocity distribution, and the results from using each of these velocity distributions are analysed and compared. The behaviour of the Bernstein waves is found to be significantly dependent on the spectral index, j, of the kappa distribution in all frequency domains of the Bernstein waves. In both the Maxwellian and kappa cases, spectral analysis of the electric field (wave) intensities, as a function of x and k, show very good agreement between the simulation results and the linear dispersion relation for Bernstein waves. This agreement serves to validate the simulation techniques used, as well as the theory of Bernstein waves in plasmas with a kappa velocity distribution. The intensity of the field fluctuations in the simulations containing an abundance of superthermal particles, i.e., where the plasma has a kappa velocity distribution with a low kappa index, is slightly higher compared to the simulations of plasmas with higher kappa values. The plasmas with low kappa values also exhibit a broader region in frequency space of high intensity field fluctuations. V C 2015 AIP Publishing LLC.

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Simulation study of Bernstein modes

Cited by 35 publications

References 22 publications

Dispersion characteristics for plasma resonances of Maxwellian and Kappa distribution plasmas and their comparisons to the IMAGE/RPI observations

Dispersion characteristics for plasma resonances of Maxwellian and Kappa distribution plasmas and their comparisons to the IMAGE/RPI observations

Microscale instabilities in stream interaction regions

One-dimensional particle-in-cell simulations of electrostatic Bernstein waves in plasmas with kappa velocity distributions

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