Hybrid simulations of quasineutral phenomena in magnetized plasma

Byers, J. A.; Cohen, B. I.; Condit, W. C.; Hanson, J.D.

doi:10.1016/0021-9991(78)90016-5

Cited by 98 publications

(30 citation statements)

References 13 publications

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“…Hybrid-kinetic method.-By treating electrons as an isothermal massless fluid, the hybrid method removes electron kinetic scales, plasma oscillations, and light waves from the Vlasov-Maxwell equations, reducing simulation cost while retaining kinetic ion dynamics [25,26]. The equations consist of (i) the Vlasov equation for the ion distribution function f i ðx; v; tÞ,…”

mentioning

confidence: 99%

Kinetic Simulations of the Interruption of Large-Amplitude Shear-Alfvén Waves in a High- β Plasma

et al. 2017

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Using two-dimensional hybrid-kinetic simulations, we explore the nonlinear "interruption" of standing and traveling shear-Alfvén waves in collisionless plasmas. Interruption involves a self-generated pressure anisotropy removing the restoring force of a linearly polarized Alfvénic perturbation, and occurs for wave amplitudes δB ⊥ =B 0 ≳ β −1=2 (where β is the ratio of thermal to magnetic pressure). We use highly elongated domains to obtain maximal scale separation between the wave and the ion gyroscale. For standing waves above the amplitude limit, we find that the large-scale magnetic field of the wave decays rapidly. The dynamics are strongly affected by the excitation of oblique firehose modes, which transition into long-lived parallel fluctuations at the ion gyroscale and cause significant particle scattering. Traveling waves are damped more slowly, but are also influenced by small-scale parallel fluctuations created by the decay of firehose modes. Our results demonstrate that collisionless plasmas cannot support linearly polarized Alfvén waves above δB ⊥ =B 0 ∼ β −1=2 . They also provide a vivid illustration of two key aspects of low-collisionality plasma dynamics: (i) the importance of velocity-space instabilities in regulating plasma dynamics at high β, and (ii) how nonlinear collisionless processes can transfer mechanical energy directly from the largest scales into thermal energy and microscale fluctuations, without the need for a scale-by-scale turbulent cascade.

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confidence: 99%

Kinetic Simulations of the Interruption of Large-Amplitude Shear-Alfvén Waves in a High- β Plasma

et al. 2017

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“…The two-dimensional hybrid code is similar to that used by Omidi et al [1994], and uses a predictorcorrector method to solve for the electromagnetic fields [Byers et al, 1978]. The simulation system is set in the At the start of the run the simulation plasma consists of a flux of ions moving in the positive ß direction and a co-moving, neutralizing, massless electron fluid.…”

Section: Shock Structurementioning

confidence: 99%

Wave and ion evolution downstream of quasi‐perpendicular bow shocks

McKean¹,

Omidi²,

Krauss‐Varban³

1995

J. Geophys. Res.

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Distribution functions of ions heated in quasi‐perpendicular bow shocks have a large perpendicular temperature anisotropy that provides free energy for the growth of Alfvén ion cyclotron (AIC) waves and mirror waves. Both types of waves have been observed in the Earth's magnetosheath downstream of quasi‐perpendicular shocks. The question of whether these waves are produced at the shock and convected downstream or whether they are produced locally in the magnetosheath has not yet been answered. If the latter were true, then under most magnetosheath conditions AIC waves should dominate the wave activity, yet frequently mirror waves either dominate or are competitive with the AIC mode. We address this question by using two‐dimensional hybrid simulations to give a self‐consistent description of the evolution of the wave spectra downstream of quasi‐perpendicular shocks. Both mirror and AIC waves are identified in the simulated magnetosheath. They are generated at or near the shock front and convected away from it by the sheath plasma. Near the shock, the waves have a broad spectrum, but downstream of the shock, shorter‐wavelength modes are heavily damped and only longer‐wavelength modes persist. The characteristics of these surviving modes can be predicted with reasonable accuracy by linear kinetic theory appropriate for downstream conditions. Throughout the downstream region, the power in compressive magnetic oscillations is of the same order as the power in transverse oscillations. We also follow the evolution of the ion distribution function. The shocked ions that provide the free energy for wave growth have a two‐component distribution function: a core population of directly transmitted ions and a smaller halo of initially reflected ions that contains the bulk of the free energy. The halo is initially gyrophase‐bunched and extremely anisotropic. Within a relatively short distance downstream of the shock (of the order of 10 ion inertial lengths), wave‐particle interactions remove these features from the halo and reduce the anisotropy of the distribution to near‐threshhold levels for the mirror and AIC instabilities. A similar evolution has been observed for ions at the Earth's bow shock.

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“…Many plasma models treat either the ions or the electrons as a fluid in local thermodynamic equilibrium while retaining the kinetic aspects of the other component [1,2]. Such models have been applied to a variety of physical systems: from fast electron transport in intense laser-plasma interactions [3] to fast ignition [4] and very recently to coronal mass ejections [5].…”

Section: Introductionmentioning

confidence: 99%

A Monte-Carlo method for coulomb collisions in hybrid plasma models

Sherlock

2008

Journal of Computational Physics

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Hybrid simulations of quasineutral phenomena in magnetized plasma

Cited by 98 publications

References 13 publications

Kinetic Simulations of the Interruption of Large-Amplitude Shear-Alfvén Waves in a High- β Plasma

Kinetic Simulations of the Interruption of Large-Amplitude Shear-Alfvén Waves in a High- β Plasma

Wave and ion evolution downstream of quasi‐perpendicular bow shocks

A Monte-Carlo method for coulomb collisions in hybrid plasma models

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