Theory of ballooning-mirror instabilities for anisotropic pressure plasmas in the magnetosphere

Cheng, C Z; Qian, Q

doi:10.2172/10190161

Cited by 34 publications

(74 citation statements)

References 21 publications

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“…Note that the unstable perturbation begins quite early at • 11:51:30 UT, ~ 1.5 min before the onset of current disruption. We have further confirmed that before onset the perturbation is in a linear growth phase because the relative wave phases of the three magnetic field components are in agreement with the wave structure of the linear ballooning instability [Cheng and Qian, 1994]. It is interesting to note that there is almost no magnetic field fluctuation before the low frequency instability was observed.…”

Section: Low-frequency Perturbationsupporting

confidence: 80%

Kinetic ballooning instability for substorm onset and current disruption observed by AMPTE/CCE

Cheng

Lui

1998

Geophysical Research Letters

164

170

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(102 -103). The waveion magnetic drift resonance effect produces a perturbed resonant ion velocity distribution centered at a duskward velocity roughly equal to the average ion magnetic drift velocity. This perturbed ion distribution explains the enhanced duskward ion flux during the explosive growth phase and can excite higher frequency instabilities (such as the cross-field current instability).

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Section: Low-frequency Perturbationsupporting

confidence: 80%

Kinetic ballooning instability for substorm onset and current disruption observed by AMPTE/CCE

Cheng

Lui

1998

Geophysical Research Letters

164

170

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“…Here the value of β is more restrictive since actual macroscopic structures in the plasma may change. For example, in this category are hydromagnetic instabilities in the ring current plasma such as the drift‐mirror instability [ Lanzerotti et al , ; Hasegawa , ], and the ballooning (or drift‐Alfven) instability [ Cheng and Qian , ]. Drift‐mirror instabilities involve compressional waves which usually require high‐ β values (i.e., β > 1).…”

Section: Introductionmentioning

confidence: 99%

Climatology of high‐β plasma measurements in Earth's inner magnetosphere

et al. 2017

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Since their launch in August 2012, the Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instruments on the NASA Van Allen Probes spacecraft have been making continuous high‐resolution measurements of Earth's ring current plasma environment. After a full traversal through all magnetic local times, a climatology (i.e., a survey of observations) of high‐beta (β) plasma events (defined here as β > 1) as measured by the RBSPICE instrument in the ∼45 keV to ∼600 keV proton energy range in the inner magnetosphere (L < 5.8) has been constructed. In this paper we report this climatology of such high‐β plasma occurrences, durations, and their general characteristics. Specifically, we show that most high‐β events in the RBSPICE energy range are associated with postdusk/premidnight sector particle injections or plasma patches and can last from minutes to hours. While most of these events have a β less than 2, there are a number of observations reaching β greater than 4. Other observations of particular note are high‐β events during relatively minor geomagnetic storms and examples of very long duration high‐β plasmas. We show that high‐β plasmas are a relatively common occurrence in the inner magnetosphere during both quiet and active times. As such, the waves generated by these plasmas may have an underappreciated role in the inner magnetosphere, and thus the study of these plasmas and their instabilities may be more important than has been currently addressed.

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“…There are several interesting but non‐trivial extensions to the present work, some of which are planned for future papers. Within the linear domain, we can include magnetic compression via finite δ B ∥ , which is expected [CH91; Cheng and Qian , 1994] to be important for high β. More detailed studies of the energetic particle modes should be interesting, especially for high‐β anisotropic equilibria.…”

Section: Resultsmentioning

confidence: 99%

Kinetic theory of geomagnetic pulsations: 4. Hybrid gyrokinetic simulation of drift‐bounce resonant excitation of shear Alfvén waves

Dettrick¹

2003

J. Geophys. Res.

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[1] A one-dimensional linear hybrid gyrokinetic-magnetohydrodynamic df particle in cell simulation code is developed to study the detailed mechanisms of energetic particle driftbounce resonant destabilization of Alfvén modes in the ring-current region of the magnetosphere. The model plasma is composed of a cold (10-100eV) component which provides inertia plus a tenuous energetic ($10 keV) ''ring-current'' component which provides both resonant destabilization and compressional stabilization of MHD modes. Full kinetic effects such as finite Larmor radii and particle magnetic bounce and precessional drift motions are retained nonperturbatively. A simple finite b dipolar equilibrium model is assumed (b is the ratio between plasma and magnetic pressures). Simulations show excellent agreement with earlier perturbative analyses. Results show that when the energetic ion thermal velocity is super-Alfvénic, the ions destabilize both odd and even parity shear Alfvén MHD modes via the drift-bounce resonances. The growth rates of the resulting modes scale linearly with plasma b. The most unstable of these modes are found to be drift-bounce resonance destabilized modes with odd parity, with wave numbers such that k ? r % 0.5 at the equator (r is the energetic ion Larmor radius). The destabilization typically occurs at a critical wave number k ? r % 0.3. When the wave number is close to this critical value and the plasma b is close to the ideal MHD critical value, the mode frequency is determined by the energetic particle dynamics, similar to the energetic particle modes (EPMs) observed in laboratory fusion plasma experiments. When the energetic particles have Alfvénic or sub-Alfvénic thermal velocity, they contribute to damping of the MHD modes via the bounce resonance.

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Theory of ballooning-mirror instabilities for anisotropic pressure plasmas in the magnetosphere

Cited by 34 publications

References 21 publications

Kinetic ballooning instability for substorm onset and current disruption observed by AMPTE/CCE

Kinetic ballooning instability for substorm onset and current disruption observed by AMPTE/CCE

Climatology of high‐β plasma measurements in Earth's inner magnetosphere

Kinetic theory of geomagnetic pulsations: 4. Hybrid gyrokinetic simulation of drift‐bounce resonant excitation of shear Alfvén waves

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