Plasma irregularities caused by cycloid bunching of the CRRES G‐2 barium release

Bernhardt, P. A.; Huba, J. D.; Pongratz, M. B.; Simons, Donald G.; Wolcott, John H.

doi:10.1029/92ja00987

Cited by 21 publications

(11 citation statements)

References 40 publications

(22 reference statements)

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“…5, the green ball on the right represents the barium neutrals, which moves with the initial injection velocity and deposits a trail of ions from photoionization; The field-aligned structure at left indicates the barium ions produced earlier. Such configurations were observed in all the releases with a large initial cross-B velocity, 7,18,25 and the simulation result is in good agreement with the observation for CRRES G2 (see Fig. 1 in Ref.…”

Section: Simulation Resultssupporting

confidence: 90%

“…21 The ambient magnetic field B 0 , the initial injection velocity V 0 , and the average radial expansion velocity V R are 5000 nT, 4.59 km/s, and 1.38 km/s, respectively, according to CRRES G2 release. 18 It is assumed that the barium cloud is in thermal equilibrium with the background, and V 0 is perpendicular to B 0 , then the gyroradius of Ba þ is about 100 m, and the Alfv en velocity V A of background plasma is 2440 km/s. Simulations are done by the BATS-R-US (Block Adaptive Tree Solarwind Roe-Type Upwind Scheme) 22 code with a user-defined module to solve the source terms.…”

Section: Model and Simulationmentioning

confidence: 99%

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Three-dimensional, two-species magnetohydrodynamic studies of the early time behaviors of the Combined Release and Radiation Effects Satellite G2 barium release

Xie

Wang

et al. 2014

Physics of Plasmas

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We present a three-dimensional, two-species (Ba þ and H þ ) MHD model to study the early time behaviors of a barium release at about 1 R E like Combined Release and Radiation Effects Satellite G2, with emphasis placed on the three-dimensional evolution of the barium cloud and its effects on the ambient plasma environment. We find that the perturbations caused by the cloud are the combined results of the initial injection, the radial expansion, and the diamagnetic effect and propagate as fast MHD waves in the magnetosphere. In return, the transverse expansion and the cross-B motion of barium ions are constrained by the magnetic force, which lead to a field-aligned striation of ions and the decoupling of these ions from the neutrals. Our simulation shows the formation and collapse of the diamagnetic cavity in the barium cloud. The estimated time scale for the cavity evolution might be much shorter if photoionization time scale and field aligned expansion of barium ions are considered. In addition, our two species MHD simulation also finds the snowplow effect resulting from the momentum coupling between barium ions and background H þ , which creates density hole and bumps in the background H þ when barium ions expanding along the magnetic field lines. V C 2014 AIP Publishing LLC. [http://dx.

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Section: Simulation Resultssupporting

confidence: 90%

Section: Model and Simulationmentioning

confidence: 99%

Three-dimensional, two-species magnetohydrodynamic studies of the early time behaviors of the Combined Release and Radiation Effects Satellite G2 barium release

Xie

Wang

et al. 2014

Physics of Plasmas

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“…(This double structure may not reproduce very well.) It must be noted that the 10-kin separation between the structures is not bunching effects associated with the 440-m ion gyromotion reported by Bernhardt and Huba [1993] for the CRRES G2 release.…”

Section: Ion Cloud Morphologymentioning

confidence: 79%

Optical observations of the early (t < 5 s) ion dynamics of the CRRES G1, G9, and G11A releases

Delamere¹,

Stenbaek‐Nielsen²,

Hampton³

et al. 1996

J. Geophys. Res.

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Video images of the CRRES Gl, G9, and G1lA barium releases made at 400–500 km altitudes over the Caribbean in July 1991 have been analyzed to identify morphological features formed in the very early phases of the releases with the aim of associating specific physical processes with these features. Three features are presented: the observation that the inner edge of the ion cloud is located some distance from the release point along the orbital track (“skidding”); the formation of an elongated striation at the inner edge of the ion cloud and an ion depleted region behind the striation; and the formation of a flat neutral barium disk perpendicular to the magnetic field B that is centered some tens of kilometers from the release point. We are linking these morphological features with effects associated with the polarization of the initially dense ion cloud created by solar UV illumination. A simple physical model of the release and the polarization process is presented. Model predictions are both qualitatively and quantitatively in good agreement with the observations. The skidding distance appears to be controlled by the background ionospheric density and the size of the release; the structure in the early ion cloud is due to electric fields primarily setup and maintained by the polarization of the densest part of the ion cloud; and the neutral disk is formed by charge exchange between counterstreaming ions and neutrals outside the polarized core. For the three releases analyzed, no additional internal plasma processes nor processes coupling the release to the ionosphere appear to be critical for the formation of the observed features in the initial ion cloud.

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“…The expected currents generated by the density striations are also shown. The vertical arrows denote fieldbeen observed in barium releases when the injection velocity exceeds the expansion speed of the cloud[Bernhardt et al, 1993]. In that case, striations are spaced by the component of the injection speed perpendicular to B times the ion gyroperiod.…”

mentioning

confidence: 99%

O⁺ phase bunching and auroral arc structure

Rothwell¹,

Silevitch²,

Block³

et al. 1994

J. Geophys. Res.

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The equations of motion are solved for ions moving in a model electric field that corresponds to the nightside equatorial region of the magnetosphere. The model represents the poleward region of the Harang discontinuity mapped to the magnetosphere. Within this region the model electric field has a constant earthward gradient superimposed on a constant dawn‐to‐dusk electric field. In combination with the earthward drift motion due to the dawn‐to‐dusk field, the electric field gradient introduces an earthward inertia drift, which is proportional to the ion mass and therefore faster for O+ ions than for H+ ions or electrons. It is also found that the entry of the ions into the gradient region causes phase bunching and as a result ion density striations form. The striations are enhanced for more abrupt changes in the electric field gradient, a weaker magnetic field, a stronger cross‐tail electric field and colder O+ ions. The first two conditions apply during the growth phase of a substorm. Using the Tsyganenko (1987) model a minimum electric field gradient value of 1 × 10−9 V/m2 ((1 mV/m)/1000 km) at L = 6‐7 is found. Charge neutrality requires coupling with the ionosphere through electrons moving along magnetic field lines, and such electrons may be the cause of multiple auroral arcs.

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Plasma irregularities caused by cycloid bunching of the CRRES G‐2 barium release

Cited by 21 publications

References 40 publications

Three-dimensional, two-species magnetohydrodynamic studies of the early time behaviors of the Combined Release and Radiation Effects Satellite G2 barium release

Three-dimensional, two-species magnetohydrodynamic studies of the early time behaviors of the Combined Release and Radiation Effects Satellite G2 barium release

Optical observations of the early (t < 5 s) ion dynamics of the CRRES G1, G9, and G11A releases

O⁺ phase bunching and auroral arc structure

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Plasma irregularities caused by cycloid bunching of the CRRES G‐2 barium release

Cited by 21 publications

References 40 publications

Three-dimensional, two-species magnetohydrodynamic studies of the early time behaviors of the Combined Release and Radiation Effects Satellite G2 barium release

Three-dimensional, two-species magnetohydrodynamic studies of the early time behaviors of the Combined Release and Radiation Effects Satellite G2 barium release

Optical observations of the early (t < 5 s) ion dynamics of the CRRES G1, G9, and G11A releases

O+ phase bunching and auroral arc structure

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O⁺ phase bunching and auroral arc structure