Early time evolution of a chemically produced electron depletion

Scales, W. A.; Bernhardt, P. A.; Ganguli, G.

doi:10.1029/94ja02490

Cited by 22 publications

(17 citation statements)

References 23 publications

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“…A similar instability driven by a sheared electron flow was discussed by Scales et al 22 It should be noted that for SPSC parameters, Re() is much smaller than the frequency near which the usual modified two-stream instability 3 occurs, i.e., the lower hybrid frequency ͓Re()Ӎ LH ϭ pi /ͱ1ϩ pe 2 /⍀ e 2 ͔. Figure 5a shows that Re()/⍀ i varies from 5 to 20 depending on the assumed value of .…”

Section: B Cylindrical Regimesupporting

confidence: 70%

Velocity shear-driven instabilities in a rotating plasma layer

et al. 1998

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The linear stability of a radially localized layer rotating about the cylindrical axis in a magnetized plasma is investigated using an eigenvalue analysis. The eigenvalue equation is solved numerically in a parameter regime characteristic of the Space Physics Simulation Chamber ͑SPSC͒ experiments ͓Amatucci et al., Phys. Rev. Lett. 77, 1978 at the Naval Research Laboratory ͑NRL͒. Four types of instabilities are predicted. They are type-A and type-B Kelvin-Helmholtz instabilities, a transverse current-driven instability, and the inhomogeneous energy density driven instability ͑IEDDI͒. A quantitative comparison between theory and experiment indicates that an experimentally observed fluctuation in a rotating plasma layer is an IEDDI.

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Section: B Cylindrical Regimesupporting

confidence: 70%

Velocity shear-driven instabilities in a rotating plasma layer

et al. 1998

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“…The mechanism for the EIH instability perpendicular to the magnetic field is the electron flow velocity V ey . The local dispersion relation in frequency x and wavenumber k y for this instability has been described previously 22,36 …”

Section: High Frequency Lower-hybrid Shear-driven Instabilitymentioning

confidence: 99%

Model for charged dust expansion across a magnetic field

Scales

2013

Physics of Plasmas

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Plasma fluctuations arise in the boundary region between charged dust clouds and background plasmas. A self-consistent computational model is developed to study expansion of a charged dust cloud across a magnetic field, creation of the inhomogeneous boundary layer and associated processes. The charging of the dust particulates produces a boundary layer and associated ambipolar electric field. This ambipolar field provides a source for low frequency dust acoustic waves in unmagnetized plasmas. A background magnetic field if sufficiently strong, may impact the dust acoustic wave evolution and dust density structures due to E Â B and diamagnetic current generation. The dust acoustic density fluctuation generation across a strong magnetic field (x pe =X ce ( 1) may be suppressed as compared to an unmagnetized dusty plasma, which will be discussed. Fluctuations generated at longer timescales propagating along the dust boundary layer will also be investigated in the lower hybrid and dust lower hybrid frequency range. Applications to space and laboratory plasmas are discussed. V C 2013 AIP Publishing LLC.

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“…The man-made ionospheric depletions have numerous potential applications including affecting the propagation of electromagnetic waves, 30 perturbation of auroral current system, 31 and acting as lens during ionospheric heating experiment. 32 In those active experiments, the injection of attachment chemicals transforms the ambient plasmas into negative ions plasmas, and electron density gradients emerge in the transition region between the two plasmas, 6,7 which results in an inhomogeneous electric fields in the boundary layer. Consequently, this inhomogeneous electric fields causes sheared E × B flows which is answerable for the satellite observation of the broadband electrostatic wave activity.…”

Section: Discussion and Space Applicationmentioning

confidence: 99%

“…6,7 This leads the generation of the electron-ion hybrid (EIH) instability, which is an intermediate frequency instability and considered to play a significant role in the nonlinear evolution of the ionospheric depletion. 34 The doping of negative ions into plasmas can significantly modify the wave dispersion and even excite other new instability and wave mode.…”

Section: -2mentioning

confidence: 99%

Laboratory experiments in the argon plasma perturbed by injections of the electronegative gases

et al. 2016

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In this study, laboratory observations of the perturbations of the magnetic field are reported due to the injection of attachment chemicals (CF4, SF6, and CO2) into argon plasmas. Besides the well-known electron density reduction, we also observed magnetic field perturbation in the experiment. The measured induced voltage Ḃ, which is taken as a proxy of the time-changing electromagnetic field, fluctuates in the boundary layer between the ambient plasmas and negative ions plasmas. Perturbations of the magnetic field were investigated by changing the ambient pressure and ratio of attachment chemicals. The measured Ḃ keeps increasing in these lower pressures; but it no longer increases as the ambient pressure higher than a threshold, e.g., for CF4, SF6, and CO2, the transition pressure is 6Pa, 5Pa and 4Pa, respectively. The magnitude of the Ḃ increase with the change of the ratio of release flow until at higher ratios, e.g., 40%. We transformed these time-sampled data into the frequency domain and found coherent modes with fundamental frequencies lying in the lower hybrid range. In addition, these coherent frequencies show a frequency drift with the increase of the contents of the negative ions. These modes were suggested as the magnetic component of electron-ion hybrid mode. This work has an important application in the study of artificially-created ionospheric depletion which is usually generated by releasing of attachment chemicals in the upper atmosphere.

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Early time evolution of a chemically produced electron depletion

Cited by 22 publications

References 23 publications

Velocity shear-driven instabilities in a rotating plasma layer

Velocity shear-driven instabilities in a rotating plasma layer

Model for charged dust expansion across a magnetic field

Laboratory experiments in the argon plasma perturbed by injections of the electronegative gases

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