Experimentally investigate ionospheric depletion chemicals in artificially created ionosphere

Liu, Yu; Cao, Jinxiang; Wang, Jian; Zheng, Zhe; Xu, Liukang; Du, Yinchang

doi:10.1063/1.4754697

Cited by 10 publications

(4 citation statements)

References 20 publications

(22 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

S F_{6} + e \to F + S F_{5}^{-}, S F_{6} + e \to S F_{6}^{-}

, are answerable for the reduction of the electron density. Figure a shows the electron density n e decreased from 8×10 8 cm −3 to 1×10 8 cm −3 in the time scales of microsecond, and the decrease of n e ( r 1 ), n e ( r 2 ), and n e ( r 3 ) were measured by probe 5, probe 6, and probe 7, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…In the work, we have experimentally investigated the coherent structure generated in the ionospheric depletion boundary layer. Based upon a previous study [ Liu et al , ], the ionospheric depletion was simulated through releasing depletion chemicals into the surrounding plasmas. Those plasmas were parted into two regions by a boundary layer of width electric scale length.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Coherent structure generated in the boundary layer of a laboratory‐created ionospheric depletion

Liu

Cao

et al. 2014

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

Laboratory experiments have been conducted to simulate the boundary processes of ionospheric depletion. The ionospheric depletion was modeled through releasing depletion chemical (SF6) into the ambient plasmas. These plasmas were segregated into two regions by a boundary layer of width electric scale length. In the localized boundary layer, the electron density decreased sharply that yielded steep density gradients. Meanwhile, the floating potential increased in the time scales of the lower hybrid (LH) period, which produced strong sheared electron flows. The shear frequency ωs=VE/LE, which characterizes the sheared flow, is much larger than the LH frequency ωLH. A coherent structure was observed when the floating potential fluctuations were analyzed using digital spectral analysis techniques. Comparison with the theory indicated that the structure is driven by the electron‐ion hybrid instability which is generated owing to the nonlinear coupling between the electron density gradient and the sheared electron flow. Our results are important to study the early phase nonlinear evolution of the ionospheric depletion, especially in the development of plasma irregularities and turbulence in the boundary layer.

show abstract

S F_{6} + e \to F + S F_{5}^{-}, S F_{6} + e \to S F_{6}^{-}

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Coherent structure generated in the boundary layer of a laboratory‐created ionospheric depletion

Liu

Cao

et al. 2014

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

show abstract

“…In the ionospheric depletion, those primary chemical processes involve electron‐ion recombination, electron attachment, desorption, ion recombination, and charge exchange [ Liu et al , ], and the dissociative electron attachment processes are answerable for the reduction of the electron density. The corresponding processes in the work are as follows:

{SF}_{6} + e \to F + {SF}_{5}^{-}, k_{1} ≃ 1.1 \times 1 0^{- 7} {cm}^{3} s^{- 1}

{CF}_{4} + e \to {CF}_{3}^{-} + F, k_{2} ≃ 4.6 \times 1 0^{- 9} {cm}^{3} s^{- 1}

{CO}_{2} + e \to {CO}^{-} + O, k_{3} = 9.4 \times 1 0^{- 10} {cm}^{3} s^{- 1}

k is the reaction rate of the corresponding dissociative electron attachment process.…”

Section: Resultsmentioning

confidence: 99%

“…Shown as the dashed line, the fractional n e varies from 0.68 to 0.92, and the peak value is larger than that of the SF 6 . The most possible reason is that primary negative ion of CF 4 , F − , is more stable than that of the SF 6 ,

{SF}_{5}^{-}

[ Liu et al , ]. Shown as the dotted line, however, the decrease of electron density attributed to the CO 2 release shows some differences with that of the SF 6 and CF 4 .…”

Section: Resultsmentioning

confidence: 99%

Laboratory investigation of the boundary layer processes of artificially created ionospheric depletion

Cao

et al. 2014

JGR Space Physics

Self Cite

View full text Add to dashboard Cite

Key Points:• We studied the boundary layer processes of ionospheric depletion Abstract In the work, we have experimentally investigated the boundary layer processes of artificially created ionospheric depletions. Those ionospheric depletions were modeled via releasing attachment chemicals, such as SF 6 , CF 4 , and CO 2 , into the ambient plasmas. Boundary layer of width of electric scale length emerged and separated those plasmas into two regions, the ambient plasmas and the negative ions plasmas. In the localized boundary layer, those fluctuations of the electron density and the floating potential were investigated varying with the plasma pressure and the partial pressure of released chemicals. The electron density decreased sharply that yielded steep density gradients ∇n e , and the floating potential increased which generated sheared electron flows. It is found that the magnitude of fluctuating floating potential is proportional to that of the ∇n e . Those fluctuations were analyzed in detail using digital spectra analysis techniques. Vortex-like coherent structures were observed in the fluctuations of electrostatic potentials. These coherent frequencies are sensitive to the mass of the negative ions, and all lie in the lower hybrid range. By comparing the experimental results with theoretical predictions, the modes have been identified as the coherent structures resulting from the electron-ion hybrid instability. Our results are important to study the early phase nonlinear evolution of the ionospheric depletion and also may be applied to the plasma sheet boundary layer in where often encounters the narrow electron density gradients and sheared electron flows.

show abstract

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

et al. 2016

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Experimentally investigate ionospheric depletion chemicals in artificially created ionosphere

Cited by 10 publications

References 20 publications

Coherent structure generated in the boundary layer of a laboratory‐created ionospheric depletion

Coherent structure generated in the boundary layer of a laboratory‐created ionospheric depletion

Laboratory investigation of the boundary layer processes of artificially created ionospheric depletion

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

Contact Info

Product

Resources

About