Observation of fluctuation-driven particle flux reduction by low-frequency zonal flow in a linear magnetized plasma

2015 ◽  
Vol 22 (1) ◽  
pp. 012306 ◽  
Author(s):  
R. Chen ◽  
J. L. Xie ◽  
C. X. Yu ◽  
A. D. Liu ◽  
T. Lan ◽  
...  
Keyword(s):  
Particle Flux ◽  
Low Frequency ◽  
Zonal Flow ◽  
Magnetized Plasma

scholarly journals Electron acoustic solitons in the Earth's magnetotail

2004 ◽  
Vol 11 (2) ◽  
pp. 215-218 ◽  
Author(s):  
S. G. Tagare ◽  
S. V. Singh ◽  
R. V. Reddy ◽  
G. S. Lakhina
Keyword(s):  
Electron Beam ◽  
Small Amplitude ◽  
Low Frequency ◽  
Frequency Component ◽  
Magnetized Plasma ◽  
Cold Electron ◽  
Ion Plasma ◽  
Electron Acoustic ◽  
Two Temperature ◽  
Perpendicular Polarization

Abstract. Small amplitude electron - acoustic solitons are studied in a magnetized plasma consisting of two types of electrons, namely cold electron beam and background plasma electrons and two temperature ion plasma. The analysis predicts rarefactive solitons. The model may provide a possible explanation for the perpendicular polarization of the low-frequency component of the broadband electrostatic noise observed in the Earth's magnetotail.

Multiple Timescales of the Southern Annular Mode

2021 ◽  
Author(s):  
Qiuyan Zhang ◽  
Yang Zhang ◽  
Zhaohua Wu
Keyword(s):  
Seasonal Variability ◽  
Low Frequency ◽  
Austral Summer ◽  
Zonal Flow ◽  
Southern Annular Mode ◽  
Multiple Timescales ◽  
Annular Mode ◽  
Flow Interactions ◽  
The Cross ◽  
Sst Anomalies

<p>Using the ensemble empirical mode decomposition (EEMD) method, this study systematically investigates the multiple timescales of the Southern Annular Mode (SAM) and identifies their relative contributions to the low-frequency persistence of SAM. Analyses show that the subseasonal sustaining of SAM mainly depends on the contribution of longer-timescale variabilities, especially the cross-seasonal variability. When subtracting the cross-seasonal variability from the SAM, the positive covariance between the eddy and zonal flow, which is suggested the positive eddy feedback in SAM, disappears. Composite analysis shows that only with strong cross-seasonal variability, the meridional shift of zonal wind, eddy momentum forcing and baroclinicity anomalies can be maintained for more than 20 days, mainly resulting from the longer-timescale (especially the cross-seasonal timescale) eddy-zonal flow interactions. This study further suggests that the dipolar sea surface temperature (SST) anomalies in the mid latitude of Southern Hemisphere (SH) is a possible cause for the cross-seasonal variability. Analysis shows that about half of the strong cross-seasonal timescale events are accompanied by evident dipolar SST anomalies, which mostly occur in austral summer. The cross-seasonal dependence of the eddy-zonal flow interactions suggests the longer-timescale (especially the cross-seasonal timescale) contribution cannot be neglected in subseasonal prediction of SAM.</p>

Observations of radially elongated particle flux induced by streamer in a linear magnetized plasma

2019 ◽  
Vol 26 (4) ◽  
pp. 042306 ◽  
Author(s):  
F. Kin ◽  
A. Fujisawa ◽  
K. Itoh ◽  
Y. Kosuga ◽  
M. Sasaki ◽  
...  
Keyword(s):  
Particle Flux ◽  
Magnetized Plasma

Turbulent diffusion in two-dimensional, strongly magnetized plasmas

1985 ◽  
Vol 34 (1) ◽  
pp. 77-94 ◽  
Author(s):  
H. L. Pécseli ◽  
T. Mikkelsen
Keyword(s):  
Turbulent Transport ◽  
Low Frequency ◽  
Two Dimensions ◽  
Magnetized Plasma ◽  
Two Dimensional ◽  
Drift Wave Turbulence ◽  
Field Fluctuations ◽  
The Mean ◽  
Wavenumber Spectrum ◽  
Convective Cells

Particle diffusion is investigated in a strictly two-dimensional collisionless guiding-centre model for a strongly magnetized plasma. An analytical expression is presented for the entire time variation of the mean square test-particle displacement in the limit of low-frequency, strongly turbulent, electric field fluctuations. The analysis relies on an explicit integral expression for the Lagrangian autocorrelation function in terms of the Eulerian wavenumber spectrum and a time-varying weight function. Bohm diffusion is discussed by means of a simple model spectrum. The analysis applies for turbulent transport associated with electrostatic convective cells, magnetostatic cells and drift wave turbulence with the assumption of local homogeneity and isotropy in two dimensions.

Flows in a rotating spherical shell: the equatorial case

1994 ◽  
Vol 276 ◽  
pp. 233-260 ◽  
Author(s):  
A. Colin de Verdière ◽  
R. Schopp
Keyword(s):  
Angular Momentum ◽  
Rotation Axis ◽  
Dynamic Pressure ◽  
Vertical Component ◽  
Low Frequency ◽  
Zonal Flow ◽  
Horizontal Component ◽  
Meridional Plane ◽  
Earth’S Rotation ◽  
Earth's Rotation

It is well known that the widely used powerful geostrophic equations that single out the vertical component of the Earth's rotation cease to be valid near the equator. Through a vorticity and an angular momentum analysis on the sphere, we show that if the flow varies on a horizontal scale L smaller than (Ha)1/2 (where H is a vertical scale of motion and a the Earth's radius), then equatorial dynamics must include the effect of the horizontal component of the Earth's rotation. In equatorial regions, where the horizontal plane aligns with the Earth's rotation axis, latitudinal variations of planetary angular momentum over such scales become small and approach the magnitude of its radial variations proscribing, therefore, vertical displacements to be freed from rotational constraints. When the zonal flow is strong compared to the meridional one, we show that the zonal component of the vorticity equation becomes (2Ω.Δ)u1 = g/ρ0)(∂ρ/a∂θ). This equation, where θ is latitude, expresses a balance between the buoyancy torque and the twisting of the full Earth's vorticity by the zonal flow u1. This generalization of the mid-latitude thermal wind relation to the equatorial case shows that u1 may be obtained up to a constant by integrating the ‘observed’ density field along the Earth's rotation axis and not along gravity as in common mid-latitude practice. The simplicity of this result valid in the finite-amplitude regime is not shared however by the other velocity components.Vorticity and momentum equations appropriate to low frequency and predominantly zonal flows are given on the equatorial β-plane. These equatorial results and the mid-latitude geostrophic approximation are shown to stem from an exact generalized relation that relates the variation of dynamic pressure along absolute vortex lines to the buoyancy field. The usual hydrostatic equation follows when the aspect ratio δ = H/L is such that tan θ/δ is much larger than one. Within a boundary-layer region of width (Ha)1/2 and centred at the equator, the analysis shows that the usually neglected Coriolis terms associated with the horizontal component of the Earth's rotation must be kept.Finally, some solutions of zonally homogeneous steady equatorial inertial jets are presented in which the Earth's vorticity is easily turned upside down by the shear flow and the correct angular momentum ‘Ωr2cos2(θ)+u1rCos(θ)’ contour lines close in the vertical–meridional plane.

Low-frequency fluctuations in a pure toroidal magnetized plasma

Pramana ◽  
2009 ◽  
Vol 73 (6) ◽  
pp. 1073-1086 ◽  
Author(s):  
P. K. Sharma ◽  
R. Singh ◽  
D. Bora
Keyword(s):  
Low Frequency ◽  
Magnetized Plasma ◽  
Frequency Fluctuations

Spatiotemporal structure of low frequency waves in a magnetized plasma device

2003 ◽  
Vol 314 (1-2) ◽  
pp. 163-167 ◽  
Author(s):  
M. Matsukuma ◽  
Th. Pierre ◽  
A. Escarguel ◽  
D. Guyomarc'h ◽  
G. Leclert ◽  
...  
Keyword(s):  
Low Frequency ◽  
Magnetized Plasma ◽  
Spatiotemporal Structure ◽  
Plasma Device ◽  
Low Frequency Waves
Sign in / Sign up

Export Citation Format

Share Document