Relativistic thermal electron scale instabilities in sheared flow plasma

2016 ◽  
Vol 82 (2) ◽  
Author(s):  
Evan D. Miller ◽  
Barrett N. Rogers
Keyword(s):  
Parameter Space ◽  
Flow Instability ◽  
Skin Depth ◽  
Unstable Region ◽  
Linear Dispersion ◽  
Thermal Electron ◽  
Sheared Flow ◽  
Depth Scale ◽  
Special Case ◽  
Two Fluid

The linear dispersion relation obeyed by finite-temperature, non-magnetized, relativistic two-fluid plasmas is presented, in the special case of a discontinuous bulk velocity profile and parallel wave vectors. It is found that such flows become universally unstable at the collisionless electron skin-depth scale. Further analyses are performed in the limits of either free-streaming ions or ultra-hot plasmas. In these limits, the system is highly unstable in the parameter regimes associated with either the electron scale Kelvin–Helmholtz instability (ESKHI) or the relativistic electron scale sheared flow instability (RESI) recently highlighted by Gruzinov. Coupling between these modes provides further instability throughout the remaining parameter space, provided both shear flow and temperature are finite. An explicit parameter space bound on the highly unstable region is found.

Structure of Alfvén waves at the skin‐depth scale

1994 ◽  
Vol 1 (12) ◽  
pp. 3765-3774 ◽  
Author(s):  
G. J. Morales ◽  
R. S. Loritsch ◽  
J. E. Maggs
Keyword(s):  
Alfven Waves ◽  
Skin Depth ◽  
Alfvén Waves ◽  
Depth Scale

Finite-core hetons: stability and interactions

2000 ◽  
Vol 423 ◽  
pp. 127-154 ◽  
Author(s):  
M. A. SOKOLOVSKIY ◽  
J. VERRON
Keyword(s):  
Parameter Space ◽  
The Other ◽  
Geometrical Parameters ◽  
Stationary States ◽  
Contour Dynamics ◽  
Surgery Technique ◽  
Special Case ◽  
Dynamics Method

The dynamics of vertically compensated two-layer vortices (hetons) with finite cores are examined within the context of the quasi-geostrophic approximation on the f-plane. The two-layer version of the contour dynamics method is used, and complemented by the so-called contour surgery technique. Special attention is paid to two-heton interactions when the initial locations of the vortex patches are symmetrical. A classification of the different regimes observed is made according to external parameters, namely geometrical parameters and stratification. In this parameter space, novel quasi-stationary states resulting from collisions between two hetons may be observed: (i) formation of a configuration consisting of two-layer vortices moving in opposite directions and, as a special case, a configuration analogous to the ‘klapstoss’ billiard shot, (ii) absorption of one heton by the other and subsequent movement of a new dipole, (iii) formation of two-layer dipoles, larger than the original hetons, associated with rotating peripheral satellite eddies in their wakes. Some of these results may have implications for the analysis of mesoscale vortices in the ocean.

The scaling of reconnection rate in the two-fluid model of a collisionless forced magnetic reconnection

2013 ◽  
Vol 79 (5) ◽  
pp. 519-524 ◽  
Author(s):  
M. HOSSEINPOUR
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Fluid Model ◽  
Skin Depth ◽  
Main Stage ◽  
Field Reversal ◽  
Two Fluid Model ◽  
Hall Reconnection ◽  
Forced Magnetic Reconnection ◽  
Two Fluid

AbstractThe two-fluid model of collisionless forced magnetic reconnection is considered where breaking the frozen-in flow constraint for magnetic field lines is provided by electron inertia. Following the Taylor problem, a tearing stable slab of plasma with a magnetic field reversal is subjected to a small-amplitude boundary perturbation that drives magnetic reconnection at the neutral surface within the plasma. It has been shown that unlike the resistive regime, where the two-fluid magnetohydrodynamics (MHD) description reduces to the single-fluid MHD regime at sufficiently small values of the ion inertial skin-depth, di ≡ c/ωpi (with ωpi as the ion plasma frequency), there is no room for the single-fluid MHD reconnection in the collisionless case, even at very small values of di. Meanwhile, contradictory to the resistive reconnection, the rate of collisionless Hall reconnection always decreases with time as reconnection proceeds. In particular, in the main stage of Hall reconnection, when transition between two main equilibria states are taking place, it scales as t−1/2.

scholarly journals Energetic Solar Electrons – Whistler Bootstrap, Magnetic Knots and Small-scale Reconnection

2010 ◽  
Vol 6 (S274) ◽  
pp. 178-181
Author(s):  
Ilan Roth
Keyword(s):  
Skin Depth ◽  
General Question ◽  
Small Scale ◽  
Topological Invariants ◽  
Relativistic Electrons ◽  
Left Behind ◽  
Seed Population ◽  
Depth Scale ◽  
Field Lines ◽  
Coronal Field

AbstractThe (near) relativistic electrons, emanating from the solar corona in long-lasting, gradual events, are generally observed at 1 AU as delayed vs the less energetic, type-III beams. The observations are consistent with the delayed electrons being energized along the stretched post-CME coronal field lines, when the tail of an anisotropic seed population, which is injected in conjunction to the observed radioheliograph bursts, interacts with the self-excited whistler waves (bootstrap mechanism). These bursts indicate efficient processes where suprathermal seed electrons are injected as a result of magnetic reconnection at the marginally stable coronal configuration left behind the emerging CME. The dependence of the bootstrap mechanism on the electron injection raises the general question of the MHD description and its deviation over the small electron skin-depth scale. The similarity between MHD and knot theories allows one to characterize any turbulent magnetic configuration through topological invariants, while deviation over electron skin-depth scale, characterized by the generalized vorticity, which is enhanced due to density inhomogeneity, creates the conditions for the potential injection sites.

Topological selection in stratified fluids: an example from air–water systems

2014 ◽  
Vol 743 ◽  
pp. 534-553 ◽  
Author(s):  
R. Camassa ◽  
S. Chen ◽  
G. Falqui ◽  
G. Ortenzi ◽  
M. Pedroni
Keyword(s):  
Variational Principles ◽  
Selection Process ◽  
Momentum Conservation ◽  
Conserved Quantities ◽  
Translational Invariance ◽  
Ideal Fluids ◽  
Horizontal Momentum ◽  
Selection Mechanisms ◽  
Special Case ◽  
Two Fluid

AbstractTopologically non-trivial configurations of stratified fluid domains are shown to generate selection mechanisms for conserved quantities. This is illustrated within the special case of a two-fluid system when the density of one of the fluids limits to zero, such as in the case of air and water. An explicit example is provided, demonstrating how the connection properties of the air domain affect total horizontal momentum conservation, despite the apparent translational invariance of the system. The correspondence between this symmetry and the selection process is also studied within the framework of variational principles for stratified ideal fluids.

Small amplitude waves in a hot relativistic two-fluid plasma

1978 ◽  
Vol 20 (2) ◽  
pp. 281-287 ◽  
Author(s):  
S. Hyun ◽  
C. F. Kennel
Keyword(s):  
Phase Velocity ◽  
Parameter Space ◽  
Small Amplitude ◽  
Relativistic Plasma ◽  
Fluid Approximation ◽  
Wave Phase ◽  
Linear Waves ◽  
Wave Phase Velocity ◽  
Two Fluid ◽  
Two Fluid Plasma

Using the two-fluid approximation, we summarize properties of linear waves in an unbounded magnetized relativistic plasma by a parameter-space diagram of wave phase velocity: a relativistic plasma pond.

scholarly journals Two-fluid tokamak equilibria with reversed magnetic shear and sheared flow

2007 ◽  
Vol 73 (3) ◽  
pp. 347-366 ◽  
Author(s):  
G. POULIPOULIS ◽  
G. N. THROUMOULOPOULOS ◽  
H. TASSO
Keyword(s):  
Pressure Gradient ◽  
Electric Fields ◽  
Fluid Model ◽  
Radial Electric Field ◽  
Plasma Phys ◽  
Magnetic Shear ◽  
Sheared Flow ◽  
Order Of Magnitude ◽  
The Impact ◽  
Two Fluid

AbstractThe aim of the present work is to investigate tokamak equilibria with reversed magnetic shear and sheared flow, which may play a role in the formation of internal transport barriers (ITBs), within the framework of the two-fluid model in cylindrical geometry. The study is based on exact self-consistent solutions by means of which the impact of the magnetic shear, s, and the ‘toroidal’ (axial) and ‘poloidal’ (azimuthal) ion velocity components, viz and viθ, on the radial electric field, Er, its shear, |dEr/dr|, and the shear of the E×B velocity, ωE×B≡|d/dr(E× B/B2)|, is examined. For a wide parametric regime of experimental concern it turns out that the contributions of the viz, viθ and pressure gradient (∇ Pi) terms to Er, |Er′| and ωE×B are of the same order of magnitude. The contribution of the ∇ Pi term is missing in the framework of magnetohydrodynamics (MHD) (G. Poulipoulis et al. 2004 Plasma Phys. Control. Fusion46, 639). The impact of s on ωE×B through the ∇ Pi term is stronger than that through the velocity terms; in particular for constant Bz the ion pressure gradient contribution to ωE×B at the point where dEr/dr=0 scales as (1−s)(2−s), whereas the ion flow contributions to ωE×B scale as (1−s). The results indicate that, like MHD, the magnetic shear and the sheared toroidal and poloidal velocities act synergetically in producing electric fields and therefore ωE×B profiles compatible with the ones observed in discharges with ITBs; owing to the ∇ Pi term, however, the impact of s on Er, |Er′| and ωE×B is stronger than that in MHD.

The surface impedance of superconductors and normal metals at high frequencies V. Analysis of experimental results for superconducting tin

1950 ◽  
Vol 203 (1073) ◽  
pp. 195-210 ◽  
Keyword(s):  
Fluid Model ◽  
Skin Depth ◽  
Experimental Results ◽  
High Frequencies ◽  
Special Cases ◽  
Normal Metals ◽  
Satisfactory Account ◽  
Surface Reactance ◽  
Two Fluid Model ◽  
Two Fluid

For the purpose of analyzing the experimental results presented in the earlier parts of this series the concept of a two-parameter two-fluid model of superconductivity is developed, and it is shown that current theories are special cases of this model. The greater part of the analysis is carried out by dimensional arguments based on the model. The part played by the resistive mechanism in modifying the surface reactance is discussed, and it is concluded that the temperature variation of inductive skin depth at the lowest temperatures represents the variation of the superconducting penetration depth. The dependence of this quantity on crystal orientation is different from what would be expected from the theory of London & London, and it is concluded that there may be grounds for doubting the validity of this theory, or at least its application to high-frequency phenomena. The dimensional analysis of the resistance measurements shows them to fit reasonably well into the framework of the two-fluid model, but the implications of the particular form of the model which is deduced from the results are in disagreement with other general considerations. In particular, the resistance is found to vary too slowly with frequency and with the fraction of normal electrons. The conclusion is drawn that the two-fluid model as formulated here does not give a satisfactory account of the phenomena, and that the detailed theories which belong to this category therefore also fail.

scholarly journals Instability Analysis of Supercritical CO2 during Transportation and Injection in Carbon Capture and Storage Systems

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2040 ◽  
Author(s):  
Il Min ◽  
Seong-Gil Kang ◽  
Cheol Huh
Keyword(s):  
Critical Region ◽  
Flow Instability ◽  
Density Wave ◽  
Sudden Change ◽  
Carbon Capture And Storage ◽  
Subcritical State ◽  
Unstable Region ◽  
Injection Process ◽  
Co2 Flow ◽  
Co2 Transportation

Captured CO2 is in a subcritical state, whereas CO2 deep underground is in a supercritical state because of the high geothermal heat and pressure. The properties of CO2 can change rapidly at the critical point and in the near-critical region during the transportation and injection process. This study aims to identify the instabilities in the CO2 flow in these regions, along with the causes and effects, during the transportation and injection process, and propose relevant design specifications. Thus, the critical points and near-critical region of CO2 flow were numerically analyzed. The unstable region is presented in terms of temperature and pressure ranges, and the changes in the CO2 properties in this region were analyzed. In the unstable region, the sudden change in density was similar to the density wave oscillation of a two-phase flow. The CO2 stability map we obtained and the stability map of supercritical water show similar trends. Flow instability was also found to occur in standard CO2 transportation pipelines. We demonstrate that flow instability in CO2 transportation and injection systems can be avoided by maintaining the proposed conditions.

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