scholarly journals Inertial Effects on Tearing Instability

2016 ◽  
Vol 3 (3) ◽  
pp. 155-157
Author(s):  
F. E. M. Silveira
Keyword(s):  
Relaxation Time ◽  
Current Density ◽  
Wave Length ◽  
Standard Theory ◽  
Inertial Effects ◽  
Plasma Parameters ◽  
Long Wavelength ◽  
Tearing Modes ◽  
Wavelength Limit ◽  
Tearing Instability

In this work, we explore inertial effects, due to charged species in a resistive plasma, on the tearing instability. The standard theory of tearing modes assumes a long wavelength limit. At shorter wave lengths, inertial effects can become important and the current density flowing in the fluid can acquire a finite relaxation time. The introduction of such a correction into the problem leads to an extension of the standard dispersion relation. In the long wave length limit, we recover the standard scaling of the growth rate γ with the plasma resistivity η, namely γ ≈ η3/5. However, in the short wavelength limit, we find that the scaling of γ with the relevant plasma parameters changes significantly due to the influence of inertia. Notwithstanding, the dependence of γ on the relaxation time of the current density is not determined. In order to achieve such a description, we propose to further rediscuss the problem in the framework of the boundary layer technique.

scholarly journals TEARING MODES GROWTH RATE AMPLIFICATION DUE TO FINITE CURRENT RELAXATION

2017 ◽  
Vol 57 (1) ◽  
pp. 32-37
Author(s):  
Francisco Eugenio Mendonça da Silveira
Keyword(s):  
Growth Rate ◽  
Electron Number Density ◽  
Number Density ◽  
Astrophysical Plasmas ◽  
Long Wavelength ◽  
Tearing Modes ◽  
Wavelength Limit ◽  
Suitable Combination ◽  
Field Lines ◽  
Current Relaxation

In this work, we explore the influence of perturbative wavelengths, shorter than those usually considered, on the growth rate γ of the tearing modes. Thus, we adopt an extended form of Ohm’s law, which includes a finite relaxation time for the current density, due to inertial effects of charged species. In the long wavelength limit, we observe the standard γ of the tearing modes. However, in the short wavelength limit, we show that γ does not depend on the fluid resistivity any longer. Actually, we find out that γ now scales with the electron number density n<sub>e</sub> as γ ~ n<sub>e</sub><sup>−3/2</sup>. Therefore, through a suitable combination of both limiting results, we show that the standard γ can be substantially amplificated, even by moderate shortenings of perturbative wavelengths. Further developments of our theory may contribute to the explanation of the fast magnetic reconnection of field lines, as observed in astrophysical plasmas.

scholarly journals Nonlinear growth of strongly unstable tearing modes

1993 ◽  
Vol 50 (3) ◽  
pp. 477-494 ◽  
Author(s):  
F. L. Waelbroeck
Keyword(s):  
Magnetic Islands ◽  
Long Wavelength ◽  
Tearing Modes ◽  
Nonlinear Growth ◽  
Tearing Instability ◽  
Aspect Ratios ◽  
Secondary Instabilities

Rutherford's theory of the tearing instability is extended to cases where current nonlinearities are important, such as long-wavelength modes in current slabs and the m = 1 instability in tokamaks with moderately large aspect ratios. Of particular interest is the possibility that the associated magnetic islands, as a result of secondary instabilities, have a singular response to the Ohmic diffusion of the current. A family of islands is used to test this possibility; it is found that the response remains bounded.

Activated Prominences; Mechanisms for Activation and Eruption

1979 ◽  
Vol 44 ◽  
pp. 307-313
Author(s):  
D.S. Spicer
Keyword(s):  
Pressure Gradient ◽  
Density Gradient ◽  
Current Density ◽  
Convective Instability ◽  
Tearing Mode ◽  
Magnetic Shear ◽  
Long Wavelength ◽  
Ideal Mhd ◽  
Gradient Change ◽  
Accelerated Particles

A possible relationship between the hot prominence transition sheath, increased internal turbulent and/or helical motion prior to prominence eruption and the prominence eruption (“disparition brusque”) is discussed. The associated darkening of the filament or brightening of the prominence is interpreted as a change in the prominence’s internal pressure gradient which, if of the correct sign, can lead to short wavelength turbulent convection within the prominence. Associated with such a pressure gradient change may be the alteration of the current density gradient within the prominence. Such a change in the current density gradient may also be due to the relative motion of the neighbouring plages thereby increasing the magnetic shear within the prominence, i.e., steepening the current density gradient. Depending on the magnitude of the current density gradient, i.e., magnetic shear, disruption of the prominence can occur by either a long wavelength ideal MHD helical (“kink”) convective instability and/or a long wavelength resistive helical (“kink”) convective instability (tearing mode). The long wavelength ideal MHD helical instability will lead to helical rotation and thus unwinding due to diamagnetic effects and plasma ejections due to convection. The long wavelength resistive helical instability will lead to both unwinding and plasma ejections, but also to accelerated plasma flow, long wavelength magnetic field filamentation, accelerated particles and long wavelength heating internal to the prominence.

scholarly journals Investigation of the long wavelength limit of soliton self-frequency shift in a silica fiber

2018 ◽  
Vol 26 (15) ◽  
pp. 19637 ◽  
Author(s):  
Bo Li ◽  
Mengran Wang ◽  
Kriti Charan ◽  
Ming-jun Li ◽  
Chris Xu
Keyword(s):  
Frequency Shift ◽  
Silica Fiber ◽  
Long Wavelength ◽  
Wavelength Limit

Stationary charged surface configuration of a conducting liquid in the long-wavelength limit

2008 ◽  
Vol 34 (2) ◽  
pp. 97-99 ◽  
Author(s):  
K. E. Bobrov ◽  
G. Sh. Boltachev ◽  
N. M. Zubarev ◽  
O. V. Zubareva
Keyword(s):  
Charged Surface ◽  
Conducting Liquid ◽  
Long Wavelength ◽  
Wavelength Limit ◽  
Surface Configuration

scholarly journals Thermodynamic, structural, transport and surface properties of Pb-Tl liquid alloy

BIBECHANA ◽  
2015 ◽  
Vol 13 ◽  
pp. 100-113 ◽  
Author(s):  
SK Yadav ◽  
LN Jha ◽  
D Adhikari
Keyword(s):  
Liquid Alloy ◽  
Surface Concentration ◽  
Heat Of Formation ◽  
Concentration Fluctuation ◽  
Heat Of Mixing ◽  
Long Wavelength ◽  
Wavelength Limit ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing ◽  
Experimental Values

Thermodynamic properties, such as free energy of mixing, heat of mixing, entropy of mixing, activities and the microscopic structural properties, such as concentration fluctuation in long-wavelength limit and chemical short-range order parameter of Pb-Tl liquid alloy at 773 K have been studied on the basis of regular associated solution model. We have estimated the mole fractions of the complex and the unassociated atoms assuming the existence of  complex as energetically favoured in the liquid state. The compositional contributions of the heat of mixing of the species Pb and Tl and the heat of formation of the compound to the net enthalpy change have also been studied. The transport properties such as, viscosity and the ratio of mutual and intrinsic coefficients have been studied using different approaches. The surface concentration of Tl atoms has been computed and it has been employed to calculate the surface tension of Pb-Tl liquid alloy. Both the theoretical and the experimental values of the concentration fluctuation in long-wavelength limit are found to be less than the ideal value, revealing that the concerned system is hetero-coordinating in nature. The interaction energies are found to be temperature dependent and respective alloy is found to be weakly interacting system. BIBECHANA 13 (2016) 100-113

The Long-wavelength Limit of the Dielectric Function for Dense Plasmas

1999 ◽  
Vol 39 (1-2) ◽  
pp. 77-80 ◽  
Author(s):  
H. Reinholz ◽  
R. Redmer ◽  
G. Röpke ◽  
A. Wierling
Keyword(s):  
Dielectric Function ◽  
Dense Plasmas ◽  
Long Wavelength ◽  
Wavelength Limit
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