Self-Consistent Dynamolike Activity in Turbulent Plasmas

Bhattacharjee, A.; Hameiri, Eliezer

doi:10.1103/physrevlett.57.206

Cited by 139 publications

(95 citation statements)

References 10 publications

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“…Finally, one should not mix up the concepts we discuss here with the so-called hyper-resistivity (Strauss 1986;Bhattacharjee & Hameiri 1986;Hameiri & Bhattacharjee 1987;Diamond & Malkov 2003), which is another attempt to derive fast reconnection from turbulence within the context of mean-field resistive MHD. The form of the parallel electric field can be derived from magnetic helicity conservation.…”

Section: Alternative Ideas On the Role Of Turbulence In Magnetic Recomentioning

confidence: 99%

Fast Magnetic Reconnection and Spontaneous Stochasticity

Eyink

Lazarían²,

Vishniac

2011

ApJ

186

260

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Magnetic field lines in astrophysical plasmas are expected to be frozen-in at scales larger than the ion gyroradius. The rapid reconnection of magnetic-flux structures with dimensions vastly larger than the gyroradius requires a breakdown in the standard Alfvén flux-freezing law. We attribute this breakdown to ubiquitous MHD plasma turbulence with power-law scaling ranges of velocity and magnetic energy spectra. Lagrangian particle trajectories in such environments become "spontaneously stochastic," so that infinitely many magnetic field lines are advected to each point and must be averaged to obtain the resultant magnetic field. The relative distance between initial magnetic field lines which arrive at the same final point depends upon the properties of two-particle turbulent dispersion. We develop predictions based on the phenomenological Goldreich & Sridhar theory of strong MHD turbulence and on weak MHD turbulence theory. We recover the predictions of the Lazarian & Vishniac theory for the reconnection rate of large-scale magnetic structures. Lazarian & Vishniac also invoked "spontaneous stochasticity," but of the field lines rather than of the Lagrangian trajectories. More recent theories of fast magnetic reconnection appeal to microscopic plasma processes that lead to additional terms in the generalized Ohm's law, such as the collisionless Hall term. We estimate quantitatively the effect of such processes on the inertial-range turbulence dynamics and find them to be negligible in most astrophysical environments. For example, the predictions of the Lazarian & Vishniac theory are unchanged in Hall MHD turbulence with an extended inertial range, whenever the ion skin depth δ i is much smaller than the turbulent integral length or injection-scale L i .

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Section: Alternative Ideas On the Role Of Turbulence In Magnetic Recomentioning

confidence: 99%

Fast Magnetic Reconnection and Spontaneous Stochasticity

Eyink

Lazarían²,

Vishniac

2011

ApJ

186

260

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“…The third term is the hyperresistivity, reÑecting the contribution to due to ! i the gradient of a large-scale current SJT \ [+2StT, where (Boozer 1986 ;Bhattacharjee & Hameiri 1986 ; Bhattacharjee & Yuan 1995). Note that the value of hyperresistivity, being proportional to mean-square potential, is related to the small-scale magnetic energy as St@2T \ where is the typical horizontal scale of b. L bH 2 Sb2T, L bH Thus, the negative magnetic di †usion (second) term and hyperresistivity (third) term are closely linked through the small-scale magnetic energy Sb2T.…”

Section: Fluctuations From Equationsmentioning

confidence: 99%

On Turbulent Reconnection

Kim

Diamond

2001

ApJ

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We examine the dynamics of turbulent reconnection in two-dimensional and three-dimensional reduced MHD by calculating the e †ective dissipation due to coupling between small-scale Ñuctuations and large-scale magnetic Ðelds. Sweet-Parker type balance relations are then used to calculate the global reconnection rate. Two approaches are employedÈquasi-linear closure and an eddy-damped Ñuid model. Results indicate that despite the presence of turbulence, the reconnection rate remains inversely proportional to as in the Sweet-Parker analysis. In two-dimensions, the global reconnection rate is JRe m , shown to be enhanced over the Sweet-Parker result by a factor of magnetic Mach number. These results are the consequences of the constraint imposed on the global reconnection rate by the requirement of mean-square magnetic potential balance. The incompatibility of turbulent Ñuid-magnetic energy equipartition and stationarity of mean-square magnetic potential is demonstrated.

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“…(8) shows that in a Taylor state [25], j /B 0 = constant, the effects of this term are vanishing, so we can say that the hyper-resistive term is driven by departures from a Taylor state. This term is also responsible for toroidal field reversal at the plasma edge in pinches [22]. The remaining two coefficients, the anomalous resistivity Eq.…”

Section: Turbulent Transport Coefficientsmentioning

confidence: 99%

“…in order to make connection to the MHD framework of mean-field [21,22], in which case hyper-resistivity η h is equivalent to the α-term in the dynamo theory, while anomalous resistivity η an to the β-term [23]. In Eq.…”

Section: Theoretical Modelmentioning

confidence: 99%

Turbulent contributions to Ohm's law in axisymmetric magnetized plasmas

Chavdarovski

Gatto

2017

Physics of Plasmas

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Abstract.The effect of magnetic turbulence in shaping the current density in axisymmetric magnetized plasma is analyzed using a turbulent extension of Ohm's law derived from the self-consistent action-angle transport theory. Besides the well-known hyperresistive (helicity-conserving) contribution, the generalized Ohm's law contains an anomalous resistivity term, and a turbulent bootstrap-like term proportional to the current density derivative. The numerical solution of the equation for equilibrium and turbulence profiles characteristic of conventional and advanced scenarios shows that, trough "turbulent bootstrap" effect and anomalous resistivity turbulence can generate power and parallel current which are a sizable portion (about 20 − 25 %) of the corresponding effects associated with the neoclassical bootstrap effect. The degree of alignment of the turbulence peak and the pressure gradient plays an important role in defining the steady-state regime. In fully bootstrapped tokamak, the hyper-resistivity is essential in overcoming the intrinsic limitation of the hollow current profile.

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Self-Consistent Dynamolike Activity in Turbulent Plasmas

Cited by 139 publications

References 10 publications

Fast Magnetic Reconnection and Spontaneous Stochasticity

Fast Magnetic Reconnection and Spontaneous Stochasticity

On Turbulent Reconnection

Turbulent contributions to Ohm's law in axisymmetric magnetized plasmas

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