Fast Zonal Field Dynamo in Collisionless Kinetic Alfven Wave Turbulence

The possibility of fast dynamo action by collisionless kinetic Alfven Wave turbulence is demonstrated. The irreversibility necessary to lock in the generated field is provided by electron Landau damping, so the induced electric field does not vanish with resistivity. Mechanisms for self-regulation of the system and the relation of these results to the theory of alpha quenching are discussed. The dynamo-generated fields have symmetry like to that of zonal flows, and thus are termed zonal fields

Ion-temperature gradient modes affected by helical magnetic field of magnetic islands

"Ion temperature gradient mode (ITG) affected by static magnetic field of magnetic islands is investigated numerically by means of Landau fluid model. The ITG is localized around O-points of magnetic islands, and the localization in poloidal direction is similar to the poloidal localization of toroidal ITG. This is because the helical magnetic field of magnetic islands causes geometrical coupling, and thus Fourier modes that have the same helicity as the islands are coupled together. The strength of coupling is characterized by the square of island width, and it corresponds to the fact that the strength of mode coupling of toroidal ITG is characterized by the inverse aspect ratio of torus in reduced fluid models

Large scale instabilities in the electromagnetic drift wave turbulence and transport

Large scale structures play an important role in self-organization of drift wave turbulence. Large scale perturbations of plasma flow and magnetic field are spontaneously generated in generic electromagnetic drift wave turbulence via the action of Reynolds stress and electromotive force. Initial large scale perturbations are amplifed by positive feedback due to the modulations of wave packets by the shearing effect of the large scale flow and/or by the perturbed large scale magnetic field. As a result, the propagation of small scale wave packets is accompanied by the instability of a low frequency, long wavelength components. Anomalous transport due to drift wave turbulence may also be unstable with respect to the large scale perturbations of plasma profile. In this case the instability occurs as a result of a positive feedback response of the anomalous flux to the large scale variations of plasma temperature

Non-perturbative statistical theory of intermittency in ITG drift wave turbulence with zonal flows

The probability distribution functions (PDFs) of momentum flux and zonal flow formation in ion-temperature-gradient (ITG) turbulence are investigated in two different models. The first is a general five-field model (ni, , Ti, Te, vi) where a reductive perturbation method is used to derive dynamical equations for drift waves and a zonal flow. The second is a reduced two-field model (, Ti) that has an exact non-linear solution (bipolar vortex soliton). In both models the exponential tails of the zonal flow PDFs are found with the same scaling ( ), but with different coefficients cZF. The PDFs of momentum flux is, however, found to be qualitatively different with the scaling (PDF ~ exp{−cMRs}), where s = 2 and s = 3/2 in the five and two-field models, respectively

The need for interdisciplinary research on exponential technologies and sustainability

Technology has a clear influence on the way we live, our culture and how society functions, and last but not least our environment. At a moment when the transformational factor of technology is accelerating at an exponential pace, it is really important to reflect the direction that we want this acceleration to go. In this paper we present some of the factors relevant to this mater: 1) the influence of technology in the society and the environment. 2) The acceleration of some technologies that have tipped and are tipping in the 20th and 21th century. 3) The problem of sustainability when exponential growth is applied to a scenario with lineal growth of resources. 4) The opportunity that represent exponential technologies to fix current humanities difficulties. And 5) technology, exponential or not, is not enough to fix the problems humanity is facing since the problems are embedded in the culture that is fueling the development of the technology. Finally we conclude that the direction that technology will take will be determined ultimately by the society's prevalent culture, and to make an influence in the culture we need not only technologists but also humanists to enter in this kind of discussions and research.Peer ReviewedPostprint (author's final draft