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The quasilinear particle flux arising from gyrokinetic instabilities is calculated in the electrostatic and collisionless approximation, keeping the geometry of the magnetic field arbitrary. In particular, the flux of electrons and heavy…

Plasma Physics · Physics 2018-08-01 Per Helander , Alessandro Zocco

The generation of large-scale magnetic fields is studied in dilaton electromagnetism in inflationary cosmology, taking into account the dilaton's evolution throughout inflation and reheating until it is stabilized with possible entropy…

Astrophysics · Physics 2008-11-26 Kazuharu Bamba , J. Yokoyama

In this note we argue that the breaking of conformal invariance because of the coupling of a charged scalar field to gravity is not sufficient for the production of seed galactic magnetic fields during inflation.

High Energy Physics - Phenomenology · Physics 2009-10-31 Massimo Giovannini , Mikhail Shaposhnikov

We discuss the implications of causality on a primordial magnetic field. We show that the residual field on large scales is much more suppressed than usually assumed and that a helical component is even more reduced. Due to this strong…

Astrophysics · Physics 2009-11-07 Ruth Durrer , Chiara Caprini

We present a simple model of composite particle tunnelling through a rectangular potential barrier in presence of magnetic field. The exact numerical solution of the problem is provided and the applicability to real physical situations is…

Quantum Physics · Physics 2024-10-22 Bernard Faulend , Jan Dragašević

It is shown that ambipolar diffusion as a toy nonlinearity leads to very similar behaviour of large scale turbulent dynamos as full MHD. This is demonstrated using both direct simulations in a periodic box and a closure model for the…

Astrophysics · Physics 2007-05-23 Axel Brandenburg , Kandaswamy Subramanian

Magnetic fields are present on all scales in the Universe. While we understand the processes which amplify the fields fairly well, we do not have a "natural" mechanism to generate the small initial seed fields. By using fully relativistic…

Cosmology and Nongalactic Astrophysics · Physics 2014-09-18 Ellie Nalson , Adam J. Christopherson , Karim A. Malik

Based on the set of nonlinear coupling equations describing the interaction of the high-frequency field, the self-generated magnetic field and the ion-acoustic field, the dispersion relation for the circular magnetic field is obtained. The…

Plasma Physics · Physics 2022-10-31 X. L. Liu , X. Q. Li

It is shown that the magnetic-field coils of a stellarator can, at least in principle, be substantially simplified by the use of permanent magnets. Such magnets cannot create toroidal magnetic flux but they can be used to shape the plasma…

Plasma Physics · Physics 2020-03-11 P. Helander , M. Drevlak , M. Zarnstorff , S. C. Cowley

A self-consistent statistical approach to the problem of planetary and stellar magnetism is suggested. The mechanism of magnetic field generation in the astronomical objects, where the existence of fields is associated with the axial…

Astrophysics · Physics 2015-06-24 S. N. Arteha

The current understanding of astrophysical magnetic fields is reviewed, focusing on their generation and maintenance by turbulence. In the astrophysical context this generation is usually explained by a self-excited dynamo, which involves…

Astrophysics · Physics 2008-11-26 Axel Brandenburg , Kandaswamy Subramanian

Multi-frequency radio polarimetry of the diffuse Galactic synchrotron background gives new viewpoints on the Galactic magnetic field. Rotation measure maps reveal magnetic structures on arcminute to degree scales, such as a ring in…

Astrophysics · Physics 2015-06-24 M. Haverkorn , P. Katgert , A. G. de Bruyn , F. Heitsch

Much work on turbulent three-dimensional dynamos has been done using triply periodic domains, in which there are no magnetic helicity fluxes. Here we present simulations where the turbulent intensity is still nearly homogeneous, but now…

Solar and Stellar Astrophysics · Physics 2019-02-20 A. Brandenburg

Straining of magnetic fields by large-scale shear flow, generally assumed to lead to intensification and generation of small scales, is re-examined in light of the persistent observation of large-scale magnetic fields in astrophysics. It is…

Plasma Physics · Physics 2022-07-20 B. Tripathi , A. E. Fraser , P. W. Terry , E. G. Zweibel , M. J. Pueschel

Primordial magnetic fields may account for all or part of the fields observed in galaxies. We consider the evolution of the magnetic fields created by pseudoscalar effects in the early universe. Such processes can create force-free fields…

Astrophysics · Physics 2009-10-31 George B. Field , Sean M. Carroll

Magnetic fields are considered to be key components of massive stars, with a far-reaching impact on their evolution and ultimate fate. A magnetic mechanism was suggested for the collimated explosion of massive stars, relevant for…

Solar and Stellar Astrophysics · Physics 2024-10-28 Swetlana Hubrig , Markus Schöller , Silva P. Järvinen , Aleksandar Cikota , Michael Abdul-Masih , Ana Escorza , Ilya Ilyin

In paper I, we obtained an equation for the evolution of density inhomogeneities in a radiation dominated universe when they are affected by magnetic fields. In this second paper we apply this equation to the case in which the subjacent…

Astrophysics · Physics 2016-08-30 E. Florido , E. Battaner

It is shown that the electric current of massive fermions along the external magnetic field can be excited in the case when particles possess anomalous magnetic moments and electroweakly interact with background matter. This current is…

High Energy Physics - Phenomenology · Physics 2018-02-15 Maxim Dvornikov

Some common properties of helical magnetic fields in decaying and driven turbulence are discussed. These include mainly the inverse cascade that produces fields on progressively larger scales. Magnetic helicity also restricts the evolution…

Astrophysics · Physics 2007-05-23 Axel Brandenburg

To better understand the dependence of the magnetic field structure in the plasma edge on the plasma boundary shape, in the context of X-point and island divertor designs, we define and develop a class of stellarators called umbilic…

Plasma Physics · Physics 2026-01-28 R. Gaur , D. Panici , T. M. Elder , M. Landreman , K. E. Unalmis , Y. Elmacioglu , D. Dudt , R. Conlin , E. Kolemen