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Context. The understanding of fossil fields origin, topology and stability is one of the corner stones of the stellar magnetism theory. On one hand, since they survive over secular time-scales, they may modify the structure and the…

Solar and Stellar Astrophysics · Physics 2010-03-16 V. Duez , S. Mathis

In order to understand the conditions which lead a highly magnetized, relativistic plasma to become unstable, and in such cases how the plasma evolves, we study a prototypical class of magnetostatic equilibria where the magnetic field…

High Energy Astrophysical Phenomena · Physics 2015-08-31 William E. East , Jonathan Zrake , Yajie Yuan , Roger D. Blandford

The plasma beta, ratio of kinetic to magnetic pressure, inside a tokamak should stay below the Troyon limit to avoid major plasma instabilities. However, this paper argues that Troyon limit occurs only when current profiles cannot sustain…

Plasma Physics · Physics 2017-10-30 P. -A. Gourdain

We present numerical magnetohydrodynamic (MHD) simulations of the effect of stellar dipole magnetic fields on line-driven wind outflows from hot, luminous stars. Unlike previous fixed-field analyses, the simulations here take full account…

Astrophysics · Physics 2011-05-05 Asif ud-Doula , Stanley P. Owocki

In this work we describe a numerical optimization method for computing stationary MHD-equilibria. The newly developed code is based on a nonlinear force-free optimization principle. We apply our code to model the solar corona using synoptic…

Solar and Stellar Astrophysics · Physics 2020-11-11 Thomas Wiegelmann , Thomas Neukirch , Dieter H. Nickeler , Iulia Chifu

The component of the neoclassical electrostatic potential that is non-constant on the magnetic surface, that we denote by $\tilde\varphi$, can affect radial transport of highly charged impurities, and this has motivated its inclusion in…

Plasma Physics · Physics 2018-09-12 Ivan Calvo , J. L. Velasco , Felix I. Parra , J. Arturo Alonso , J. M. García-Regaña

The time evolution of angular momentum and surface rotation of massive stars is strongly influenced by fossil magnetic fields via magnetic braking. We present a new module containing a simple, comprehensive implementation of such a field at…

Solar and Stellar Astrophysics · Physics 2020-02-05 Z. Keszthelyi , G. Meynet , M. E. Shultz , A. David-Uraz , A. ud-Doula , R. H. D. Townsend , G. A. Wade , C. Georgy , V. Petit , S. P. Owocki

The theory of large scale dynamos is reviewed with particular emphasis on the magnetic helicity constraint in the presence of closed and open boundaries. In the presence of closed or periodic boundaries, helical dynamos respond to the…

Astrophysics · Physics 2009-11-07 A. Brandenburg , W. Dobler , K. Subramanian

Multiple analytical and empirical stability criteria have been derived in the literature for two planet systems. But, the dependence of the stability limit on the initial mutual inclination between the inner and outer orbits is not well…

Earth and Planetary Astrophysics · Physics 2024-04-12 Hareesh Gautham Bhaskar , Hagai Perets

Independent tests aiming to constrain the value of the cosmological constant $\Lambda$ are usually difficult because of its extreme smallness $\left(\Lambda \simeq 1\times 10^{-52}~\textrm{m}^{-2},~\textrm{or}~2.89\times…

General Relativity and Quantum Cosmology · Physics 2018-03-28 Lorenzo Iorio

Context. For the last thirty years, most of the studies on the relaxation of stressed magnetic fields in the solar environment have onlyconsidered the Lorentz force, neglecting plasma contributions, and therefore, limiting every equilibrium…

Solar and Stellar Astrophysics · Physics 2011-10-25 Jorge Fuentes-Fernández , Clare E. Parnell , Alan W. Hood

First observations of electrostatic potential variations within the flux surfaces of a toroidal magnetic confinement device are presented. Measurements are taken in the TJ-II stellarator with two distant Langmuir probe arrays. The edge…

An analysis of instability dynamics in a stochastic magnetic field is presented for the tractable case of the resistive interchange. Externally prescribed static magnetic perturbations convert the eigenmode problem to a stochastic…

Plasma Physics · Physics 2023-06-14 Mingyun Cao , P. H. Diamond

Numerical simulations with self-similar initial and boundary conditions provide a link between theoretical and numerical investigations of jet dynamics. We perform axisymmetric resistive magnetohydrodynamic (MHD) simulations for a…

Astrophysics · Physics 2009-11-13 Miljenko Cemeljic , Jose Gracia , Nektarios Vlahakis , Kanaris Tsinganos

Magnetic fields vary in complexity for different stars. The stability of dipolar magnetic fields is known to depend on different quantities, e.g., the stellar rotation, the stratification, and the intensity of convective motions. Here, we…

Solar and Stellar Astrophysics · Physics 2020-09-30 Bonnie Zaire , Laurene Jouve

The temperature dependence of conductance resonances is used to measure the evolution with the magnetic field of the average level spacing $\Delta\epsilon$ of a droplet containing $\sim 30$ electrons created by lateral confinement of a…

Condensed Matter · Physics 2009-10-28 O. Klein , D. Goldhaber-Gordon , C. de C. Chamon , M. A. Kastner

This paper presents the calculation of the bounce-averaged drift of trapped particles in a near-axis framework for axisymmetric and quasisymmetric magnetic fields that possess up-down and stellarator symmetry respectively. This analytic…

Plasma Physics · Physics 2023-09-15 E. Rodriguez , R. J. J. Mackenbach

An important question for the outlook of stellarator reactors is their robustness against pressure driven modes, and the underlying mechanism behind experimentally observed soft $\beta$ limits. Towards building a robust answer to these…

We calculate the magnetic-field dependence of the critical current due to both geometrical edge barriers and bulk pinning in a periodic coplanar array of narrow superconducting strips. We find that in zero or low applied magnetic fields the…

Superconductivity · Physics 2010-08-31 John R. Clem , Ali A. Babaei Brojeny , Yasunori Mawatari

We have recently demonstrated that by expanding in small distance from the magnetic axis compared to the major radius, stellarator shapes with low neoclassical transport can be generated efficiently. To extend the utility of this new design…

Plasma Physics · Physics 2020-10-28 Matt Landreman , Rogerio Jorge