Conservation laws and theorems of confinement and stability   for a charged 
 equatorial disk in a pulsar magnetosphere

Aly, J. J.

doi:10.1051/0004-6361:20041707

Cited by 3 publications

(4 citation statements)

References 15 publications

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“…When there is no external source of charges feeding the magnetosphere, it has been found that the plasma remains confined in regions close to the equilibrium state as also shown by Aly (2005).…”

Section: Introductionmentioning

confidence: 64%

“…The non linear development of this instability was studied by Pétri et al (2003), still in the framework of an infinitely thin disk model. When there is no external source of charges feeding the magnetosphere, it was found that the plasma remains confined in regions close to the equilibrium state, as also shown by Aly (2005). When however the disk can be fed by some charge source, Pétri et al (2003) have shown that the instability causes a cross-field transport of these charges in the equatorial disk, evolving into a net out-flowing flux of charges.…”

Section: Introductionmentioning

confidence: 86%

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The diocotron instability in a pulsar cylindrical electrosphere

Pétri¹

2006

A&A

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Context. The physics of the pulsar inner magnetosphere remains poorly constrained by observations. Although about 2000 pulsars have been discovered to date, little is known about their emission mechanism. Large vacuum gaps probably exist and a non-neutral plasma made of electrons in some regions and of positrons in some other regions fills space to form an electrosphere. Aims. The purpose of this work is to study the stability properties of the differentially rotating equatorial disk in the pulsar's electrosphere for which the magnetic field is assumed to be dipolar. In contrast to previous studies, the magnetic field is not restricted to being uniform. Methods. A pseudo-spectral Galerkin method using Tchebyshev-polynomial expansion is developed to compute the spectrum of the diocotron instability in a non-neutral plasma column confined between two cylindrically conducting walls. Moreover, the inner wall carries a given charge per unit length in order to account for the presence of a charged neutron star at the centre of the electrosphere. Results. We show several eigenfunctions and eigenspectra obtained for different initial density profiles and electromagnetic field configurations useful for laboratory plasmas. The algorithm is very efficient in computing the fastest growing modes. Applications to a "cylindrical" electrosphere are also shown for several differential rotation profiles. It is found that the growth rates of the diocotron instability have the same order of magnitude as the rotation rate. Conclusions. The instability develops on a very short timescale and can account for very efficient particle diffusion across the magnetic field lines, as already claimed in a previous work. The exact geometry of the confined plasma, whether a thin disk or a cylinder, does not significantly affect the spectrum of the diocotron instability.

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Section: Introductionmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 86%

The diocotron instability in a pulsar cylindrical electrosphere

Pétri¹

2006

A&A

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“…MHD type instabilities of non-neutral plasmas can lead to short time variability in the magnetosphere possibly related to radio emission fluctuations (Urpin 2014). Moreover, the evolution of the non-neutral plasma, especially in the disk, has to satisfy some conservation laws (Aly 2005) stipulating that an isolated disk, i.e. without particle injection, will remain confined in the vicinity of the neutron star.…”

Section: Stabilitymentioning

confidence: 99%

Theory of pulsar magnetosphere and wind

Pétri

2016

J. Plasma Phys.

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Neutron stars are fascinating astrophysical objects immersed in strong gravitational and electromagnetic fields, at the edge of our current theories. These stars manifest themselves mostly as pulsars, emitting a timely very stable and regular electromagnetic signal. Even though discovered almost fifty years ago, they still remain mysterious compact stellar objects. In this review, we summarize the most fundamental theoretical aspects of neutron star magnetospheres and winds. The main competing models explaining their radiative properties like multi-wavelength pulse shapes and spectra and the underlying physical processes such as pair creation and radiation mechanisms are scrutinized. A global but still rather qualitative picture slowly emerges thanks to recent advances in numerical simulations on the largest scales. However considerations about pulsar magnetospheres remain speculative. For instance, the exact composition of the magnetospheric plasma is not yet known. Is it solely filled with a mixture of e ± leptons or does it contain a non-negligible fraction of protons and/or ions? Is it almost entirely filled or mostly empty except for some small anecdotal plasma filled regions? Answers to these questions will strongly direct the description of the magnetosphere to seemingly contradictory results leading sometimes to inconsistencies. Nevertheless, accounts are given as to the latest developments in the theory of pulsar magnetospheres and winds, the existence of a possible electrosphere and physical insight obtained from related observational signatures of multi-wavelength pulsed emission.

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“…The differentially rotating disk is shown to suffer from diocotron instability [77,79,80], thus exhibits non-axisymmetric charge modulations and radial expansion [77], and the actual equatorial charge distribution likely is more complicated than just laminar flow around a simple torus, with macroparticles/vortices likely showing up [76] (also note that the disk is not bound by a trap surface, so there is no aforementioned self-maintenance mechanism at work to regulate the shape of the disk; nevertheless, the disk remains confined, at least in the absence of pair injection, and cannot escape to infinity [128]).…”

Section: Appendix A3 With Plasma: the Charge-separated Electrospheresmentioning

confidence: 99%

A Magnetospheric Dichotomy for Pulsars with Extreme Inclinations

Zhang

2021

Universe

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In this work, we expand on a comment by Lyne et al. (2017), that intermittent pulsars tend to congregate near a stripe in the logarithmic period versus period-derivative diagram. Such a stripe represents a small range of polar cap electric potential. Taking into account also the fact (already apparent in their Figure 7, but not explicitly stated there) that high-fraction nulling pulsars also tend to reside within this and an additional stripe, we make the observation that the two stripes further match the “death lines” for double- and single-pole interpulses, associated with nearly orthogonal and aligned rotators, respectively. These extreme inclinations are known to suffer from pair production deficiencies, so we propose to explain intermittency and high-fraction nulling by reinvigorating some older quiescent (no pulsar wind or radio emission) “electrosphere” solutions. Specifically, as the polar potential drops below the two threshold bands (i.e., the two stripes), corresponding to the aligned and orthogonal rotators, their respective magnetospheres transition from being of the active pair-production-sustained-type into becoming the electrospheres, in which charges are only lifted from the star. The borderline cases sitting in the gap outside of the stable regime of either case manifest as high-fraction nullers. Hall evolution of the magnetic field inside orthogonally rotating neutron stars can furthermore drive secular regime changes, resulting in intermittent pulsars.

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Conservation laws and theorems of confinement and stability for a charged equatorial disk in a pulsar magnetosphere

Cited by 3 publications

References 15 publications

The diocotron instability in a pulsar cylindrical electrosphere

The diocotron instability in a pulsar cylindrical electrosphere

Theory of pulsar magnetosphere and wind

A Magnetospheric Dichotomy for Pulsars with Extreme Inclinations

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