The stability of propagating slab electron holes in a magnetized plasma

The influence of a realistic energy equation on the stability of a cylindrical magnetized plasma in a force-free magnetic field is discussed. Thermal conduction, heating and line radiation are included in the treatment. Explicit growth rates for the m = 0 and m = 1 modes are derived and compared with the standard adiabatic or incompressible time-scales. Finally, the relevance of these results for laboratory and solar plasmas is discussed.

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The influence of the methionine residue on the dissociation mechanisms of photoionized methionine-enkephalin probed by VUV action spectroscopy

The European Physical Journal D ◽

10.1140/epjd/s10053-021-00147-y ◽

2021 ◽

Vol 75 (4) ◽

Author(s):

Simon Dörner ◽

Lucas Schwob ◽

Kaja Schubert ◽

Marion Girod ◽

Luke MacAleese ◽

...

Keyword(s):

High Electron ◽

Amino Acid Residues ◽

Methionine Enkephalin ◽

Action Spectroscopy ◽

Methionine Residue ◽

Electron Holes ◽

The Stability ◽

Dissociation Mechanisms ◽

Fragmentation Patterns ◽

Sulfur Containing

Abstract VUV action spectroscopy has recently gained interest for the study of peptides and proteins. However, numerous aspects of the fundamental processes involved in the photodissociation are yet to be understood. It can, for example, be expected that sulfur-containing amino-acid residues have a significant impact on the dissociation processes following photoionization because of their potential involvement in the transport of electron holes in proteins. In order to investigate the influence of the sulfur-containing methionine residue on the VUV photodissociation of a small peptide a VUV action spectroscopy study of gas-phase protonated methionine-enkephalin and leucine-enkephalin in the photon energy range of 6–35 eV was performed. The results show that upon non-ionizing photoexcitation, the fragmentation patterns of the two peptides are nearly identical, whereas significant differences were observed upon photoionization. The differences between the fragment yields and the identified specific dissociation channels for methionine-enkephalin could be explained by the high electron hole affinity of sulfur, which efficiently directs the radical to the methionine side chain. Additionally, for both peptides the presence of the intact photoionized precursor ions was confirmed by their isotopic patterns and the stability of these species could be evaluated. Graphic abstract

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Analysis and simulation of BGK electron holes

Nonlinear Processes in Geophysics ◽

10.5194/npg-6-211-1999 ◽

1999 ◽

Vol 6 (3/4) ◽

pp. 211-219 ◽

Cited By ~ 30

Author(s):

L. Muschietti ◽

I. Roth ◽

R. E. Ergun ◽

C. W. Carlson

Keyword(s):

Magnetic Field ◽

Incident Beam ◽

Distribution Functions ◽

Simulation Code ◽

Nonlinear Structure ◽

Trapped Electrons ◽

Particle In Cell ◽

Cell Simulation ◽

Electron Holes ◽

The Stability

Abstract. Recent observations from satellites crossing regions of magnetic-field-aligned electron streams reveal solitary potential structures that move at speeds much greater than the ion acoustic/thermal velocity. The structures appear as positive potential pulses rapidly drifting along the magnetic field, and are electrostatic in their rest frame. We interpret them as BGK electron holes supported by a drifting population of trapped electrons. Using Laplace transforms, we analyse the behavior of one phase-space electron hole. The resulting potential shapes and electron distribution functions are self-consistent and compatible with the field and particle data associated with the observed pulses. In particular, the spatial width increases with increasing amplitude. The stability of the analytic solution is tested by means of a two-dimensional particle-in-cell simulation code with open boundaries. We consider a strongly magnetized parameter regime in which the bounce frequency of the trapped electrons is much less than their gyrofrequency. Our investigation includes the influence of the ions, which in the frame of the hole appear as an incident beam, and impinge on the BGK potential with considerable energy. The nonlinear structure is remarkably resilient

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On the Stability of a Magnetized Plasma in a Large Amplitude Circularly Polarized Wave

Physica Scripta ◽

10.1088/0031-8949/21/6/010 ◽

1980 ◽

Vol 21 (6) ◽

pp. 831-835 ◽

Cited By ~ 20

Author(s):

L Stenflo

Keyword(s):

Large Amplitude ◽

Magnetized Plasma ◽

Circularly Polarized ◽

The Stability

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Three-dimensional stability of solitary shear kinetic Alfvén waves in a low-beta plasma

Journal of Plasma Physics ◽

10.1017/s002237780001374x ◽

1989 ◽

Vol 41 (1) ◽

pp. 171-184 ◽

Cited By ~ 24

Author(s):

K. P. Das ◽

L. P. J. Kamp ◽

F. W. Sluijter

Keyword(s):

Growth Rate ◽

Dimensional Stability ◽

Three Dimensional ◽

Alfven Waves ◽

Magnetized Plasma ◽

Alfvén Waves ◽

Ion Acoustic Solitons ◽

The Stability ◽

External Uniform Magnetic Field ◽

Kinetic Alfvén Waves

The three-dimensional stability of solitary shear kinetic Alfvén waves in a low-β plasma is investigated by the method of Zakharov & Rubenchik (1974). It is found that there is no instability if the direction of perturbation falls within a certain region of space. The growth rate of the instability for the unstable region is determined. This growth rate is found to decrease with increasing angle between the direction of propagation of the solitary wave and the direction of the external uniform magnetic field. A particular case of the present analysis gives results on the stability of ion-acoustic solitons in a magnetized plasma.

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Cold fronts: probes of plasma astrophysics in galaxy clusters

Journal of Plasma Physics ◽

10.1017/s0022377816000544 ◽

2016 ◽

Vol 82 (3) ◽

Cited By ~ 26

Author(s):

John A. ZuHone ◽

E. Roediger

Keyword(s):

Galaxy Clusters ◽

Mean Free Path ◽

Magnetized Plasma ◽

X Ray ◽

Gas Phases ◽

Cold Fronts ◽

The Mean ◽

The Stability

The most massive baryonic component of galaxy clusters is the ‘intracluster medium’ (ICM), a diffuse, hot, weakly magnetized plasma that is most easily observed in the X-ray band. Despite being observed for decades, the macroscopic transport properties of the ICM are still not well constrained. A path to determine macroscopic ICM properties opened up with the discovery of ‘cold fronts’. These were observed as sharp discontinuities in surface brightness and temperature in the ICM, with the property that the denser side of the discontinuity is the colder one. The high spatial resolution of the Chandra X-ray Observatory revealed two puzzles about cold fronts. First, they should be subject to Kelvin–Helmholtz instabilities, yet in many cases they appear relatively smooth and undisturbed. Second, the width of the interface between the two gas phases is typically narrower than the mean free path of the particles in the plasma, indicating negligible thermal conduction. It was thus realized that these special characteristics of cold fronts may be used to probe the properties of the cluster plasma. In this review, we will discuss the recent simulations of cold fronts in galaxy clusters, focusing on those which have attempted to use these features to constrain ICM physics. In particular, we will examine the effects of magnetic fields, viscosity, and thermal conductivity on the stability properties and long-term evolution of cold fronts. We conclude with a discussion on what important questions remain unanswered, and the future role of simulations and the next generation of X-ray observatories.

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Stability of Alfvén wings in uniform plasmas

Journal of Plasma Physics ◽

10.1017/s0022377807006460 ◽

2007 ◽

Vol 73 (6) ◽

pp. 957-966

Author(s):

P. A. SALLAGO ◽

A. M. PLATZECK

Keyword(s):

Solar System ◽

Normal Modes ◽

Background Field ◽

Alfven Waves ◽

Magnetized Plasma ◽

Alfvén Waves ◽

Solar System Bodies ◽

Uniform Background ◽

The Stability ◽

Magnetohydrodynamic System

AbstractA conducting source moving uniformly through a magnetized plasma generates, among a variety of perturbations, Alfvén waves. An interesting characteristic of Alfvén waves is that they can build up structures in the plasma called Alfvén wings. These wings have been detected and measured in many solar system bodies, and their existence has also been theoretically proven. However, their stability remains to be studied. The aim of this paper is to analyze the stability of an Alfvén wing developed in a uniform background field, in the presence of an incompressible perturbation that has the same symmetry as the Alfvén wing, in the magnetohydrodynamic approximation. The study of the stability of a magnetohydrodynamic system is often performed by linearizing the equations and using either the normal modes method or the energy method. In spite of being applicable for many problems, both methods become algebraically complicated if the structure under analysis is a highly non-uniform one. Palumbo has developed an analytical method for the study of the stability of static structures with a symmetry in magnetized plasmas, in the presence of incompressible perturbations with the same symmetry as the structure (Palumbo 1998 Thesis, Universidad de Firenze, Italia). In the present paper we extend this method for Alfvén wings that are stationary structures, and conclude that in the presence of this kind of perturbation they are stable.

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On the modeling of planetary plasma environments by a fully kinetic electromagnetic global model HYB-em

Annales Geophysicae ◽

10.5194/angeo-28-743-2010 ◽

2010 ◽

Vol 28 (3) ◽

pp. 743-751 ◽

Cited By ~ 5

Author(s):

V. Pohjola ◽

E. Kallio

Keyword(s):

Magnetic Field ◽

Kinetic Model ◽

Electromagnetic Waves ◽

Dimensional Space ◽

Spherical Wave ◽

Three Dimensional ◽

Magnetized Plasma ◽

Electromagnetic Model ◽

The Stability ◽

Propagation Of Waves

Abstract. We have developed a fully kinetic electromagnetic model to study instabilities and waves in planetary plasma environments. In the particle-in-a-cell (PIC) model both ions and electrons are modeled as particles. An important feature of the developed global kinetic model, called HYB-em, compared to other electromagnetic codes is that it is built up on an earlier quasi-neutral hybrid simulation platform called HYB and that it can be used in conjunction with earlier hybrid models. The HYB models have been used during the past ten years to study globally the flowing plasma interaction with various Solar System objects: Mercury, Venus, the Moon, Mars, Saturnian moon Titan and asteroids. The new stand-alone fully kinetic model enables us to (1) study the stability of various planetary plasma regions in three-dimensional space, (2) analyze the propagation of waves in a plasma environment derived from the other global HYB models. All particle processes in a multi-ion plasma which are implemented on the HYB platform (e.g. ion-neutral-collisions, chemical processes, particle loss and production processes) are also automatically included in HYB-em model. In this brief report we study the developed approach by analyzing the propagation of high frequency electromagnetic waves in non-magnetized plasma in two cases: We study (1) expansion of a spherical wave generated from a point source and (2) propagation of a plane wave in plasma. The analysis shows that the HYB-em model is capable of describing these space plasma situations successfully. The analysis also suggests the potential of the developed model to study both high density-high magnetic field plasma environments, such as Mercury, and low density-low magnetic field plasma environments, such as Venus and Mars.

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