scholarly journals Hydromagnetic Dynamo in Astrophysical Jets

1993 ◽  
Vol 157 ◽  
pp. 367-371 ◽  
Author(s):  
A. Shukurov ◽  
D.D. Sokoloff
Keyword(s):  
Magnetic Field ◽  
Cylindrical Shell ◽  
Plasma Flow ◽  
Wave Number ◽  
Astrophysical Jets ◽  
Thin Cylindrical Shell ◽  
Azimuthal Wave Number ◽  
Hydromagnetic Dynamo ◽  
Field Lines ◽  
Jet Plasma

The origin of a regular magnetic field in astrophysical jets is discussed. It is shown that jet plasma flow can generate a magnetic field provided the streamlines are helical. The dynamo of this type, known as the screw dynamo, generates magnetic fields with the dominant azimuthal wave number m = 1 whose field lines also have a helical shape. The field concentrates into a relatively thin cylindrical shell and its configuration is favorable for the collimation and confinement of the jet plasma.

scholarly journals Study of relativistic magnetized outflows with relativistic equation of state

2019 ◽  
Vol 488 (4) ◽  
pp. 5713-5727
Author(s):  
Kuldeep Singh ◽  
Indranil Chattopadhyay
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Equation Of State ◽  
Polar Angle ◽  
Relativistic Equation ◽  
Azimuthal Velocity ◽  
Astrophysical Jets ◽  
Composition Parameter ◽  
Field Lines ◽  
Flow Experiences

ABSTRACT We study relativistic magnetized outflows using relativistic equation of state having variable adiabatic index (Γ) and composition parameter (ξ). We study the outflow in special relativistic magnetohydrodynamic regime, from sub-Alfvénic to super-fast domain. We showed that, after the solution crosses the fast point, magnetic field collimates the flow and may form a collimation-shock due to magnetic field pinching/squeezing. Such fast, collimated outflows may be considered as astrophysical jets. Depending on parameters, the terminal Lorentz factors of an electron–proton outflow can comfortably exceed few tens. We showed that due to the transfer of angular momentum from the field to the matter, the azimuthal velocity of the outflow may flip sign. We also study the effect of composition (ξ) on such magnetized outflows. We showed that relativistic outflows are affected by the location of the Alfvén point, the polar angle at the Alfvén point and also the angle subtended by the field lines with the equatorial plane, but also on the composition of the flow. The pair dominated flow experiences impressive acceleration and is hotter than electron–proton flow.

scholarly journals Intermediate-<I>m</I> ULF waves generated by substorm injection: a case study

2010 ◽  
Vol 28 (8) ◽  
pp. 1499-1509 ◽  
Author(s):  
T. K. Yeoman ◽  
D. Yu. Klimushkin ◽  
P. N. Mager
Keyword(s):  
Phase Variation ◽  
Wave Activity ◽  
Wave Number ◽  
Ulf Wave ◽  
Azimuthal Wave ◽  
Azimuthal Wave Number ◽  
Source Particle ◽  
Phase Propagation ◽  
Field Lines

Abstract. A case study of SuperDARN observations of Pc5 Alfvén ULF wave activity generated in the immediate aftermath of a modest-intensity substorm expansion phase onset is presented. Observations from the Hankasalmi radar reveal that the wave had a period of 580 s and was characterized by an intermediate azimuthal wave number (m=13), with an eastwards phase propagation. It had a significant poloidal component and a rapid equatorward phase propagation (~62° per degree of latitude). The total equatorward phase variation over the wave signatures visible in the radar field-of-view exceeded the 180° associated with field line resonances. The wave activity is interpreted as being stimulated by recently-injected energetic particles. Specifically the wave is thought to arise from an eastward drifting cloud of energetic electrons in a similar fashion to recent theoretical suggestions (Mager and Klimushkin, 2008; Zolotukhina et al., 2008; Mager et al., 2009). The azimuthal wave number m is determined by the wave eigenfrequency and the drift velocity of the source particle population. To create such an intermediate-m wave, the injected particles must have rather high energies for a given L-shell, in comparison to previous observations of wave events with equatorward polarization. The wave period is somewhat longer than previous observations of equatorward-propagating events. This may well be a consequence of the wave occurring very shortly after the substorm expansion, on stretched near-midnight field lines characterised by longer eigenfrequencies than those involved in previous observations.

Physical and Chemical Processes Research of Isotope Separation in Plasma under Magnetic Field

2014 ◽  
Vol 880 ◽  
pp. 128-133 ◽  
Author(s):  
Vyacheslav F. Myshkin ◽  
Dmitry A. Izhoykin ◽  
Ivan A. Ushakov ◽  
Viktor F. Shvetsov
Keyword(s):  
Magnetic Field ◽  
Carbon Dioxide ◽  
Plasma Flow ◽  
High Frequency ◽  
Isotope Separation ◽  
Carbon Dioxide Concentration ◽  
Plasma Stream ◽  
Reaction Products ◽  
Valence Electrons ◽  
Field Lines

It is known that chemical bonding is only possible when particles with antiparallel valence electrons spins orientation collide [1, 2]. In an external magnetic field unpaired electrons spins precession around the field lines is observed. Precession frequencies of valence electrons of magnetic and nonmagnetic nuclei differ, resulting in a different probability to collide in reactive state for different isotopes. The investigations results of magnetic field influence on the carbon isotopes redistribution between carbon dioxide and disperse carbon in plasmachemical processes are given. Argon-oxygen plasma by a high-frequency generator was produced. Carbon placed into reaction zone by the high-frequency electrode evaporation. The plasmachemical reaction products quenching in the plasma flow at the sampler probe were examined. It is found that the Laval nozzle sampler is more efficient for plasma stream cooling versus the cylindrical sampler. The effects of flow rate, pressure and carbon dioxide concentration on the plasma flow cooling efficiency were estimated.

Localization of the magnetic field in a plasma flow in laboratory simulations of astrophysical jets at the KPF-4-PHOENIX installation

2017 ◽  
Vol 61 (9) ◽  
pp. 775-782 ◽  
Author(s):  
K. N. Mitrofanov ◽  
S. S. Anan’ev ◽  
D. A. Voitenko ◽  
V. I. Krauz ◽  
G. I. Astapenko ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Plasma Flow ◽  
Astrophysical Jets ◽  
Laboratory Simulations ◽  
The Magnetic Field

scholarly journals Plasma Flow and Solar Wind Acceleration in Non-Radial Coronal Magnetic Fields

1983 ◽  
Vol 102 ◽  
pp. 473-477
Author(s):  
H. Biernat ◽  
N. Kömle ◽  
H. Rucker
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Plasma Flow ◽  
Coronal Holes ◽  
Expansion Velocity ◽  
The Sun ◽  
Solar Wind Acceleration ◽  
Coronal Magnetic Fields ◽  
Field Lines ◽  
The Magnetic Field

In the vicinity of the Sun — especially above coronal holes — the magnetic field lines show strong non-radial divergence and considerable curvature (see e.g. Kopp and Holzer, 1976; Munro and Jackson, 1977; Ripken, 1977). In the following we study the influence of these characteristics on the expansion velocity of the solar wind.

scholarly journals Rotation of the magnetic field in Earth's magnetosheath by bulk magnetosheath plasma flow

2006 ◽  
Vol 24 (1) ◽  
pp. 339-354 ◽  
Author(s):  
M. Longmore ◽  
S. J. Schwartz ◽  
E. A. Lucek
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Plasma Flow ◽  
Mean Value ◽  
Flow Coupling ◽  
Parker Spiral ◽  
Magnetic Field Model ◽  
Field Lines ◽  
The Magnetic Field

Abstract. Orientations of the observed magnetic field in Earth's dayside magnetosheath are compared with the predicted field line-draping pattern from the Kobel and Flückiger static magnetic field model. A rotation of the overall magnetosheath draping pattern with respect to the model prediction is observed. For an earthward Parker spiral, the sense of the rotation is typically clockwise for northward IMF and anticlockwise for southward IMF. The rotation is consistent with an interpretation which considers the twisting of the magnetic field lines by the bulk plasma flow in the magnetosheath. Histogram distributions describing the differences between the observed and model magnetic field clock angles in the magnetosheath confirm the existence and sense of the rotation. A statistically significant mean value of the IMF rotation in the range 5°-30° is observed in all regions of the magnetosheath, for all IMF directions, although the associated standard deviation implies large uncertainty in the determination of an accurate value for the rotation. We discuss the role of field-flow coupling effects and dayside merging on field line draping in the magnetosheath in view of the evidence presented here and that which has previously been reported by Kaymaz et al. (1992).

Crustal magnetic field advection on Mars from MAVEN observations

2020 ◽  
Author(s):  
Isabela de Oliveira ◽  
Markus Fränz ◽  
Adriane Franco ◽  
Ezequiel Echer
Keyword(s):  
Magnetic Field ◽  
Plasma Flow ◽  
Ionospheric Plasma ◽  
Global Analysis ◽  
Dynamic Pressure ◽  
General Idea ◽  
Mars Atmosphere ◽  
Low Intensity ◽  
Single Orbit ◽  
Field Lines

&lt;p&gt;The plasma environment of Mars is highly influenced by regions of remnant magnetism in the planetary crust, above which mini-magnetospheres are created. In this work, we study whether the ionospheric plasma flow can move crustal magnetic field lines, by the process of advection. According to this hypothesis, the magnetic field lines are dragged away in anti-solar direction, westward at dawn and eastward at dusk-side, due to the day-to-night flow of the ionospheric plasma. The altitude of interest is between 200 km and 1000 km, because the plasma flow velocity is significant in this region.&lt;/p&gt;&lt;p&gt;MAVEN (Mars Atmosphere and Volatile EvolutioN) data is used for a direct comparison between magnetic field data and a crustal magnetic field model. The difference between the observed and the model field at each point of the grid is a measure of the sum of the induced day magnetic field and the possible displacement of the crustal field lines by advection. The results of the analysis show that, except for the lowest altitude range, minimum value of this difference is always observed for westward shift at dawn-side and eastward shift at dusk-side, in agreement with the expected motion of the crustal magnetic field lines.&lt;/p&gt;&lt;p&gt;For a general idea of the relative forces between the moving plasma and the crustal fields, we use MAVEN data to analyze the pressures involved in the advection process. These are the dynamic pressure of the ionospheric plasma flow, the magnetic pressure of the field lines and the thermal pressure of the plasma related to the mini-magnetospheres. The balance between these quantities should dictate the occurrence of advection. This analysis suggests that advection could take place at low altitude (up to ~450 km) dawn-side regions above low intensity magnetic fields.&lt;/p&gt;&lt;p&gt;Although the global analysis results showed agreement with our hypothesis, we could not observe evidence of advection from the local observations in order to unambiguously prove the occurrence of this process. Future works include the investigation of single orbit data in regions of low intensity magnetic field, especially at dawn-side, and also magnetohydrodynamic modeling of the process using the plasma conditions prevalent in the Martian ionosphere.&lt;/p&gt;

Properties of the distribution of azimuthal magnetic field in a plasma flow during laboratory simulations of astrophysical jets in a plasma-focus installation

2017 ◽  
Vol 61 (2) ◽  
pp. 138-152 ◽  
Author(s):  
K. N. Mitrofanov ◽  
V. I. Krauz ◽  
V. V. Myalton ◽  
V. P. Vinogradov ◽  
A. M. Kharrasov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Plasma Flow ◽  
Plasma Focus ◽  
Astrophysical Jets ◽  
Azimuthal Magnetic Field ◽  
Laboratory Simulations

PERTURBATION THEORY FOR THE ALFVÉN WAVE

1995 ◽  
Vol 09 (22) ◽  
pp. 2857-2898 ◽  
Author(s):  
Z. YOSHIDA ◽  
S.M. MAHAJAN
Keyword(s):  
Magnetic Field ◽  
Perturbation Theory ◽  
Electron Beam ◽  
Continuous Spectrum ◽  
Point Spectrum ◽  
Alfven Wave ◽  
Wave Number ◽  
Ambient Magnetic Field ◽  
Field Lines ◽  
The Magnetic Field

The Alfvén wave is the dominant low frequency transverse mode of a magnetized plasma. The Alfvén wave propagates along the magnetic field, and displays a continuous spectrum even in a bounded plasma. This is essentially due to the degeneracy of the wave characteristics, i.e. the frequency (ω) is primarily determined by the wave number in the direction parallel to the ambient magnetic field (k||) and is independent of the perpendicular wavenumbers. The characteristics, that are the direction along which the wave energy propagates, are identical to the ambient magnetic field lines. Therefore, the spectral structure of the Alfvén wave has a close relationship with the geometric structure of the magnetic field lines. In an inhomogeneous plasma, the Alfvén resonance (ω−cAk||=0; cA is the phase velocity of the Alfvén wave) constitutes a singularity for the defining wave equation; this results in a singular eigenfunction corresponding to the continuous spectrum. The aim of this review is to present an overview of the perturbation theory for the Alfvén wave. Emphasis is placed on those perturbations of the continuous spectrum which lead to the creation of point spectra. Such qualitative changes in the spectrum are relevant to many plasma phenomena. The first category of perturbations consists of nonideal effects such as the finite conductivity, kinetic effects arising from the finite electron inertia, and finite gyroradius. These effects add singular perturbations to the mode equation, and modify the spectrum dramatically. These modification, viz. the conversion of the continuous to the point spectrum, can lead to interesting physical phenomenon. A case in point is that of an electron beam propagating in a plasma which Cherenkov emits a left-hand circularly polarized Alfvén wave. The helicity of the ambient magnetic field imparts a frequency shift to the eigenmodes changing the critical velocity for Cherenkov emission. It, then, becomes possible for a sub-Alfvénic electron beam to excite a nonsingular Alfvén wave corresponding to a point spectrum. The second category comprises of geometric perturbations associated with higher dimensional inhomogeneity of the ambient field. Forbidden bands occur when a periodic modulation is applied. In a chaotic magnetic field, the weak localization of the wave occurs, resulting in a point spectrum.

Static paramagnetic response of thin soft superconductors

1980 ◽  
Vol 58 (6) ◽  
pp. 812-819
Author(s):  
K. N. Piyakis ◽  
G. Papini ◽  
R. G. Rystephanick
Keyword(s):  
Magnetic Field ◽  
Cylindrical Shell ◽  
External Magnetic Field ◽  
Scalar Potential ◽  
Electrochemical Potential ◽  
Thin Cylindrical Shell ◽  
A Current

We calculate the static paramagnetic response of thin superconductors of the first kind to terms proportional to a static external magnetic field and a static scalar potential. The response is in the form of a current. The corresponding magnetic field is calculated for a thin cylindrical shell and is proportional to the electrochemical potential.

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