The origin of primeval magnetic fields: Self-consistent simulation of magnetic field generation and amplification

2000 ◽  
Vol 7 (2) ◽  
pp. 701-705 ◽  
Author(s):  
H. Wiechen ◽  
G. T. Birk ◽  
H. Lesch
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Field Generation ◽  
Field Generation ◽  
Self Consistent

scholarly journals Generation of strong magnetic fields with a laser-driven coil

2018 ◽  
Vol 6 ◽  
Author(s):  
Zhe Zhang ◽  
Baojun Zhu ◽  
Yutong Li ◽  
Weiman Jiang ◽  
Dawei Yuan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Experimental Studies ◽  
Diagnostic Techniques ◽  
Magnetic Field Generation ◽  
Field Generation ◽  
Research Fields ◽  
Laser Facility ◽  
Spatio Temporal ◽  
The Magnetic Field

As a promising new way to generate a controllable strong magnetic field, laser-driven magnetic coils have attracted interest in many research fields. In 2013, a kilotesla level magnetic field was achieved at the Gekko XII laser facility with a capacitor–coil target. A similar approach has been adopted in a number of laboratories, with a variety of targets of different shapes. The peak strength of the magnetic field varies from a few tesla to kilotesla, with different spatio-temporal ranges. The differences are determined by the target geometry and the parameters of the incident laser. Here we present a review of the results of recent experimental studies of laser-driven magnetic field generation, as well as a discussion of the diagnostic techniques required for such rapidly changing magnetic fields. As an extension of the magnetic field generation, some applications are discussed.

scholarly journals Magnetic Field Generation within Molecular Clouds

1993 ◽  
Vol 157 ◽  
pp. 429-430
Author(s):  
A. Lazarian
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Molecular Clouds ◽  
Molecular Complexes ◽  
Magnetic Field Generation ◽  
Field Problem ◽  
Field Generation ◽  
Internal Motions ◽  
Turbulent Dynamo ◽  
Seed Field

Magnetic field generation in molecular (atomic) clouds at the early stages of galactic evolution is considered. It is shown that if there is no internal motions immersed the cloud, battery mechanisms (Lazarian 1992a) can account for the generation of thin magnetic shells around clouds insides in plasma with temperature gradients. If turbulent motions are present, the dynamo can be essential. The operation of α — ω, α2 and turbulent dynamos within molecular clouds is discussed. It is shown that the turbulent dynamo leads to generation of magnetic fields in the trace behind the cloud. These magnetic fields within the molecular clouds and in their vicinity are important for the solution of the galactic seed field problem (see Lazarian 1992b) and the formation of structures in clumpy molecular complexes.

Spontaneous excitation of magnetic fields and collapse dynamics in a Langmuir plasma

1981 ◽  
Vol 26 (1) ◽  
pp. 123-146 ◽  
Author(s):  
M. Kono ◽  
M. M. Škorić ◽  
D. Ter Haar
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Ponderomotive Force ◽  
Modulational Instability ◽  
The Self ◽  
Spontaneous Generation ◽  
Magnetic Field Generation ◽  
Langmuir Waves ◽  
Field Generation ◽  
The Magnetic Field

We discuss various aspects of the spontaneous generation of magnetic fields in a Langmuir plasma. We first of all show that the correct general expression for the ponderomotive force leads to the solenoidal current responsible for the magnetic-field generation. We derive the ponderomotive-force expression and also the magnetic-field generation equations from a two-time-scale two-fluid description. We also use a kinetic approach to derive the magnetic-field generation equations. We discuss the stability of monochromatic Langmuir waves and show that they are subject to both the ordinary modulational instability and to a magneto-modulational instability. We show that the coupled nonlinear equations describing the electric field strength amplitude, the plasma density, and the self-generated magnetic field can, under certain conditions, be reduced to a generalized cubic nonlinear Schrodinger equation. We finally show, by using a virial theorem, that the self-generated magnetic field does not stabilize the wave collapse.

scholarly journals Electronic Currents and Magnetic Fields in H2+ Induced by Coherent Resonant Bichromatic Circularly Polarized Laser Pulses: Effects of Orientation, Phase, and Helicity

2021 ◽  
Vol 9 ◽  
Author(s):  
André D. Bandrauk ◽  
Szczepan Chelkowski ◽  
Kai-Jun Yuan
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Numerical Solutions ◽  
Resonant Excitation ◽  
Electron Dynamics ◽  
Magnetic Field Generation ◽  
Phase Dependence ◽  
Circularly Polarized ◽  
Field Generation ◽  
Pulse Phase

We theoretically study pulse phase and helicity effects on ultrafast magnetic field generation in intense bichromatic circularly polarized laser fields. Simulations are performed on the aligned molecular ion H2+ from numerical solutions of corresponding time-dependent Schrödinger equations. We demonstrate how electron coherent resonant excitation influences the phase and helicity of the optically induced magnetic field generation. The dependence of the generated magnetic field on the pulse phase arises from the interference effect between multiple excitation and ionization pathways, and is shown to be sensitive to molecular alignment and laser polarization. Molecular resonant excitation induces coherent ring electron currents, giving enhancement or suppression of the phase dependence. Pulse helicity effects control laser-induced electron dynamics in bichromatic circular polarization excitation. These phenomena are demonstrated by a molecular attosecond photoionization model and coherent electron current theory. The results offer a guiding principle for generating ultrafast magnetic fields and for studying coherent electron dynamics in complex molecular systems.

scholarly journals Maximizing magnetic field generation in high power laser–solid interactions

2019 ◽  
Vol 7 ◽  
Author(s):  
L. G. Huang ◽  
H. Takabe ◽  
T. E. Cowan
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
High Power ◽  
Incident Angle ◽  
Absorption Efficiency ◽  
High Power Laser ◽  
Magnetic Field Generation ◽  
Power Laser ◽  
X Ray ◽  
Field Generation

In order to understand the transport of fast electrons within solid density targets driven by an optical high power laser, we have numerically investigated the dynamics and structure of strong self-generated magnetic fields in such experiments. Here we present a systematic study of the bulk magnetic field generation due to the ponderomotive current, Weibel-like instability and resistivity gradient between two solid layers. Using particle-in-cell simulations, we observe the effect of varying the laser and target parameters, including laser intensity, focal size, incident angle, preplasma scale length, target thickness and material and experimental geometry. The simulation results suggest that the strongest magnetic field is generated with laser incident angles and preplasma scale lengths that maximize laser absorption efficiency. The recent commissioning of experimental platforms equipped with both optical high power laser and X-ray free electron laser (XFEL), such as European XFEL-HED, LCLS-MEC and SACLA beamlines, provides unprecedented opportunities to probe the self-generated bulk magnetic field by X-ray polarimetry via Faraday rotation with simultaneous high spatial and temporal resolution. We expect that this systematic numerical investigation will pave the way to design and optimize near future experimental setups to probe the magnetic fields in such experimental platforms.

scholarly journals Stationary Turbulent Dynamo as Spontaneous Symmetry Breaking

1993 ◽  
Vol 157 ◽  
pp. 237-241
Author(s):  
M. Hnatich
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Large Scale ◽  
Magnetic Field Generation ◽  
Field Generation ◽  
Motion Energy ◽  
Turbulent Dynamo ◽  
Large Scale Magnetic Field

The large-scale magnetic field generation by the turbulent motion energy, known as turbulent dynamo [1], is perspective candidate to explain the observed stationary magnetic fields of cosmic objects.

scholarly journals Magnetic-field generation by the ablative nonlinear Rayleigh–Taylor instability

2014 ◽  
Vol 81 (2) ◽  
Author(s):  
Philip M. Nilson ◽  
L. Gao ◽  
I. V. Igumenshchev ◽  
G. Fiksel ◽  
R. Yan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Atmospheric Pressure ◽  
Large Scale ◽  
Taylor Instability ◽  
Magnetic Field Generation ◽  
Field Generation ◽  
Rayleigh Taylor Instability ◽  
Astrophysical Flows ◽  
Rt Instability

Experiments reporting magnetic-field generation by the ablative nonlinear Rayleigh–Taylor (RT) instability are reviewed. The experiments show how large-scale magnetic fields can, under certain circumstances, emerge and persist in strongly driven laboratory and astrophysical flows at drive pressures exceeding one million times atmospheric pressure.

scholarly journals An 84-μG Magnetic Field in a Galaxy at Z=0.692?

2008 ◽  
Vol 4 (S254) ◽  
pp. 95-96
Author(s):  
Arthur M. Wolfe ◽  
Regina A. Jorgenson ◽  
Timothy Robishaw ◽  
Carl Heiles ◽  
Jason X. Prochaska
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Faraday Rotation ◽  
Large Scale ◽  
Dynamo Model ◽  
Magnetic Field Generation ◽  
Interstellar Gas ◽  
Splitting Technique ◽  
Average Value ◽  
The Magnetic Field

AbstractThe magnetic field pervading our Galaxy is a crucial constituent of the interstellar medium: it mediates the dynamics of interstellar clouds, the energy density of cosmic rays, and the formation of stars (Beck 2005). The field associated with ionized interstellar gas has been determined through observations of pulsars in our Galaxy. Radio-frequency measurements of pulse dispersion and the rotation of the plane of linear polarization, i.e., Faraday rotation, yield an average value B ≈ 3 μG (Han et al. 2006). The possible detection of Faraday rotation of linearly polarized photons emitted by high-redshift quasars (Kronberg et al. 2008) suggests similar magnetic fields are present in foreground galaxies with redshifts z > 1. As Faraday rotation alone, however, determines neither the magnitude nor the redshift of the magnetic field, the strength of galactic magnetic fields at redshifts z > 0 remains uncertain.Here we report a measurement of a magnetic field of B ≈ 84 μG in a galaxy at z =0.692, using the same Zeeman-splitting technique that revealed an average value of B = 6 μG in the neutral interstellar gas of our Galaxy (Heiles et al. 2004). This is unexpected, as the leading theory of magnetic field generation, the mean-field dynamo model, predicts large-scale magnetic fields to be weaker in the past, rather than stronger (Parker 1970).The full text of this paper was published in Nature (Wolfe et al. 2008).

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