scholarly journals Use of Stokes’ theorem for plasma confinement

2020 ◽  
Vol 378 (2174) ◽  
pp. 20190519
Author(s):  
R. S. MacKay
Keyword(s):  
Magnetic Fields ◽  
Original Form ◽  
Plasma Confinement ◽  
Theme Issue ◽  
Ionized Gas

Stokes’ theorem, in its original form and Cartan’s generalization, is crucial for designing magnetic fields to confine plasma (ionized gas). The paper illustrates its use, in particular to address the question whether quasi-symmetric fields, those for which guiding-centre motion is integrable, can be made with little or no toroidal current. This article is part of the theme issue ‘Stokes at 200 (Part 1)’.

scholarly journals Magnetic Fields and Ionized Gas in the Inner Galaxy: An Outer Scale for Turbulence and the Possible Role of HiiRegions

2004 ◽  
Vol 609 (2) ◽  
pp. 776-784 ◽  
Author(s):  
M. Haverkorn ◽  
B. M. Gaensler ◽  
N. M. McClure‐Griffiths ◽  
John M. Dickey ◽  
A. J. Green
Keyword(s):  
Magnetic Fields ◽  
Outer Scale ◽  
Ionized Gas

scholarly journals Rheology of magnetic colloids containing clusters of particle platelets and polymer nanofibres

2020 ◽  
Vol 378 (2171) ◽  
pp. 20190255 ◽  
Author(s):  
Mariem Mekni Abrougui ◽  
Ezzeddine Srasra ◽  
Modesto T. Lopez-Lopez ◽  
Juan D. G. Duran
Keyword(s):  
Magnetic Fields ◽  
Magnetic Particles ◽  
Polymer Network ◽  
Soft Materials ◽  
Design Parameters ◽  
Heterogeneous Structure ◽  
High Porosity ◽  
Theme Issue ◽  
Wide Range ◽  
Magnetorheological Effect

Magnetic hydrogels (ferrogels) are soft materials with a wide range of applications, especially in biomedicine because (i) they can be provided with the required biocompatibility; (ii) their heterogeneous structure allows their use as scaffolds for tissue engineering; (iii) their mechanical properties can be modified by changing different design parameters or by the action of magnetic fields. These characteristics confer them unique properties for acting as patterns that mimic the architecture of biological systems. In addition, and (iv) given their high porosity and aqueous content, ferrogels can be loaded with drugs and guided towards specific targets for local (non-systemic) pharmaceutical treatments. The ferrogels prepared in this work contain magnetic particles obtained by precipitation of magnetite nanoparticles onto the porous surface of bentonite platelets. Then, the particles were functionalized by adsorption of alginate molecules and dispersed in an aqueous solution of sodium alginate. Finally, the gelation was promoted by cross-linking the alginate molecules with Ca 2+ ions. The viscoelastic properties of the ferrogels were measured in the absence/presence of external magnetic fields, showing that these ferrogels exhibited a strong enough magnetorheological effect. This behaviour is explained considering the field-induced strengthening of the heterogeneous (particle–polymer) network generated inside the ferrogel. This article is part of the theme issue ‘Patterns in soft and biological matters'.

scholarly journals Magnetic Fields & Ionized Gas in Elliptical Galaxy Halos

1990 ◽  
Vol 140 ◽  
pp. 459-462
Author(s):  
Richard G. Strom
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Elliptical Galaxy ◽  
Radio Sources ◽  
Early Type ◽  
Ionized Gas ◽  
X Ray ◽  
Galaxy Halos ◽  
Field Strengths

Faraday depolarization estimates of thermal densities within the components of double radio sources agree well with estimates from X-ray observations of hot halos around early-type galaxies, provided magnetic field strengths are close to their equipartition values. Internal Faraday dispersion is the main cause of the depolarization observed.

scholarly journals Turbulence in the diffuse magneto-ionized medium: observational aspects

2015 ◽  
Vol 11 (A29B) ◽  
pp. 720-722
Author(s):  
Marijke Haverkorn
Keyword(s):  
Magnetic Fields ◽  
Milky Way ◽  
Turbulent Energy ◽  
Spectral Lines ◽  
Observational Methods ◽  
Interstellar Gas ◽  
Ionized Gas ◽  
Neutral Gas ◽  
Velocity Information ◽  
Gas Component

AbstractTurbulence in the interstellar medium is ubiquitous. The turbulent energy density in the gas is significant, and comparable to energy densities of magnetic fields and cosmic rays. Studies of the turbulent interstellar gas in the Milky Way have mostly focused on the neutral gas component, since various spectral lines can give velocity information. Probing turbulent properties in the ionized gas, let alone in magnetic fields, is observationally more difficult. A number of observational methods are discussed below which provide estimates of the maximum scale of fluctuations, the Mach number and other turbulence characteristics.

scholarly journals 9.10. The cause of the spectral turnover in the GPS source 0108+388: free-free absorption or SSA?

1998 ◽  
Vol 184 ◽  
pp. 401-402
Author(s):  
J. M. Marr ◽  
F. Crawford ◽  
G. B. Taylor
Keyword(s):  
Magnetic Fields ◽  
Radio Source ◽  
High Frequency ◽  
Radio Sources ◽  
Host Galaxies ◽  
Ionized Gas ◽  
High Frequencies ◽  
Extragalactic Radio Sources ◽  
Competing Models ◽  
Frequency Radiation

The radio source 0108 + 388 is a canonical example of a class of extragalactic radio sources, referred to as Gigahertz-Peaked Spectrum (GPS) sources, whose spectra peak at high frequencies. There are two competing models for the cause of the high frequency turnover: free-free absorption (f-f) of the lower frequency radiation by ionized gas in the host galaxies (e.g. van Breugel 1984), or synchrotron self-absorption (SSA) due to exceptionally large magnetic fields, (e.g. Hodges, Mutel, & Phillips 1984).

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