Effect of magnetic field structure on collisional drift waves

A 3-field model for collisional drift waves, in the ballooning representation, for a low-pressure stellarator plasma is presented. The 3-field model, which includes the effects of a finite radial mode number (θk) , is solved as an initial-value problem along the magnetic field line. It is shown that for a stellarator with low global magnetic shear, θk= 0 corresponds to the fastest linear growth rate. The effects of the magnetic field structure for the tokamak and stellarator configurations are discussed in a comparative way. PACS Nos.: 52.35Kt, 52.30Jb, 52.35Ra

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Effect of Radial Wavevector on Collisional Drift Waves in a Toroidal Heliac

Australian Journal of Physics ◽

10.1071/p98071 ◽

1999 ◽

Vol 52 (1) ◽

pp. 71 ◽

Cited By ~ 1

Author(s):

J. L. V. Lewandowski ◽

R. M. Ellem

Keyword(s):

Growth Rate ◽

Electrostatic Potential ◽

Growth Rates ◽

Initial Value Problem ◽

Linear Growth ◽

Field Model ◽

Linear Growth Rate ◽

Drift Waves ◽

Initial Value ◽

Magnetic Shear

A 3-field model for collisional drift waves, in the ballooning representation, for a low-pressure stellarator plasma is presented. In particular, the effect of a finite radial mode number (≡ θk) is studied, and the linear growth rates for the fluctuating plasma density, electrostatic potential and electron temperature are computed numerically by solving the 3-field model as an initial-value problem. Numerical results for a 3-field period stellarator with low global magnetic shear are then presented. It is found that, in a system with small global magnetic shear, the case θk = 0 yields the fastest linear growth rate.

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A novel analytical model of the magnetic field configuration in the Galactic center

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936081 ◽

2020 ◽

Vol 644 ◽

pp. A71

Author(s):

M. Guenduez ◽

J. Becker Tjus ◽

K. Ferrière ◽

R.-J. Dettmar

Keyword(s):

Magnetic Field ◽

Large Scale ◽

Field Model ◽

Galactic Center ◽

Cosmic Ray ◽

Field Structure ◽

Magnetic Field Structure ◽

Center Region ◽

Magnetic Field Model ◽

The Magnetic Field

Context. Cosmic-ray propagation is strongly dependent on the large-scale configuration of the Galactic magnetic field. In particular, the Galactic center region provides highly interesting cosmic-ray data from gamma-ray maps and it is clear that a large fraction of the cosmic rays detected at Earth originate in this region of the Galaxy. Yet because of confusion from line-of-sight integration, the magnetic field structure in the Galactic center is not well known and no large-scale magnetic field model exists at present. Aims. In this paper, we develop a magnetic field model, derived from observational data on the diffuse gas, nonthermal radio filaments, and molecular clouds. Methods. We derive an analytical description of the magnetic field structure in the central molecular zone by combining observational data with the theoretical modeling of the basic properties of magnetic fields. Results. We provide a first description of the large-scale magnetic field in the Galactic center region. We present first test simulations of cosmic-ray propagation and the impact of the magnetic field structure on the cosmic-ray distribution in the three dimensions. Conclusions. Our magnetic field model is able to describe the main features of polarization maps; it is particularly important to note that they are significantly better than standard global Galactic magnetic field models. It can also be used to model cosmic-ray propagation in the Galactic center region more accurately.

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The Magnetic Be Star Sigma Orionis E

International Astronomical Union Colloquium ◽

10.1017/s0252921100116057 ◽

1987 ◽

Vol 92 ◽

pp. 82-83 ◽

Cited By ~ 3

Author(s):

C. T. Bolton ◽

A. W. Fullerton ◽

D. Bohlender ◽

J. D. Landstreet ◽

D. R. Gies

Keyword(s):

Magnetic Field ◽

Field Structure ◽

High Signal ◽

Rotational Period ◽

Magnetic Field Structure ◽

The Past ◽

Distribution Of Elements ◽

Be Star ◽

Hα Emission ◽

The Magnetic Field

Over the past two years, we have obtained high resolution high signal/noise (S/N) spectra of the magnetic Be star σ Ori E at the Canada-France-Hawaii Telescope and McDonald Observatory. These spectra, which cover the spectral regions 399-417.5 and 440-458.5 nm and the Hα line and have typical S/N>200 and spectral resolution ≃0.02 nm, were obtained at a variety of rotational phases in order to study the magnetic field structure, the distribution of elements in the photosphere, and the effects of the magnetic field on the emission envelope. Our analysis of these spectra confirms, refines and extends the results obtained by Landstreet & Borra (1978), Groote & Hunger (1982 and references therein), and Nakajima (1985).The Hα emission is usually double-peaked, but it undergoes remarkable variations with the 1.19081 d rotational period of the star, which show that the emitting gas is localized into two regions which co-rotate with the star.

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