scholarly journals On the Role of Magnetic Field Fluctuations in Diffusive Shock Acceleration

2011 ◽  
Vol 21 (3) ◽  
pp. 199
Author(s):  
Doan Kim The ◽  
Pham Tuan Anh ◽  
Pham Ngoc Diep ◽  
Pham Ngoc Dong ◽  
Nguyen Van Hiep ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Uniform Magnetic Field ◽  
Field Component ◽  
Larmor Radius ◽  
Shock Acceleration ◽  
Simultaneous Presence ◽  
Diffusive Shock Acceleration ◽  
Cosmic Particle ◽  
Field Fluctuations

A simple numerical simulation of the mechanism of diffusive shock acceleration, responsible for the acceleration of cosmic rays in the environment of young Super Nova Remnants, is presented. The relative roles of a uniform magnetic field component, inherited from the parent collapsed star, and of magnetic turbulences, known to be present in the vicinity of the shock, are investigated. It is shown that a uniform magnetic field allows for only doubling the energy of the cosmic particle. Important accelerations require the simultaneous presence of magnetic field turbulences at a scale commensurable with its Larmor radius.

Stability of a plasma stream in a magnetic field

1971 ◽  
Vol 6 (1) ◽  
pp. 169-186
Author(s):  
A. Lamont ◽  
J. C. Taylor ◽  
E. W. Laing
Keyword(s):  
Magnetic Field ◽  
Differential Equation ◽  
Uniform Magnetic Field ◽  
Transverse Direction ◽  
Equilibrium Distribution ◽  
Larmor Radius ◽  
Equilibrium Distribution Function ◽  
Plasma Stream ◽  
Vlasov Equations ◽  
The Fourier Transform

The system studied is a plasma streaming parallel to a uniform magnetic field with a velocity which varies in a transverse direction. The flow is bounded at y =± a by perfectly conducting planes.The Poisson-Vlasov equations are used to derive an integro-differential equation for ø the Fourier transform of the electrostatic potential. The kernel of this equation is expanded using a small Larmor radius expansion for ø and for the equilibrium distribution function f0.

The role of magnetic field fluctuations in nonadiabatic acceleration of ions during dipolarization

2009 ◽  
Vol 114 (A5) ◽  
pp. n/a-n/a ◽  
Author(s):  
Y. Ono ◽  
M. Nosé ◽  
S. P. Christon ◽  
A. T. Y. Lui
Keyword(s):  
Magnetic Field ◽  
Field Fluctuations

THE EINSTEIN–BRILLOUIN–KELLER ACTION QUANTIZATION FOR DIRAC FERMIONS

2011 ◽  
Vol 25 (08) ◽  
pp. 537-549 ◽  
Author(s):  
P. ONORATO
Keyword(s):  
Magnetic Field ◽  
Carbon Nanostructures ◽  
Uniform Magnetic Field ◽  
Graphene Nanoribbons ◽  
Maslov Index ◽  
Transverse Magnetic ◽  
Dirac Fermions ◽  
Integral Calculus ◽  
Classical Trajectories

The Einstein–Brillouin–Keller semiclassical quantization and the topological Maslov index are used to compute the electronic structure of carbon based nanostructures with or without transverse magnetic field. The calculation is based on the Dirac Fermions approach in the limit of strong coupling for the pseudospin. The electronic bandstructure for carbon nanotubes and graphene nanoribbons are discussed, focusing on the role of the chirality and of the unbonded edges configuration respectively. The effects of a transverse uniform magnetic field are analyzed, the different kinds of classical trajectories are discussed and related to the corresponding energies. The development is concise, transparent, and involves only elementary integral calculus and provides a conceptual and intuitive introduction to the quantum nature of carbon nanostructures.

A cosmic-ray-driven plasma instability

1989 ◽  
Vol 41 (1) ◽  
pp. 89-95 ◽  
Author(s):  
G. P. Zank
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Thermal Plasma ◽  
Cosmic Ray ◽  
Mhd Equations ◽  
Mutual Interaction ◽  
Shock Acceleration ◽  
Wave Effects ◽  
The Stability

The stability of the MHD equations describing the mutual interaction of cosmic rays, thermal plasma, magnetic field and Alfvén waves used in cosmic-ray-shock acceleration theory (e.g. McKenzie & Völk 1982) is analysed for linear compressive instabilities. It is found that the inclusion of wave effects implies that the forward propagating sub-Alfvénic mode is unstable on wavelength scales greater than 1 parsec. The role of the instability in astrophysical models is considered.

ON THE APPLICATION OF PLASMA KINETIC THEORY TO IONIC SOUND-WAVE EXPERIMENTS IN MAGNETIC FIELDS

1965 ◽  
Vol 43 (10) ◽  
pp. 1750-1765 ◽  
Author(s):  
M. J. Haggerty
Keyword(s):  
Magnetic Field ◽  
Uniform Magnetic Field ◽  
Critical Frequency ◽  
Magnetic Field Intensity ◽  
Sound Waves ◽  
Cyclotron Radius ◽  
The Mean ◽  
The Magnetic Field ◽  
Theoretical Results

The kinetic theoretical results for a homogeneous plasma in a uniform magnetic field are discussed qualitatively. The role of the mean cyclotron radius as a natural long-range cutoff is clarified. A relationship between a critical frequency for ionic sound waves and the magnetic-field intensity is predicted.

Weak magnetohydrodynamic turbulence and intermittency

2015 ◽  
Vol 770 ◽  
Author(s):  
R. Meyrand ◽  
K. H. Kiyani ◽  
S. Galtier
Keyword(s):  
Magnetic Field ◽  
Uniform Magnetic Field ◽  
Three Dimensional ◽  
Leading Order ◽  
Magnetohydrodynamic Turbulence ◽  
Asymptotic Regime ◽  
Resonant Interactions ◽  
Vector Separation ◽  
Parallel Current

Three-dimensional numerical simulation is used to investigate intermittency in incompressible weak magnetohydrodynamic turbulence with a strong uniform magnetic field $\boldsymbol{b}_{\mathbf{0}}$ and zero cross-helicity. At leading order, this asymptotic regime is achieved via three-wave resonant interactions with the scattering of a wave on a 2D mode for which $k_{\Vert }=0$. When the interactions with the 2D modes are artificially reduced, we show numerically that the system exhibits an energy spectrum with $k_{\bot }^{-3/2}$, whereas the expected exact solution with $k_{\bot }^{-2}$ is recovered with the full nonlinear system. In the latter case, strong intermittency is found when the vector separation of structure functions is taken transverse to $\boldsymbol{b}_{\mathbf{0}}$. This result may be explained by the influence of the 2D modes whose regime belongs to strong turbulence. In addition to shedding light on the origin of this intermittency, we derive a log-Poisson law, ${\it\zeta}_{p}=p/8+1-(1/4)^{p/2}$, which fits the data perfectly and highlights the important role of parallel current sheets.

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