642,987 research outputs found
Plasma kinetic theory
The description of plasma using fluid model is mostly insufficient and requires the consideration of velocity distribution which leads to kinetic theory. Kinetic theory of plasma describes and predicts the condition of plasma from microscopic interactions and motions of its constituents. It provides an essential basis for an introductory course on plasma physics as well as for advanced kinetic theory. Plasma kinetics deals with the relationship between velocity and forces and the study of continua in velocity space. Plasma kinetics mathematical equations provide aid to the readers in understanding simple tools to determine the plasma dynamics and kinetics as described in this chapter. Kinetic theory provides the basics and essential introduction to plasma physics and subsequently advanced kinetic theory. Plasma waves, oscillations, frequencies, and applications are the subjects of kinetic theory. In this chapter, mathematical formulations
essential for exploring plasma kinetics are compiled and described simplistically along with a precise discussion on basic plasma parameters in simple language with illustrations in some cases
Chiral Kinetic Theory
We derive the non-equilibrium kinetic equation describing the motion of
chiral massless particles in the regime where it can be considered classically.
We show that the Berry monopole which appears at the origin of the momentum
space due to level crossing is responsible for the chiral magnetic and vortical
effects.Comment: 4 page
Spin kinetic theory - quantum kinetic theory in extended phase space
The concept of phase space distribution functions and their evolution is used
in the case of en enlarged phase space. In particular, we include the intrinsic
spin of particles and present a quantum kinetic evolution equation for a scalar
quasi-distribution function. In contrast to the proper Wigner transformation
technique, for which we expect the corresponding quasi-distribution function to
be a complex matrix, we introduce a spin projection operator for the density
matrix in order to obtain the aforementioned scalar quasi-distribution
function. There is a close correspondence between this projection operator and
the Husimi (or Q) function used extensively in quantum optics. Such a function
is based on a Gaussian smearing of a Wigner function, giving a positive
definite distribution function. Thus, our approach gives a Wigner-Husimi
quasi-distribution function in extended phase space, for which the reduced
distribution function on the Bloch sphere is strictly positive. We also discuss
the gauge issue and the fluid moment hierarchy based on such a quantum kinetic
theory.Comment: 10 pages, to appear in Transport Theory and Statistical Physics,
proceedings of Vlasovia III, 200
Kinetic Integrals in the Kinetic Theory of dissipative gases
The kinetic theory of gases, including Granular Gases, is based on the
Boltzmann equation. Many properties of the gas, from the characteristics of the
velocity distribution function to the transport coefficients may be expressed
in terms of functions of the collision integral which we call kinetic
integrals. Although the evaluation of these functions is conceptually
straightforward, technically it is frequently rather cumbersome. We report here
a method for the analytical evaluation of kinetic integrals using computer
algebra. We apply this method for the computation of some properties of
Granular Gases, ranging from the moments of the velocity distribution function
to the transport coefficients. For their technical complexity most of these
quantities cannot be computed manually.Comment: 32 page
The Breakdown of Kinetic Theory in Granular Shear Flows
We examine two basic assumptions of kinetic theory-- binary collisions and
molecular chaos-- using numerical simulations of sheared granular materials. We
investigate a wide range of densities and restitution coefficients and
demonstrate that kinetic theory breaks down at large density and small
restitution coefficients. In the regimes where kinetic theory fails, there is
an associated emergence of clusters of spatially correlated grains
Construction of the Vacuum String Field Theory on a non-BPS Brane
In the framework of the Sen conjectures a construction of vacuum superstring
field theory on a non-BPS brane is discussed. A distinguished feature of this
theory is a presence of a ghost kinetic operator mixing GSO+/- sectors. A
candidate for such kinetic operator with zero cohomology is discussed.Comment: expression for the pure ghost kinetic operator corrected, Comments
added; 21 pages, 1 figure, LaTeX 2
Spin diffusion and relaxation in three-dimensional isotropic Heisenberg antiferromagnets
A theory is proposed for kinetic effects in isotropic Heisenberg
antiferromagnets at temperatures above the Neel point. A metod based on the
analysis of a set of Feynman diagrams for the kinetic coefficients is developed
for studying the critical dynamics. The scaling behavior of the generalized
coefficient of spin diffusion and relaxation constant in the paramagnetic phase
is studied in terms of the approximation of coupling modes. It is shown that
the kinetic coefficients in an antiferromagnetic system are singular in the
fluctuation region. The corresponding critical indices for diffusion and
relaxation processes are calculated. The scaling dimensionality of the kinetic
coefficients agrees with the predictions of dynamic scaling theory and a
renormalization group analysis. The proposed theory can be used to study the
momentum and frequency dependence of the kinetic parameters, and to determine
the form of the scaling functions. The role of nonlocal correlations and
spin-liquid effects in magnetic systems is briefly discussed.Comment: 10 pages, RevTeX, 3 EPS figures include
- …
