337 research outputs found
The Energy of a Plasma in the Classical Limit
When \lambda_{T} << d_{T}, where \lambda_{T} is the de Broglie wavelength and
d_{T}, the distance of closest approach of thermal electrons, a classical
analysis of the energy of a plasma can be made. In all the classical analysis
made until now, it was assumed that the frequency of the fluctuations \omega <<
T (k_{B}=\hbar=1). Using the fluctuation-dissipation theorem, we evaluate the
energy of a plasma, allowing the frequency of the fluctuations to be arbitrary.
We find that the energy density is appreciably larger than previously thought
for many interesting plasmas, such as the plasma of the Universe before the
recombination era.Comment: 10 pages, 2 figures, accepted for publication in Phys.Rev.Let
Vlasov Equation In Magnetic Field
The linearized Vlasov equation for a plasma system in a uniform magnetic
field and the corresponding linear Vlasov operator are studied. The spectrum
and the corresponding eigenfunctions of the Vlasov operator are found. The
spectrum of this operator consists of two parts: one is continuous and real;
the other is discrete and complex. Interestingly, the real eigenvalues are
infinitely degenerate, which causes difficulty solving this initial value
problem by using the conventional eigenfunction expansion method. Finally, the
Vlasov equation is solved by the resolvent method.Comment: 15 page
On the Ground State of Electron Gases at Negative Compressibility
Two- and three-dimensional electron gases with a uniform neutralizing
background are studied at negative compressibility. Parametrized expressions
for the dielectric function are used to access this strong-coupling regime,
where the screened Coulomb potential becomes overall attractive for like
charges. Closely examining these expressions reveals that the ground state with
a periodic modulation of the charge density, albeit exponentially damped,
replaces the homogeneous one at positive compressibility. The wavevector
characterizing the new ground state depends on the density and is complex,
having a positive imaginary part, as does the homogeneous ground state, and
real part, as does the genuine charge density wave.Comment: 6 double-column pages, 2 figures. 2nd version is an extension of the
1st one, giving more detail
Theory of spin and charge fluctuations in the Hubbard model
A self-consistent theory of both spin and charge fluctuations in the Hubbard
model is presented. It is in quantitative agreement with Monte Carlo data at
least up to intermediate coupling . It includes both
short-wavelength quantum renormalization effects, and long-wavelength thermal
fluctuations which can destroy long-range order in two dimensions. This last
effect leads to a small energy scale, as often observed in high temperature
superconductors. The theory is conserving, satisfies the Pauli principle and
includes three-particle correlations necessary to account for the incipient
Mott transition.Comment: J1K 2R1 10 pages, Revtex 3.0, 4 uuencoded postscript figures, report#
CRPS-93-4
Application of a new screening model to thermonuclear reactions of the rp process
A new screening model for astrophysical thermonuclear reactions was derived
recently which improved Salpeter's weak-screening one. In the present work we
prove that the new model can also give very reliable screening enhancement
factors (SEFs) when applied to the rp process. According to the results of the
new model, which agree well with Mitler's SEFs, the screened rp reaction rates
can be, at most, twice as fast as the unscreened ones.Comment: 8 RevTex pages + 7 ps figures. (Revised version). Accepted for
publication in Journal of Physics
Neutrino Trapping in a Supernova and Ion Screening
Neutrino-nucleus elastic scattering is reduced in dense matter because of
correlations between ions. The static structure factor for a plasma of
electrons and ions is calculated from Monte Carlo simulations and parameterized
with a least squares fit. Our results imply a large increase in the neutrino
mean free path. This strongly limits the trapping of neutrinos in a supernova
by coherent neutral current interactions.Comment: 9 pages, 1 postscript figure using epsf.st
Polarizational stopping power of heavy-ion diclusters in two-dimensional electron liquids
The in-plane polarizational stopping power of heavy-ion diclusters in a
two-dimensional strongly coupled electron liquid is studied. Analytical
expressions for the stopping power of both fast and slow projectiles are
derived. To go beyond the random-phase approximation we make use of the inverse
dielectric function obtained by means of the method of moments and some recent
analytical expressions for the static local-field correction factor.Comment: 9 pages, 5 figures. Published in Physical Review B
http://link.aps.org/abstract/PRB/v75/e11510
Effective dynamics of a nonabelian plasma out of equilibrium
Starting from kinetic theory, we obtain a nonlinear dissipative formalism
describing the nonequilibrium evolution of scalar colored particles coupled
selfconsistently to nonabelian classical gauge fields. The link between the
one-particle distribution function of the kinetic description and the variables
of the effective theory is determined by extremizing the entropy production.
This method does not rely on the usual gradient expansion in fluid dynamic
variables, and therefore the resulting effective theory can handle situations
where these gradients (and hence the momentum-space anisotropies) are expected
to be large. The formalism presented here, being computationally less demanding
than kinetic theory, may be useful as a simplified model of the dynamics of
color fields during the early stages of heavy ion collisions and in phenomena
related to parton energy loss.Comment: 20 two-column pages, 2 figures. v3: minor changes. Accepted for
publication in Phys. Rev.
Stationary Velocity and Charge Distributions of Grains in Dusty Plasmas
Within the kinetic approach velocity and charge distributions of grains in
stationary dusty plasmas are calculated and the relations between the effective
temperatures of such distributions and plasma parameters are established. It is
found that the effective temperature which determines the velocity grain
distribution could be anomalously large due to the action of accelerating ionic
bombarding force. The possibility to apply the results obtained to the
explanation of the increasing grain temperature in the course of the
Coulomb-crystal melting by reduction of the gas pressure is discussed. This
paper was received by Phys.Rev.Lett. on 11 August 1999. As potential referees
the authors offered to Editor the following persons: V.N.Tsytovich, Russia;
R.Bingham, UK; D.Resendes, Portugal; G.Morfill, P.Shukla, Y.M.Yu., Germany.Comment: 8 pages, no figure
Collective and static properties of model two-component plasmas
Classical MD data on the charge-charge dynamic structure factor of
two-component plasmas (TCP) modeled in Phys. Rev. A 23, 2041 (1981) are
analyzed using the sum rules and other exact relations. The convergent power
moments of the imaginary part of the model system dielectric function are
expressed in terms of its partial static structure factors, which are computed
by the method of hypernetted chains using the Deutsch effective potential.
High-frequency asymptotic behavior of the dielectric function is specified to
include the effects of inverse bremsstrahlung. The agreement with the MD data
is improved, and important statistical characteristics of the model TCP, such
as the probability to find both electron and ion at one point, are determined.Comment: 25 pages, 6 figures, 5 tables. Published in Physical Review E
http://link.aps.org/abstract/PRE/v76/e02640
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