92 research outputs found
The mechanical action of powerful energy fluxes upon the high porous heterogeneous material
The development of new particle boosters requires new models, describing of behavior of powerful beam interaction with heterogeneous insulator materials. The method of thermal properties determination of high porous material, irradiated by powerful electron and X-ray beam was developed. The differential equation of state for porous matter was used. The powerful flux action upon various material types is numerically studied. Calculated data are compared with experimental one
Long-range attraction between particles in dusty plasma and partial surface tension of dusty phase boundary
Effective potential of a charged dusty particle moving in homogeneous plasma
has a negative part that provides attraction between similarly charged dusty
particles. A depth of this potential well is great enough to ensure both
stability of crystal structure of dusty plasma and sizable value of surface
tension of a boundary surface of dusty region. The latter depends on the
orientation of the surface relative to the counter-ion flow, namely, it is
maximal and positive for the surface normal to the flow and minimal and
negative for the surface along the flow. For the most cases of dusty plasma in
a gas discharge, a value of the first of them is more than sufficient to ensure
stability of lenticular dusty phase void oriented across the counter-ion flow.Comment: LATEX, REVTEX4, 7 pages, 6 figure
EXPERIMENTS ON PHASE TRANSITIONS IN 3D DUSTY PLASMA UNDER MICROGRAVITY CONDITIONS
The investigations have been performed onboard the International Space Station (ISS) with the help of the PK-3 Plus laboratory. Due to the manipulation of the interaction potential between the microparticles it is possible to initiate a phase transition from isotropic plasma into electrorheological plasma. The crystal-liquid phase transition was obtained in large 3D isotropic dusty plasma system. First observations of a transition of the dusty plasma system state due to variations of the plasma component density are presented.64-6
Enhancement of fusion rates due to quantum effects in the particles momentum distribution in nonideal media
This study concerns a situation when measurements of the nonresonant
cross-section of nuclear reactions appear highly dependent on the environment
in which the particles interact. An appealing example discussed in the paper is
the interaction of a deuteron beam with a target of deuterated metal Ta. In
these experiments, the reaction cross section for d(d,p)t was shown to be
orders of magnitude greater than what the conventional model predicts for the
low-energy particles. In this paper we take into account the influence of
quantum effects due to the Heisenberg uncertainty principle for particles in a
non-ideal medium elastically interacting with the medium particles. In order to
calculate the nuclear reaction rate in the non-ideal environment we apply both
the Monte Carlo technique and approximate analytical calculation of the Feynman
diagram using nonrelativistic kinetic Green's functions in the medium which
correspond to the generalized energy and momentum distribution functions of
interacting particles. We show a possibility to reduce the 12-fold integral
corresponding to this diagram to a fivefold integral. This can significantly
speed up the computation and control accuracy. Our calculations show that
quantum effects significantly influence reaction rates such as p +7Be, 3He
+4He, p +7Li, and 12C +12C. The new reaction rates may be much higher than the
classical ones for the interior of the Sun and supernova stars. The possibility
to observe the theoretical predictions under laboratory conditions is
discussed
Metallic liquid hydrogen and likely Al2O3 metallic glass
Dynamic compression has been used to synthesize liquid metallic hydrogen at
140 GPa (1.4 million bar) and experimental data and theory predict Al2O3 might
be a metallic glass at ~300 GPa. The mechanism of metallization in both cases
is probably a Mott-like transition. The strength of sapphire causes shock
dissipation to be split differently in the strong solid and soft fluid. Once
the 4.5-eV H-H and Al-O bonds are broken at sufficiently high pressures in
liquid H2 and in sapphire (single-crystal Al2O3), electrons are delocalized,
which leads to formation of energy bands in fluid H and probably in amorphous
Al2O3. The high strength of sapphire causes shock dissipation to be absorbed
primarily in entropy up to ~400 GPa, which also causes the 300-K isotherm and
Hugoniot to be virtually coincident in this pressure range. Above ~400 GPa
shock dissipation must go primarily into temperature, which is observed
experimentally as a rapid increase in shock pressure above ~400 GPa. The
metallization of glassy Al2O3, if verified, is expected to be general in strong
oxide insulators. Implications for Super Earths are discussed.Comment: 8 pages, 5 figures, 14th Liquid and Amorphous Metals Conference, Rome
201
Spallative ablation of dielectrics by X-ray laser
Short laser pulse in wide range of wavelengths, from infrared to X-ray,
disturbs electron-ion equilibrium and rises pressure in a heated layer. The
case where pulse duration is shorter than acoustic relaxation time
is considered in the paper. It is shown that this short pulse may cause
thermomechanical phenomena such as spallative ablation regardless to
wavelength. While the physics of electron-ion relaxation on wavelength and
various electron spectra of substances: there are spectra with an energy gap in
semiconductors and dielectrics opposed to gapless continuous spectra in metals.
The paper describes entire sequence of thermomechanical processes from
expansion, nucleation, foaming, and nanostructuring to spallation with
particular attention to spallation by X-ray pulse
Wigner crystal in snaked nanochannels
We study properties of Wigner crystal in snaked nanochannels and show that
they are characterized by conducting sliding phase at low charge densities and
insulating pinned phase emerging above a certain critical charge density. The
transition between these phases has a devil's staircase structure typical for
the Aubry transition in dynamical maps and the Frenkel-Kontorova model. We
discuss implications of this phenomenon for charge density waves in
quasi-one-dimensional organic conductors and for supercapacitors in nanopore
materials.Comment: 4 pages, 6 figs, research at http://www.quantware.ups-tlse.f
Relativistic Laser-Matter Interaction and Relativistic Laboratory Astrophysics
The paper is devoted to the prospects of using the laser radiation
interaction with plasmas in the laboratory relativistic astrophysics context.
We discuss the dimensionless parameters characterizing the processes in the
laser and astrophysical plasmas and emphasize a similarity between the laser
and astrophysical plasmas in the ultrarelativistic energy limit. In particular,
we address basic mechanisms of the charged particle acceleration, the
collisionless shock wave and magnetic reconnection and vortex dynamics
properties relevant to the problem of ultrarelativistic particle acceleration.Comment: 58 pages, 19 figure
Liquid metals and liquid carbon: some similar properties at high temperatures
Liquid carbon resistivity ρ (just after the melting) diminishes with rising of input energy and pressure P (for P - lower than 50 kbar). Far above melting point, at high pressure (higher ~50 kbar) liquid carbon resistivity rises sharply, up to 3000 µΩ⋅cm. It was shown that the liquid carbon (as some other metals, for example W, Li) has one and the same property: a denser phase (in liquid state) has higher resistivit
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