Relativistic and Nonlinear Radiation Interaction Between Laser Beams and Plasmas

1981 ◽  
Vol 34 (4) ◽  
pp. 385 ◽  
Author(s):  
Edward L Kane ◽  
Heinrich Hora
Keyword(s):  
Time History ◽  
Number Density ◽  
Plasma Dynamic ◽  
Density Distributions ◽  
Laser Propagation ◽  
Plasma Density Distribution ◽  
Target Plasma ◽  
Laser Pulse Power ◽  
The One ◽  
Focused Beam

Starting from a combination of Maxwell's laws for the electromagnetic field and the conservation. equations for a fully ionized plasma, the appropriate equations describing electrodynamic laser propagation and plasma dynamic particle motion are developed and solved. Calculations for multiply ionized transient conditions are carried out to yield electric field amplitudes, radial electron number density distributions and the progress of formation of a self-focused beam filament as a function of the target plasma density distribution and the laser pulse power-time history, among other parameters. Separate solutions emphasizing field-induced plasma motion on the one hand and significant beam contraction on the other are illustrated.

scholarly journals APPLICATIONS OF DENSITY MATRICES IN A TRAPPED BOSE GAS

2006 ◽  
Vol 20 (15) ◽  
pp. 2189-2221 ◽  
Author(s):  
K. CH. CHATZISAVVAS ◽  
S. E. MASSEN ◽  
CH. C. MOUSTAKIDIS ◽  
C. P. PANOS
Keyword(s):  
Quantum Information ◽  
Bose Gas ◽  
Einstein Condensation ◽  
Density Distributions ◽  
Occupation Numbers ◽  
The One ◽  
Bose Einstein ◽  
Jensen Shannon Divergence ◽  
Analytical Expressions ◽  
Short Range Correlations

An overview of the Bose–Einstein condensation of correlated atoms in a trap is presented by examining the effect of interparticle correlations to one- and two-body properties of the above systems at zero temperature in the framework of the lowest order cluster expansion. Analytical expressions for the one- and two-body properties of the Bose gas are derived using Jastrow-type correlation function. In addition numerical calculations of the natural orbitals and natural occupation numbers are also carried out. Special effort is devoted for the calculation of various quantum information properties including Shannon entropy, Onicescu informational energy, Kullback–Leibler relative entropy and the recently proposed Jensen–Shannon divergence entropy. The above quantities are calculated for the trapped Bose gases by comparing the correlated and uncorrelated cases as a function of the strength of the short-range correlations. The Gross–Piatevskii equation is solved, giving the density distributions in position and momentum space, which are employed to calculate quantum information properties of the Bose gas.

scholarly journals A new Description of Probability Density Distributions of Polar Mesospheric Clouds (PMC)

2018 ◽  
Author(s):  
Uwe Berger ◽  
Gerd Baumgarten ◽  
Jens Fiedler ◽  
Franz-Josef Lübken
Keyword(s):  
Probability Density ◽  
Mass Density ◽  
Particle Radius ◽  
Number Density ◽  
Data Set ◽  
Statistical Probability ◽  
Polar Mesospheric Clouds ◽  
Density Distributions ◽  
Mesospheric Clouds ◽  
Probability Density Distributions

Abstract. In this paper we present a new description about statistical probability density distributions (pdfs) of Polar Mesospheric Clouds (PMC) and noctilucent clouds (NLC). The analysis is based on observations of maximum backscatter, ice mass density, ice particle radius, and number density of ice particles measured by the ALOMAR RMR-lidar for all NLC seasons from 2002 to 2016. From this data set we derive a new class of pdfs that describe the statistics of PMC/NLC events which is different from previously statistical methods using the approach of an exponential distribution commonly named g-distribution. The new analysis describes successfully the probability statistic of ALOMAR lidar data. It turns out that the former g-function description is a special case of our new approach. In general the new statistical function can be applied to many kinds of different PMC parameters, e.g. maximum backscatter, integrated backscatter, ice mass density, ice water content, ice particle radius, ice particle number density or albedo measured by satellites. As a main advantage the new method allows to connect different observational PMC distributions of lidar, and satellite data, and also to compare with distributions from ice model studies. In particular, the statistical distributions of different ice parameters can be compared with each other on the basis of a common assessment that facilitate, for example, trend analysis of PMC/NLC.

The Measurement of f-values for Lines of Astrophysical Interest by Beam-Foil Spectroscopy

1978 ◽  
Vol 3 (4) ◽  
pp. 263-264
Author(s):  
J. E. Ross ◽  
B. J. O’Mara
Keyword(s):  
Life Time ◽  
Absolute Number ◽  
Branching Ratios ◽  
Oscillator Strengths ◽  
Separate Experiment ◽  
Number Density ◽  
Reasonable Accuracy ◽  
Initial Excitation ◽  
The One ◽  
Beam Foil

The necessity of having accurate oscillator strengths in astrophysical applications is well known. The apparent discrepancy which existed between the solar and meteoritic abundance of iron is just one example of the problems which can arise from poor f-values. An excellent critique of methods for determining both absolute and relative f-values has been given by Blackwell & Collins (1972). Their comments on life-time techniques provide a clear indication of both the advantages and difficulties associated with these techniques: “In principle, a life-time method, as exemplified by the technique of beam foil spectroscopy, described for example by Wiese (1970), has the fundamental advantage that in some restricted circumstances its application does not depend upon a temperature measurement or any assumption of themodynamic equilibrium in the source: in addition it gives an absolute result without the need of an absolute number density of atoms. The hope is sometimes expressed that the method of beam foil spectroscopy will yield oscillator strengths of the required accuracy. In practice, the technique suffers from the difficulty that although the life-time of an excited state can be measured with reasonable accuracy, it is also necessary to measure in a separate experiment the branching ratios for radiative de-excitation. As these ratios are usually measured by an arc method, the accuracy of the final oscillator strengths is limited by the deficiencies of this source. Also, some atoms in the beam may be excited to higher levels than the one being examined, and because of the nature of the initial excitation is unknown, radiative de-excitation (cascading) takes place to this lower level in a way that is wholly unpredictable. This difficulty is especially important for levels of low excitation.” In this talk techniques will be described for overcoming the cascading problem in beam foil spectroscopy and for measuring the associated branching ratios.

scholarly journals Evidence that Emission and Absorption Outflows in Quasars Are Related

2020 ◽  
Author(s):  
Xinfeng Xu ◽  
Nadia L Zakamska ◽  
Nahum Arav ◽  
Timothy Miller ◽  
Chris Benn
Keyword(s):  
Electron Number Density ◽  
Physical Parameters ◽  
Evolutionary Stage ◽  
Number Density ◽  
Ionized Gas ◽  
Measured Velocity ◽  
Broad Absorption Line ◽  
James Webb Space Telescope ◽  
The Mean ◽  
The One

Abstract We analyze VLT/X-shooter data for 7 quasars, where we study the relationships between their broad absorption line (BAL) and emission line outflows. We find: 1) the luminosity of the [O iii] λ5007 emission profile decreases with increasing electron number density ($n_\mathrm{\scriptstyle e}$) derived from the BAL outflow in the same quasar, 2) the measured velocity widths from the [O iii] emission features and C iv absorption troughs in the same object are similar, and 3) the mean-radial-velocity derived from the BAL outflow is moderately larger than the one from the [O iii] emission outflow. These findings are consistent with [O iii] and BAL outflows being different manifestations of the same wind, and the observed relationships are likely a reflection of the outflow density distribution. When we have outflows with smaller distances to the central source, their $n_\mathrm{\scriptstyle e}$ is higher. Therefore, the [O iii] emission is collisionally de-excited and the [O iii] luminosity is then suppressed. Comparisons to previous studies show that the objects in our sample exhibit broad [O iii] emission features similar to the ones in extremely-red-quasars (ERQs). This might imply that BAL quasars and ERQs have the same geometry of outflows or are at a similar evolutionary stage. We find that the physical parameters derived from the BAL outflows can explain the amount of observed [O iii] luminosity, which strengthens our claim that both BAL and [O iii] outflows are from the same wind. These estimates can be tested with upcoming James Webb Space Telescope, which will be able to spatially resolve some of the ionized gas outflows.

scholarly journals Structures and number-density distributions in clusters of galaxies

1978 ◽  
Vol 79 ◽  
pp. 198-199
Author(s):  
F. W. Baier
Keyword(s):  
Clusters Of Galaxies ◽  
Number Density ◽  
Multiple Systems ◽  
Preliminary Results ◽  
Density Distributions ◽  
Sky Survey

I would like to present some preliminary results of an investigation of 50 clusters of galaxies. For studying the clusters, Schmidt plates taken with the 2-metre universal telescope at Tautenburg and the prints of the Palomar Sky Survey were used. For all the clusters we determined isopleths to obtain detailed information about the distribution of galaxies. We have found well isolated clusters, double clusters, multiple systems and rather complicated structures.

scholarly journals Rare temperature histories and cirrus ice number density in a parcel and a one-dimensional model

2014 ◽  
Vol 14 (23) ◽  
pp. 13013-13022 ◽  
Author(s):  
D. M. Murphy
Keyword(s):  
Temperature Dependence ◽  
Low Temperatures ◽  
Ice Crystals ◽  
Strong Increase ◽  
Number Density ◽  
Dimensional Model ◽  
One Dimensional ◽  
Slow Growth Rate ◽  
Wide Range ◽  
The One

Abstract. A parcel and a one-dimensional model are used to investigate the temperature dependence of ice crystal number density. The number of ice crystals initially formed in a cold cirrus cloud is very sensitive to the nucleation mechanism and the detailed history of cooling rates during nucleation. A possible small spread in the homogeneous freezing threshold due to varying particle composition is identified as a sensitive nucleation parameter. In a parcel model, the slow growth rate of ice crystals at low temperatures inherently leads to a strong increase in ice number density at low temperatures. This temperature dependence is not observed. The model temperature dependence occurs for a wide range of assumptions and for either homogeneous or, less strongly, heterogeneous freezing. However, the parcel model also shows that random temperature fluctuations result in an extremely wide range of ice number densities. A one-dimensional model is used to show that the rare temperature trajectories resulting in the lowest number densities are disproportionately important. Low number density ice crystals sediment and influence a large volume of air. When such fall streaks are included, the ice number becomes less sensitive to the details of nucleation than it is in a parcel model. The one-dimensional simulations have a more realistic temperature dependence than the parcel mode. The one-dimensional model also produces layers with vertical dimensions of meters even if the temperature forcing has a much broader vertical wavelength. Unlike warm clouds, cirrus clouds are frequently surrounded by supersaturated air. Sedimentation through supersaturated air increases the importance of any process that produces small numbers of ice crystals. This paper emphasizes the relatively rare temperature trajectories that produce the fewest crystals. Other processes are heterogeneous nucleation, sedimentation from the very bottom of clouds, annealing of disordered to hexagonal ice, and entrainment.

Weak interactions in chain polymers [M(μ-X)2 L 2]∞ (M = Zn, Cd; X = Cl, Br; L = substituted pyridine) – an electron density study

2009 ◽  
Vol 65 (5) ◽  
pp. 600-611 ◽  
Author(s):  
Ruimin Wang ◽  
Christian W. Lehmann ◽  
Ulli Englert
Keyword(s):  
Hydrogen Bonds ◽  
Electron Density ◽  
Critical Points ◽  
Weak Interactions ◽  
Data Sets ◽  
X Ray Diffraction ◽  
Density Distributions ◽  
The One ◽  
Experimental Electron Density ◽  
Density Study

The experimental electron-density distributions in crystals of five chain polymers [M(μ-X)2(py)2] (M = Zn, Cd; X = Cl, Br; py = 3,5-substituted pyridine) have been obtained from high-resolution X-ray diffraction data sets (sin θ/λ > 1.1 Å−1) at 100 K. Topological analyses following Bader's `Atoms in Molecules' approach not only confirmed the existence of (3, −1) critical points for the chemically reasonable and presumably strong covalent and coordinative bonds, but also for four different secondary interactions which are expected to play a role in stabilizing the polymeric structures which are unusual for Zn as the metal center. These weaker contacts comprise intra- and inter-strand C—H...X—M hydrogen bonds on the one hand and C—X...X—C interhalogen contacts on the other hand. According to the experimental electron-density studies, the non-classical hydrogen bonds are associated with higher electron density in the (3, −1) critical points than the halogen bonds and hence are the dominant interactions both with respect to intra- and inter-chain contacts.

Sequential Nano-Patterning Using Electron and Laser Beams: A Numerical Methodology

2006 ◽  
Vol 3 (2) ◽  
pp. 219-230 ◽  
Author(s):  
Basil T. Wong ◽  
M. Pinar Mengüç ◽  
R. Ryan Vallance
Keyword(s):  
Monte Carlo ◽  
Electron Beam ◽  
Ray Tracing ◽  
Electron Scattering ◽  
Gold Film ◽  
Quartz Substrate ◽  
Experimental Studies ◽  
Machining Processes ◽  
Laser Propagation ◽  
The One

A methodology is presented for nanometer-size patterning of a workpiece using both an electron-beam and a laser. A Monte Carlo/Ray Tracing technique is used in modeling the electron-beam propagation inside a thin gold film. This approach is identical to that of a typical Monte Carlo simulation in radiative transfer except that proper electron scattering properties are employed. The laser propagation within the one-dimensional, non-scattering film on top of a quartz substrate is modeled using a ray-tracing approach and reflections at the boundaries are accounted for with the Fresnel-expressions. The temperature distribution inside a gold film is then predicted using the Fourier law of heat conduction, after evaluating the accuracy of the model for the range considered. A sequential nano-pattern is created using these coupled numerical simulations. The procedure we present here is the first to outline the sequential nano-machining processes and likely to guide the experimental studies to success with less trial-and-error attempts.

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