Thermal equilibration behind an ionizing shock

1966 ◽  
Vol 26 (3) ◽  
pp. 459-479 ◽  
Author(s):  
H. Wong ◽  
D. Bershader
Keyword(s):  
Refractive Index ◽  
Theoretical Analysis ◽  
Thermal Equilibrium ◽  
Mass Density ◽  
Relaxation Times ◽  
Ionization Mechanism ◽  
Density Profiles ◽  
Physical Mechanisms ◽  
Thermal Equilibration ◽  
Equilibrium Region

The physical mechanisms underlying the relaxation process leading to thermal equilibrium behind ionizing shock waves in argon have been studied through use of optical techniques. The non-equilibrium condition in the relaxation region was investigated experimentally by measuring the shift in the fringes due to a change in the refractive index of the medium with a Mach–Zehnder interferometer. Both electron- and mass-density profiles from the shock front to the equilibrium region were determined. The experimental work has been supplemented by a theoretical analysis of the ionization mechanism to explain the measured profiles and relaxation times.

scholarly journals Are ultra-diffuse galaxies Milky Way-sized?

2020 ◽  
Vol 633 ◽  
pp. L3 ◽  
Author(s):  
Nushkia Chamba ◽  
Ignacio Trujillo ◽  
Johan H. Knapen
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Size Range ◽  
Mass Density ◽  
Effective Radius ◽  
Density Profiles ◽  
Gas Density ◽  
Undesirable Consequence ◽  
Definition Of ◽  
Density Threshold

Now almost 70 years since its introduction, the effective or half-light radius has become a very popular choice for characterising galaxy size. However, the effective radius measures the concentration of light within galaxies and thus does not capture our intuitive definition of size which is related to the edge or boundary of objects. For this reason, we aim to demonstrate the undesirable consequence of using the effective radius to draw conclusions about the nature of faint ultra-diffuse galaxies (UDGs) when compared to dwarfs and Milky Way-like galaxies. Instead of the effective radius, we use a measure of galaxy size based on the location of the gas density threshold required for star formation. Compared to the effective radius, this physically motivated definition places the sizes much closer to the boundary of a galaxy. Therefore, considering the sizes and stellar mass density profiles of UDGs and regular dwarfs, we find that the UDGs have sizes that are within the size range of dwarfs. We also show that currently known UDGs do not have sizes comparable to Milky Way-like objects. We find that, on average, UDGs are ten times smaller in extension than Milky Way-like galaxies. These results show that the use of size estimators sensitive to the concentration of light can lead to misleading results.

scholarly journals NONLINEAR OPTICAL WAVEGUIDE STRUCTURE FOR SENSOR APPLICATION: TM CASE

2007 ◽  
Vol 21 (30) ◽  
pp. 5075-5089 ◽  
Author(s):  
HALA M. KHALIL ◽  
MOHAMMED M. SHABAT ◽  
SOFYAN A. TAYA ◽  
MAZEN M. ABADLA
Keyword(s):  
Refractive Index ◽  
Theoretical Analysis ◽  
Closed Form ◽  
Optical Waveguide ◽  
Effective Refractive Index ◽  
Nonlinear Optical ◽  
Waveguide Structure ◽  
Analytical Expressions ◽  
Evanescent Waveguide ◽  
Waveguide Sensor

In this work, we present an extensive theoretical analysis of nonlinear optical waveguide sensor. The waveguide under consideration consists of a thin dielectrica film surrounded by a self-focused nonlinear cladding and a linear substrate. The nonlinearity of the cladding is considered to be of Kerr-type. Both cases, when the effective refractive index is greater and when it is smaller than the index of the guiding layer, are discussed. The sensitivity of the effective refractive index to any change in the cladding index in evanescent optical waveguide sensor is derived for TM modes. Closed form analytical expressions and normalized charts are given to provide the conditions required for the sensor to exhibit its maximum sensitivity. The results are compared with those of the well-known linear evanescent waveguide sensors.

Nonlinear Refractive Index of Silicon Nanoparticles: A Short Review

2014 ◽  
Vol 1 (2) ◽  
pp. 87-97
Author(s):  
Sudakshina Prusty
Keyword(s):  
Refractive Index ◽  
Nonlinear Refractive Index ◽  
Phase Modulation ◽  
Silicon Nanoparticles ◽  
Nonlinear Coefficient ◽  
Short Review ◽  
Self Phase Modulation ◽  
Physical Mechanisms ◽  
Self Focusing ◽  
Physical Phenomena

This article discusses the nonlinear refractive index of silicon nanoparticles starting from the basic formalism to some of the consequent physical phenomena like self focusing and self phase modulation. Several experimental techniques mainly based on Z-scan are discussed to measure the nonlinear refractive index. Another less explored technique for silicon nanoparticles, which studies the far-field optical fringe pattern formed by spatial self-phase modulation, is also discussed. Computation of the nonlinear refractive index is shown in detail by employing these two techniques. While Z-scan can estimate the nonlinear coefficient of a medium in a chosen time scale, the optical fringe method can predict the overall nonlinear refractive index due to all possible physical mechanisms. Some of the recent results for silicon nanoparticles using these two techniques are also discussed.

(OR-135)THEORETICAL ANALYSIS OF AMETROPIA CORRECTION AND ACCOMMODATION AMPLITUDE BY VARYING REFRACTIVE INDEX IN PHACO-ERSATZ

2000 ◽  
Vol 77 (SUPPLEMENT) ◽  
pp. 192
Author(s):  
Arthur Ho ◽  
Paul Erickson ◽  
Therese Pham ◽  
Fabrice Manns ◽  
Jean-Marie Parel
Keyword(s):  
Refractive Index ◽  
Theoretical Analysis

scholarly journals The intracluster light as a tracer of the total matter density distribution: a view from simulations

2020 ◽  
Vol 494 (2) ◽  
pp. 1859-1864 ◽  
Author(s):  
Isaac Alonso Asensio ◽  
Claudio Dalla Vecchia ◽  
Yannick M Bahé ◽  
David J Barnes ◽  
Scott T Kay
Keyword(s):  
Mass Density ◽  
Radial Profile ◽  
Stellar Mass ◽  
Matter Density ◽  
Density Profiles ◽  
Radial Profiles ◽  
Intracluster Light ◽  
Baryonic Mass ◽  
Mass Density Profile ◽  
Total Matter

ABSTRACT By using deep observations of clusters of galaxies, it has been recently found that the projected stellar mass density closely follows the projected total (dark and baryonic) mass density within the innermost ∼140 kpc. In this work, we aim to test these observations using the Cluster-EAGLE simulations, comparing the projected densities inferred directly from the simulations. We compare the iso-density contours using the procedure of Montes & Trujillo, and find that the shape of the stellar mass distribution follows that of the total matter even more closely than observed, although their radial profiles differ substantially. The ratio between stellar and total matter density profiles in circular apertures shows a slope close to −1, with a small dependence on the cluster’s total mass. We propose an indirect method to calculate the halo mass and mass density profile from the radial profile of the intracluster stellar mass density.

scholarly journals Computational modeling of Krypton gas puffs with tailored mass density profiles on Za)

2015 ◽  
Vol 22 (5) ◽  
pp. 056316 ◽  
Author(s):  
C. A. Jennings ◽  
D. J. Ampleford ◽  
D. C. Lamppa ◽  
S. B. Hansen ◽  
B. Jones ◽  
...  
Keyword(s):  
Computational Modeling ◽  
Mass Density ◽  
Density Profiles

Scaling relationships for nonadiabatic energy relaxation times in warm dense matter: toward understanding the equation of state

2016 ◽  
Vol 18 (47) ◽  
pp. 32466-32476 ◽  
Author(s):  
Ekadashi Pradhan ◽  
Rudolph J. Magyar ◽  
Alexey V. Akimov
Keyword(s):  
Energy Transfer ◽  
Equation Of State ◽  
Electron Energy ◽  
Mass Density ◽  
Relaxation Times ◽  
Dense Matter ◽  
Energy Relaxation ◽  
Warm Dense Matter ◽  
Transfer Rates ◽  
Scaling Relationships

The dependence of nonadiabatic ion-electron energy transfer rates in warm dense aluminum on the mass density and temperature with decoherence changing this relationship qualitatively.

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