On the Decelerating Shock Instability of a Plane‐Parallel Slab with Finite Thickness

AbstractIn order to explore how supernova blast waves might catalyze star formation, we investigate the stability of a slab of decelerating gas of finite thickness. We examine the early work in the field by Elmegreen and Lada and Elmegreen and Elmegreen and demonstrate that it is flawed. Contrary to their claims, blast waves can indeed accelerate the rate of star formation in the interstellar medium. Also, we demonstrate that in an incompressible fluid, the symmetric and antisymmetric modes in the case of zero acceleration transform continuously into Rayleigh-Taylor and gravity-wave modes as acceleration grows more important.

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Star-forming instabilities of a decelerating plane-parallel slab of finite thickness

The Astrophysical Journal ◽

10.1086/166560 ◽

1988 ◽

Vol 331 ◽

pp. 343 ◽

Cited By ~ 11

Author(s):

G. Mark Voit

Keyword(s):

Finite Thickness ◽

Star Forming ◽

Plane Parallel

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Effects of the thickness of the substrate on the performance and the design of planar kinoform lenses for axial stigmatism in finite conjugate-imaging

Canadian Journal of Physics ◽

10.1139/p93-068 ◽

1993 ◽

Vol 71 (9-10) ◽

pp. 434-441 ◽

Cited By ~ 3

Author(s):

L. N. Hazra ◽

Y. Han ◽

C. A. Delisle

Keyword(s):

Ab Initio ◽

Diffraction Efficiency ◽

Parallel Plate ◽

Finite Thickness ◽

Invariance Property ◽

Substrate Thickness ◽

Object Space ◽

Plane Parallel ◽

Plane Parallel Plate ◽

Imaging Performance

The imaging performance of zero-thickness substrate planar kinoform lenses designed for infinite conjugate-imaging is not affected when a plane parallel plate, placed in the object space, is used as a substrate. This invariance property does not hold good in the case of kinoform lenses designed for finite conjugate-imaging purposes. It is shown that the imaging performance of a planar kinoform lens, designed with the assumption of zero substrate thickness for stigmatic imaging between two axial points, is drastically changed when the lens is used in combination with a plane parallel substrate of finite thickness. For ensuring axial stigmatism as well as 100% diffraction efficiency at the desired image, the thickness of the substrate has to be taken into account ab initio in the design of the kinoform lens. A seminumerical procedure for implementing the same is presented and the convenient amenability of our method in the design of planar kinoform lenses on substrate of prespecified thicknesses is demonstrated with some illustrative examples.

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Backward waves leaving the metamaterial

Izvestiya vysshikh uchebnykh zavedenii. Fizika ◽

10.17223/00213411/64/5/116 ◽

2021 ◽

pp. 116-122

Author(s):

B.B. Averbukh ◽

◽

I.B. Averbukh ◽

Keyword(s):

Refractive Index ◽

Finite Thickness ◽

Negative Real Part ◽

Magnetic Mirror ◽

Plane Parallel ◽

Medium Layer ◽

Extinction Theorem

The medium is composed of plane-parallel monolayers consisting of Huygens elements. In the molecular optics model, expressions are obtained for the reflected field, the field in the medium, and (in the case of a layer of finite thickness) behind the medium. An extinction theorem is considered, and an expression for the refractive index is introduced. Under certain conditions, such a medium can behave like a medium with a unit, zero, or negative real part of the refractive index at a given frequency. The condition for the realization of a magnetic mirror is formulated. In the case of a medium layer of finite thickness, the exit of backward waves outside the medium is shown.

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The restoration of blurred electron micrographs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100142529 ◽

1986 ◽

Vol 44 ◽

pp. 180-181

Author(s):

Bridget Carragher ◽

David A. Bluemke ◽

Michael J. Potel ◽

Robert Josephs

Keyword(s):

Cross Section ◽

Electron Micrographs ◽

Relative Motion ◽

Finite Thickness ◽

Image Plane ◽

Helical Axis ◽

Thin Sections ◽

Structural Details

We have investigated the feasibility of restoring blurred electron micrographs. Two related problems have been considered; the restoration of images blurred as a result of relative motion between the specimen and the image plane, and the restoration of images which are rotationally blurred about an axis. Micrographs taken while the specimen is drifting result in images which are blurred in the direction of motion. An example of rotational blurring arises in micrographs of thin sections of helical particles viewed in cross section. The twist of the particle within the finite thickness of the section causes the image to appear rotationally blurred about the helical axis. As a result, structural details, particularly at large distances from the helical axis, will be obscured.

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