scholarly journals Trapped surfaces in vacuum arising dynamically from mild incoming radiation

2017 ◽  
Vol 21 (1) ◽  
pp. 1-120 ◽  
Author(s):  
Xinliang An ◽  
Jonathan Luk
1984 ◽  
Vol 79 ◽  
pp. 607-616
Author(s):  
R. R. Shannon

The requirements on gratings and coatings for astronomical use differ from the general industrial requirements primarily in the scale of the components to be fabricated. Telescopes have large primary mirrors which require large coating plants to handle the components. Dispersive elements are driven by the requirement to be efficient in the presence of large working apertures, and usually optimize to large size in order to efficiently use the incoming radiation. Beyond this, there is a “new” technology of direct electronic sensors that places specific limits upon the image scale that can be used at the output of a telescope system, whether direct imagery or spectrally divided imagery is to be examined. This paper will examine the state of the art in these areas and suggest some actions and decisions that will be required in order to apply current technology to the predicted range of large new telescopes.


1976 ◽  
Vol 31 (12) ◽  
pp. 1517-1519 ◽  
Author(s):  
P. K. Shukla ◽  
M. Y. Yu ◽  
S. G. Tagare

Abstract We show analytically that the nonlinear coupling of a large amplitude electromagnetic wave with finite amplitude ion fluctuations leads to filamentation. The latter consists of striations of the electromagnetic radiation trapped in depressions of the plasma density. The filamentation is found to be either standing or moving normal to the direction of the incoming radiation. Criteria for the existence of localized filaments are obtained. Small amplitude results are discussed.


2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Maxence Corman ◽  
William E. East ◽  
Matthew C. Johnson

Abstract We study the nonlinear evolution of unstable flux compactifications, applying numerical relativity techniques to solve the Einstein equations in D dimensions coupled to a q-form field and positive cosmological constant. We show that initially homogeneous flux compactifications are unstable to dynamically forming warped compactifications. In some cases, we find that the warping process can serve as a toy-model of slow-roll inflation, while in other instances, we find solutions that eventually evolve to a singular state. Analogous to dynamical black hole horizons, we use the geometric properties of marginally trapped surfaces to characterize the lower dimensional vacua in the inhomogeneous and dynamical settings we consider. We find that lower-dimensional vacua with a lower expansion rate are dynamically favoured, and in some cases find spacetimes that undergo a period of accelerated expansion followed by contraction.


1963 ◽  
Vol 30 (2) ◽  
pp. 237-244 ◽  
Author(s):  
E. M. Sparrow ◽  
V. K. Jonsson

The amount of energy absorbed when a stream of external radiation enters a rectangular-groove cavity has been calculated for a variety of surface conditions, cavity depths, and incident energy distributions. The surfaces of the cavity are either diffuse reflectors or specular reflectors, and a wide range of reflectivity values has been considered. The incoming radiation is either diffusely distributed across the cavity opening or else arrives in a bundle of parallel rays. The results show that for diffuse incoming radiation, a specular cavity absorbs more effectively than does a diffuse cavity. For incoming radiation in a parallel ray bundle, the comparison depends on the angle of inclination of the rays.


2003 ◽  
Vol 35 (8) ◽  
pp. 1309-1319 ◽  
Author(s):  
George F. R. Ellis
Keyword(s):  

2010 ◽  
Author(s):  
José M. M. Senovilla ◽  
Alfredo Macias ◽  
Marco Maceda
Keyword(s):  

Author(s):  
Brian C. Archambault ◽  
Joseph R. Lapinskas ◽  
Jing Wang ◽  
Jeffrey A. Webster ◽  
R. P. Taleyarkhan

Unprecedented capabilities for the detection of nuclear particles are presented by tensioned metastable fluid states which can be attained via tailored resonant acoustic systems such as the acoustic tensioned metastable fluid detection (ATMFD) systems. Radiation detection in tensioned metastable fluids is accomplished via macro-mechanical manifestations of femto-scale nuclear interactions. Incident nuclear particles interact with the dynamically tensioned metastable fluid wherein the intermolecular bonds are sufficiently weakened such that the recoil of ionized nuclei generates nano-scale vapor cavities which grow to visible scales. Ionized nuclei form preferentially in the direction of incoming radiation, therefore, enabling the capability to ascertain information on directionality of incoming radiation — an unprecedented development in the field of radiation detection. Nuclear particle detection via ATMFD systems has been previously reported, demonstrating the ability to detect a broad range of nuclear particles, to detect neutrons over an energy range of eight orders of magnitude, to operate with intrinsic detection efficiencies beyond 90%, and to ascertain information on directionality of incoming radiation. This paper presents advancements that expand on these accomplishments, thereby increasing the accuracy and precision of ascertaining directionality information utilizing enhanced signal processing-cum-signal analysis, refined computational algorithms, and on demand enlargement of the detector sensitive volume. Advances in the development of ATMFD systems were accomplished utilizing a combination of experimentation and theoretical modeling. Modeling methodologies include Monte-Carlo based nuclear particle transport using MCNP5 and complex multi-physics based assessments accounting for acoustic, structural, and electromagnetic coupling of the ATMFD system via COMSOL’s Multi-physics simulation platform. Benchmarking and qualification studies have been conducted with special nuclear material (SNM), Pu-based neutron-gamma sources, with encouraging results. These results show that the ATMFD system, in its current configuration, is capable of locating the direction of a radioactive source to within 30° with 80% confidence.


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