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Shields

About: Shields is a research topic. Over the lifetime, 1456 publications have been published within this topic receiving 10896 citations.


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Journal ArticleDOI
TL;DR: In this paper , a coupled finite element-discrete element method (FEM/DEM) was used to predict the shape of the debris cloud as a function of shield thickness, and a parametric study was performed to investigate the sensitivity of key model parameters.

3 citations

Proceedings ArticleDOI
31 Dec 1995
TL;DR: In this article, a heat pipe-cooled Faraday shield is used for protection of ion cyclotron range of frequencies (ICR) antennae in Tokamaks.
Abstract: Alternative advanced technologies are being evaluated for use in cooling the Faraday shields used for protection of ion cyclotron range of frequencies (ICR) antennae in Tokamaks. Two approaches currently under evaluation include heat pipe cooling and gas cooling. Both of these technologies offer attractive alternatives to water-cooled designs primarily because they remove the time-consuming cleanup required in the event of tube weld failures and because they increase the operating temperature range for the shield. A Monel/water heat pipe cooled Faraday shield has been successfully demonstrated. Heat pipe cooling offers the advantage of reducing the amount of water discharged into the Tokamak in the event of a tube weld failure. The device was recently tested on an antenna at Oak Ridge National Laboratory. The heat pipe design uses inclined water heat pipes with warm water condensers located outside of the plasma chamber. This approach can passively remove absorbed heat fluxes in excess of 200 W/cm/sup 2/. Helium-cooled Faraday shields are also being evaluated. This approach offers the advantage of no liquid discharge into the Tokamak in the event of a tube failure. Innovative internal cooling structures based on porous metal cooling are being used to develop a helium-cooled Faraday shield structure. This approach can dissipate the high heat fluxes typical of Faraday shield applications while minimizing the required helium blower power. Preliminary analysis shows that nominal helium flow and pressure drop can sufficiently cool a Faraday shield in typical applications. Plans are in progress to fabricate and test prototype hardware based on this approach.

3 citations

Journal Article
TL;DR: In this paper, the detection efficiency of the scintillation detector NaI(Tl) (2? x 2?) and radioactive source Cs-137, and by using absorbent material (shield) aluminum and iron between radioactive source and detector for thickness ( 0.1 -1 ) cm.
Abstract: In the present work, detection efficiency has been Calculated for the scintillation detector NaI(Tl) (2? x 2?) and radioactive source Cs-137, and by using absorbent material (shield) aluminum and iron between radioactive source and detector for thickness ( 0.1 – 1 ) cm. The effect of the shield movement and its thickness and also the speed of the shield movement on the detection efficiency have been studied. It is found that detection efficiency decrease with a moving shield and with the thickness of the shield. It is found, also that detection efficiency decrease with the speed of the shield movement for all shields aluminum and iron. Keywords: detection efficiency, Scintillation Detector NaI(Tl) , shields

3 citations

Proceedings ArticleDOI
13 Nov 1994
TL;DR: A new method for scattered radiation compensation in 2D projection radiographic imaging by comparing the detected signal under a small partially transparent shield, positioned between the X-ray source and the object being imaged, and the radiation scatter signal in the location of the shield is calculated.
Abstract: A new method for scattered radiation compensation in 2D projection radiographic imaging is presented. By comparing the detected signal under a small partially transparent shield (e.g. aluminum disk or strip), positioned between the X-ray source and the object being imaged, with the detected signal near the border of the shadow of the shield, the radiation scatter signal in the location of the shield is calculated. For polychromatic X-radiation, calibration with two known basis materials allows accurate calculation of the radiation scatter. Shields are positioned at several locations between object and source. By an interpolation technique, the radiation scatter in every region of interest can be calculated. The radiation scatter image is then subtracted from the original image of the object. The method needs only one exposure of the object. The primary radiation signals at the locations of the shields have undergone an extra drop, but the information about the object under the shields is not lost. One could restore the image by compensating for the effect of the shields on the primary signal. The theory of PTS is presented and results of experiments are given. >

3 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023105
2022241
202124
202035
201941
201832