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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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Proceedings ArticleDOI
06 Dec 1995
TL;DR: In this paper, the authors compared the shielding effectiveness for a few selected materials like copper, tin-plated iron, Mu-metal and their composites in single and nested configurations, for wall thicknesses in the range of 50 /spl mu/m to 250 /splmu/m.
Abstract: Electromagnetic (EM) shielding studies on totally closed box shields, one inside the other, were carried out earlier for steady magnetic fields in the frequency range from 50 Hz to 150 kHz and for plane waves from 1 MHz to 1 GHz. The calculated and the experimental values of the shielding effectiveness for a few selected materials like copper, tin-plated iron, Mu-metal and their composites in single and nested configurations, for wall thicknesses in the range of 50 /spl mu/m to 250 /spl mu/m were compared. In order to explain the discrepancies in the calculated and experimental results, need was felt to simplify the experiments and improve the accuracy and sensitivity of the measurements. The present study is a sequel to the one above but differs essentially in two aspects, viz.; (a) the shielding effectiveness is measured for the broadband (DC to 100 MHz) transient, intense (E-field in the range of 50 to 100 kV/m) and fast (rise time less than 10 nano seconds) EM fields generated in a simulation facility, and (b) the closed nested box shields are configured as open ended structures, to overcome the experimental complexities of the former. The transient fields comprising E-field, D-Dot field and B-Dot field, were characterised by indigenously developed sensor probes. A high sensitivity of 750 mV/kV/m has been achieved for the electric field sensor. The open-ended shield structures are made from 1.5 mm. thick aluminium sheets supported at the four corners of the sheets by copper rods of 6 mm. diameter. The corresponding dimensions for the shields are 250/spl times/200/spl times/75 mm. and 200/spl times/150/spl times/50 mm respectively. The paper discusses the results of the measurements thus performed on shielding effectiveness and sufficiently elaborates the design and development of E, D-Dot and B-Dot field probes. Also, discussed are the characteristics of the transient intense EM fields generated in the simulation facility.

2 citations

Journal ArticleDOI
16 Feb 2021
TL;DR: In this paper, a parameterized finite-element model of braided cable shields is developed to investigate the analytical model and study the influence of parameter and material dependencies of the transfer impedance of the cable shields.
Abstract: A parameterized finite-element model of braided cable shields is developed to investigate the analytical model and study the influence of parameter and material dependencies of the transfer impedance of braided cable shields. The parameter influences and their interrelations are analyzed by the use of global sensitivity analysis. Measurements are only needed for the validation of the finite-element model but not for parameter variations. This reduces time and costs and eliminates measurement uncertainties occurring at different measurement procedures.

2 citations

Journal ArticleDOI
R. Pryor1, C. Zeller, W. Chen
TL;DR: In this article, the effects of a multiple-shell geometry are treated in the equations of this analysis, and a significantly improved method of estimating the induction and permeability of the shield is presented The results of these magnetic field calculations allowed the selection of optimization criteria and showed how system requirements could be met by choosing a suitable shell structure arrangement.
Abstract: The basic concepts of shielding theory have existed since the last century [1,2] There have been many publications on the subject of magnetic shielding, treating the case of shielding apparatus from static fields by means of multiple concentric shields and deriving several principles of fundamental importance Unfortunately, however, theory has been applied to only the most ideal shield configurations, for the case of constant permeability [3-5] This paper covers the analysis of shielding effectiveness of variable Permeability cylindrical shielded enclosures for the DC magnetic field case When the permeability is a function of magnetic induction, the simple boundary solution for spherical or cylindrical shields can no longer be applied since the induction, through the permeability, is caused to vary as much as two orders of magnitude, causing nonuniformity in the field in the cavity and inside the shield Thus, the permeability of the shielding material is considered as a function of the induction, and a significantly improved method of estimating the induction and permeability of the shield is presented The effects of a multiple-shell geometry are treated in the equations of this analysis This method gives fast, accurate results and can be run on a small computer for shielding optimization Results of these magnetic field calculations allowed the selection of optimization criteria and showed how system requirements could be met by choosing a suitable shell structure arrangement Experimental measurements on real materials for various shell structures confirmed the accuracy of this method

2 citations

01 Dec 1964
TL;DR: In this paper, the results of an experimental study to determine the capabilities and limitations of a thermal protection system utilizing thin-gage, refractory-metal shields are presented, and a heat-shield panel with columbium-alloy shields was subjected to supersonic flow conditions at a Mach number of 3 and dynamic pressure of l,5OO lb/ft2 (71.8 kN/m2).
Abstract: : The results of an experimental study to determine the capabilities and limitations of a thermal protection system utilizing thin-gage, refractory-metal shields are presented. Cyclic radiant-heating tests to 2,4OO F (l,589 K) were performed on a heat-shield panel with molybdenum-alloy shields coated with a silicide-base coating, and a radiographic technique was used to detect oxidation damage and brittle cracking of the coated shields. A heat-shield panel with columbium-alloy shields was subjected to supersonic flow conditions at a Mach number of 3 and dynamic pressure of l,5OO lb/ft2 (71.8 kN/m2). The results of preliminary tests on a prototype panel with nickel-alloy shields subjected to radiant-heating and wind-tunnel conditions are also reported. Evaluation tests on the molybdenum-alloy shield material were made at temperatures ranging from room temperature to 2,9000 F (1,8660 K). Oxidation results and metallurgical studies covering diffusion phenomena for coated molybdenum-alloy coupons and small riveted configurations under continuous and cyclic conditions at temperatures to 2,9000 F are also given.

2 citations


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