Shields

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

The Technique for Manufacturing Flexible Electromagnetic Shields Based on Resistive Materials

Abstract: The article introduces the technique for manufacturing flexible electromagnetic shields based on resistive materials ( powdered charcoals and sheet foil ), as well as the results of experimental justification of the use prospects of this technique in the development of new functional materials . This justification consisted of : 1) manufacturing of the experimental samples in accordance with the presented technique ; 2) carrying out the measurements of the electromagnetic radiation reflection and transmission coefficient values in the frequency range of 0.7–17.0 GHz of the manufactured experimental samples . It was discovered that flexible electromagnetic shields based on the powdered charcoals manufactured in accordance with the presented technique are characterized by the electromagnetic radiation reflection coefficient values in the frequency range of 0.7–17.0 GHz , reaching –10.0 dB , when electromagnetic radiation reflection coefficient values reach –20.0 dB . Due to this fact it is possible to r ecommend to use them in order to ensure electromagnetic compatibility of radioelectronic equipment and to protect people from exposure to radiation , emitted by such equipment , as well as to hide ground objects from detection in the radar wavelength range .

Triaxial cable designs with optimum braided shields

Abstract: An investigation into the shielding effectiveness of triaxial cables employing wire shields, with optimum braid constructions, is described. Several triaxial configurations with different braid designs, for inner and outer cables, were simulated. It is shown that crosstalk performances of the triaxial cables are affected by both absolute values and polarities of the surface transfer impedances of the shields. The effect of electric field coupling, on the overall crosstalk within the triaxial system, has also been studied in both frequency and time domains. For triaxial cables with shorted braids, the effects of electric field coupling are limited to high frequencies and their effects at low frequencies are small. >

Charts for estimating the axial shielding factors for triple-shell open-ended cylindrical shields

Abstract: Describing the shields with the number of shells greater than two differs from the previously done work in having a significant increase in the number of charts needed. To limit the number of charts, only the shields were examined that have the most-used exterior aspect ratio, namely, equal to 5. It was also assumed that all the shielding shells are made of the same material with an equal and relatively small thickness, which is a practical case as well. Since the three-shell structure does not allow much freedom for variations in the air gaps between the shells, only the shields having air gaps of 5% and 10% of the diameter of the outermost shell were considered. Finally, a set of charts was computed with the help of a standard ANSYS(R) software employing an FEM method. The charts are represented as logarithmic contour plots where the ratio of the inner to outer shells' lengths and permeability normalized to the thickness-to-diameter ratio of the outermost shell are independent variables; and the air gaps and ratio of the middle to outer shells' lengths are fixed parameters. The charts calculated allow one to quickly estimate the axial shielding factor and to clearly observe the effect of the shield's parameters on the axial shielding.

Effect of electropolishing on vacuum furnace design

Abstract: The use of thermal shields of materials having low emissivity in vacuum furnaces is wellknown. However, the surface condition of the heat shields is one of the most important factors governing their efficiency as radiation resistances. The emissivity of the thermal shields dictates the power rating of the heaters in furnace design. The unpolished materials used in the heater tests showed poor performance leading to loss of a significant percentage of the input power. The present work deals with the refurbishment of the radiation heat shields used in a furnace for heating graphite structure. The effect of refurbishment of the heat shields by the buffing and subsequently electropolishing was found to improve the performance of the shields as heat reflectors. The composition of the electrolyte was chosen in such a way that the large shields of Mo, Inconel and SS can be polished using the same reagents in different ratios. The present work deals with the development of a standard electropolishing procedure for large metallic sheets and subsequently qualifying them by roughness and emissivity measurements. The improvement noted in the shielding efficiency of the furnace in the subsequent runs is also discussed here.

Vacuum interrupter for high voltage applications

Abstract: This vacuum interrupter is for high voltage applications and comprises a tubular metal central shield around its arcing gap for condensing arc-generated vapors and two tubular metal end shields located at opposite ends of the interrupter. Two tubular metal intermediate shields are respectively provided at opposite ends of the central shield between the central shield and the adjacent end shields. These intermediate shields are normally electrically isolated from the central shield and the end shields. Each intermediate shield is disposed adjacent to the central shield but does not axially overlap with the central shield. Each intermediate shield also surrounds the inner end of its associated end shield in radially-spaced, axially-overlapping relationship with the associated end shield.