Shields

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

Development of lightweight single bumper shield

Abstract: The purpose of this study was to develop and consider new lightweight and flexible shields composed of high strength fibers and foamed metals against medium size debris impacts. We developed three kinds of shields using Vectran sheets/fibers and SUS316L metal foams. Compared with the above conventional shield, the newly developed shields are 30 - 40 mm in thickness. Vectran sheet is composed of three layers with different functions, i.e., crashing projectiles, releasing kinetic energy and receiving fragments. Hypervelocity impact tests were carried out by a two-stage light-gas gun. The experimental results showed that the developed single bumper shield could absorb the energy created by collision of the polycarbonate, 10mm in diameter, 10mm in thickness, 1 gram in mass, flying at a speed of 2.46km/sec. We compared performance of developed shields with one of shield using JEM or previos data, examined the possibility to be useful as shield.

Installation for growing monocrystals, for example sapphire

Abstract: FIELD: chemistry. ^ SUBSTANCE: installation has a cylindrical chamber 1 with a cover 2 and a tray 3, a block of heat shields fitted in the chamber, a melting crucible with a seed holder on top, which is joined to a rod 9, a bearing swivel arm 11, a column 10 with rotary and displacement actuators 12 and 13 for the rod 9, a vacuum system 14, a feed system with a control cabinet 15 and a cooling system 16. The block of heat shields comprises upper and lower shields. The installation is fitted with a mechanism for raising the cover in form of an actuator 23 mounted on the swivel arm 11 and connected to the cover 2 of the chamber 1 by a flexible element 24 which is made in form of a chain, wherein the actuator 23 of the mechanism for raising the cover has a controlled torque-limiting clutch adjusted to a force which is sufficient for raising the cover 2, but slides when raising the rod 9 and the fixed cover. The installation is also fitted with a hoisting device 26 for raising the crucible and lower heat shields which is mounted on the column with possibility of turning about the axis of the column, wherein the hoisting device 26 is fitted with a withdrawing device for fitting and withdrawing the crucible. The upper heat shields are attached on the inner side of the cover 2 of the chamber 1, on the outside of which there are three inspection windows 21, 22, and the tray 3 of the chamber 1 has a water-cooled plug with a channel for feeding inert gas, and the control cabinet is fitted with a remote console 30 in form of an electronic knob mounted on the lateral surface of the cabinet. ^ EFFECT: high efficiency, possibility of growing bulk monocrystals with a cylindrical shape in automatic mode, perfection of the structure of monocrystals and uniformity of their size on the entire length owing to use of high-precision control mechanisms based on an industrial computer. ^ 6 dwg

Study of Stray Light Suppression by Cold Shield in Dewar

Abstract: To further study the stray light suppression effect of a cold shield in a Dewar,four different combinations of cold shields and vanes are put forward according to the basic structure of the original cylindrical cold shield and the design principles of a cold shield and a vane.The four combinations of cold shields and vanes are simulated and analyzed by using the Light Tools software.The analysis results show that among the vanes,the vertical one is better and among the cold shields,the conical second-order one is better.It is finally concluded that the conical second-order cold shield with a vertical vane is the best one of the four combinations.

A novel thermal insulation method for a next-generation conduction : cooled superconducting magnet

Abstract: We have developed a new thermal insulation method for use with superconducting magnets or in applications where temperature needs to be maintained within a limit. Termed as Multi-shell-insulation (MSI) method, this method uses several thermal-energy storage shields to intercept heat flowing into the superconducting magnet. The shields are arranged in a vacuum vessel so that each shield is inside another slightly bigger shield and the superconducting magnet is inside the innermost shield. To use MSI, the shields are first cooled to about the same temperature as the superconducting magnet and then they are thermally separated from the cooling means. The temperature of the outermost shield would rapidly rise, but those of inner shields would rise only slowly; the closer the shield to the center, the slower the temperature rise. To demonstrate MSI effect, we used 10 copper shields, five of which were cooled to 30K and the other five to 4K by a two-stage Gifford-McMahon refrigerator. The 3kg-innermost shield could be maintained below 30K for a one-month period: a promising result for the realization of a cryocooler-detached, high-Tc superconducting magnet. It was also possible to maintain the inner shield below 10K for 8 days by coating the three inner copper shields with HoCu2 and Er3Ni.