Showing papers on "Shields published in 1998"

Shielded magnetic tunnel junction magnetoresistive read head

Abstract: A magnetic tunnel junction (MTJ) magnetoresistive read head for a magnetic recording system has the MTJ device located between two spaced-apart magnetic shields. The magnetic shields, which allow the head to detect individual magnetic transitions from the magnetic recording medium without interference from neighboring transitions, also function as electrical leads for connection of the head to sense circuitry. Electrically conductive spacer layers are located at the top and bottom of the MTJ device and connect the MTJ device to the shields. The thickness of the spacer layers is selected to optimize the spacing between the shields, which is a parameter that controls the linear resolution of the data that can be read from the magnetic recording medium. To reduce the likelihood of electrical shorting between the shields if the shield-to-shield spacing is too small, each of the shields can have a pedestal region with the MTJ device located between the two pedestals, so that the shield-to-shield spacing outside the pedestal regions is greater than in the pedestal regions.

Description of Multilayered Gamma-Ray Exposure Buildup Factors up to 40 mfp by the Approximating Model

Abstract: An approximating formula recently proposed by the authors for γ-ray buildup factors of multilayered shields was applied for very thick shields up to 40 mfp. For this purpose, modifications were made to the model and the fitting method to improve the data reproducibility. The previous model was expanded so that it included both the plane-normal and point isotropic geometries. The verification test of the modified model was made for three materials; water, iron and lead. The separately published data of double-layered shields for point isotropic buildup factors calculated by EGS4 from 0.1 MeV to 10 MeV were used as well as newly calculated data at 1 MeV for the plane-normal geometry, and data for the point isotropic geometry of triple-layered shields at 1and 10 MeV. The present formula generally shows a very good reproducibility of the multilayer buildup factors, even in case of very thick shielding problems. The observed error between the approximating description and the EGS4 data is 15% in the intermedia...

Cryogenic current comparator measurements at 77 K using thallium-2223 thick-film shields

Abstract: Several different magnetic shield geometries were used to study cryogenic current comparator (CCC) operation with thallium-based thick film superconducting shields at 77 K. These shields are found to have good magnetic shielding properties and to support low-level persistent currents. This study investigates geometric properties of the magnetic coupling between the CCC and one type of superconducting quantum interference device (SQUID) sensor. The sensitivity of the SQUID and its coupling to the shielding currents limit ten-to-one CCC resistance ratio measurements to approximately 0.2 /spl mu//spl Omega///spl Omega/ in relative uncertainty.

Sputtering device and formation of coating using this device

Abstract: PROBLEM TO BE SOLVED: To prolong the interval of maintenance by heating and controlling a sticking preventing shield and a target shield. SOLUTION: In this device, a substrate 3 is heated and controlled, e.g. to >=200 deg.C by a heating heater 5, and simultaneously, a target shield 6 and a sticking preventing shield 7 are heated by a heater 8. The temps. of the shields at this time are controlled by a temp. controlling unit 10 so as to be regulated to the ones increased by radiation from plasma and the heater 5 in the process of coating formation or above. After the temps. are stabilized, electric power is fed from a power source 11, and sputtering is executed. After the coating is formed to a required coating thickness, the feed of the electric power is stopped, but, the heating control is continued as it is till the following coating forming stage. In this way, the shields are always heated, by which the temp. changes of the shields are eliminated, and the peeling of the stuck coating with different expansion coefficients is prevented to suppress the increase of particles, so that the exchanging period of the shields can be prolonged.

Robust recording head for proximity contact operation

Abstract: PROBLEM TO BE SOLVED: To prevent formation of short circuits between a magnetic guide and shields of a recording head by allowing a magnetic element provided in a spin tunnel detecting element to act as a magnetic flux guide for a magnetic flux from a recording medium to the active area of the spin tunnel detecting element away from a boundary SOLUTION: A magnetic guide 30 guides a magnetic flux from the surface 20 of a recording medium 22 to a direction away from the surface 20 and is combined with a pin retaining magnetic film 32 and an interposed dielectric barrier 34 to form a a magnetoresistive spin tunnel detecting element in a recording head 10 Gap between magnetic shields 12, 14 is separated by a dielectric area 16 spreading to the surface 50 of the head 10 The dielectric area 16 specifies the width 40 of the gap in a direction along the track of the recording medium 22 traversing transistors 80 to 81 Since this structure keeps the magnetic guide 30 and the shields 12, 14 at the same potential, short circuits between the magnetic flux guide 30 and the shields 12, 14 are not formed at the boundary between the head and the recording medium COPYRIGHT: (C)1999,JPO

Continuous siliconizing treating equipment for steel strip

Abstract: PROBLEM TO BE SOLVED: To carry out the initial sheet passing of a steel strip in a state that shields are set in a continuous siliconizing treating equipment in which shields for a treating gas flow is provided at the position almost directly below a carrying roll in a furnace. SOLUTION: Relation to a flat furnace type continuous siliconizing treating equipment in which, by spraying a treating gas from a gas nozzle 3 on both faces of a steel strip S to be carried from a carrying roll 2, the steel strip S is subjected to siliconizing treatment, at the position almost directly above the carrying roll, shields 5 for damminga treating gas flow flowing along the upper face of the steel strip are arranged along the direction of the furnace width. Then, this shields 5 are provided with a structure of being held so as to freely oscillate or rotate in the direction of the furnace length via the upper parts thereof, and, in the case a bar for sheet passing passes at the time of inithial sheet passing, the shields are pushed by the bar for sheet passing and are oscillated or rotated, by which they are pushed up in the upper direction, therefore, the bar for sheet passing can pass the place of each shield without troubles.

Shield type magnetic tunnel junction magneto-resistance read head and assembly

Abstract: PROBLEM TO BE SOLVED: To reduce the gap between magnetic shields to obtain a high surface density. SOLUTION: The magnetic shield enables a head to detect each magnetic transition from a magnetic recording medium without interference of adjacent transitions and functions as an electric lead which connects the head to a detection circuit. Conductive spacer layer 102 and 104 are arranged above and below an MTJ(magnetic tunnel junction) element to connect the MTJ element to the shield. The thickness of spacer layere 102 and 104 are selected so as to optimize the gap between shields. This thickness is a parameter which controls the linear resolution of data read from the magnetic recording medium. If the gap between shields is narrow, each shield has a pedestal area for the purpose of reducing a possibility of electric short-circuit between shields, and the MTJ element can be arranged between these two pedestals. In this case, the gap between shields on the outside of pedestals is larger than the inside of pedestal areas.

Practical application of a theoretical equation derived for representing water stopping mechanism of earth pressure balanced shields subject to high mater pressure

Abstract: シールドの切羽安定問題の内, 高水圧下における土圧式シールドの止水機構に関しては様々な研究が行われている, しかし, 止水機構に関する理論構築については, 未解決の課題として残されているのが現状である. 筆者らはこの課題を解決するために, スクリューコンベヤーの止水機構に関する理論構築ならびに模型実験を行い, 研究を進めている. 本論文では, 筆者らが構築した理論式に関し, 実施工への適用を図った結果について報告する. 実施工への適用内容としては, 施工中に発生する現象と理論式との相関関係についての考察, 実機の土質データ・機械諸元を入力物性値とした理論式による試算に基づくΦ値の分布に関する実績調査, 実施工時の土水圧実測データによる理論値の精度検証等である.

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.

Filtering shields in vacuum-arc plasma sources

Abstract: The applicability of a labyrinth system of intercepting shields for suppressing macroparticle flows in the plasma of vacuum-arc sources with a magnetic focusing was investigated. Two variants of the source acceptable for using the metal cathode and the graphite cathode are described. Being advantageously distinguished from all other similar-purpose devices by the simplicity in the design, the plasma sources with the filtering shields under study are approximately equivalent in their capacity and in the coating roughness to the filter with the magnetic isle, and also to the pulsed source with laser ignition.

Development of a system of anticoronal shields for the ion beam injector and accelerator of a diagnostic complex for plasma physics research

Abstract: A system of anticoronal shields is proposed, designed, and tested. The system is found to work efficiently.

Constructing method of underground structure and retaining wall

Abstract: PROBLEM TO BE SOLVED: To construct an underground dam without receiving the constraint of the ground by executing a plurality of shields in parallel from a shaft to an underground section at intervals, integrally connecting sections among the shields and placing concrete into the shields. SOLUTION: A shaft 1 is excavated at a place receiving no constraint on the ground, a shield machine 2 is started in approximately the horizontal direction from the shaft 1 to an underground-dam construction predetermined place, and shields 3 are built extending over a plurality of layers at regular intervals in the vertical direction. The shaft 1 is excavated gradually to lower sections with successive starting from upper layers of the shields 3. All of the shields 3 are constructed, and the connecting sections of reinforced concrete construction, PC structure, plain concrete structure, SRC structure, steel structure, etc., are erected among the shields 3. All of the connecting sections among the shields 3 are built, and concrete is placed into the shields 3, thus completing the construction of an underground dam.

Movable radiation shields for the CLEO II silicon vertex detector

Abstract: Two movable tungsten radiation shields were installed on the beam pipe during the upgrade of the CLEO II detector, operating at the Cornell Electron Storage Ring (CESR). This upgrade included the installation of a silicon vertex detector (SVX) and the purpose of the shields is to protect the SVX readout electronics from synchrotron radiation produced during injection and non-high-energy physics operation of CESR. Shield motion is controlled remotely by cables, keeping the associated motors and controls outside the detection volume. We discuss the design and performance of the radiation shields and the associated control system.

Safety shield for hot sticks-protection from electric arcs. Test results and field experience

Abstract: This paper presents test results on safety shields conducted in accordance with ASTM PS 57 and PS 58 methods, utilizing the same equipment, fault current and duration as in testing of flame retardant fabrics. Safely shields on hot sticks were subjected to power arcs with fault current of 15.4 kA for 22 to 30 cycles. The test results show that the safety shield provides protection from the electric arc to the user and will limit injuries caused by radiant bursts of heat energies and by arc blast shock wave explosions that contain flying fragmentation particles. In addition to test results, the paper also covers safety issues dealing with protection of workers from electric arcs and field experience in using the safety shield.