Shields

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

A comparison of shielded and unshielded antennas for Alfven wave heating in a Tokamak

Abstract: Experimental results are presented which demonstrate the beneficial influence of Faraday shields on antennas used for Alfven wave heating in a Tokamak. For the RF power levels available in the experiment, the addition of the shields resulted in total suppression of the uncontrolled density rise observed using unshielded antennas. Evidence of an associated strong decrease in the power deposited in the scrape-off plasma, both by Langmuir currents drawn by the antennas and by direct wave excitation, is also presented.

Periodic magnetic field focusing type electron beam tube

Abstract: PURPOSE:To make it feasible to adjust a magnetic field in a cathode position where no magnetic eccentricity occurs so as to realize an electron beam tube in a stably permeable state of electron beams by insulating two cylindrical magnetic shields whose inner surface and the external surface are in contact with each other on the outer periphery of an electron gun, and making one of the magnetic shields movable in one axial direction. CONSTITUTION:Magnetic shield 9, 12 of two different diameters, which are made of pure iron so that the magnetic field in the cathode position is 1 to 2% of a first magnet, are disposed on the outer periphery of an electron gun. One of the two magnetic shields is fixed in advance, and the other magnetic shield 12 of which the inner part is fitted to the outer side of the former shield is installed and it is fixed to the inside magnetic shield 9 by a screw 13. The outside magnetic shield 12 is movable in the axial direction when the screw 13 is loosened, so that the magnetic eccentricity in the magnetic field in a circumferential direction does not occur, whereby the lowering of performance of the electron beam tube may be prevented.

Colemanite filler from wastes in recycled concrete

Abstract: With the advancement of technology and the use of radioactive materials in medical systems for more accurate diagnosis of diseases, the need to maintain the health of medical staff and people who are constantly exposed to these rays has become a matter of urgency. To prevent the spread of these rays, either thick concrete walls should be used or composite walls including iron sheets and concrete should be used to reduce the thickness of the walls. To solve this problem, colemanite is a good option with a high percentage of boron, which is a very good absorber of harmful radioactive rays. In this regard, new research has been started to use this material as an aggregate and filler in concrete, which has yielded good results. This chapter introduces boron and in particular introduces colemanite, which is used in the radiation protection industry. The current trend is the use of boron-based compounds, abundant materials with relatively affordable costs and with which developers have extensive experience. More efficient boron-based compounds are still being developed today. An optimal solution for the development of new neutron shields is the use of boron-based materials that incorporate rare earth, allowing a compromise to develop optimal neutron absorption solutions for different energy spectra.

Magnetic shield device

Abstract: PROBLEM TO BE SOLVED: To provide a magnetic shield device having a wall structure whose shield performance is improved. SOLUTION: The magnetic shield device shields an inner space surrounded by a wall 500 consisting of high-conductive material layers 521, 522 and 523 and magnetic material layers 531, 532 and 533. In the wall 500, the outer high-conductive material layers 521, 522 and 523 and the inner magnetic material layers 531, 532 and 533 respectively form pairs. COPYRIGHT: (C)2009,JPO&INPIT