Internal EM Field and Absorbed Power Density in Human Torsos Induced by 1-500-MHz EM Waves

1977 ◽  
Vol 25 (9) ◽  
pp. 746-756 ◽  
Author(s):  
Kun-Mu Chen ◽  
B.S. Guru
Keyword(s):  
Power Density ◽  
Absorbed Power ◽  
Em Field

scholarly journals Structural Phase States and Surface Properties of Steel 45 after Electroexplosive Borocoppering and Electron-Beam Treatment

2021 ◽  
pp. 17-23
Author(s):  
E.S. Vashchuk ◽  
E.A. Budovskikh ◽  
L.P. Bashchenko ◽  
V.E. Gromov ◽  
K.V. Aksenova
Keyword(s):  
Wear Resistance ◽  
Electron Beam ◽  
Power Density ◽  
Structural Phase ◽  
Combined Treatment ◽  
Grain Structure ◽  
Electron Beam Treatment ◽  
Boron Powder ◽  
Near Surface ◽  
Absorbed Power

The paper concerns improving the microhardness and wear resistance of steel 45 by the combined treatment of electroexplosive borocoppering with the subsequent electron-beam treatment. It is found that surface roughness at the area of the electroexplosive treatment increases along with the absorbed power density and the mass of boron powder. The electron-beam treatment leads to a decrease of roughness and appearance of craters instead of radial melt flow traces. The depth structure of the electroexplosive alloying area with a thickness of 25 µm includes a coating layer, near-surface, intermediate, and boundary layers. The surface microhardness and the depth of the hardening zone after the electroexlosive alloying increase along with the absorbed power density and boron concentration and reach the values of 1400 HV The electron-beam treatment causes merging of the coating and the surface layers and increases the hardening zone depth up to 80 µm. A cellular or dendritic crystallization structure is formed near the surface, and a grain structure is formed in the depth. The inhomogeneous distribution of alloying elements over the volume of the alloying area and its adjustment during the electron-beam treatment are established. The inter-dendritic distances and grain diameters increase as the absorbed power density becomes higher with the increase of the electron-beam treatment exposure time. Also, the size of martensite needles increases in the depth. The combined treatment produces the sub microcrystalline strengthening phases-borides FeB, Fe2B, FeB2, carboboride Fe23 (C, B)6 , and carbide B4C. The microhardness level is reduced to 800 HV, and the wear resistance increases up to five times when compared to the wear resistance of the base.

Critical Factors in Laser and Electron Beam Glazing of Materials.

1981 ◽  
Vol 8 ◽  
Author(s):  
P. R. Strutt ◽  
B. G. Lewis ◽  
B. H. Kear
Keyword(s):  
Electron Beam ◽  
Fluid Flow ◽  
Power Density ◽  
Interaction Time ◽  
Solidification Microstructure ◽  
Processing Conditions ◽  
Critical Factors ◽  
Absorbed Power ◽  
Flow Effects

ABSTRACTThe major effects of laser and electron beam glazing on solidification microstructure and melt zone geometry are described. It is shown that under comparable processing conditions, i.e. absorbed power density and interaction time, the glazed microstructures are similar. Some variations in microstructure of laser and electron beam glazed M2 steel have been noted, which seem to be related to fluid flow effects in the melt zone and possible interactions with the environment.

scholarly journals Analysis of Vase Shaped Pumping Cavity for Solar-Pumped Laser

2021 ◽  
Vol 25 (2) ◽  
pp. 242-247
Author(s):  
Hayato Koshiji ◽  
Tomomasa Ohkubo ◽  
Takumi Shimoyama ◽  
Takeru Nagai ◽  
Ei-ichi Matsunaga ◽  
...  
Keyword(s):  
Power Density ◽  
Absorption Rate ◽  
Laser Light ◽  
Laser System ◽  
Absorption Efficiency ◽  
Laser Medium ◽  
Power Density Distribution ◽  
Absorbed Power ◽  
Ray Tracing Simulation ◽  
Absorption Power

Although sunlight is a promising renewable energy source, the light is incoherent and difficult to use directly. Therefore, a solar-pumped laser, which directly converts sunlight into coherent laser light of, is a promising technology. A solar-pumped laser collects sunlight into the laser medium to realize laser oscillation. In order to realize an efficient solar-pumped laser system, it is necessary to design a pumping cavity that absorbs maximal sunlight into the laser medium with minimal thermal shock. In this research, the pumping cavity shape was studied using a numerical ray tracing simulation. As a result, it was found that a cone shaped pumping cavity can be expected to improve the absorption rate by approximately 30% over a cylindrically shaped pumping cavity. Furthermore, the absorption power density distribution can be flattened by a vase shaped pumping cavity, while maintaining the same absorption efficiency. The vase shaped pumping cavity has almost half the dispersion of the absorbed power density in the laser medium when compared with the cone shaped pumping cavity.

scholarly journals Сравнительное исследование термостойкости пелликлов на основе бериллия

2022 ◽  
Vol 92 (1) ◽  
pp. 92
Author(s):  
С.Ю. Зуев ◽  
А.Я. Лопатин ◽  
В.И. Лучин ◽  
Н.Н. Салащенко ◽  
Д.А. Татарский ◽  
...  
Keyword(s):  
Power Density ◽  
Ultrathin Films ◽  
Vacuum Annealing ◽  
Multilayer Structures ◽  
Free Standing ◽  
Full Size ◽  
Short Period ◽  
Absorbed Power ◽  
Vacuum Heating

We demonstrate the possibility of manufacturing Be-based ultrathin films with high transmission at wavelengths of 11.4 and 13.5 nm. For free-standing films of Be and Be-based multilayer structures (Si/Be, ZrSi2/Be, Be/BexNy, Zr/Be, Ru/Be, Mo/Be), we determine the thresholds of the absorbed power at which over a short period (tens of minutes) of vacuum annealing, initially sagging free-standing films became visibly stretched over the hole. Of the film structures tested here, the Be/BexNy structure (with beryllium nitride interlayers) showed the highest threshold for the absorbed power (1 W/cm2). However, due to the low strength of this structure, ZrSi2/Be, Mo/Be, and Be films seem to be more promising for the manufacture of a full-size pellicle. Long-term vacuum annealing of Mo/Be and Be ultrathin films showed that they could withstand 24 hours of vacuum heating at an absorbed power density of 0.2 W/cm2 (film temperature ~250°C) without noticeable changes in EUV transmission or sagging of films. With comparable transmission (~83% at 13.5 nm and ~88% at 11.4 nm), a multilayer Mo/Be structure with a thickness of 30 nm appears to be preferable, as it shows less brittleness than a monolayer Be film with a thickness of 50 nm.

Suppression of γ’ Precipitation in a Laser-Melted Nickel-Base Alloy

1977 ◽  
Vol 35 ◽  
pp. 270-271
Author(s):  
J. M. Walsh ◽  
J. C. Whittles ◽  
B. H. Kear ◽  
E. M. Breinan
Keyword(s):  
Cooling Rate ◽  
Base Alloy ◽  
Material Surface ◽  
Intimate Contact ◽  
Absorbed Power ◽  
Perfect Contact ◽  
Nickel Base ◽  
Rapidly Solidified ◽  
Limiting Case ◽  
The Heat Transfer Coefficient

Conventionally cast γ’ precipitation hardened nickel-base superalloys possess well-defined dendritic structures and normally exhibit pronounced segregation. Splat quenched, or rapidly solidified alloys, on the other hand, show little or no evidence for phase decomposition and markedly reduced segregation. In what follows, it is shown that comparable results have been obtained in superalloys processed by the LASERGLAZE™ method.In laser glazing, a sharply focused laser beam is traversed across the material surface at a rate that induces surface localized melting, while avoiding significant surface vaporization. Under these conditions, computations of the average cooling rate can be made with confidence, since intimate contact between the melt and the self-substrate ensures that the heat transfer coefficient is reproducibly constant (h=∞ for perfect contact) in contrast to the variable h characteristic of splat quenching. Results of such computations for pure nickel are presented in Fig. 1, which shows that there is a maximum cooling rate for a given absorbed power density, corresponding to the limiting case in which melt depth approaches zero.

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