Optoacoustic cross-section measurements for ir pulses: CO2 laser absorption by CF3I

1981 ◽  
Vol 24 (4) ◽  
pp. 363-368 ◽  
Author(s):  
J. M. Weulersse ◽  
R. Genier
Keyword(s):  
Cross Section ◽  
Co2 Laser ◽  
Laser Absorption

Thickness and volume measurements of a Richtmyer–Meshkov instability-induced mixing zone in a square shock tube

1997 ◽  
Vol 349 ◽  
pp. 67-94 ◽  
Author(s):  
G. JOURDAN ◽  
L. HOUAS ◽  
J.-F. HAAS ◽  
G. BEN-DOR
Keyword(s):  
Shock Wave ◽  
Shock Tube ◽  
Cross Section ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Mixing Zone ◽  
Laser Absorption ◽  
Shock Wave Mach Number ◽  
Atwood Number ◽  
Absorption Technique

A simultaneous three-directional laser absorption technique for the study of a shock-induced Richtmyer–Meshkov instability mixing zone is reported. It is an improvement of a CO2 laser absorption technique, using three detectors during the same run, through three different directions of the test section, for the simultaneous thickness measurement of the mixing zone near the corner, near the wall and at the centre of a square-cross-section shock tube. The three-dimensional mean front and rear shapes of the mixing zone, its thickness and volume are deduced from the experimental measurements. The cases when the shock wave passes from a heavy gas to a light one, from one gas to another of similar densities and from a light gas to a heavy one, are investigated before and after the mixing zone compression by the reflected shock, for different incident shock wave Mach numbers. It is shown that the mixing zone is strongly deformed by the wall boundary layer when it becomes turbulent. Consequently, the thickness of the mixing zone is not constant along the shock tube cross-section, and the measurement of the mean volume of the mixing zone appears to be more appropriate than its mean thickness at the centre of the shock tube. The influence of the incident shock wave Mach number is also studied. When the Atwood number tends to zero, we observe a limit-like regime and the thickness, or the volume, of the mixing zone no longer varies with the incident shock wave Mach number. Furthermore, a series of experiments undertaken with an Atwood number close to zero enabled us to define a membrane-induced minimum mixing thickness, L0, depending on the initial configuration of the experiments. From the experimental data, a hypothesis about the mixing zone thickness evolution law with time is deduced on the basis of L0. The results are found to follow two very different laws depending on whether they are considered before or after the establishment of the plenary turbulent regime. However, no general trend can be determined to describe the entire phenomenon, i.e. from the initial conditions until the turbulent stage.

Plasma Diagnostics Using CO2 Laser Absorption and Interferometry

1972 ◽  
Vol 43 (2) ◽  
pp. 574-577 ◽  
Author(s):  
A. A. Offenberger ◽  
R. D. Kerr ◽  
P. R. Smy
Keyword(s):  
Co2 Laser ◽  
Plasma Diagnostics ◽  
Laser Absorption

Simple efficient c.w. TE, BF, CO2 laser with large cross-section

1985 ◽  
Vol 42 (1) ◽  
pp. 32-34 ◽  
Author(s):  
S. Marchetti ◽  
R. Simili
Keyword(s):  
Cross Section ◽  
Co2 Laser ◽  
Large Cross Section

Thermal Shock Behaviors of Laser Cladding NiCoCrAlY Coatings Strengthened by Nanometric SiC Particles

2010 ◽  
Vol 431-432 ◽  
pp. 5-8
Author(s):  
Hong Yu Wang ◽  
Dun Wen Zuo ◽  
Xiang Feng Li ◽  
Yong Jun Chen
Keyword(s):  
Oxide Scale ◽  
Thermal Shock ◽  
Cross Section ◽  
Co2 Laser ◽  
Room Temperature ◽  
Internal Crack ◽  
Thermal Shock Test ◽  
Shock Test ◽  
Sic Particles ◽  
The Cross

Three NiCoCrAlY coatings strengthened by different contents of nano-SiCp (nanometric SiC particles)were prepared on Ni-based superalloy substrates using crosscurrent CO2 laser, and the thermal shock test of these coatings was conducted by cycling between 1050°C and room temperature (10-15°C). The spalled area in the oxide scale of coatings after 10 thermal shock cycles and the thermal shock cracks in the cross-section of coatings after 100 thermal shock cycles were investigated using SEM, OM, and other means. The results show that the thermal shock resistances of NiCoCrAlY coatings are improved after adding nano-SiCp. Among nano-SiCp-added coatings, the coating added with 1.0 wt% nano-SiCp performs best. After 10 thermal shock cycles, there is a slight spallation whose area is only 2.65% in the oxide scale of the coating; after 100 thermal shock cycles, no internal crack is observed in the cross-section, and the amount and size of propagating cracks are slight.

Effects of Nano-Al2O3p on Thermal Shock Behaviors of NiCoCrAlY Coatings by Laser Cladding

2009 ◽  
Vol 79-82 ◽  
pp. 779-782 ◽  
Author(s):  
Hong Yu Wang ◽  
Dun Wen Zuo ◽  
Y.B. Sun ◽  
Ming Min Huang
Keyword(s):  
Oxide Scale ◽  
Thermal Shock ◽  
Cross Section ◽  
Co2 Laser ◽  
Room Temperature ◽  
Internal Crack ◽  
Oxide Scales ◽  
Propagating Crack ◽  
Different Content ◽  
Better Than

NiCoCrAlY coatings strengthened by different content of nano-Al2O3p, using crosscurrent CO2 laser, were prepared on Ni-based superalloy substrates, and thermal shock behaviors of these coatings were investigated by cycling between 1050°C and room temperature (forced water quenching).The results show that the thermal shock resistances of nano-Al2O3p-added coatings are definitely better than that without adding nano-Al2O3p. Among the nano-Al2O3p-added coatings, the coating added with 0.5wt% nano-Al2O3p performs best. After 10 thermal shock cycles, the spalled and spalling area in the oxide scale of the no-nano-Al2O3p coating reaches up to 27.7%, and the main failure form of the oxide scale is an expanding unit-spalling type in thermal shock cycles. While the area in the oxide scale of nano-Al2O3p-added coatings is only 10%~60% to the no-nano-Al2O3p one, and the failure of these oxide scales is mainly in the form of unit-spalling type. After 100 thermal shock cycles, many cracks turn up in the cross-section of the no-nano-Al2O3p coating, including propagating crack and internal crack. While no internal crack appeared in nano-Al2O3p-added coatings, and the propagating cracks are smaller than no-nano-Al2O3p one.

Cu-Direct Via-Hole Drilling of Aramid Fiber Reinforced Build-Up Layer by CO2 Laser Beam

2005 ◽  
Author(s):  
Eiichi Aoyama ◽  
Toshiki Hirogaki ◽  
Keiji Ogawa ◽  
Nobuyuki Doi ◽  
Ryu Minagi
Keyword(s):  
Co2 Laser ◽  
Copper Foil ◽  
Effective Means ◽  
Hole Diameter ◽  
Hole Drilling ◽  
Printed Wiring Boards ◽  
Laser Absorption ◽  
Direct Laser ◽  
Via Hole ◽  
The Difference

This report describes the features of Cu-direct laser drilled hole quality on multi-layer Printed Wiring Boards (PWBs). Cu-direct laser drilling drills the outer copper foil and build-up layer at the same time, which makes it difficult to form a blind via hole (BVH) with high quality because the copper foil has high reflection coefficient for a CO2 laser with wavelength 10.6 μm. Therefore, this study focused on improving drilled hole qualities such as diameter and overhang. First, the influence of laser irradiation conditions on forming BVH and the drilled hole diameter were investigated in detail. Second, a new method employing thermography was proposed in order to evaluate the absorption of copper foil after surface treatment. Third, the effect of mixing fillers into the build-up layer in order to reduce the amount of overhang was shown to be effective both experimentally and theoretically. As a result, it is clear that decreasing the difference in the laser absorption rate of the outer copper foil is an effective means to control the hole diameter and reducing the heat characteristic difference between the outer copper foil and the build-up layer can effectively decrease overhang.

CO2 laser absorption in SF6-air boundary layers

1989 ◽  
Vol 3 (3) ◽  
pp. 353-355
Author(s):  
H. F. Nelson ◽  
E. A. Eiswirth
Keyword(s):  
Boundary Layers ◽  
Co2 Laser ◽  
Laser Absorption
Sign in / Sign up

Export Citation Format

Share Document