Synchrotron X-ray Photography Study of Cavitation Bubble Distribution in an Al-Cu Melt

2021 ◽  
Author(s):  
Ruiquan Wang ◽  
Jiafei Qiu ◽  
Haijun Huang
Keyword(s):  
Cavitation Bubble ◽  
X Ray ◽  
Bubble Distribution

scholarly journals A Model for Material Strengthening under the Combined Effect of Cavitation-Bubble Collapse and Al2O3 Particles, and Its Test Verification

2021 ◽  
Vol 67 (1-2) ◽  
pp. 36-44
Author(s):  
Lei Liu ◽  
Huafeng Guo ◽  
Ping Yu
Keyword(s):  
Cavitation Bubble ◽  
Binding Capacity ◽  
Sample Surface ◽  
Combined Effect ◽  
Al2o3 Content ◽  
Bubble Collapse ◽  
Al2o3 Nanoparticles ◽  
X Ray ◽  
Al2o3 Particles ◽  
Test Verification

A magnesium alloy was subjected to strengthening treatment by coupling cavitation bubbles with Al2O3 nanoparticles. The samples were strengthened by embedding Al2O3 nanoparticles with the energy generated by cavitation-bubble collapse, following which a strengthening model was established to perform test verification. The result showed that, after experiencing the combined effect for 5 min, nanoparticles appear on the sample surface, observed under the scanning electron microscope (SEM); by applying the X-ray diffractometer (XRD) and X-ray photoelectron spectrometer (XPS), it is found that the Al2O3 content increases, implying that Al2O3 particles have been embedded in the sample surface. The microhardness of the samples improves by 36 %. In terms of the strengthening mechanism under the combined effect, the energy generated due to cavitation-bubble collapse is transferred to the Al2O3 particles to enable them to strike the sample surface. Thus, the samples have a more gentle impact, and the transition zone with pits formed on the sample surface is significantly smoother and more continuous. Moreover, the samples are further strengthened after Al2O3 nanoparticles are embedded within the sample surface, as these nanoparticles present high strength and microhardness. However, with the increasing duration of the strengthening process, the failure characteristics of surface morphologies of the samples gradually develop; after experiencing the combined effect for 10 min, a large area of the surface is damaged. XRD and XPS results indicate that Al2O3 particles induce a decrease in the binding capacity with the surface layer of the samples and thus gradually separate from the samples. Therefore, the properties of the samples are adversely affected.

Preparation and Characterization of Starch Acetate/Polyvinyl Alcohol Foams

2014 ◽  
Vol 513-517 ◽  
pp. 193-196
Author(s):  
Xian Zhong Mo ◽  
Jian Bo Jiang ◽  
Xue Mei Huang ◽  
Feng Nv Yu ◽  
Jiang Ying Wu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Polyvinyl Alcohol ◽  
Absorption Capacity ◽  
Starch Granules ◽  
X Ray Diffraction ◽  
Elongation At Break ◽  
X Ray ◽  
Moulding Process ◽  
Bubble Distribution

The starch-based foam was preprared by moulding process and studied the effects on the density, mechanical properties, hardness and water absorption capacity of the foams with different polyvinyl alcohol (PVA) contents. The microstructure and crystallization of the foam was observed through the scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that the addition of PVA could better improve the material mechanical properties, the elongation at break was increased from 15.72% to 113.86% while the hardness was reduced from 37.3 to 16.7. The density of foam reached to the minimum value of 0.261 g/cm3, attaining to the maximum tensile strength of 1.08 Mpa. SEM and XRD showed that the compatility of starch and PVA was very good and the addition of PVA helped to improve the bubble distribution of foam and inhibit the retrogradation of starch granules.

Observation of cavitation bubble cloud using a stroboscopic x-ray generator

2001 ◽  
Author(s):  
Eiichi Sato ◽  
Hidenori Ojima ◽  
Kazuyoshi Takayama ◽  
Masatoshi Matsumasa ◽  
Haruo Obara ◽  
...  
Keyword(s):  
Cavitation Bubble ◽  
X Ray ◽  
Bubble Cloud

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

Some Problems in Understanding the Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 1-9
Author(s):  
A. H. Gabriel
Keyword(s):  
Solar Corona ◽  
Solar Atmosphere ◽  
Theoretical Modelling ◽  
Total System ◽  
Major Advance ◽  
X Ray ◽  
Proper Perspective ◽  
Space Observations

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

Iron K-Line Emission from X-Ray Binaries

1988 ◽  
Vol 102 ◽  
pp. 47-50
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
F. Nagase
Keyword(s):  
Accretion Disk ◽  
Radiative Recombination ◽  
Characteristic Temperature ◽  
Line Emission ◽  
Ionization Front ◽  
Continuum Radiation ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

AbstractEmission mechanisms of the iron Kα-lines in X-ray binaries are discussed in relation with the characteristic temperature Txof continuum radiation thereof. The 6.7 keV line is ascribed to radiative recombination followed by cascades in a corona of ∼ 100 eV formed above the accretion disk. This mechanism is attained for Tx≲ 10 keV as observed for low mass X-ray binaries. The 6.4 keV line observed for binary X-ray pulsars with Tx> 10 keV is likely due to fluorescence outside the He II ionization front.

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

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