Diffusion of helium gas bubbles in gold and copper foils

1970 ◽  
Vol 1 (8) ◽  
pp. 2217-2223 ◽  
Author(s):  
L. E. Willertz ◽  
P. G. Shewmon
Keyword(s):  
Gas Bubbles ◽  
Copper Foils ◽  
Helium Gas

Helium gas bubbles in vanadium

1973 ◽  
Vol 46 (2) ◽  
pp. 207-209 ◽  
Author(s):  
M. Heerschap ◽  
E. Schüller ◽  
B. Langevin ◽  
A. Trapani
Keyword(s):  
Gas Bubbles ◽  
Helium Gas

scholarly journals Behavior of Helium Gas Bubbles in Neutron-Irradiated Beryllium

1971 ◽  
Vol 8 (10) ◽  
pp. 546-552 ◽  
Author(s):  
Ryukichi NAGASAKI ◽  
Shozo OHASHI ◽  
Satoru KAWASAKI ◽  
Yoichi KARITA ◽  
Nobuo TSUNO
Keyword(s):  
Gas Bubbles ◽  
Helium Gas

Effect of helium gas bubbles on the creep ductility of an austenitic alloy

1969 ◽  
Vol 29 (1) ◽  
pp. 103-110 ◽  
Author(s):  
D.A. Woodford ◽  
J.P. Smith ◽  
J. Moteff
Keyword(s):  
Gas Bubbles ◽  
Creep Ductility ◽  
Austenitic Alloy ◽  
Helium Gas

A Model for Surface Induced Growth of Inert Gas Bubbles in Irradiated Copper-Boron Alloys

2006 ◽  
Author(s):  
G. P. Tiwari ◽  
E. Ramadasan
Keyword(s):  
Present Model ◽  
External Surface ◽  
Gas Bubbles ◽  
Lattice Diffusion ◽  
Inert Gas ◽  
Limited Extent ◽  
Direct Proportion ◽  
Helium Gas ◽  
The Matrix ◽  
Crystalline Matrix

A matrix containing inert gas bubbles dilates in direct proportion to the growth experienced by the gas bubbles. This phenomenon is termed as swelling. A model for the swelling induced by the growth of the helium gas bubbles in irradiated copper-boron alloys is presented. The bubbles grow by acquiring vacancies from the external surface, which acts as a source of vacancies. The vacancies reach the surface of the bubbles mainly via lattice diffusion and to a limited extent via diffusion through short-circuiting paths such as grain boundaries and dislocation pipes. The model predicts that overall swelling of the matrix varies as 1.5th power of time. Another consequence of the present model is that the growth rate of a gas bubble varies inversely as the cube of its distance from the external surface. The model has been applied to the data on irradiated copper-boron alloys and found to be in accord with the experimental results. The model is general and can be applied to the growth of all kinds of stationary inert gas bubbles trapped within a crystalline matrix.

scholarly journals Acoustic Characterization of Fluorinert FC-43 Liquid with Helium Gas Bubbles: Numerical Experiments

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Christian Vanhille ◽  
Cristian Pantea ◽  
Dipen N. Sinha
Keyword(s):  
Sound Speed ◽  
Numerical Experiments ◽  
Underwater Acoustics ◽  
Gas Bubbles ◽  
Acoustic Characteristics ◽  
Parametric Generation ◽  
Acoustic Characterization ◽  
Helium Gas ◽  
High Sound

In this work, we define the acoustic characteristics of a biphasic fluid consisting of static helium gas bubbles in liquid Fluorinert FC-43 and study the propagation of ultrasound of finite amplitudes in this medium. Very low sound speed and high sound attenuation are found, in addition to a particularly high acoustic nonlinear parameter. This result suggests the possibility of using this medium as a nonlinear enhancer in various applications. In particular, parametric generation of low ultrasonic frequencies is studied in a resonator cavity as a function of driving pressure showing high conversion efficiency. This work suggests that this medium could be used for applications such as parametric arrays, nondestructive testing, diagnostic medicine, sonochemistry, underwater acoustics, and ultrasonic imaging and to boost the shock formation in fluids.

In-situ electrical-resistivity measurements in the high-voltage electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 68-69
Author(s):  
W. E. King
Keyword(s):  
Electrical Resistivity ◽  
Electron Microscope ◽  
High Voltage ◽  
Resistivity Measurements ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Wide Range ◽  
Helium Gas

A side-entry type, helium-temperature specimen stage that has the capability of in-situ electrical-resistivity measurements has been designed and developed for use in the AEI-EM7 1200-kV electron microscope at Argonne National Laboratory. The electrical-resistivity measurements complement the high-voltage electron microscope (HVEM) to yield a unique opportunity to investigate defect production in metals by electron irradiation over a wide range of defect concentrations.A flow cryostat that uses helium gas as a coolant is employed to attain and maintain any specified temperature between 10 and 300 K. The helium gas coolant eliminates the vibrations that arise from boiling liquid helium and the temperature instabilities due to alternating heat-transfer mechanisms in the two-phase temperature regime (4.215 K). Figure 1 shows a schematic view of the liquid/gaseous helium transfer system. A liquid-gas mixture can be used for fast cooldown. The cold tip of the transfer tube is inserted coincident with the tilt axis of the specimen stage, and the end of the coolant flow tube is positioned without contact within the heat exchanger of the copper specimen block (Fig. 2).

Fission Gas Bubbles in Fractured UO2

1968 ◽  
Vol 26 ◽  
pp. 286-287
Author(s):  
O. M. Katz
Keyword(s):  
Electron Microscopy ◽  
Thermal Gradient ◽  
Gas Bubbles ◽  
Inert Gas ◽  
Thermal Gradients ◽  
Fission Gas ◽  
Beam Heating ◽  
Limited Application ◽  
Bubble Characteristics ◽  
Electron Beam Heating

The swelling of irradiated UO2 has been attributed to the migration and agglomeration of fission gas bubbles in a thermal gradient. High temperatures and thermal gradients obtained by electron beam heating simulate reactor behavior and lead to the postulation of swelling mechanisms. Although electron microscopy studies have been reported on UO2, two experimental procedures have limited application of the results: irradiation was achieved either with a stream of inert gas ions without fission or at depletions less than 2 x 1020 fissions/cm3 (∼3/4 at % burnup). This study was not limited either of these conditions and reports on the bubble characteristics observed by transmission and fractographic electron microscopy in high density (96% theoretical) UO2 irradiated between 3.5 and 31.3 x 1020 fissions/cm3 at temperatures below l600°F. Preliminary results from replicas of the as-polished and etched surfaces of these samples were published.

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