Adiabatic curve of a metastable plasma

1994 ◽  
Vol 37 (1) ◽  
pp. 13-18
Author(s):  
A. N. Tkachev ◽  
S. I. Yakovlenko
Keyword(s):  
Adiabatic Curve ◽  
Metastable Plasma

Harnessing the Power of Adiabatic Curve Crossing to Populate the Highly Vibrationally Excited H2 ( v=7 , j=0 ) Level

2020 ◽  
Vol 124 (16) ◽  
Author(s):  
William E. Perreault ◽  
Haowen Zhou ◽  
Nandini Mukherjee ◽  
Richard N. Zare
Keyword(s):  
Vibrationally Excited ◽  
Adiabatic Curve ◽  
Curve Crossing

Loading and Unloading Split Hopkinson Tension Bar Technique for Studying Dynamic Microstructure Evolution of Materials

2010 ◽  
Vol 160-162 ◽  
pp. 891-894 ◽  
Author(s):  
Wen Huang ◽  
Zhong Wei Huang ◽  
Xiao Qing Zhou
Keyword(s):  
Microstructure Evolution ◽  
Pure Titanium ◽  
Dynamic Mechanical Properties ◽  
Post Test ◽  
Split Hopkinson ◽  
Adiabatic Curve ◽  
Loading And Unloading ◽  
Different Strains ◽  
Strength And Ductility ◽  
Split Hopkinson Tension Bar

In order to investigate the microstructure evolution of materials, loading and unloading experiments with specimens deformed at different strains are required. In this paper, momentum traps were introduced for rendering the conventional Split Hopkinson Tension Bar suitable for loading-unloading experiment. The new technique allows a specimen to be loaded to a preset strain for post-test characterization. This technique was applied to study the dynamic mechanical properties of pure titanium. The results show that: 1) the twinning density of titanium increases rapidly as the strain increases. 2) The strength and ductility of titanium exhibited on the adiabatic curve are much smaller then those exhibited on the isothermal curve, which may be caused by the adiabatic heat generated during the transient deformation process.

The cold drawing of high polymers

1954 ◽  
Vol 221 (1147) ◽  
pp. 541-557 ◽  
Keyword(s):  
Experimental Data ◽  
Cross Section ◽  
Temperature Rise ◽  
Draw Ratio ◽  
Room Temperature ◽  
Cold Drawing ◽  
Negative Slope ◽  
Extension Curve ◽  
Constant Tension ◽  
Adiabatic Curve

Like many other polymers, amorphous polyethyleneterephthalate cold draws in the shoulders of a neck when stretched at room temperature. The draw ratio across the shoulders is not a constant for the polymer, but is found to depend on the temperature and speed of stretching, and on the initial specimen cross-section and birefringence. A local temperature rise is also observed in the shoulders. Isothermal load-extension curves have therefore been measured from 20 to 140°C, and from them an adiabatic load-extension curve has been calculated. This has a negative slope range which appears to be unstable. An alternative process of extension at constant tension in a shoulder, coupled with exchanges of heat along the specimen by conduction, appears to be possible at a lower tension than that needed for pure adiabatic extension. For this second process the length of the shoulder, the tension at which it operates, and the draw ratio across it, can be calculated from the simple adiabatic curve and are found to agree with experimental data within a factor of two. This theory is then used to discuss cold drawing in some other polymers.

Metastable plasma of hydrated ions

1995 ◽  
Vol 38 (4) ◽  
pp. 329-335
Author(s):  
S. I. Yakovlenko
Keyword(s):  
Hydrated Ions ◽  
Metastable Plasma

A Time Effect in the Rapid Elongation of Rubber

1939 ◽  
Vol 12 (3) ◽  
pp. 518-519 ◽  
Author(s):  
V. Hauk ◽  
W. Neumann
Keyword(s):  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Steep Ascent ◽  
Decisive Effect ◽  
Elapsed Time ◽  
Adiabatic Curve ◽  
Thermodynamic Effects ◽  
The Difference ◽  
Thermodynamic Basis

Abstract It has already been pointed out elsewhere (Monatshefte für Chemie 72, 32 (1938); Rubber Chem. Tech. 12, 64(1939)) that the difference between the adiabatic and isothermal stress-strain curves of rubber is too great to be explained on a thermodynamic basis alone. It was suggested that the position of the adiabatic curves might be governed by the fact that the rate of stretching itself has a decisive effect on the behavior of the chains of molecules during stretching. To throw light on this phenomenon, stress-strain curves were obtained, by means of the stretching apparatus already described in the paper mentioned, at various rates of elongation which still fell within the range of adiabatic stretching. The operation was carried out in such a way that a chronometer started electrically when the rubber began to elongate, and stopped again when the rubber reached an elongation of 450 per cent. With the aid of this contrivance, stress-strain curves were obtained at rates corresponding to 0.68, 2.5, 5.7 and 9.1 seconds' elapsed time for the stretching. For comparison, an isotherm was obtained by loading rubber strips of the same dimensions with various weights. A vulcanizate containing 2 per cent of combined sulfur was used as experimental material. The temperature was 13° C. The results of these measurements are shown graphically in Fig. 1. It may be seen that the adiabatic curve corresponding to the highest rate of elongation has the least steep ascent, i.e., at the highest rate of elongation the stress is greatest at a given elongation. With increase in the time of stretching, the curves approach nearer and nearer to the isothermal stress-strain curve. This would seem to prove that the rate of elongation plays an important part, wholly independent of any thermodynamic effects. Perhaps during rapid stretching there is actual rupture of chains which are still coiled and which mutually obstruct the smooth course of the stress-strain curve. It can also be seen from the position of the curves that the decisive effect shown by the time factor is of the order of seconds, since the difference between the curves corresponding to 0.68 and 2.5 seconds is very small, whereas the difference between the curves corresponding to 2.5 and 5.7 seconds appears to be considerable.

scholarly journals Photofragmentation of Cl2 at 308 nm

1998 ◽  
Vol 17 (4) ◽  
pp. 185-190 ◽  
Author(s):  
Peter C. Samartzis ◽  
Theodosia Gougousi ◽  
Theofanis N. Kitsopoulos
Keyword(s):  
Electronic States ◽  
Angular Distributions ◽  
Ion Imaging ◽  
Excited Electronic States ◽  
Adiabatic Curve ◽  
Anisotropy Parameters ◽  
Yield Anisotropy ◽  
Curve Crossing

The velocity distributions for the Cl(2P3/2) and Cl(2P1/2) photofragments produced by the photolysis of Cl2 at 308 nm are measured using ion imaging. The angular distributions yield anisotropy parameters of β(2P3/2)=−1.00±0.05,β(2P1/2)=−0.95±0.05, suggesting that Cl(2P3/2) and Cl(2P1/2) is essentially produced via non-adiabatic curve crossing between the lu and the 0u+ excited electronic states.

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