Temperature relaxation in a parametrically unstable inhomogeneous plasma

2000 ◽  
Vol 64 (3) ◽  
pp. 205-210 ◽  
Author(s):  
V. G. PANCHENKO
Keyword(s):  
Relaxation Time ◽  
Relaxation Process ◽  
Pump Wave ◽  
Inhomogeneous Plasma ◽  
Parametric Instability ◽  
Drift Waves ◽  
Lower Hybrid ◽  
Electron Drift ◽  
Inverse Relaxation Time ◽  
Temperature Relaxation

On the basis of kinetic fluctuation theory, the relaxation process between the electron and ion temperatures in a magnetized inhomogeneous plasma is considered when an external pump wave parametrically decays into lower-hybrid and electron drift waves. In the region above the instability threshold, the inverse relaxation time is calculated, and its dependence on the density gradient and the pump-wave intensity and frequency is obtained. It is shown that the presence of the parametric instability leads to a decrease of the relaxation time.

Stress-Time-Temperature Relations in Polysulfide Rubbers

1946 ◽  
Vol 19 (4) ◽  
pp. 1178-1192 ◽  
Author(s):  
M. D. Stern ◽  
A. V. Tobolsky
Keyword(s):  
Activation Energy ◽  
Relaxation Time ◽  
High Temperature ◽  
Stress Relaxation ◽  
Relaxation Process ◽  
Network Structure ◽  
Constant Load ◽  
Internal Structures ◽  
Relaxation Measurements ◽  
Temperature Relaxation

Abstract Polysulfide rubbers of various internal structures have been investigated by measurements of continuous and intermittent relaxation of stress and by creep under constant load at temperatures between 35° C and 120° C. Continuous stress relaxation measurements indicate that these rubbers obey approximately the simple Maxwellian law of relaxation of stress, which indicates that one definite type of bond in the network structure is responsible for stress decay. The activation energy for the relaxation process in each of the polysulfide rubbers is nearly the same, indicating that the same type of bond is responsible for the relaxation behavior of all the polysulfides investigated. In contrast to hydrocarbon rubbers, oxygen is not the cause of high temperature relaxation in polysulfide rubbers, nor does heating in air at moderate temperatures for times comparable to the relaxation time produce changes in physical properties as determined by modulus or by appearance of the samples. Several possibilities regarding the mechanism of the relaxation process and the type of bond involved are considered in the light of the experimental results.

Influence of an upper-hybrid pump on temperature relaxation processes in a magnetized plasma

2008 ◽  
Vol 74 (1) ◽  
pp. 47-51
Author(s):  
V. N. PAVLENKO ◽  
V. G. PANCHENKO
Keyword(s):  
Acoustic Waves ◽  
Pump Wave ◽  
Magnetized Plasma ◽  
Relaxation Processes ◽  
Plasma Parameters ◽  
Ion Acoustic Waves ◽  
Turbulent Fluctuations ◽  
Inverse Relaxation Time ◽  
Temperature Relaxation ◽  
Convective Cells

AbstractBy means of kinetic fluctuation theory, the relaxation process between the electron and ion temperatures in a magnetized homogeneous plasma is considered. The cases when the external upper-hybrid pump wave excites modified convective cells and ion-acoustic waves are analysed. The inverse relaxation time in the regime where the turbulent fluctuations are developed is calculated for these cases and its dependence on the pump wave and plasma parameters is deduced.

Scattering of electromagnetic waves in a magnetized plasma with an HF pump

2002 ◽  
Vol 67 (5) ◽  
pp. 309-320 ◽  
Author(s):  
V. N. PAVLENKO ◽  
V. G. PANCHENKO ◽  
S. A. NAZARENKO
Keyword(s):  
Cross Sections ◽  
Electromagnetic Waves ◽  
Pump Wave ◽  
Parametric Instability ◽  
Density Fluctuations ◽  
Magnetized Plasma ◽  
Lower Hybrid ◽  
Ion Temperature ◽  
Temperature Anisotropy ◽  
Transverse Electromagnetic

The scattering of transverse electromagnetic waves by turbulent density fluctuations in a magnetized plasma in the presence of external pump fields is investigated. The case where a lower-hybrid pump wave decays into daughter and ion-cyclotron waves in a plasma with ion-temperature anisotropy is considered. The situation where an upper-hybrid pump wave parametrically excites modified convective cells and electron drift waves is also analyzed. The differential scattering cross-sections in the region above the parametric instability thresholds for these three cases are calculated.

scholarly journals Influence of Inhomogeneity on Transformation and Radiation Processes in Plasma with Upper Hybrid Pump

2019 ◽  
Vol 64 (9) ◽  
pp. 814
Author(s):  
V. G. Panchenko ◽  
P. V. Porytsky
Keyword(s):  
Pump Wave ◽  
Inhomogeneous Plasma ◽  
Parametric Instability ◽  
Langmuir Wave ◽  
Wave Transformation ◽  
Transformation Coefficient ◽  
Radiation Emission ◽  
Parametric Decay ◽  
Radiation Processes ◽  
Transverse Electromagnetic

On the basis of the kinetic theory of fluctuations, the processes of the longitudinal Langmuir wave transformation into a transverse electromagnetic wave in the turbulent inhomogeneous plasma have been studied. The plasma turbulence is assumed to arise owing to the parametric decay of the upper hybrid pump wave into a daughter wave and electron-drift oscillations. The transformation coefficient under the parametric instability saturation conditions is determined. The intensity of the electromagnetic radiation emission from the plasma is calculated, and its dependence on the plasma and pump wave parameters is found.

Parametric excitation of low-frequency convective cell modes by a large amplitude lower-hybrid wave in a plasma

1977 ◽  
Vol 55 (10) ◽  
pp. 866-867 ◽  
Author(s):  
P. K. Shukla ◽  
M. Y. Yu
Keyword(s):  
Growth Rate ◽  
Pump Wave ◽  
Parametric Instability ◽  
Low Frequency ◽  
Convective Cell ◽  
Lower Hybrid ◽  
Hybrid Wave ◽  
Lower Hybrid Wave ◽  
Hybrid Frequency ◽  
Temporal Growth Rate

It is shown that convective cell modes can become purely growing modes in the presence of an intense pump wave near the lower-hybrid frequency. The temporal growth rate and threshold of the parametric instability are presented.

Scattering of electromagnetic waves by anomalous fluctuations of a magnetized plasma

1990 ◽  
Vol 43 (2) ◽  
pp. 165-172 ◽  
Author(s):  
V. N. Pavlenko ◽  
V. G. Panchenko
Keyword(s):  
Cross Section ◽  
Electromagnetic Waves ◽  
Pump Wave ◽  
Density Fluctuations ◽  
Scattering Cross Section ◽  
Magnetized Plasma ◽  
Lower Hybrid ◽  
Scattering Cross ◽  
Parametric Decay ◽  
Ion Acoustic

Fluctuations and scattering of transverse electromagnetic waves by density fluctuations in a magnetized plasma in the presence of parametric decay of the pump wave are investigated. The spectral density of electron-density fluctuations is calculated. It is shown that the differential scattering cross-section has sharp maxima at the ion-acoustic and lower-hybrid frequencies when parametric decay of the lower-hybrid pump wave occurs. We note that scattering at the ion-acoustic frequency is dominant. When the pump-wave amplitude tends to the threshold strength of the electric field the scattering cross-section increases anomalously, i.e. there is critical opalescence.

Parametric Side-Scattering by Waves Near the Hybrid Resonance Frequencies in Inhomogeneous Plasmas

1975 ◽  
Vol 30 (6-7) ◽  
pp. 911-912 ◽  
Author(s):  
P. K. Shukla ◽  
M. Y. Yu ◽  
K. H. Spatschek
Keyword(s):  
Growth Rates ◽  
Inhomogeneous Plasma ◽  
Lower Hybrid ◽  
Hybrid Resonance ◽  
Resonance Frequencies

Abstract The temporal growth rates are calculated for side-scat-tering of light by modes near the upper and lower hybrid frequencies in a turbulent, inhomogeneous plasma.

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