Small amplitude transverse wave propagation in a weakly Langmuir turbulent plasma

1969 ◽  
Vol 3 (4) ◽  
pp. 593-601
Author(s):  
N. Bel ◽  
J. Heynaerts
Keyword(s):  
High Frequency ◽  
Small Amplitude ◽  
Cold Plasma ◽  
Plasma Frequency ◽  
Turbulent Plasma ◽  
Distribution Functions ◽  
Isotropic Plasma ◽  
Particle Correlation ◽  
Special Cases ◽  
Corrective Term

The high frequency conductivity tensor of an isotropic plasma is derived taking into account particle correlations at the lowest consistent order in the parameter ωp/ω these correlations describe a weakly Langmuir turbulent plasma. Two special cases are investigated in which the two-particle correlation function is related to the turbulent electrostatic field spectrum. Particular distribution functions and spectra are considered and approximate dispersion relations are derived in both cases in ‘the cold plasma limit’. The importance of the corrective term is discussed in terms of three dimensionless parameters measuring the strength of the turbulence, the shape of the spectrum, and the frequency. The effect could be important for frequencies not too far from the plasma frequency.

Anomalous high-frequency conductivity of a turbulent plasma

1968 ◽  
Vol 2 (3) ◽  
pp. 465-482 ◽  
Author(s):  
B. Bertotti ◽  
O. De Barbieri
Keyword(s):  
High Frequency ◽  
Plasma Frequency ◽  
Electron Plasma ◽  
Turbulent Plasma ◽  
Distribution Functions ◽  
Conductivity Tensor ◽  
Three Dimensional Model ◽  
Electron Plasma Frequency ◽  
Wide Range ◽  
Anisotropic Character

In this work we evaluate the anomalous high-frequency conductivity arising from particle—wave interactions in a multi-species turbulent plasma with no external magnetic field. The calculation is made by using the full three-dimensional model of the quasi-linear theory of plasma turbulence for a wide range of frequencies embracing the electron plasma frequency. It is found that the conductivity tensor is anisotropic and slowly time dependent; this reflects the slow time dependence and the anisotropic character of the distribution functions of the velocities of the particles. It is also found that there is a very narrow range of frequencies (just above the electron plasma frequency) for which the components of the conductivity tensor are negative. The particular case of the two- stream instability is examined in detail. The anisotropic character of the components of the conductivity tensor and their dependence on the frequency of the external field is studied. Finally some possible means for an experimental check of our calculations are suggested.

Radio-Frequency Probes in a Nonlinear Isotropic Plasma

1974 ◽  
Vol 52 (4) ◽  
pp. 291-301 ◽  
Author(s):  
Colin C. Bantin ◽  
Keith G. Balmain
Keyword(s):  
Radio Frequency ◽  
Cold Plasma ◽  
Nonlinear Response ◽  
Plasma Frequency ◽  
Second Harmonic ◽  
Second Order ◽  
Constant Current ◽  
Constant Voltage ◽  
Isotropic Plasma ◽  
Input Signals

Nonlinear cold-plasma and scalar-pressure theories are derived and applied to a spherical RF probe in a plasma. With two specified RF potentials on the probe at different frequencies, calculations are presented for the second-order probe output responses. These include the second harmonic, the sum and difference frequencies, and the d.c. increment (resonance rectification). The nonlinear response as a function of frequency is shown to depend strongly on whether the input signals are maintained at a constant current or a constant voltage; for diagnostics, the constant-current technique permits identification of the plasma frequency, whereas the constant-voltage technique does not.

Characterization of Ni/γ-Al2O3 Catalyst Prepared by Atmospheric High Frequency Cold Plasma Jet for CO2 Reforming of CH4

2010 ◽  
Vol 31 (3) ◽  
pp. 353-359
Author(s):  
Xiaoyan CHAI ◽  
Shuyong SHANG ◽  
Gaihuan LIU ◽  
Xumei TAO ◽  
Xiang LI ◽  
...  
Keyword(s):  
High Frequency ◽  
Cold Plasma ◽  
Plasma Jet

Coupling of Upper Hybrid Surface Plasmon Modes in Magnetoplasma Waveguide Structure

2021 ◽  
Vol 14 (2) ◽  
pp. 155-160
Keyword(s):  
High Frequency ◽  
Cyclotron Frequency ◽  
Plasma Frequency ◽  
Single Mode ◽  
Homogeneous System ◽  
Slab Waveguide ◽  
Surface Modes ◽  
Plasma Slab ◽  
Warm Plasma ◽  
Hybrid Waves

Abstract: We investigate the spectra of high-frequency electrostatic surface electron plasmon oscillations propagating normal to a dc-magnetic field. These oscillations are supported by two identical magnetoplasma slabs separated by a vacuum slab. Propagation characteristics of surface magnetoplasma oscillations and their coupling are studied by simultaneously solving the homogeneous system of equations obtained by matching the electrostatic fields at the interfaces together with the warm plasma dielectric function of upper hybrid waves. We demonstrate the existence of two propagating magnetoplasma electrostatic surface modes (backward and forward modes). The backward mode emerges at frequency ω=ω_uh=√(ω_pe^2+ω_ce^2 ), where ω_pe and ω_ce are the electron plasma frequency and the electron cyclotron frequency, respectivily, and the forward propagating mode emerges at a lower frequency ω=ω_uh-ω_pe. The forward and backward surface modes become coupled and form a single mode at upper hybrid resonance quasi-static value ω=ω_uh/√2. Keywords: Upper hybrid modes, Plasma slab waveguide, Coupled plasmon surface modes.

The effects of pH on force and stiffness development in mouse muscles

1987 ◽  
Vol 65 (8) ◽  
pp. 1798-1801 ◽  
Author(s):  
J. M. Renaud ◽  
R. B. Stein ◽  
T. Gordon
Keyword(s):  
High Frequency ◽  
Small Amplitude ◽  
Force Production ◽  
Muscle Length ◽  
Low Ph ◽  
Muscle Stiffness ◽  
Average Force ◽  
Cross Bridge ◽  
Effects Of Ph ◽  
Cross Bridges

Changes in force and stiffness during contractions of mouse extensor digitorum longus and soleus muscles were measured over a range of extracellular pH from 6.4 to 7.4. Muscle stiffness was measured using small amplitude (<0.1% of muscle length), high frequency (1.5 kHz) oscillations in length. Twitch force was not significantly affected by changes in pH, but the peak force during repetitive stimulation (2, 3, and 20 pulses) was decreased significantly as the pH was reduced. Changes in muscle stiffness with pH were in the same direction, but smaller in extent. If the number of attached cross-bridges in the muscle can be determined from the measurement of small amplitude, high frequency muscle stiffness, then these findings suggest that (a) the number of cross-bridges between thick and thin filaments declines in low pH and (b) the average force per cross-bridge also declines in low pH. The decline in force per cross-bridge could arise from a reduction in the ability of cross-bridges to generate force during their state of active force production and (or) in an increased percentage of bonds in a low force, "rigor" state.

scholarly journals Potential Use of Cold Plasma Discharges for Frequency Reconfigurability in a Sievenpiper Mushroom Metasurface

2021 ◽  
Vol 11 (23) ◽  
pp. 11342
Author(s):  
Francisco Pizarro ◽  
Pablo Stuardo ◽  
Ricardo Olivares ◽  
Eva Rajo-Iglesias
Keyword(s):  
Parametric Study ◽  
Cold Plasma ◽  
Collision Frequency ◽  
Plasma Frequency ◽  
Stop Band ◽  
Plasma Discharges ◽  
Electronic Density ◽  
Full Wave ◽  
Insertion Losses ◽  
Potential Use

This article presents a parametric study using full-wave simulations about the potential use of cold plasma discharges to achieve frequency reconfiguration on a Sievenpiper mushroom metasurface. The study was done by inserting plasma tubes in between the patches of the mushroom structure, in three different positions with respect to the top of the metasurface, and varying the electronic density while keeping the plasma collision frequency. The obtained results show that it is possible to shift the stop-band generated by the metasurface around 25% towards lower frequencies for an electron density value inside the tubes of 1014 cm−3, when they are placed in between the top patches of the metasurface. Additional insertion losses are exhibited when operating near the plasma frequency.

scholarly journals Contact and Chord Length Distribution Functions of the Poisson-Voronoi Tessellation in High Dimensions

2010 ◽  
Vol 42 (1) ◽  
pp. 48-68 ◽  
Author(s):  
L. Muche
Keyword(s):  
Voronoi Tessellation ◽  
Length Distribution ◽  
Distribution Functions ◽  
Chord Length ◽  
Dimensional Euclidean Space ◽  
Spherical Contact ◽  
Chord Length Distribution ◽  
Special Cases ◽  
Contact Distribution ◽  
Contact Distribution Function

In this paper we present formulae for contact distributions of a Voronoi tessellation generated by a homogeneous Poisson point process in the d-dimensional Euclidean space. Expressions are given for the probability density functions and moments of the linear and spherical contact distributions. They are double and simple integral formulae, which are tractable for numerical evaluation and for large d. The special cases d = 2 and d = 3 are investigated in detail, while, for d = 3, the moments of the spherical contact distribution function are expressed by standard functions. Also, the closely related chord length distribution functions are considered.

scholarly journals Lossless Linear Integer signal Resampling

2012 ◽  
pp. 225-233
Author(s):  
S.Raghavendra Prasad ◽  
Dr.P.Ramana Reddy
Keyword(s):  
Matrix Factorization ◽  
High Frequency ◽  
Irreversible Process ◽  
Polynomial Interpolation ◽  
Factorization Method ◽  
Special Cases ◽  
The Matrix ◽  
Frequency Components ◽  
Linear Transform ◽  
Signal Resampling

This paper describes about signal resampling based on polynomial interpolation is reversible for all types of signals, i.e., the original signal can be reconstructed losslessly from the resampled data. This paper also discusses Matrix factorization method for reversible uniform shifted resampling and uniform scaled and shifted resampling. Generally, signal resampling is considered to be irreversible process except in some special cases because of strong attenuation of high frequency components. The matrix factorization method is actually a new way to compute linear transform. The factorization yields three elementary integer-reversible matrices. This method is actually a lossless integer-reversible implementation of linear transform. Some examples of lower order resampling solutions are also presented in this paper.

Statistical Theory of the SASE Fel Based on the Two-Particle Correlation Function Equation

2013 ◽  
Vol 8 (4) ◽  
pp. 25-34
Author(s):  
Oleg Shevchenko ◽  
Nikolay Vinokurov
Keyword(s):  
Correlation Function ◽  
Initial Conditions ◽  
Initial Density ◽  
Bbgky Hierarchy ◽  
Density Fluctuations ◽  
Distribution Functions ◽  
Time Coordinate ◽  
Particle Correlation ◽  
Sase Fel ◽  
Special Time

The startup from noise problem in SASE FELs is usually treated in linear approximation. In this case amplification of initial density fluctuations may be calculated, and averaging over initial conditions may be fulfilled explicitly. In general nonlinear case the direct averaging is not applicable. During last years we developed the approach based on the BBGKY hierarchy for the n-particle distribution functions. The interaction of particles in FEL is retarded. Nevertheless, using special time-coordinate transformation, it is possible to eliminate the interaction lag and then to write down the BBGKY equations. Similar to plasma physics, the equations may be truncated after the second one (for the two-particle correlation function). Using this approach we consider several particular cases which illustrate some peculiar features of the SASE FEL operation

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