Plasma Waves in an Inhomogeneous Plasma Carrying a Current

1975 ◽  
Vol 53 (4) ◽  
pp. 385-390
Author(s):  
T. N. Bhatnagar ◽  
S. R. Sharma
Keyword(s):  
Wave Propagation ◽  
Density Gradient ◽  
Inhomogeneous Plasma ◽  
Low Frequency ◽  
Magnetoactive Plasma ◽  
Plasma Waves ◽  
Constant Current ◽  
Helicon Wave ◽  
Weak Density ◽  
A Current

Wave propagation in a magnetoactive plasma carrying a constant current is considered for the case of uniform and nonuniform media having a weak density gradient. The effect of drift velocity and nonuniformity is examined in detail for the longitudinal electrokinetic wave and the low frequency helicon wave propagation.

Study of lower-hybrid wave propagation in the presence of low-frequency fluctuations

1992 ◽  
Vol 48 (3) ◽  
pp. 435-452 ◽  
Author(s):  
B. Fischer ◽  
M. Krämer
Keyword(s):  
Wave Propagation ◽  
Inhomogeneous Plasma ◽  
Low Frequency ◽  
Density Fluctuations ◽  
Lower Hybrid ◽  
Lower Hybrid Wave ◽  
Nonuniform Plasma ◽  
Point Correlation ◽  
Phase Sensitive ◽  
Frequency Fluctuations

Phase-sensitive probe diagnostics as well as two-point-correlation analysis of radio-frequency probe signals are applied to investigate small-amplitude lower-hybrid (LH) waves launched into a linear nonuniform plasma column by a slow-wave antenna. The LH wave propagation in the inhomogeneous plasma is described by a model taking into account the wavenumber spectrum of the antenna. Special attention is focused on the interaction of the LH waves with the low-frequency density fluctuations. The LH frequency and wavenumber spectra observed can be explained by scattering of the LH waves from the (incoherent) low-frequency density fluctuations. Moreover, the enhanced damping, which is found to be much higher than expected from collisional and electron Landau dampings, is correlated with the level of low-frequency fluctuations.

Transformation of waves and electron heating in a radially inhomogeneous plasma

1969 ◽  
Vol 3 (2) ◽  
pp. 179-188 ◽  
Author(s):  
V. Kopecký ◽  
J. Preinhaelter ◽  
J. Václavík
Keyword(s):  
High Frequency ◽  
Inhomogeneous Plasma ◽  
Magnetoactive Plasma ◽  
Plasma Waves ◽  
Electron Heating ◽  
Electrostatic Waves ◽  
Long Wavelength ◽  
Hybrid Resonance ◽  
Radially Inhomogeneous ◽  
The Waves

The propagation and the linear transformation of high-frequency electrostatic waves in a hot magnetoactive plasma with a radially decreasing density is investigated. It is shown that in the region of the hybrid resonance cold plasma waves with a long wavelength are transformed into the Bernstein modes with a short wavelength. By this shortening of the wavelength the absorption of the waves increases, particularly for the frequencies near the electron cyclotron harmonics. It might be the cause of the electron heating in plasma—beam experiments.

Effects of Helicon Wave Propagation Based on a Conical Antenna Design: Part I (Preprint)

2007 ◽  
Author(s):  
Michael P. Reilly ◽  
George H. Miley ◽  
David E. Kirtley ◽  
Justin Koo ◽  
Jr. Hargus ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Antenna Design ◽  
Helicon Wave

scholarly journals Non-linear Terahertz driving of plasma waves in layered cuprates

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Francesco Gabriele ◽  
Mattia Udina ◽  
Lara Benfatto
Keyword(s):  
Low Frequency ◽  
Plasma Waves ◽  
Meissner Effect ◽  
High Energy ◽  
Plasma Mode ◽  
Light Pulses ◽  
High Frequency Plasma ◽  
Non Linear ◽  
Out Of Plane ◽  
Layered Cuprates

AbstractThe hallmark of superconductivity is the rigidity of the quantum-mechanical phase of electrons, responsible for superfluid behavior and Meissner effect. The strength of the phase stiffness is set by the Josephson coupling, which is strongly anisotropic in layered cuprates. So far, THz light pulses have been used to achieve non-linear control of the out-of-plane Josephson plasma mode, whose frequency lies in the THz range. However, the high-energy in-plane plasma mode has been considered insensitive to THz pumping. Here, we show that THz driving of both low-frequency and high-frequency plasma waves is possible via a general two-plasmon excitation mechanism. The anisotropy of the Josephson couplings leads to markedly different thermal effects for the out-of-plane and in-plane response, linking in both cases the emergence of non-linear photonics across Tc to the superfluid stiffness. Our results show that THz light pulses represent a preferential knob to selectively drive phase excitations in unconventional superconductors.

Galvanotropic Reactions of Polycelis nigra in Relation to Inherent Electrical Polarity

1927 ◽  
Vol 5 (1) ◽  
pp. 66-88
Author(s):  
J. ARMITAGE ROBERTSON
Keyword(s):  
Electrical Circuit ◽  
The Body ◽  
Constant Current ◽  
Forward Movement ◽  
Electrical Currents ◽  
Turning Mechanism ◽  
Electrical Polarity ◽  
Metabolic Activities ◽  
Physiological Gradients ◽  
A Current

The galvanotropic reactions of Polycelis nigra were investigated in constant and "intermittent" (that is, a current showing slight commutator ripple) electrical currents, varying in strength from one to about ten milliamperes. Galvanotropic reactions were most readily forthcoming at about 2 m.a. constant current, higher current strengths producing signs of discomfort or rigor, and intermittent current being slightly more effective in producing such disturbances than constant current. As a rule, Polycelis places itself longitudinally, with head facing the kathode, and moves thither by means of looping, its normal gliding motion being in abeyance. If facing the kathode on application of the current, it simply loops forward, but if moving parallel to the electrodes it turns its anterior end first, and then movesmore or less directly towards the kathode. If previously facing the anode, a turn in the direction of the kathode is usually accomplished only after more or less headwaving and apparent difficulty or hesitation. Decapitate animals, if facing the anode in the current, at some time or other almost invariably loop backwards to the kathode, tail foremost, for a varying number of times, before turning their anterior end to the kathode and orientating normally. This was never observed in normal animals. Decaudate animals behave like unmutilated individuals. Decapitate-and-decaudate Polycelis (middle-pieces) reactin the same manner as do decapitate specimens, i.e. show backward looping. Longitudinal halves of Polycelis are usually curved towards the injured side, and show little or no movement, either in or out of the current; it is supposed that this curvature is mechanical and the result of the injury. Higher amperages (above 2 m.a.) produce, progressively, cessation of forward movement with twisting and apparent discomfort, and, finally, flattening of the kathodic end of the body. This last reaction is often accompanied by various postures, presumably the result of arrested movement. An explanation of these reactions, in normal and unmutilated animals, is attempted, based on the supposed interaction of the experimental current with the external portion of an inherent electrical circuit. If this inherent circuit be obstructed it is suggested that the metabolic activities, with which it is apparently correlated, are to some extent upset. Further, that to avoid this derangement, and concomitant malaise, the animals orientate themselves so that the experimental current does not flow counter to the external portion of their inherent circuit; that the turning mechanism of the flanks which affects this orientation can be explained upon similar grounds; finally that backward looping can be explained as a transference of control or dominance to the tail end, due to the combined inhibitory action of mutilation and of a contrary experimental current upon the normal physiological gradients at the anterior end. A variety of points related to the theory, and some cases of galvanotropism bearing on the work, together with their theoretical explanations, are discussed.

Numerical Simulation of the Buried Object Detection Based on Underwater Plasma Acoustic Source

2011 ◽  
Vol 105-107 ◽  
pp. 80-83
Author(s):  
Jun Zhang ◽  
Xin Wu Zeng ◽  
Yi Bo Wang ◽  
Zhen Fu Zhang ◽  
Dan Chen
Keyword(s):  
Wave Propagation ◽  
Object Detection ◽  
Pulse Length ◽  
Low Frequency ◽  
Basic Mechanism ◽  
Propagation Model ◽  
Staggered Grid ◽  
Acoustic Source ◽  
Buried Objects ◽  
Buried Object

Detection and classification of buried objects is of great importance in underwater counterterrorism and archaeology. To penetrate the sediment, a low frequency intensive acoustic source is needed. Underwater plasma acoustic source (UPAS) with high voltage discharge has the advantage of adjustable pulse length, high source level output and no pollution to the environment, which can satisfy these needs. In this paper, we introduced the UPAS, including its basic mechanism, structure and pressure output. Then we build up an elastic wave propagation model, solved it with finite difference and staggered grid methods, and combined with certain source and boundary condition, we simulated and analyzed the pressure wave propagation in time domain with an aluminum cylinder buried in sediment, from the results we validated the effectiveness of UPAS in the application of buried object detection.

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