Propagation of Strong-Field Modulated Electromagnetic Waves in Plasmas

1971 ◽  
Vol 49 (24) ◽  
pp. 3208-3220
Author(s):  
M. P. Bachynski ◽  
B. W. Gibbs
Keyword(s):  
Electron Temperature ◽  
Electromagnetic Waves ◽  
Strong Field ◽  
Plane Electromagnetic Wave ◽  
Low Frequency ◽  
Wave Form ◽  
Plasma Properties ◽  
Polarized Waves ◽  
Effective Collision Frequency ◽  
Low Frequency Waves

The distortion of the wave form of a modulated plane electromagnetic wave propagating in an anisotropic plasma has been experimentally investigated over a range of field strengths of the wave and plasma properties. By using right-hand circularly polarized waves, the effective frequency is [Formula: see text] (where ω is the r.f. radian frequency and ωb the cyclotron frequency) and hence the results are also applicable to the propagation of low-frequency waves in an isotropic plasma. Severe "overmodulation" of the wave form transmitted through the plasma is found in the regime [Formula: see text] where ν is the effective collision frequency for momentum transfer. The distortion of the wave form is found to increase with depth of modulation of the incident wave and decrease with increasing modulation frequency.The "demodulation" is in qualitative agreement with theory for an unmodulated wave with a non-Maxwellian (Druyvesteyn) velocity distribution for the electrons. Many of the effects of the modulation frequencies can also be qualitatively predicted by considering the variation of electron temperature in the presence of the strong-field modulated wave. A theory is developed for large changes in electron temperature induced by the incident field which shows that marked distortion of the modulation is possible.

Scattering of electromagnetic waves by hybrid waves in a two-electron-temperature plasma

1991 ◽  
Vol 46 (1) ◽  
pp. 99-106 ◽  
Author(s):  
S. K. Sharma ◽  
A. Sudarshan
Keyword(s):  
Growth Rate ◽  
Electron Temperature ◽  
High Frequency ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Lower Hybrid ◽  
Stimulated Scattering ◽  
Coupled Modes ◽  
Temperature Plasma ◽  
Electrostatic Perturbation

In this paper, we use the hydrodynamic approach to study the stimulated scattering of high-frequency electromagnetic waves by a low-frequency electrostatic perturbation that is either an upper- or lower-hybrid wave in a two-electron-temperature plasma. Considering the four-wave interaction between a strong high-frequency pump and the low-frequency electrostatic perturbation (LHW or UHW), we obtain the dispersion relation for the scattered wave, which is then solved to obtain an explicit expression for the growth rate of the coupled modes. For a typical Q-machine plasma, results show that in both cases the growth rate increases with noh/noc. This is in contrast with the results of Guha & Asthana (1989), who predicted that, for scattering by a UHW perturbation, the growth rate should decrease with increasing noh/noc.

scholarly journals Low frequency waves in plasmas with spatially varying electron temperature

2000 ◽  
Vol 18 (12) ◽  
pp. 1613-1622 ◽  
Author(s):  
P. Guio ◽  
S. Børve ◽  
H. L. Pécseli ◽  
J. Trulsen
Keyword(s):  
Numerical Simulation ◽  
Electron Temperature ◽  
Acoustic Waves ◽  
Low Frequency ◽  
Plasma Temperature ◽  
Electrostatic Waves ◽  
Radio Science ◽  
Particle In Cell ◽  
Ionosphere Plasma ◽  
Low Frequency Waves

Abstract. Low frequency electrostatic waves are studied in magnetized plasmas with an electron temperature which varies with position in a direction perpendicular to the magnetic field. For wave frequencies below the ion cyclotron frequency, the waves need not follow any definite dispersion relation. Instead a band of phase velocities is allowed, with a range of variation depending on the maximum and minimum values of the electron temperature. Simple model equations are obtained for the general case which can be solved to give the spatial variation of a harmonically time varying potential. A simple analytical model for the phenomenon is presented and the results are supported by numerical simulations carried out in a 2½-dimensional particle-in-cell numerical simulation. We find that when the electron temperature is striated along B0 and low frequency waves (ω ≪ Ωci) are excited in this environment, then the intensity of these low frequency waves will be striated in a manner following the electron temperature striations. High frequency ion acoustic waves (ω ≫ Ωci) will on the other hand have a spatially more uniform intensity distribution.Key words: Ionosphere (plasma temperature and density) · Radio science (waves in plasma) · Space plasma physics (numerical simulation studies)

TRANSMISSION AND REFLECTION OF ELECTROMAGNETIC WAVES AT A PLASMA BOUNDARY FOR ARBITRARY ANGLES OF INCIDENCE

1961 ◽  
Vol 39 (11) ◽  
pp. 1544-1562 ◽  
Author(s):  
K. A. Graf ◽  
M. P. Bachynski
Keyword(s):  
Electromagnetic Waves ◽  
Plane Electromagnetic Wave ◽  
Space Plasma ◽  
Plasma Boundary ◽  
Brewster Angle ◽  
Angle Of Incidence ◽  
Elliptical Polarization ◽  
Plasma Parameters ◽  
Polarized Waves ◽  
Transmission And Reflection

The interaction of a plane electromagnetic wave with a flat free-space – plasma interface has been considered for arbitrary angles of incidence. It is shown that the plasma can support independent horizontally and vertically polarized waves. Expressions and graphical representations are given showing the amount of energy entering the plasma as a function of angle of incidence and plasma parameters. The vertically polarized case shows a maximum in the energy entering the plasma at the "Brewster angle". For a lossy plasma, at this maximum, there will be reflection. Loci of constant Brewster angle appear as concentric curves centered on the origin of the complex dielectric coefficient plane.The elliptical polarization of a plane wave reflected from the interface, when a wave with equal horizontally and vertically polarized components is incident on the interface, suggests the similarity of lossless plasmas to ordinary dielectrics and of lossy plasmas to metals.

scholarly journals The tune of the universe: the role of plasma in tests of strong-field gravity

2021 ◽  
Author(s):  
Vitor Cardoso ◽  
Wen-Di Guo ◽  
Caio F B Macedo ◽  
Paolo Pani
Keyword(s):  
Gravitational Wave ◽  
Electromagnetic Waves ◽  
Degrees Of Freedom ◽  
Strong Field ◽  
Low Frequency ◽  
Electromagnetic Emission ◽  
Modified Theories Of Gravity ◽  
Black Hole Binaries ◽  
Long Baseline ◽  
Electromagnetic Probes

Abstract Gravitational-wave astronomy, together with precise pulsar timing and long baseline interferometry, is changing our ability to perform tests of fundamental physics with astrophysical observations. Some of these tests are based on electromagnetic probes or electrically charged bodies, and assume an empty universe. However, the cosmos is filled with plasma, a dilute medium which prevents the propagation of low-frequency, small-amplitude electromagnetic waves. We show that the plasma hinders our ability to perform some strong-field gravity tests, in particular: (i) nonlinear plasma effects dramatically quench plasma-driven superradiant instabilities; (ii) the contribution of electromagnetic emission to the inspiral of charged black hole binaries is strongly suppressed; (iii) electromagnetic-driven secondary modes, although present in the spectrum of charged black holes, are excited to negligible amplitude in the gravitational-wave ringdown signal. The last two effects are relevant also in the case of massive fields that propagate in vacuum and can jeopardize tests of modified theories of gravity containing massive degrees of freedom.

ELECTROMAGNETIC WAVES IN A BOUNDED, ANISOTROPIC PLASMA

1962 ◽  
Vol 40 (7) ◽  
pp. 887-905 ◽  
Author(s):  
K. A. Graf ◽  
M. P. Bachynski
Keyword(s):  
Magnetic Field ◽  
Static Magnetic Field ◽  
Electromagnetic Waves ◽  
Plane Electromagnetic Wave ◽  
Plasma Boundary ◽  
Plasma Properties ◽  
Magnetic Field Data ◽  
Reflected Waves ◽  
Quartic Equation ◽  
The Magnetic Field

The interaction of a plane, electromagnetic wave with a flat, uniform free-space – plasma interface in a static magnetic field has been considered for arbitrary angles of incidence. The dispersion relation for the plasma is a complex quartic equation which reduces to a quadratic if the static magnetic field and plasma boundary are oriented along any one of the rectangular co-ordinate axes. (These axes need not simultaneously be the same for the plasma and the magnetic field.)Numerical results are presented for the attenuation and phase constants for each of the two possible waves in the plasma, for each orientation of the static magnetic field. Data are given for various angles of incidence, plasma properties, and orientations of the static magnetic field relative to the plasma boundary.Inspection of the fields in the plasma reveals some interesting aspects. In certain cases, waves which appear to move upward towards the plasma interface exist. Since these waves may carry energy into the plasma, they have been referred to as "backward" waves. Totally reflected waves which have both finite attenuation and finite phase coefficients can also exist in the plasma. These have been termed "modified Sommerfeld" waves.

New low-frequency waves and negative mass instability in dusty plasmas

2003 ◽  
Vol 69 (5) ◽  
pp. 439-448
Author(s):  
D. P. RESENDES ◽  
R. BINGHAM ◽  
A. GUERREIO ◽  
V. N. TSYTOVICH
Keyword(s):  
Electron Temperature ◽  
Free Path ◽  
Low Frequency ◽  
Mean Free Path ◽  
Sound Waves ◽  
Plasma Particle ◽  
Effective Collision Frequency ◽  
Charging Mode ◽  
Dust Charging ◽  
Effective Collision

Low-frequency dusty plasma waves with frequencies much smaller than the frequency of charging collisions of plasma particles with dust particles are considered, taking into account elastic and charging collisions of plasma particles with dust and with neutrals. The usual dust sound waves with an upper frequency equal to the dust plasma frequency are found to be present only for wavelengths much smaller than the plasma particle effective mean free path due to the effective collision frequency. The effective collision frequency is found to be inversely proportional to the square root of the product of the charging frequency and the frequency of particle momentum losses, involving processes due to elastic plasma particle–dust collisions, and collisions with neutrals. It is shown that when the wavelength of the wave is much larger than the mean free path for effective collisions the properties of the waves are different from those previously considered. A negative mass instability is found in this domain of frequencies when the effective mean free path of ions is larger than the effective mean free path of electrons. In the absence of neutrals this appears to be possible only if the temperature of ions exceeds the electron temperature. This can occur in laboratory experiments and space plasmas but not in plasma-etching experiments. In the absence of instability a new dust oscillation, a dust charging mode, is found the frequency of which is almost constant over a certain range of wavenumbers. It is inversely proportional to the dust mass and charging frequency of the dust. A new dust electron sound wave is found for frequencies less than the frequency of the dust charging mode. The velocity of the dust electron sound wave is determined by the electron temperature but not the ion temperatures, as for the usual dust sound waves, with the electron temperature exceeding the ion temperature substantially.

Instability of low-frequency waves in a cold plasma mixed with hot electrons

1985 ◽  
Vol 33 (3) ◽  
pp. 437-441 ◽  
Author(s):  
Hiromitsu Hamabata ◽  
Tomikazu Namikawa
Keyword(s):  
Equilibrium State ◽  
Electron Temperature ◽  
Cold Plasma ◽  
Low Frequency ◽  
Hot Electrons ◽  
Hot Electron ◽  
Temperature Anisotropy ◽  
First Order ◽  
Cold Electrons ◽  
Low Frequency Waves

The instability of low-frequency waves in a cold plasma mixed with hot electrons is investigated using the first-order CGL equations for electrons. It is assumed that in an equilibrium state the electrons consist of two components, cold electrons and hot electrons with bi-Maxwellians. It is shown that low-frequency waves with right-hand polarization can be generated by the hot electron temperature anisotropy and the existence of cold electrons.

scholarly journals Attenuation of low-frequency electromagnetic waves in the Earth's lower ionosphere under the influence of strong local disturbances in the atmosphere.

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
A.V. Moshkov ◽  
Keyword(s):  
Electromagnetic Waves ◽  
Low Frequency ◽  
Lower Ionosphere ◽  
Macroscopic Model ◽  
Electromagnetic Pulses ◽  
Horizontal Size ◽  
Lightning Discharges ◽  
Instantaneous Point ◽  
Fading Time ◽  
Low Frequency Waves

The value and duration of attenuation of low frequency waves (1...10 kHz) in the presence of a strong local disturbance of the atmosphere have been estimated. Sources of significant local disturbances of the atmosphere are, for example, precipitation of energetic particles of radiation belts; electromagnetic pulses of lightning discharges; radiation of powerful low-frequency ground-based transmitters; invasion of large meteors. Strong local disturbances lead to an increase of ionization (concentration of free electrons) of the environment by several orders of magnitude in the region of space whose characteristic dimensions are comparable to the length of the wave (tens and hundreds of kilometers). As such a disturbance, we use the previously developed macroscopic model of an instantaneous, point release of a relatively large amount of energy in the atmosphere below the ionosphere. This model makes it possible to estimate the features of the propagation of low-frequency waves through the disturbed layer of the lower ionosphere by changing only two initial parameters: the disturbance energy and its initial height. It is shown that the attenuation value is almost independent of frequency and geo- and heliophysical conditions. For initial heights up to 50 km, the fading duration does not exceed ~ 2 min. With an increase of the initial altitude, the attenuation in the lower ionosphere becomes extremely large. However, for heights of 50 ... 70 km (depending on the value of energy), the horizontal size of the disturbance decreases significantly, which leads to a decrease in the fading time to tens of seconds for initial heights of more than 80 km.

PEMANFAATAN RADIASI ENERGI TEGANGAN 150 KV UNTUK LAMPU LED PENERANGAN JALAN

Jurnal Teknik ◽  
2018 ◽  
Vol 7 (1) ◽  
Author(s):  
Mauludi Manfaluthy
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
High Voltage ◽  
Low Frequency ◽  
Energy Utilization ◽  
World Health ◽  
Electromagnetic Signals ◽  
Health Organization ◽  
The Magnetic Field ◽  
Low Frequency Waves

WHO (World Health Organization) concludes that not much effect is caused by electric field up to 20 kV / m in humans. WHO standard also mentions that humans will not be affected by the magnetic field under  100 micro tesla and that the electric field will affect the human body with a maximum standard of 5,000 volts per meter. In this study did not discuss about the effect of high voltage radiation SUTT (High Voltage Air Channel) with human health. The research will focus on energy utilization of SUTT radiation. The combination of electric field and magnetic field on SUTT (70-150KV) can generate electromagnetic (EM) and radiation waves, which are expected to be converted to turn on street lights around the location of high voltage areas or into other forms. The design of this prototype works like an antenna in general that captures electromagnetic signals and converts them into AC waves. With a capacitor that can store the potential energy of AC and Schottky diode waves created specifically for low frequency waves, make the current into one direction (DC). From the research results obtained the current generated from the radiation is very small even though the voltage is big enough.Keywords : Radiance Energy, Joule Thief, and  LED Module.

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