scholarly journals Nonlinear structure of electromagnetic field, electron temperature and electron density in interaction of relativistic laser and plasma with density ripple

2014 ◽  
Vol 32 (4) ◽  
pp. 591-597 ◽  
Author(s):  
Xiongping Xia
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Field ◽  
Electron Temperature ◽  
Electron Density ◽  
Plasma Density ◽  
Relativistic Effect ◽  
Ohmic Heating ◽  
Field Profile ◽  
Nonlinear Structure ◽  
Field Electron

AbstractIn the paper, nonlinear structure of electromagnetic field, electron temperature, and electron density in interaction with relativistic laser and collisional underdense rippled plasma are investigated. The results are shown that due to the combination influence of relativistic effect, ohmic heating and plasma density ripple, electromagnetic field profile presents obvious asynchronism, which the peak of electric field run ahead of the peak of magnetic field. Furthermore, the electromagnetic field profiles show obvious non-sinusoidal, and the profile of electron temperature and density become highly peaked. Especially, compared with the previous work, due to the added influence of plasma density ripple, electromagnetic field, electron temperature and electron density present obvious oscillation along plasma length rather than stabilization amplitude, and their peak are out of sync.

scholarly journals Comparison of the measured and modelled electron densities and temperatures in the ionosphere and plasmasphere during 20-30 January, 1993

2000 ◽  
Vol 18 (10) ◽  
pp. 1257-1262 ◽  
Author(s):  
A. V. Pavlov ◽  
T. Abe ◽  
K.-I. Oyama
Keyword(s):  
Magnetic Field ◽  
Heat Flux ◽  
Electron Temperature ◽  
Field Line ◽  
Electron Density ◽  
Magnetic Field Line ◽  
New Approach ◽  
Additional Heating ◽  
Vibrational Levels ◽  
The Magnetic Field

Abstract. We present a comparison of the electron density and temperature behaviour in the ionosphere and plasmasphere measured by the Millstone Hill incoherent-scatter radar and the instruments on board of the EXOS-D satellite with numerical model calculations from a time-dependent mathematical model of the Earth's ionosphere and plasmasphere during the geomagnetically quiet and storm period on 20–30 January, 1993. We have evaluated the value of the additional heating rate that should be added to the normal photoelectron heating in the electron energy equation in the daytime plasmasphere region above 5000 km along the magnetic field line to explain the high electron temperature measured by the instruments on board of the EXOS-D satellite within the Millstone Hill magnetic field flux tube in the Northern Hemisphere. The additional heating brings the measured and modelled electron temperatures into agreement in the plasmasphere and into very large disagreement in the ionosphere if the classical electron heat flux along magnetic field line is used in the model. A new approach, based on a new effective electron thermal conductivity coefficient along the magnetic field line, is presented to model the electron temperature in the ionosphere and plasmasphere. This new approach leads to a heat flux which is less than that given by the classical Spitzer-Harm theory. The evaluated additional heating of electrons in the plasmasphere and the decrease of the thermal conductivity in the topside ionosphere and the greater part of the plasmasphere found for the first time here allow the model to accurately reproduce the electron temperatures observed by the instruments on board the EXOS-D satellite in the plasmasphere and the Millstone Hill incoherent-scatter radar in the ionosphere. The effects of the daytime additional plasmaspheric heating of electrons on the electron temperature and density are small at the F-region altitudes if the modified electron heat flux is used. The deviations from the Boltzmann distribution for the first five vibrational levels of N2(v) and O2(v) were calculated. The present study suggests that these deviations are not significant at the first vibrational levels of N2 and O2 and the second level of O2, and the calculated distributions of N2(v) and O2(v) are highly non-Boltzmann at vibrational levels v > 2. The resulting effect of N2(v > 0) and O2(v > 0) on NmF2 is the decrease of the calculated daytime NmF2 up to a factor of 1.5. The modelled electron temperature is very sensitive to the electron density, and this decrease in electron density results in the increase of the calculated daytime electron temperature up to about 580 K at the F2 peak altitude giving closer agreement between the measured and modelled electron temperatures. Both the daytime and night-time densities are not reproduced by the model without N2(v > 0) and O2(v > 0), and inclusion of vibrationally excited N2 and O2 brings the model and data into better agreement.Key words: Ionosphere (ionospheric disturbances; ionosphere-magnetosphere interactions; plasma temperature and density)  

Self-focusing of electromagnetic beams in the ionosphere considering Earth's magnetic field

2008 ◽  
Vol 74 (4) ◽  
pp. 473-491 ◽  
Author(s):  
MAHENDRA SINGH SODHA ◽  
ASHUTOSH SHARMA
Keyword(s):  
Magnetic Field ◽  
Electron Temperature ◽  
Cyclotron Frequency ◽  
Ohmic Heating ◽  
Electron Collision ◽  
Earth’S Magnetic Field ◽  
Self Focusing ◽  
Electron Collision Frequency ◽  
Earth's Magnetic Field ◽  
Electromagnetic Beams

AbstractIn this paper the focusing/defocusing of (i) a single Gaussian electromagnetic beam and (ii) a number of coaxial Gaussian electromagnetic beams, propagating in the extraordinary mode along the Earth's magnetic field in the ionosphere has been investigated in the paraxial approximation. The growth of a sinusoidal instability on account of self-focusing has also been studied. The nonlinearity in the dielectric function, responsible for the focusing/defocusing arises from the redistribution of the electron density, caused by the non-uniform distribution of the electron temperature. The electron temperature is determined by the energy balance for electrons/ions taking into account the Ohmic heating, the collisions and the radiation from the sun. The wave frequency has been assumed to be greater than the plasma frequency. The electron cyclotron frequency due to the Earth's magnetic field in the ionosphere is much larger than the electron collision frequency. This is specifically true for a height of 150 km. Numerical results have been presented for a range of parameters and a discussion of the same has been presented.

scholarly journals Ohmic heating and space charge effects in microwave-plasma interaction

2015 ◽  
Vol 33 (1) ◽  
pp. 87-95
Author(s):  
A. R. Niknam ◽  
T. Mirzaye ◽  
S. M. Khorashadizadeh
Keyword(s):  
Density Distribution ◽  
Space Charge ◽  
Electron Temperature ◽  
Electron Density ◽  
Electron Density Distribution ◽  
Microwave Plasma ◽  
Ohmic Heating ◽  
Microwave Frequency ◽  
Nonlinear Propagation ◽  
Microwave Beam

AbstractThe nonlinear propagation of high power microwave beam in unmagnetized collisional plasma is studied taking into account the ponderomotive force, space charge and Ohmic heating effects. It is shown that the amplitude of electron temperature distribution is enhanced by increasing the microwave energy flux, and decreases when the microwave frequency increases. It is also demonstrated that the steepening of the electron density distribution increases when the amplitude of electron temperature profiles reduces and vice versa. Furthermore, by increasing the initial electron density, the amplitude and number of peaks are decreased, but the electron density distribution, the space charge field and the dielectric permittivity profiles are increased.

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