International Journal of Theoretical and Mathematical Physics
p-ISSN: 2167-6844 e-ISSN: 2167-6852
2016; 6(4): 117-122
doi:10.5923/j.ijtmp.20160604.02

Fereydoon Ataei1, Davoud Dorranian2, Negar Motakef-Kazemi3
1Department of Computer, Shahryar Branch, Islamic Azad University, Tehran, Iran
2Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran
3Department of Nanochemistry, Faculty of Pharmaceutical Chemistry, Pharmaceutical Sciences Branch, Islamic Azad University, Tehran, Iran (IAUPS)
Correspondence to: Fereydoon Ataei, Department of Computer, Shahryar Branch, Islamic Azad University, Tehran, Iran.
| Email: | ![]() |
Copyright © 2016 Scientific & Academic Publishing. All Rights Reserved.
This work is licensed under the Creative Commons Attribution International License (CC BY).
http://creativecommons.org/licenses/by/4.0/

This research is theoretically studied the nonlinear interaction of high-intensity laser pulse by underdense plasma. Also ohm heat and driving force effects of ponderomotive energy is considered. The driving force can be obtained by electron density, temperature and dielectric magnetic influence distribution in a nonrelativistic system through indirectly plasma. The ponderomotive energy is nonlinearly and the ponderomotive force of laser pulse is included compressed plasma electrons from the regions of high-intensity laser. The plasma length parameter and fixed solution in Maxwell and hydrodynamic equations can be obtained by the electron density, temperature distribution, effective magnetic influence change, electric and magnetic field. Also the fourth method of the Runge-Kutta programming language is used in this study. It has been shown that intensity increase of laser pulse is caused decrease of electron density and increase of dielectric constant. Since electron decrease, electric and magnetic field oscillation wavelength are resulted increase of dielectric constant. Increasing of laser pulse intensity, electric and magnetic field are nonsinusoidal and nonlinear in plasma. The oscillation of the electron density is sharply peaked. Also the effect of laser intensity increase is caused the spread increase and wavelength decrease in fluctuation of electron.
Keywords: Nonlinear interaction, Underdense plasma, Laser pulse
Cite this paper: Fereydoon Ataei, Davoud Dorranian, Negar Motakef-Kazemi, Nonlinear Interaction of Underdense Plasma by a High-intensity Pulse, International Journal of Theoretical and Mathematical Physics, Vol. 6 No. 4, 2016, pp. 117-122. doi: 10.5923/j.ijtmp.20160604.02.
function where
and
are the size of laser and speed of sound respectively if
and
is the length of laser pulse. In this case, the radiation effect of laser pulse can be ignored on the ions in the plasma as the ions are considered resident. While if
the ions can be fluctuated with ion plasma frequency
This research has been showed the interaction of high-intensity laser pulse with underdense plasma of magnetic collision in the presence of external charge. In the case
is used, and the effect of laser pulse radiation is ignored on ions in plasma. If the intensity of electromagnetic wave was carried the lower energy for the relativistic self–focusing that considered:![]() | (1) |
and
are electromagnetic wave frequency and electron plasma frequency respectively. The critical density, electron density, and flow intensity are considered 
respectively. Based on
where d is the diameter of focal point and lower than 6 micrometer since the laser wavelength could be applied within 8 µm. The radiation effects are ignored according to the initial assumptions. The laser intensity is increased according to the formula
where (e) the electron charge, (A) the number vector potential, (me) the electron mass and (c) the light speed. The range of natural vector potential can have ignored from
Based on the hypothesis, the electron density is higher than critical density therefore laser pulse duration is longer than plasma thickness and electron density is lower than original density. The length of space pulse would be longer than 30 µm that involved plasma density and standing wave, which could be considered through a generated pulse. So the Maxwell's and hydrodynamic equations can be calculated electric and magnetic field, temperature and density distribution for electron in the presence of a magnetic field. The fluctuation wavelength of magnetic and electric field was decreased by the increasing of laser intensity. At the same time, the dielectric constant is increased that caused the significant increase of electron density. Thus the effective magnetic diffusion and electron temperature fluctuation are increased. Also the wavelength of fluctuation, electron temperature and effective magnetic influence fluctuation are reduced. The temperature distribution could be obtained by
in plasma where Ti and Te are ion temperature and electron temperature respectively. The nonlinear propagation is considered for high-intensity laser pulse with collision of underdense plasma in a magnetic field for the area Z> 0. The laser pulse was spread during Z in plasma thus based on the assumptions in above the ion is immovability in plasma because it is heavily. The Maxwell's and hydrodynamic equations will have: 
![]() | (2) |
![]() | (3) |
![]() | (4) |
![]() | (5) |
![]() | (6) |
![]() | (7) |
![]() | (8) |
and
are laser frequency, dielectric constant coefficient, electric field of plasma, speed of light respectively. To solve of equation 8, dielectric constant of the plasma is equal: ![]() | (9) |
is
that is plasma electron frequency. The
and
are electron density, electron charge, electron mass, electron collision frequency, electromagnetic wave frequency respectively. The plasma electric constant is used to solve equation through MATLAB programming language and fourth method of Runge-Kutta as follows: 1=0.58del =le-3;kesi =1;function dy = nonlinear(t, y)dy =zeros(2,1)l =0.58;del =le-3;kesi =1;dy(1)=y(2);dy(2)=(1.*exp(-y (1).^2/3*del.*kesi)+0.004* y(1) /kesi.*(1+(y(1).^2)/3*del.*kesi))-1).*y(1);[t,y]=ode 45 (@nonlinear, [0 30], [0 0.8]);Figure ('name ', E field);Plot (t, y (:1);The
is represented dielectric constant. In electromagnetic waves, the propagation of laser pulse is same something that makes the difference in propagation circumstances and
plays a very important role in propagation. The dielectric constant in plasma interaction is as follows:![]() | (10) |
where e, ne and me are electron charge, electron charge density and electron mass respectively. The plasma does not adapt to the temperature of interaction thus the electron temperature can be changed. The change of electron temperature will be resulted to collisions during the interaction. The electron oscillation velocity and electron vibrational motion are obtained in laser pulse through equation as follows: ![]() | (11) |
![]() | (12) |
![]() | (13) |
and
where vth is the velocity of electron temperature. If the free mean time of electron is small, the first letter of left side is ignored and the electron temperature is finally obtained as follows:![]() | (14) |
![]() | (15) |
![]() | (16) |
![]() | (17) |
The term of plasma length is obtained through a longitudinal section of electromagnetic field, electron density, temperature distribution and effective magnetic permeability. The equation is resolved as follows: ![]() | (18) |
![]() | (19) |
![]() | (20) |
![]() | (21) |
![]() | (22) |
![]() | (23) |
![]() | (24) |
. The longitudinal section of field is nonlinear and nonsinusoidal through the current increase in laser energy. Figure 1 and 2 are shown the effect of laser intensity on electric field (E) and magnetic field (B) as a function of plasma length (Z). Figure 3 and 4 are shown the effect of laser intensity on electron density
and electron temperature
as a function of plasma length. At the same time, the increase of laser intensity is caused the decrease of wavelength. The high-intensity laser is observed that the start point of sinusoidal shape change in electron density
is stronger than the start point of field. Also, the start point of sinusoidal shape is observed the equal for the distribution of normalized electron temperature. Figure 5 is shown the effect of laser intensity on effective permeability
as a function of plasma length. The increase of laser intensity is resulted to the electron temperature and the increase of magnetic permeability that the electron temperature is more than the ion temperature at this time and the wavelength is decreased for these oscillations. Furthermore, the increase of laser intensity can be deviated the effective magnetic oscillation from the sinusoidal shape [30]. There is
as the normalized electric field where
is sound velocity,
and 
In all figures, the normalized frequency
is fixed by which
is close to the main density, moreover the wavelength of normalized plasma is made as the
function.![]() | Figure 1. Changes in normalized electric field (E) as a function of plasma length (Z) for the various laser intensities dotted line bold dotted line - line) |
![]() | Figure 2. Changes in normalized magnetic field (B) as a function of plasma length (Z) for the various laser intensities dotted line - bold dotted line - line) |
![]() | Figure 3. Changes in normalized electron density as a function of plasma length (Z) for the various laser intensities dotted line - bold dotted line - line) |
![]() | Figure 4. Changes in normalized electron temperature as a function of plasma length (Z) for the various laser intensities dotted line - bold dotted line - line) |
![]() | Figure 5. Changes in effective magnetic permeability as a function of plasma length (Z) for the various laser intensities dotted line - bold dotted line - line) |
when
as the sound speed,
as natural collision frequency in plasma, and
that there is
due to
is given.