Journal of Nuclear and Particle Physics

p-ISSN: 2167-6895    e-ISSN: 2167-6909

2019;  9(2): 43-50

doi:10.5923/j.jnpp.20190902.01

 

Nonlinear Underdense Plasma by High Intensity Laser Pulse

Fereydoon Ataei1, Negar Motakef-Kazemi2

1Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran

2Department of Medical Nanotechnology, Faculty of Advanced Sciences and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran

Correspondence to: Fereydoon Ataei, Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran.

Email:

Copyright © 2019 The Author(s). Published by Scientific & Academic Publishing.

This work is licensed under the Creative Commons Attribution International License (CC BY).
http://creativecommons.org/licenses/by/4.0/

Abstract

This research is studied the nonlinear interaction of underdense plasma by high intensity laser pulse regard to ohmic heating and effect of ponderomotive force. The nonlinear ponderomotive force was depended on particle oscillation in laser pulse that resulted to electron charge and electron density oscillation in plasma. The oscillation of heterogeneous electric field was imported to plasma electrons. Using the solutions of Maxwell's and hydrodynamic equations were investigated electron density, magnetic and electric field during plasma. Also Maxwell's equations were obtained through plasma and laser interaction by MATLAB programming language and fourth method of the Runge-Kutta. Based on results, increase of intensity of laser pulse was resulted to decrease of wavelength of magnetic and electric field. At the same time, oscillation of electron density was sharply peaked. Also temperature oscillation was increased and wavelength was decreased.

Keywords: Nonlinear, Underdense plasma, High intensity laser pulse

Cite this paper: Fereydoon Ataei, Negar Motakef-Kazemi, Nonlinear Underdense Plasma by High Intensity Laser Pulse, Journal of Nuclear and Particle Physics, Vol. 9 No. 2, 2019, pp. 43-50. doi: 10.5923/j.jnpp.20190902.01.

Article Outline

1. Introduction
2. Theoretical Model and Formulation
3. Result and Discussion
4. Conclusions

1. Introduction

The production of high energy electron was considered in laboratory scale with high-power lasers as very active field of research [1-4]. Recently, the application of plasma was separated as new common method [5-6]. The acceleration of electron has important applications in various domains in the interaction of a high-intensity laser beam with plasma [7]. In underdense plasma, the propagation of high intensity laser pulse as many important researches caused to the relativistic plasma wave [8-14]. In last decade, the nonlinear interaction of high intensity laser was the subject of many important researches in underdense plasma [15-16].
Recently, the nonlinear propagation of intense laser pulse was studied through underdense magnetized plasma. The Maxwell equations were used to achieve the nonlinear equation for the electric field in plasma. The plasma wave is generated by the ponderomotive force as a nonlinear force from regions of high intensity laser in an inhomogeneous oscillating electromagnetic. The equation of electron motion was taken into the average ponderomotive force per unit volume acting on the plasma electrons. Since the ion mass is much greater than the electron mass, the effect of the ponderomotive force was neglected on the ions [17]. Also, the ions motion and the nonlinear ohmic heating of the electrons were neglected in underdense collisional plasma by a laser pulse [18].
The effect of magnetic field was showed on waves in plasma [19-21]. The high magnetic field was played an essential role in particle transport, propagation of laser pulse, laser beam self-focusing, and penetration of laser radiation into over dense plasma. The plasma electron density was increased in the presence of the external magnetic field [17]. The effect of external magnetic field was characterized on electron density distribution and electromagnetic field in interaction of laser pulse with plasma [22-23]. The increase of laser intensity was caused the decrease of the wavelength of electric and magnetic field oscillations and the increase of the electron density, the oscillations amplitude of electron temperature, and the oscillations amplitude of the effective permittivity [18]. The collision of nonlinear electromagnetic plasma was created the nonlinear ohmic heating in plasma [24-25]. The plasma density and laser energy were affected on the stability of laser monoenergetic electron beam [7].
Theoretical studies of plasma wave propagation are importance for a vast range of problems. The Maxwell's equations were studied the collision effect in heating of underdense plasma by high intensity laser. The Maxwell’s and hydrodynamic equations were used for propagation of nonlinear wave in hot plasma [26]. The hydrodynamic equations were calculated electron density distribution and field profile in magnetized underdense plasma in theoretical section [27]. In the present work, the nonlinear interaction of high intensity laser pulse was studied with underdense plasma using Maxwell's and hydrodynamic equations. The changes were investigated for wavelength, intensity of laser pulse, density and temperature of electron, electric and magnetic field.

2. Theoretical Model and Formulation

The electron can be generated electric field in uniform filed of ion to protection neutral plasma. In this case, electrons were oscillated by specified frequency that called plasma frequency . When magnetic field is zero (B=0), product of Boltzmann constant (k) and temperature (T) is zero (KT=0), ions are resident, plasma dimension is unlimited and electrons are moved in x-direction, is as follows:
(1)
Which is electron density, e is electron charge, is electric constant, and is electron mass. The ponderomotive force is as follows:
(2)
In the above equations, the plasma was depended on electron density. The interaction of laser with plasma has two general forms that depended on function where and are laser pulse and sound speed respectively [28]. If where is length of laser pulse, the laser radiation effect can be ignored on ions in plasma and ions were considered resident. The gas particles were ionized by laser pulse (Fig. 1), and caused ponderomotive force.
Figure 1. Schematic view of the ionized particles of gas by laser pulse
Hence, the ponderomotive force is as follows:
(3)
Which C is light velocity in weak field of one-dimensional. This force was resulted to particle oscillation and move electron in laser field. The effect of ponderomotive force on electron in unit volume is as follows:
(4)
Which is electron plasma frequency, is frequency, is constant number and E is electric field. The relation of ponderomotive force for electron relative ion is as follows:
(5)
Which and are ponderomotive force for ion and electron respectively. Also is ion mass. Based on the result, the ponderomotive force had poor effect with larger electron mass. The electron density by considering potential and electron temperature is as follows:
(6)
When is electromagnetic wave frequency, electron density is and critical density is , and laser flux is in order of . According to the initial assumptions, parameter of focal point qatar (d) is 0.8 micrometer and laser pulse length 0.12 micrometer and radiation effects were ignored. The intensity of laser pulse was increased according to the formula where A is number vector potential and is base electron mass. Also, intensity of electromagnetic wave (P) is as follows:
(7)
The laser pulse was spread during Z direction in plasma. The nonlinear propagation was considered for high intensity laser pulse through collision of non-magnetic underdense plasma at the area Z> 0. Based on the assumptions, the ion is heavily and immovability in plasma. The geometry of coordinate system was shown for laser pulse in figure 2.
Figure 2. The geometry of coordinate system for laser pulse
In absence of any external current and charge, the Maxwell's equation is as follows:
(8)
(9)
(10)
Which is dielectric constant coefficient. The electric field in plasma is as follows:
(11)
The dispersion relation can be calculated as follows:
(12)
(13)
Which V is electron speed and the amount of and were assumed zero as the result electron speed is zero in y and z direction for wave propagation in z direction. So and .
(14)
Which and are electric filed in x direction and magnetic field in y direction respectively and is electron speed in x direction. For electric field in plasma, differential equation is as follows:
(15)
(16)
In plasma collision, the equation of electron motion is as follows:
(17)
That is electron pressure. The mean ponderomotive potential is as follows:
(18)
Which oscillation domain of electron (A) is as follows:
(19)
And the maximum of electron oscillation acceleration is as follows:
(20)
The ponderomotive force was affected on plasma electrons in unit of volume, so the overall relation is as follows:
(21)
That and is dielectric tensor that calculated for isotropic magnetic plasma. Using first order approximation, the motion equation is as follows:
(22)
(23)
Which is base magnetic field and is base electron density. When is as follows:
(24)
(25)
(26)
By division of the relation of 22 to electron temperature, the relation is as follows:
(27)
(28)
(29)
(30)
That the amount of is discarded, the relation is as follows:
(31)
By replacement relation of 31 to relation of 27, the relation is as follows:
(32)
(33)
(34)
The maximum of electron density is when magnetic and electric filed are zero . Nonlinear differential equation of electromagnetic field in plasma is as follows:
(35)
The calculation of plasma conductivity coefficient is as follows:
(36)
(37)
By derivative from time, the relation is as follows:
(38)
That and relation is as follows:
(39)
Which electron conductivity is . The electric constant is as follows:
(40)
That is cyclotron frequency and is refractive index of material. So , and and the change of is always positive.
(41)
The plasma is considered non-isothermal and collision is changed during laser radiation into plasma electron temperature. With regard to collisions, the result of electron vibrational motion is as follows:
(42)
The ohmic heating is produced in plasma therefore:
(43)
By considering power of heating convection and collisions between electrons and natural particles, the equation is as follows:
(44)
There are and where is velocity of electron temperature. If the free mean time of electron is small, the first letter of left side is ignored and electron temperature is finally obtained as follows:
(45)
The hydrodynamic equation and the observation of semi-neutral circumstance are as follows:
(46)
By replacing of electron temperature, plasma electron density, approximation study of semi-neutralize, and ion temperature of constant are as follows:
(47)
As a result, non-magnetic plasma of compact is excited by high intensity laser pulse for non-relativistic. The Maxwell's and hydrodynamic equation are as follows:
(48)
The Maxwell's equations are obtained for interaction of laser and plasma using MATLAB programming language and Runge-Kutta method of fourth in right numbers and later. The change of electric field is shown as function of plasma length (Z) for intensity of various laser pulses (Fig. 3 and Fig. 4). Based on the result, the longitudinal section of electric field is increased by increasing of laser pulse intensity in plasma.
Figure 3. Changes in electric field as the function of plasma length (Z) for intensity of various laser pulses
Figure 4. Changes in electric field as the function of plasma length (Z) for intensity of various laser pulses
The laser pulse intensity is as follows:
The critical density, base electron density and electron temperature are as follows:
The change of electron density ratio is shown as the function of plasma length (Z) for intensity of various laser pulses (Fig. 5). Based on the results, the oscillation of electron density is strongly increased by increasing of laser pulse intensity in plasma.
Figure 5. Changes in electron density ratio as the function of plasma length (Z) for intensity of various laser pulses
The laser pulse intensity is as follows:
The critical density, base electron density and electron temperature are as follows:
The change of electric field is shown as function of plasma length (Z) for various magnetic fields (Fig. 6). Based on the result, the wavelength oscillation of electric field is had little change by increasing of magnetic field in plasma.
Figure 6. Changes in electric field as the function of plasma length (Z) for various magnetic fields
The laser pulse intensity is as follows:
The magnetic field is as follows:
The critical density, base electron density and electron temperature are as follows:
The change of magnetic field is shown as the function of plasma length (Z) for various magnetic fields (Fig. 7). Based on the result, the longitudinal section of magnetic field and the wavelength oscillation of magnetic field are increased a little in constant laser pulse intensity.
Figure 7. Changes in magnetic field as the function of plasma length (Z) for various magnetic fields
The intensity of laser pulse is as follows:
The magnetic field is as follows:
The critical density, base electron density and electron temperature are as follows:
The change of electron density ratio is shown as the function of plasma length (Z) for various magnetic fields (Fig. 8) and the oscillation of electron density is increased.
Figure 8. Changes in electron density ratio as the function of plasma length (Z) for various magnetic fields
The laser pulse intensity is as follows:
The magnetic field is as follows:
The critical density, base electron density and electron temperature are as follows:
The change of electric field is shown as the function of plasma length (Z) for various electron temperatures (Fig. 9) and the wavelength oscillation of electron temperature is decreased.
Figure 9. Changes in electric field as the function of plasma length (Z) for electron various temperatures
The laser pulse intensity is as follows:
The electron temperature is as follows:
The critical density and base electron density are as follows:
The change of electric field is shown as the function of plasma length (Z) (Fig. 10) and the oscillation of electric field is increased.
Figure 10. Changes in electric field as the function of plasma length (Z).
The magnetic field is as follows:
The change of magnetic field is shown as the function of plasma length (Z) for electron various temperatures (Fig. 11) and the longitudinal section of magnetic field and the ratio of effective magnetic field are increased.
Figure 11. Changes in magnetic field as the function of plasma length (Z) for electron various temperatures
The laser pulse intensity is as follows:
The electron temperature is as follows:
The critical density and base electron density are as follows:
The change of magnetic field is shown as the function of plasma length (Z) (Fig. 12) and the oscillation of magnetic field is increased.
Figure 12. Changes in magnetic field as the function of plasma length (Z).
The magnetic field is as follows:
The change of electron density ratio is shown as the function of plasma length (Z) for electron various temperatures (Fig. 13). Based on the result, the electron density is decreased since electric constant is increased.
Figure 13. Changes in electron density ratio as the function of plasma length (Z) for electron various temperatures
The laser pulse intensity is as follows:
The electron temperature is as follows:
The critical density and base electron density are as follows:

3. Result and Discussion

The theoretical pattern was studied for interaction of underdense plasma. Based on the results, interaction of high intensity laser pulse is strongly nonlinear equation and there is no analytical solution. The fourth method of Runge-Kutta and MATLAB programming language were used to solve the equation in the numerical form. The interaction of high intensity laser pulse was decreased oscillation wavelength. The increase of laser pulse intensity was resulted to the increase of oscillation, the decrease of electron density, and the increase of electric constant. The oscillation wavelength of plasma was reduced by the decrease of electron density. And the electron wavelength was decreased by the increase of electric constant. The longitudinal section of field was shown nonlinear and non-sinusoidal because of the current increase of laser energy. The laser pulse intensity and electron density were increased as the function of plasma length along the z axis in images.
The laser pulse duration is greater than plasma thickness therefore the increase of dielectric constant is caused the decrease of electron density in plasma. This physical subject is increased size of magnetic and electric field oscillations. Also the changes of laser pulse intensity are caused the increase of electron density oscillations, temperature and magnetic influence. Based on the physical phenomenon, the created ohmic changes are caused the decrease of the electron wavelength that this subject is increased length section of magnetic electric and field for non-sinusoidal and nonlinear. In this article , and radiation effect of laser pulse is ignored on ions via consideration of created ohmic heating by the interaction of laser and plasma. The Maxwell's, hydrodynamics, energy equations are indicated that oscillation wavelength of electric field, wavelength of electron temperature oscillation domain and oscillation domain of magnetic influence is reduced.

4. Conclusions

In this study, high intensity laser interaction with underdense plasma was investigated by Maxwell's and hydrodynamic equations, ponderomotive force, electron ohmic heating, the longitudinal section in the electric and magnetic field, oscillation and density of electron. The oscillation wavelength of the longitudinal section was decreased and the oscillation was increased. The increase of intensity of laser pulse was strongly peaked the effective magnetic permeability, temperature and electron density oscillation because of the nonlinear ohmic heating effect. At same time, the wavelength was simultaneously decreased. In length section of electric and magnetic field, the oscillation wavelength was reduced but oscillation expansion was increased. The increase of intensity of laser pulse was dramatically increased density, temperature and effective magnetic permeability for electron in plasma. Also they were reduced because of the ohmic heating effect of the field.

References

[1]  J. Faure, C. Rechatin, A. Norlin, A. Lifschitz, Y. Glinec, and V. Malka, “Controlled injection and acceleration of electrons in plasma wake fields by colliding laser pulses,” Nature., vol. 444, pp. 737-739, Nov. 2006.
[2]  S. Fritzler, E. Lefebvre, V. Malka, F. Burgy, A.E. Dangor, K. Krushelnick, S.P.D. Mangles, Z. Najmudin, J.P. Rousseau, and B. Walton, “Emittance measurements of a laser-wake field-accelerated electron beam,” Phys Rev Lett., Vol. 92, pp. 165006, Nov. 2004.
[3]  S. Saha Ray, “New double periodic exact solutions of the coupled Schrödinger–Boussinesq equations describing physical processes in laser and plasma physics,” Chinese Journal of Physics., vol. 55, pp. 2039–2047, Nov. 2017.
[4]  S.P.D. Mangles, C.D. Murphy, Z. Najmudin, A.G.R. Thomas, J.L. Collier, A.E. Dangor, E.J. Divall, P.S. Foster, J G. Gallacher, C.J. Hooker, D.A. Jaroszynski, A.J. Langley, W.B. Mori, P.A. Norreys, F.S. Tsung, R. Viskup, B.R. Walton, and K. Krushelnick, “Monoenergetic beams of relativistic electrons from intense laser–plasma interactions,” Nature., vol. 431, pp. 535-538, Nov. 2004.
[5]  E.A. Benkhelifa, and M. Djebli, “Plasma expansion dynamics in the presence of a relativistic electron beam,” Laser and Particle Beams., vol. 33, pp. 273-277, Nov. 2015.
[6]  M.K. Guttal, and A. Sharief, “Evaluation of thermal properties and life time of multilayered thermal barrier coating obtained from suspension plasma spray,” Asian Journal of Science and Technology., vol. 8(1), pp. 4078-4083, Nov. 2017.
[7]  S.P.D. Mangles, A.G.R. Thomas, O. Lundh, F. Lindau, M.C. Kaluza, A. Persson, C.G. Wahlstrom, K. Krushelnick, and Z. Najmudin, “On the stability of laser wake field electron accelerators in the monoenergetic regime,” Phy Plasmas., vol. 14(5), pp. 056702, Nov. 2007.
[8]  S. Abedi, D. Dorranian, M. Etehadi Abari, and B. Shokri, “Relativistic effects in the interaction of high intensity ultra-short laser pulse with collisional underdense plasma,” Phys Plasmas., vol. 18, pp. 093108, Nov. 2011.
[9]  Z.Y. Chen, S. Chen, J.K. Dan, J.F. Li, and Q.X. Peng, “Analytical model for electromagnetic radiation from a wake field excited by intense short laser pulses in an unmagnetized plasma,” Phys Scr., vol. 84(4), pp. 045506, Nov. 2011.
[10]  M.A. Bari, M. Chen, W.M. Wang, Y.T. Li, M.Q. He, Z.M. Sheng, and J. Zhang, “Ion acceleration in the interaction of an intense laser pulse with structured plasma,” Phys Scr., vol. 77(6), pp. 065502, Nov. 2008.
[11]  A.R. Niknam, M.R. Jafari Milani, B. Bokaei, and M. Hashemzadeh, “Weakly relativistic and ponderomotive effects in interaction of intense laser beam with inhomogeneous collisionless and collisional plasmas,” Wave Random Complex., vol. 24(1), pp. 1-18, Nov. 2014.
[12]  K. Hajizadeh, M. Etehadi Abari, Y. Ahmadizadeh, and B. Shokri, “Collisions effect in the heating of underdense plasma by a high-intensity short laser pulse,” Phys Scr., vol. 85(5), pp. 055501, Nov. 2012.
[13]  X. Xia, Z. Quin, B. Xu, and Z. Cai, “Dielectric constant and laser beam propagation in an underdense collisional plasma: effects of electron temperature,” Phys Scr., vol. 84, pp. 015508, Nov. 2011.
[14]  L.M. Gorbunov, P. Mora, and R.R. Ramazashvili, “Laser surface wake field in a plasma column,” Phys Plasmas., vol. 10, pp. 4563, Nov. 2003.
[15]  A.R. Niknam, M. Hashemzadeh, and B. Shokri, “Weakly relativistic and ponderomotive effects on the density steepening in the interaction of an intense laser pulse with an underdense plasma,” Phys Plasmas., vol. 16(3), pp. 033105, Nov. 2009.
[16]  M. Amina, S.A. Ema, A.A. Mamun, “Higher order nonlinear dust-acoustic waves in a dusty plasma with dust of opposite polarity,” Chinese Journal of Physics., vol. 55, pp. 619–629, Nov. 2017.
[17]  M. Mahmoodi-Darian, M. Ettehadi-Abari, and M. Sedaghat, “The effect of external magnetic field on the density distributions and electromagnetic fields in the interaction of high-intensity short laser pulse with collisionless underdense plasma,” J Theor Appl Phys., vol. 10, pp. 33-39, Nov. 2016.
[18]  M. Etehadi Abari, and B. Shokri, “Nonlinear heating of underdense collisional plasma by a laser pulse,” Phys Plasmas., vol. 18, pp. 053111, Nov. 2011.
[19]  I.V. Timofeev, “Two-dimensional simulations of nonlinear beam-plasma interaction in isotropic and magnetized plasmas,” Phys Plasmas., vol. 19, pp. 042108, Nov. 2012.
[20]  A.N. Erokhin, N.N. Zolnikova, and N.S. Erokhin, “Analysis of the dependence of surfatron acceleration of electrons by an electromagnetic wave in space plasma on the particle momentum along the wave front,” Plasma Physics Reports., vol. 42(1), pp. 32-37, Nov. 2016.
[21]  G.V. Ostrovskaya, V.S. Markov, and A.G. Frank, “Influence of the initial parameters of the magnetic field and plasma on the spatial structure of the electric current and electron density in current sheets formed in helium,” Plasma Physics Reports., vol. 42(1), pp. 1-13, Nov. 2016.
[22]  M.S. Sodha, A. Sharma, and S.K. Agarwal, “Focusing of electromagnetic beams in collisional plasmas, with finite thermal conduction,” Phys Plasmas., vol. 13, pp. 083105, Nov. 2006.
[23]  M. Manouchehrizadeh, and D. Dorranian, “Effect of obliqueness of external magnetic field on the characteristics of magnetized plasma wake field,” J Theor Appl Phys., vol. 7, pp. 43-48, Nov. 2013.
[24]  V.B. Pathak, and V.K. Tripathi, “Propagation of terahertz electromagnetic wave in plasma with inhomogeneous collision frequency,” Phys Plasmas., vol. 14(2), pp. 022105, Nov. 2007.
[25]  V.N. Tokarev, E.A. Cheshev, V.V. Bezotosnyi, V. Yu Khomich, S.I. Mikolutskiy, and N.V. Vasilyeva, “Optimization of plasma effect in laser drilling of high aspect ratio microvias,” Laser Phys., vol. 25(5), pp. 056003, Nov. 2015.
[26]  V.G. Dorofeenko, V.B. Krasovitskiy, and V.A. Turikovc, “Parametric decay of an extraordinary electromagnetic wave in relativistic plasma,” Asian Journal of Science and Technology., vol. 41(3), pp. 286–293, Nov. 2015.
[27]  R. Sadighi-Bonabi, and M. Etehadi-Abari, “The electron density distribution and field profile in underdense magnetized plasma,” Phy Plasmas., vol. 17(3), pp. 032101, Nov. 2010.
[28]  X. Nitikant and A. K. Shamra, “Resonant second-harmonic generation of a short pulse laser in a plasma channel,” J. Phys. D., vol. 37, pp. 2395-2398, Nov. 2004.