Filamentation instability in a collisional magnetoplasma with thermal conduction

2009 ◽  
Vol 75 (4) ◽  
pp. 563-573 ◽  
Author(s):  
MAHENDRA SINGH SODHA ◽  
MOHAMMAD FAISAL
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Static Magnetic Field ◽  
Power Loss ◽  
Thermal Conduction ◽  
Ohmic Heating ◽  
Wave Number ◽  
Main Beam ◽  
Rate Of Growth ◽  
Filamentation Instability

AbstractThis paper presents an analysis of the spatial growth of a transverse instability, corresponding to the propagation of an electromagnetic beam, with uniform irradiance along the wavefront in a collisional plasma, along the direction of a static magnetic field; expressions have been derived for the rate of growth, the maximum value of the rate of growth and the corresponding value of the wave number of the instability. The instability arises on account of the ejection of electrons from regions where the irradiance of the perturbation is large. The energy balance of the electrons taking into account ohmic heating and the power loss of electrons on account of (i) collisions with ions and neutral species and (ii) thermal conduction has been taken into account for the evaluation of the perturbation in electron temperature, which determines the subsequent growth of the instability. Further, the relationship between the electron density and temperature, as obtained from the kinetic theory, has been used. The filamentation instability becomes enhanced with the increase of the static magnetic field for the extraordinary mode while the reverse is true for the ordinary mode. Dependence of growth rate on irradiance of the main beam, magnetic field and a parameter proportional to the ratio of power loss of electrons by conduction to that by collisions has been numerically studied and illustrated by figures. The dependence of the maximum growth rate and the corresponding optimum value of the wave number of the instability on the irradiance of the main beam has also been studied. The paper concludes with a discussion of the numerical results, so obtained.

Magnetic stabilization of transverse plasma instabilitiest

1971 ◽  
Vol 5 (3) ◽  
pp. 467-474 ◽  
Author(s):  
B. Buti ◽  
G. S. Lakhina
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Cyclotron Frequency ◽  
Plasma Frequency ◽  
Electron Plasma ◽  
Wave Number ◽  
Uniform External Magnetic Field ◽  
Magnetic Stabilization ◽  
Streaming Velocity ◽  
The Magnetic Field

Waves, propagating transverse to the direction of the streaming of a plasma in the presence of a uniform external magnetic field, are unstable if the streaming exceeds a certain minimum value. The magnetic field reduces the growth rate of this instability, and also increases the value of the minimum streaming velocity, above which the system is unstable. The thermal motions in the plasma, however, tend to stabilize the system if the magnetic field is weak (i.e. , Ω being the electron cyclotron frequency, k the characteristic wave-number, and Vt the thermal velocity); but, in case of strong magnetic field (i.e. ), they increase the growth rate, provided (ωp being the electron plasma frequency).

A temperature-anisotropy instability for electromagnetic waves propagating across a static magnetic field

1970 ◽  
Vol 4 (1) ◽  
pp. 13-20 ◽  
Author(s):  
R. W. Landau ◽  
S. Cuperman
Keyword(s):  
Magnetic Field ◽  
Static Magnetic Field ◽  
Electromagnetic Waves ◽  
Maximal Rate ◽  
Temperature Anisotropy ◽  
Thermal Anisotropy ◽  
Rate Of Growth ◽  
Interplanetary Plasma ◽  
Set Up ◽  
Fire Hose

The instability of electromagnetic waves propagating across a static magnetic field in the presence of a thermal anisotropy (T∥ > T⊥) is investigated. The marginal stabifity criterion as well as the rate of growth of the instability are derived. When compared with the fire hose instability (of electromagnetic waves propagating along the static magnetic field) it is found that higher electron pressures are required for this new instability to be set up; however, the maximal rate of growth is much larger than in the fire hose case.The interplanetary plasma is stable to this thermal anisotropy instability; high β plasma devices may be unstable.The T⊥ = 0 case treated by Hamasaki is recovered.

Stimulated backscattering of electromagnetic ordinary waves from extraordinary waves below the upper hybrid frequency

1979 ◽  
Vol 21 (1) ◽  
pp. 97-106 ◽  
Author(s):  
Behrooz Maraghechi ◽  
Joseph E. Willett
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Static Magnetic Field ◽  
Inhomogeneous Plasma ◽  
Extraordinary Wave ◽  
Threshold Power ◽  
Ordinary Wave ◽  
Homogeneous Plasma ◽  
Parametric Decay ◽  
Hybrid Frequency

The parametric decay of an intense electromagnetic ordinary wave, propagating perpendicular to a uniform static magnetic field, into an extraordinary wave and a backscattered ordinary wave is investigated. Formulae are derived for the growth rate and threshold power associated with the instability in a homogeneous plasma. An analysis of the spatial amplification of the decay waves in an inhomogeneous plasma is presented. The effects of the uniform static magnetic field on the backscattering in both homogeneous and inhomogeneous plasmas are studied numerically.

scholarly journals Effect of dc-magnetic field on the growth rate of Raman backscattering of X-mode laser in magnetized collisional plasma

2015 ◽  
Vol 34 (1) ◽  
pp. 80-85 ◽  
Author(s):  
Alireza Paknezhad
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Ponderomotive Force ◽  
Fluid Model ◽  
Transverse Magnetic ◽  
Wave Number ◽  
Hybrid Wave ◽  
Incident Laser ◽  
Mode Laser ◽  
Relativistic Regime

AbstractStimulated Raman backward scattering of an X-mode laser beam propagating in a homogenous plasma is studied in the presence of a transverse magnetic field. As the laser propagates in its X-mode in plasma, it decays into an upper hybrid wave and a down-shifted sideband wave. Beating the incident laser with the sideband exerts a nonlinear ponderomotive force acting on plasma electrons driving the excited upper hybrid wave. The incident wave then parametrically couples with the upper hybrid wave to drive the sideband. Using the fluid model and nonlinear current density, the nonlinear ponderomotive force is obtained to find the dispersion relation of the scattered sideband wave and the growth rate of the instability in the weakly relativistic regime. It is shown that the growth rate decreases and the cut-off points in the normalized wave number of the upper-hybrid wave become smaller by increasing the static magnetic field.

scholarly journals Improvement of SiC Crystal Growth Rate and Uniformity via Top-Seeded Solution Growth under External Static Magnetic Field: A Numerical Investigation

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 651
Author(s):  
Minh-Tan Ha ◽  
Le Van Lich ◽  
Yun-Ji Shin ◽  
Si-Young Bae ◽  
Myung-Hyun Lee ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Fluid Flow ◽  
Crystal Growth ◽  
Static Magnetic Field ◽  
Crystal Surface ◽  
Solution Growth ◽  
Helmholtz Coils ◽  
External Static Magnetic Field ◽  
Top Seeded Solution Growth

Silicon carbide (SiC) is an ideal material for high-power and high-performance electronic applications. Top-seeded solution growth (TSSG) is considered as a potential method for bulk growth of high-quality SiC single crystals from the liquid phase source material. The crystal growth performance, such as growth rate and uniformity, is driven by the fluid flow and constitutional flux in the solution. In this study, we numerically investigate the contribution of the external static magnetic field generated by Helmholtz coils to the fluid flow in the silicon melt. Depending on the setup of the Helmholtz coils, four static magnetic field distributions are available, namely, uniform vertical upward/downward and vertical/horizontal cusp. Based on the calculated carbon flux coming to the crystal surface, the vertical downward magnetic field proved its ability to enhance the growth rate as well as the uniformity of the grown crystal.

Filamentation instability of a laser beam in an inhomogeneous plasma in an arbitrarily oriented external magnetic field

2013 ◽  
Vol 79 (5) ◽  
pp. 921-926
Author(s):  
A. HASANBEIGI ◽  
A. MOUSAVI ◽  
H. MEHDIAN
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
External Magnetic Field ◽  
Laser Beam ◽  
Short Pulse ◽  
Inhomogeneous Plasma ◽  
Plasma Inhomogeneity ◽  
Short Pulse Laser ◽  
Filamentation Instability ◽  
Applied External Magnetic Field

AbstractThe interaction of a short pulse laser beam with an inhomogeneous plasma has been studied in the presence of an obliquely applied external magnetic field. The dispersion relation and the analytical growth rate have been obtained solving the nonlinear wave equation. It is found that the growth rate and the cut-off wavenumber are strongly influenced by the direction and magnitude of the applied magnetic field. Moreover, the growth rate has been modified by plasma inhomogeneity.

Longitudinal waves in a perpendicular collisionless plasma shock: I. Cold ions

1970 ◽  
Vol 4 (4) ◽  
pp. 739-751 ◽  
Author(s):  
S. Peter Gary ◽  
J. J. Sanderson
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Collisionless Plasma ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Wave Number ◽  
Zero Magnetic Field ◽  
Linear Dispersion ◽  
Electrostatic Waves ◽  
Cold Ions

This paper considers electrostatic waves in a Vlasov plasma of unmagnetized ions and magnetized, Maxwellian electrons. The linear dispersion relation is derived for waves in a perpendicular shock such that the most important sources of instability are the E × B and ∇B electron drifts. For the case of cold ions, propagation perpendicular to the applied magnetic field, and the E × B drift alone, a numerical analysis of frequency vs. wave-number is presented. The effects of the ∇B drift are also considered, and it is shown that the maximum growth rate can be larger than the maximum growth rate for the zero magnetic field ion acoustic instabifity under comparable conditions.

Interaction of a highly relativistic helical electron stream and a cold magnetoactive plasma

1969 ◽  
Vol 47 (2) ◽  
pp. 161-177 ◽  
Author(s):  
P. C. W. Fung
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Static Magnetic Field ◽  
Pitch Angle ◽  
Magnetoactive Plasma ◽  
Electron Stream ◽  
Amplification Rate ◽  
Wave Normal ◽  
Normal Angle ◽  
Temporal Growth Rate

When a nearly monoenergetic relativistic electron stream is gyrating along a cold magnetoactive plasma with general pitch angle Φ (defined as the angle between the static magnetic field of the plasma and the momentum of a particle in the stream), the system is shown to be radiatively unstable with respect to synchrotron radiation. Using the classical kinetic approach, the temporal growth rate is derived for general wave-normal angle θ (defined as the angle between the static magnetic field and wave vector k). Deducing the spatial amplification rate from the temporal growth rate, the result obtained here is shown to be identical with that obtained from the Einstein-coefficients approach deduced by Fung earlier.

Intermediate Phase Growth of Mg-Al Diffusion Couple under a Strong Static Magnetic Field

2007 ◽  
Vol 546-549 ◽  
pp. 491-494 ◽  
Author(s):  
Jie Dong ◽  
Z.F. Li ◽  
Xiao Qin Zeng ◽  
Wen Jiang Ding
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Diffusion Couple ◽  
Static Magnetic Field ◽  
Intermediate Phase ◽  
Thickness Measurement ◽  
Magnetic Field Direction ◽  
Diffusion Couples ◽  
Phase Growth ◽  
Intermediate Phases

Intermediate phase growth in Mg-Al diffusion couples were studied with different intensity of a strong static magnetic field from 0 to 10 Tesla. Thickness measurement of the intermediate phases (Mg17Al12 and Al3Mg2) shows that with the increasing of magnetic field intensity, the growth rate of both intermediate phases is retarded. The decrease of the phase growth rate is ascribed to the suppressed Al, Mg atom interdiffusion in the diffusion couple under the static magnetic field. It is also found that the orientation relationship between couple interface and magnetic field direction has no influence on the growth of intermediate phases.

scholarly journals Brillouin-shifted third-harmonic backscattering of laser in a magnetized plasma

2015 ◽  
Vol 33 (1) ◽  
pp. 97-102 ◽  
Author(s):  
Alireza Paknezhad
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Static Magnetic Field ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Magnetized Plasma ◽  
Third Harmonic ◽  
Coupled Equations ◽  
Relativistic Mass ◽  
Weakly Coupled

AbstractThird-harmonic Brillouin backscattering (3HBBS) instability is investigated in the interaction of a picosecond extraordinary laser pulse with a homogeneous transversely magnetized underdense plasma. Nonlinear coupled equations that describe the instability are derived and solved for a weakly coupled regime to find the maximum growth rate. The nonlinearity arises through the combined effect of relativistic mass increase, static magnetic field, and ponderomotive acceleration of plasma electrons. The growth rate is found to decrease as the static magnetic field increases. It also increases by increasing both plasma density and laser intensity. It is also established that the growth rate of 3HBBS instability in a magnetized plasma is lower than that of fundamental Brillouin backscattering instability.

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