scholarly journals Magnetosonic wave-aided terahertz emission by nonlinear mixing of lasers in plasmas

2019 ◽  
Vol 37 (4) ◽  
pp. 341-345
Author(s):  
Narender Kumar ◽  
Ram Kishor Singh ◽  
R. Uma ◽  
R. P. Sharma
Keyword(s):  
Ponderomotive Force ◽  
Beat Frequency ◽  
Density Perturbation ◽  
Magnetized Plasma ◽  
Magnetosonic Wave ◽  
Phase Matching ◽  
Background Magnetic Field ◽  
Nonlinear Mixing ◽  
Electron Density Perturbation ◽  
Thz Power

AbstractA scheme of phase-matched terahertz generation by beating two co-propagating lasers in magnetized plasma, in the presence of a magnetosonic wave (MSW), is developed. The beat frequency ponderomotive force of the lasers imparts an oscillatory drift to electrons. The electron drift velocity couples with the electron density perturbation associated with the MSW to produce an irrotational nonlinear current $\left(\nabla \times {\vec J}\;{}^{\rm NL}\ne 0\right)$. The beat current density resonantly excites a THz (Terahertz) radiation when the phase-matching conditions are satisfied. The MSW mediates the phase matching. At 9.6 and 10.6 µm wavelengths, and background magnetic field of 285 kG, one may achieve normalized THz wave amplitude of the order of 10−3 and one obtains the ratio of THz power to pump power of the order of 10−6.

scholarly journals Strong terahertz field generation by relativistic self-focusing of hollow Gaussian laser beam in magnetoplasma

2015 ◽  
Vol 34 (1) ◽  
pp. 86-93 ◽  
Author(s):  
Saba Hussain ◽  
Ram Kishor Singh ◽  
R. P. Sharma
Keyword(s):  
Beat Frequency ◽  
Thz Radiation ◽  
Phase Matching ◽  
Electron Mass ◽  
Gaussian Laser Beam ◽  
Electron Plasma Wave ◽  
Self Focusing ◽  
Highly Sensitive ◽  
Background Magnetic Field ◽  
Density Plasma

AbstractThe present paper proposes a model for the generation of Terahertz (THz) radiation by self-focused hollow Gaussian beam (HGB) in collisionless magnetized rippled density plasma. At high intensities, the change in the electron mass occurs due to relativistic effect, introducing a nonlinearity in the plasma leading to the self-focusing of the HGB. The nonlinear interaction of this highly intense self-focused HGB with the electron plasma wave in the rippled density plasma, satisfying proper phase matching conditions, results in the resonant excitation of THz radiations at the beat frequency. We have studied the dependence of generated THz radiations on the order of the HGB as well as on the static background magnetic field. The results show that the intensity of the generated radiations is highly sensitive to both of these parameters. For the current scheme the power of the generated THz waves comes out to be of the order of Gigawatts.

scholarly journals Beat wave cyclotron heating of rippled density plasma

2018 ◽  
Vol 36 (4) ◽  
pp. 465-469 ◽  
Author(s):  
Pushplata ◽  
A. Vijay
Keyword(s):  
Magnetic Field ◽  
Large Amplitude ◽  
Ponderomotive Force ◽  
Beat Frequency ◽  
Magnetized Plasma ◽  
Larmor Radius ◽  
Finite Larmor Radius ◽  
Wave Heating ◽  
The Magnetic Field ◽  
Density Plasma

AbstractLaser beat wave heating of magnetized plasma via electron cyclotron damping is proposed and analyzed. A plasma density ripple is presumed to exist across the magnetic field. Two collinear lasers propagating along the magnetic field exert a beat frequency ponderomotive force on electrons, driving a large amplitude Bernstein quasi-mode which suffers cyclotron damping on electrons. Finite Larmor radius effects play an important role in the heating. Electron temperature initially rises linearly with time. As the temperature rises cyclotron damping becomes stronger and temperature rises rapidly. The process, however, requires ripple wavelength shorter than the wavelength of the beat wave.

scholarly journals Strong terahertz radiation generation by cosh-Gaussian laser beams in axially magnetized collisional plasma under non-relativistic ponderomotive regime

2018 ◽  
Vol 36 (2) ◽  
pp. 236-245 ◽  
Author(s):  
Prateek Varshney ◽  
Ajit Upadhayay ◽  
K. Madhubabu ◽  
Vivek Sajal ◽  
J. A. Chakera
Keyword(s):  
Magnetic Field ◽  
Ponderomotive Force ◽  
Beat Frequency ◽  
Magnetized Plasma ◽  
Laser Beams ◽  
Thz Radiation ◽  
Thz Wave ◽  
Oscillatory Velocity ◽  
Non Linear ◽  
Radiation Generation

AbstractWe propose a scheme for terahertz (THz) radiation generation by non-linear mixing of two cosh-Gaussian laser beams in axially magnetized plasma with spatially periodic density ripple where electron-neutral collisions have been taken into account. The laser beams exert a non-linear ponderomotive force due to spatial non-uniformity in the intensity. The plasma electrons acquire non-linear oscillatory velocity under the influence of ponderomotive force. This oscillatory velocity couples with preformed density ripples (n′ = n0αeiαz) to generate a strong transient non-linear current that resonantly derives THz radiation of frequency ~ωh (upper hybrid frequency). Laser frequencies (ω1 and ω2) are chosen such that the beat frequency (ω) lies in the THz region. The periodicity of density ripple provides phase-matching conditions (ω = ω1 − ω2 and $\vec k = \vec k_1 - \vec k_2 + {\rm \vec \alpha} $) to transfer maximum momentum from laser to THz radiation. The axially applied external magnetic field can be utilized to enhance the non-linear coupling and control various parameters of generated THz wave. The effects of decentered parameters (b), collisional frequency (νen), and magnetic field strength (B0 = ωcm/e) are analyzed for strong THz radiation generation. Analytical results show that the amplitude of THz wave enhances with decentered parameters as well as with the magnitude of axially applied magnetic field. The THz amplitude is found to be highly sensitive to collision frequency.

Electron Density Perturbation Before the 27 February 2010 ChileM8.8 Earthquake

2011 ◽  
Vol 54 (6) ◽  
pp. 737-746 ◽  
Author(s):  
Jing LIU ◽  
Wei-Xing WAN ◽  
Jian-Ping HUANG ◽  
Xue-Min ZHANG ◽  
Shu-Fan ZHAO ◽  
...  
Keyword(s):  
Electron Density ◽  
Density Perturbation ◽  
Electron Density Perturbation

scholarly journals The synthesis of travelling ionospheric disturbance (TID) signatures in HF radar observations using ray tracing

2000 ◽  
Vol 18 (1) ◽  
pp. 56-64 ◽  
Author(s):  
A. J. Stocker ◽  
N. F. Arnold ◽  
T. B. Jones
Keyword(s):  
Ray Tracing ◽  
Electron Density ◽  
Ionospheric Disturbance ◽  
Density Perturbation ◽  
Hf Radar ◽  
Ionospheric Disturbances ◽  
F Region ◽  
Abstract Characteristic ◽  
Electron Density Perturbation ◽  
Radar Frequency

Abstract. Characteristic signatures are often observed in HF radar range-time-intensity plots when travelling ionospheric disturbances (TIDs) are present. These signatures, in particular the variation of the F-region skip distance, have been synthesised using a ray tracing model. The magnitude of the skip variation is found to be a function of the peak electron density perturbation associated with the TID and radar frequency. Examination of experimental observations leads to an estimate of the peak electron density perturbation amplitude of around 25% for those TIDs observed by the CUTLASS radar system. The advantage of using the skip variation over the radar return amplitude as an indicator of density perturbation is also discussed. An example of a dual radar frequency experiment has been given. The investigation of the effect of radar frequency on the observations will aid the optimisation of future experiments..Key words. Ionosphere (auroral ionosphere; ionosphere -atmosphere interactions; ionospheric disturbances)

Particle acceleration by interstellar plasma shock waves in non-uniform background magnetic field

2020 ◽  
Vol 498 (4) ◽  
pp. 5517-5523
Author(s):  
P Rashed-Mohassel ◽  
M Ghorbanalilu
Keyword(s):  
Magnetic Field ◽  
Particle Acceleration ◽  
Shock Waves ◽  
Electric Field ◽  
Background Field ◽  
Magnetized Plasma ◽  
Background Magnetic Field ◽  
Positive Variation ◽  
Uniform Background ◽  
Plasma Shock

ABSTRACT Particle acceleration by plasma shock waves is investigated for a magnetized plasma cloud propagating in a non-uniform background magnetic field by means of analytical and numerical calculations. The mechanism studied here is mainly, magnetic trapping acceleration (MTA) which is previously investigated for a cloud moving through the uniform interstellar magnetic field (IMF). In this work, the acceleration is studied for a cloud moving in an antiparallel background field with spatial variations along the direction of motion. For negative variation, the cloud moves towards an antiparallel magnetic field with an increasing intensity, the trapped particle moves to locations with higher convective electric field and therefore gains more energy over time. For positive variation, the background field decreases to zero and changes into a parallel field with an increasing intensity. It is concluded that, when the background field vanishes, the MTA mechanism ceases and the particle escapes into the space. This leads to a bouncing acceleration which further increases energy of the gyrating particle. The two processes are followed by a shock drift acceleration, where due to the background magnetic field gradient, the particle drifts along the electric field and gains energy. Although for positive variation, three different mechanisms are involved, energy gain is less than in the case of a uniform background field.

Electrostatic Rossby-type ion plasma waves

1988 ◽  
Vol 39 (1) ◽  
pp. 103-114 ◽  
Author(s):  
J. F. McKenzie ◽  
M. K. Dougherty
Keyword(s):  
Magnetic Field ◽  
Rossby Wave ◽  
Vertical Component ◽  
Rotational Frequency ◽  
Rate Of Change ◽  
Magnetized Plasma ◽  
Propagation Mechanism ◽  
Wave Operators ◽  
Geostrophic Balance ◽  
Background Magnetic Field

It is shown that a plasma in which the background magnetic field varies in a direction perpendicular to its line of action can support ‘Rossby-type’ electrostatic waves at frequencies very much less than the ion gyrofrequency. The intrinsic wave propagation mechanism at work is structurally similar to that in the atmospheric Rossby wave, which comes about from fluid perturbations being in quasi-geostrophic equilibrium (i.e. the Coriolis force nearly balances the pressure gradient) and the latitudinal variation of the vertical component of rotational frequency vector (the β-effect) so that the time rate of change of the vertical component of the fluid vorticity is equal to the northward transport of the planetary vorticity. In a plasma this ‘geostrophic balance’ arises from the near-vanishing of the Lorentz force on the ion motion while the β-effect is provided by the transverse spatial variation of the ambient magnetic field. Unlike the atmosphere, however, such a magnetized plasma is capable of supporting two distinct types of Rossby wave. The interesting dispersive and anisotropic features of these waves are revealed by the properties of their wave operators and described in terms of the geometry of their wavenumber surfaces. Since these surfaces intersect, inhomogeneity or nonlinearity will give rise to strong mode-mode coupling in regions where the phases of both modes nearly match.

The ponderomotive force of a high-frequency electromagnetic field in a cold magnetized plasma

1982 ◽  
Vol 27 (2) ◽  
pp. 215-224 ◽  
Author(s):  
V. I. Karpman ◽  
A. G. Shagalov
Keyword(s):  
Electromagnetic Field ◽  
Liquid Medium ◽  
Magnetic Moment ◽  
High Frequency ◽  
Ponderomotive Force ◽  
Frequency Dispersion ◽  
Magnetized Plasma ◽  
Complete Agreement ◽  
Microscopic Approach ◽  
High Frequency Electromagnetic Field

An expression is derived for the ponderomotive force acting in a cold collisionless magnetized plasma in a high-frequency electromagnetic field. Some related topics, such as the magnetic moment and solenoidal currents induced by the HF field are considered. A microscopic approach is used. The results are in complete agreement with the general expression for the ponderomotive force in a liquid medium with frequency dispersion obtained earlier by Washimi & Karpman by means of phenomenological considerations.

scholarly journals Ionospheric shock waves triggered by rockets

2014 ◽  
Vol 32 (9) ◽  
pp. 1145-1152 ◽  
Author(s):  
C. H. Lin ◽  
J. T. Lin ◽  
C. H. Chen ◽  
J. Y. Liu ◽  
Y. Y. Sun ◽  
...  
Keyword(s):  
Shock Wave ◽  
Electron Density ◽  
Density Perturbation ◽  
Rate Of Change ◽  
Dimensional Structure ◽  
Electron Content ◽  
Wave Direction ◽  
Total Electron ◽  
Electron Density Perturbation ◽  
Rocket Exhaust

Abstract. This paper presents a two-dimensional structure of the shock wave signatures in ionospheric electron density resulting from a rocket transit using the rate of change of the total electron content (TEC) derived from ground-based GPS receivers around Japan and Taiwan for the first time. From the TEC maps constructed for the 2009 North Korea (NK) Taepodong-2 and 2013 South Korea (SK) Korea Space Launch Vehicle-II (KSLV-II) rocket launches, features of the V-shaped shock wave fronts in TEC perturbations are prominently seen. These fronts, with periods of 100–600 s, produced by the propulsive blasts of the rockets appear immediately and then propagate perpendicularly outward from the rocket trajectory with supersonic velocities between 800–1200 m s−1 for both events. Additionally, clear rocket exhaust depletions of TECs are seen along the trajectory and are deflected by the background thermospheric neutral wind. Twenty minutes after the rocket transits, delayed electron density perturbation waves propagating along the bow wave direction appear with phase velocities of 800–1200 m s−1. According to their propagation character, these delayed waves may be generated by rocket exhaust plumes at earlier rocket locations at lower altitudes.

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