The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform
Young-dae Jung - One of the best experts on this subject based on the ideXlab platform.
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Temperature effects on the propagation and Landau Damping of the dust surface waves
Physics of Plasmas, 2019Co-Authors: Myoung-jae Lee, Young-dae JungAbstract:The integral of the kinetic electrostatic surface wave dispersion relation is evaluated to determine the wave frequency and the corresponding Landau Damping rate for the surface mode of dust ion-acoustic waves including the effect of ion temperature by using the general perturbation and the transverse truncation methods. It is demonstrated that the increase in ion temperature enhances the wave frequency. The effect of ion temperature is more prominent in the range of large wave numbers, and the wave frequency increases in proportion to a quarter power of the ion temperature in the realm of large wave number. The Landau Damping of the dust ion-acoustic surface wave is found to be suppressed as the ion temperature increases. However, the effect of ion temperature becomes negligible as the wave number increases. The effects of dust charge and electron density on the Landau Damping rate are also presented in this work.
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The first radial-mode Lorentzian Landau Damping of dust acoustic space-charge waves
Physics of Plasmas, 2016Co-Authors: Myoung-jae Lee, Young-dae JungAbstract:The dispersion properties and the first radial-mode Lorentzian Landau Damping of a dust acoustic space-charge wave propagating in a cylindrical waveguide dusty plasma which contains nonthermal electrons and ions are investigated by employing the normal mode analysis and the method of separation of variables. It is found that the frequency of dust acoustic space-charge wave increases as the wave number increases as well as the radius of cylindrical plasma does. However, the nonthermal property of the Lorentzian plasma is found to suppress the wave frequency of the dust acoustic space-charge wave. The Landau Damping rate of the dust acoustic space-charge wave is derived in a cylindrical waveguide dusty plasma. The Damping of the space-charge wave is found to be enhanced as the radius of cylindrical plasma and the nonthermal property increase. The maximum Lorentzian Landau Damping rate is also found in a cylindrical waveguide dusty plasma. The variation of the wave frequency and the Landau Damping rate due t...
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Landau Damping effects on the low-energy bremsstrahlung process in a quantum plasma
Europhysics Letters (EPL), 2007Co-Authors: Hwa-min Kim, Young-dae JungAbstract:The Landau Damping effects on the low-energy bremsstrahlung process are investigated for both the soft- and hard-photon radiations in a quantum plasma composed of electrons and holes. The impact parameter method is applied to the motion of the projectile in order to investigate the variation of the bremsstrahlung cross-section as a function of the effective Debye length, impact parameter, and radiation photon energy. The results show that the Landau Damping effects significantly enhance the bremsstrahlung radiation cross-section. It is important to note that the domain of the Landau Damping effects is extended with increasing the radiation photon energy.
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Landau Damping Effect on Elastic Collision in Uniformly Magnetized Plasmas
Physica Scripta, 2005Co-Authors: Chang-geun Kim, Young-dae JungAbstract:The Landau Damping effect on electron-ion elastic collision in uniformly mag-netized dense plasmas is investigated. The scattering phase and cross section for electron-ion elastic collisions in magnetized plasmas are obtained by introduction of the longitudinal plasma dielectric function with the eikonal method. The domains of the velocity, frequency, and impact parameter for the Landau Damping effect on the scattering cross section are discussed. It is also found that the Landau Damping effect reduces the collision cross section and is more significant when the projectile velocity is greater than the electron thermal velocity.
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Landau Damping effects on classical electron–ion Coulomb bremsstrahlung in dense plasmas
Physics of Plasmas, 2001Co-Authors: Young-dae Jung, Chang-geun KimAbstract:Landau Damping effects on the classical electron–ion Coulomb bremsstrahlung process in dense Maxwellian plasmas are investigated. The electron–ion dynamic interaction potential is obtained by introduction of the longitudinal plasma dielectric function. The classical trajectory method is applied to represent the differential bremsstrahlung radiation cross section as a function of the impact parameter, photon energy, projectile velocity, electron thermal velocity, and Debye length. The Landau Damping effect in the soft photon case is found to be more important than that in the hard photon case. It is also found that the Landau Damping effect is important when the projectile velocity is equal to the electron thermal velocity (vT/ve=1), for example, the Landau Damping effect is about 3.4% for Ep/Ee=0.1.
Yoshifumi Saitou - One of the best experts on this subject based on the ideXlab platform.
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Observation of ion-acoustic shock wave transition due to enhanced Landau Damping
Physics of Plasmas, 2008Co-Authors: H. Bailung, Yoshiharu Nakamura, Yoshifumi SaitouAbstract:Ion-acoustic shock waves are observed experimentally introducing strong Landau Damping by increasing the ion temperature in a double plasma device. An oscillatory ion-acoustic shock wave undergoes transition with enhanced Landau Damping and forms a monotonic shock wave. Numerical results of the Korteweg–de Vries equation with an additional integral term to account for the strength of Landau Damping are compared with the experimental findings. Enhancement of Landau Damping is found to increase the dissipation of the wave, which manifests in quenching of the oscillatory structure behind the shock front.
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Ion-acoustic soliton-like waves undergoing Landau Damping
Physics Letters A, 2005Co-Authors: Yoshifumi Saitou, Yoshiharu NakamuraAbstract:Abstract Effects of Landau Damping on ion-acoustic soliton-like waves are investigated experimentally and numerically. Landau Damping is enhanced by increasing the ion temperature in the experiments. A ramp which is composed of resonant ions is observed in front of a soliton-like wave. The ramp is also seen in numerical simulations of an extended Korteweg–de Vries equation with a term of Landau Damping. Experimental results of the height of the ramp are found to agree with numerical ones.
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Observation of ion-acoustic shock waves undergoing Landau Damping
Physics of Plasmas, 2004Co-Authors: Yoshiharu Nakamura, H. Bailung, Yoshifumi SaitouAbstract:Numerical results of a modified Korteweg–de Vries equation with an integral term which describes Landau Damping have been compared with the experimental findings. In the linear regime, the wave Damping rate is proportional to wave number, which conforms to a kinetic dispersion relation. Transition of an oscillatory ion-acoustic shocklike structure into a monotonic shock has been observed when Landau Damping is introduced by mixing H2 ions with an Ar plasma. Quenching of the oscillatory stucture behind the wave front is identified as a dissipation charateristic governed by the strength of Landau Damping.
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Ion-acoustic shock waves undergoing Landau Damping
Physics of Plasmas, 2003Co-Authors: Yoshifumi Saitou, Yoshiharu NakamuraAbstract:The Korteweg–de Vries equation with an additional term of Landau Damping is numerically and analytically investigated. It is shown that the equation has a shock-like solution for an initial ramp signal. The temporal evolution of waveforms with various magnitudes of the Landau Damping is studied for several values of the initial amplitude. Dependences of widths and velocities of the leading part on initial conditions are shown. It is found that a steepening is suppressed due to the Landau Damping even when its coefficient is two orders less than those of nonlinear and dispersive terms. There is a critical relation for such a steepening to take place for a fixed height of the initial ramp. An analytical estimate of the magnitude of temporal Landau Damping is given for a linear sinusoidal wave.
Yoshiharu Nakamura - One of the best experts on this subject based on the ideXlab platform.
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Observation of ion-acoustic shock wave transition due to enhanced Landau Damping
Physics of Plasmas, 2008Co-Authors: H. Bailung, Yoshiharu Nakamura, Yoshifumi SaitouAbstract:Ion-acoustic shock waves are observed experimentally introducing strong Landau Damping by increasing the ion temperature in a double plasma device. An oscillatory ion-acoustic shock wave undergoes transition with enhanced Landau Damping and forms a monotonic shock wave. Numerical results of the Korteweg–de Vries equation with an additional integral term to account for the strength of Landau Damping are compared with the experimental findings. Enhancement of Landau Damping is found to increase the dissipation of the wave, which manifests in quenching of the oscillatory structure behind the shock front.
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Ion-acoustic soliton-like waves undergoing Landau Damping
Physics Letters A, 2005Co-Authors: Yoshifumi Saitou, Yoshiharu NakamuraAbstract:Abstract Effects of Landau Damping on ion-acoustic soliton-like waves are investigated experimentally and numerically. Landau Damping is enhanced by increasing the ion temperature in the experiments. A ramp which is composed of resonant ions is observed in front of a soliton-like wave. The ramp is also seen in numerical simulations of an extended Korteweg–de Vries equation with a term of Landau Damping. Experimental results of the height of the ramp are found to agree with numerical ones.
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Observation of ion-acoustic shock waves undergoing Landau Damping
Physics of Plasmas, 2004Co-Authors: Yoshiharu Nakamura, H. Bailung, Yoshifumi SaitouAbstract:Numerical results of a modified Korteweg–de Vries equation with an integral term which describes Landau Damping have been compared with the experimental findings. In the linear regime, the wave Damping rate is proportional to wave number, which conforms to a kinetic dispersion relation. Transition of an oscillatory ion-acoustic shocklike structure into a monotonic shock has been observed when Landau Damping is introduced by mixing H2 ions with an Ar plasma. Quenching of the oscillatory stucture behind the wave front is identified as a dissipation charateristic governed by the strength of Landau Damping.
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Ion-acoustic shock waves undergoing Landau Damping
Physics of Plasmas, 2003Co-Authors: Yoshifumi Saitou, Yoshiharu NakamuraAbstract:The Korteweg–de Vries equation with an additional term of Landau Damping is numerically and analytically investigated. It is shown that the equation has a shock-like solution for an initial ramp signal. The temporal evolution of waveforms with various magnitudes of the Landau Damping is studied for several values of the initial amplitude. Dependences of widths and velocities of the leading part on initial conditions are shown. It is found that a steepening is suppressed due to the Landau Damping even when its coefficient is two orders less than those of nonlinear and dispersive terms. There is a critical relation for such a steepening to take place for a fixed height of the initial ramp. An analytical estimate of the magnitude of temporal Landau Damping is given for a linear sinusoidal wave.
Myoung-jae Lee - One of the best experts on this subject based on the ideXlab platform.
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Temperature effects on the propagation and Landau Damping of the dust surface waves
Physics of Plasmas, 2019Co-Authors: Myoung-jae Lee, Young-dae JungAbstract:The integral of the kinetic electrostatic surface wave dispersion relation is evaluated to determine the wave frequency and the corresponding Landau Damping rate for the surface mode of dust ion-acoustic waves including the effect of ion temperature by using the general perturbation and the transverse truncation methods. It is demonstrated that the increase in ion temperature enhances the wave frequency. The effect of ion temperature is more prominent in the range of large wave numbers, and the wave frequency increases in proportion to a quarter power of the ion temperature in the realm of large wave number. The Landau Damping of the dust ion-acoustic surface wave is found to be suppressed as the ion temperature increases. However, the effect of ion temperature becomes negligible as the wave number increases. The effects of dust charge and electron density on the Landau Damping rate are also presented in this work.
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The first radial-mode Lorentzian Landau Damping of dust acoustic space-charge waves
Physics of Plasmas, 2016Co-Authors: Myoung-jae Lee, Young-dae JungAbstract:The dispersion properties and the first radial-mode Lorentzian Landau Damping of a dust acoustic space-charge wave propagating in a cylindrical waveguide dusty plasma which contains nonthermal electrons and ions are investigated by employing the normal mode analysis and the method of separation of variables. It is found that the frequency of dust acoustic space-charge wave increases as the wave number increases as well as the radius of cylindrical plasma does. However, the nonthermal property of the Lorentzian plasma is found to suppress the wave frequency of the dust acoustic space-charge wave. The Landau Damping rate of the dust acoustic space-charge wave is derived in a cylindrical waveguide dusty plasma. The Damping of the space-charge wave is found to be enhanced as the radius of cylindrical plasma and the nonthermal property increase. The maximum Lorentzian Landau Damping rate is also found in a cylindrical waveguide dusty plasma. The variation of the wave frequency and the Landau Damping rate due t...
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Landau Damping of dust acoustic waves in a lorentzian plasma
Physics of Plasmas, 2007Co-Authors: Myoung-jae LeeAbstract:The Landau Damping of dust acoustic waves propagating in a dusty plasma modeled by a Lorentzian (kappa) distribution for electrons and ions, and by a Maxwellian distribution for the dust grains is kinetically investigated. The dust acoustic waves are found in the range of kvd≪ω≪kvi≪kve, where vα is the thermal velocity of species α(=i,e,d). The Damping rate is shown to be dependent on the spectral index κ as well as the ratio of ion density to electron. The maximum Landau Damping rate is derived and found to be approximately 0.2σκωpd where ωpd is the dust plasma frequency and σκ is a κ-dependent factor, which has the maximum value of 1.33 (for the smallest κ) and reduces to unity as the nonthermal effect disappears.
Nathaniel J. Fisch - One of the best experts on this subject based on the ideXlab platform.
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effect of nonlinear Landau Damping in plasma based backward raman amplifier
Physics of Plasmas, 2009Co-Authors: Nikolai A. Yampolsky, Nathaniel J. FischAbstract:A plasma wave can mediate laser coupling in a plasma-based resonant backward Raman amplifier for high power amplification of short laser pulses. The resonant nature of amplification requires a long lifetime of the plasma wave. However, the plasma wave can be heavily Landau damped in warm plasma. On the other hand, Landau Damping can be saturated in the presence of a strong plasma wave. We study backward Raman amplifier in the nonlinear regime of Landau Damping using a simplified fluid model. We find the regime in which initially high linear Landau Damping can be significantly saturated. Because of the saturation effect, higher temperatures can be tolerated in achieving efficient amplification. The plasma temperature can be as much as 50% larger compared to the case of unsaturated Landau Damping.
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Simplified Model of Nonlinear Landau Damping
Physics of Plasmas, 2009Co-Authors: Nikolai A. Yampolsky, Nathaniel J. FischAbstract:The nonlinear interaction of a plasma wave with resonant electrons results in a plateau in the electron distribution function close to the phase velocity of the plasma wave. As a result, Landau Damping of the plasma wave vanishes and the resonant frequency of the plasma wave downshifts. However, this simple picture is invalid when the external driving force changes the plasma wave fast enough so that the plateau cannot be fully developed. A new model to describe amplification of the plasma wave including the saturation of Landau Damping and the nonlinear frequency shift is proposed. The proposed model takes into account the change of the plasma wave amplitude and describes saturation of the Landau Damping rate in terms of a single fluid equation, which simplifies the description of the inherently kinetic nature of Landau Damping. A proposed fluid model, incorporating these simplifications, is verified numerically using a kinetic Vlasov code.
