Plasma Wave Instability Research Articles

The effect of external magnetic field on the instability of THz plasma waves in nanoscale graphene field-effect transistors

Abstract The instability of plasma waves in the channel of field-effect transistors will cause the electromagnetic waves with THz frequency. Based on a self-consistent quantum hydrodynamic model, the instability of THz plasmas waves in the channel of graphene field-effect transistors has been investigated with external magnetic field and quantum effects. We analyzed the influence of weak magnetic fields, quantum effects, device size, and temperature on the instability of plasma waves under asymmetric boundary conditions numerically. The study results show that the magnetic fields, quantum effects, and the thickness of the dielectric layer between the gate and the channel can increase the radiation frequency. Additionally, we observed that increase in temperature leads to a decrease in both oscillation frequency and instability increment. The numerical results and accompanying images obtained from our simulations provide support for the above conclusions.

Effect of spin on the instability of THz plasma waves in field-effect transistors under non-ideal boundary conditions

Terahertz (THz) radiation can be generated due to the instability of THz plasma waves in field-effect transistors (FETs). In this work, we discuss the instability of THz plasma waves in the channel of FETs with spin and quantum effects under non-ideal boundary conditions. We obtain a linear dispersion relation by using the hydrodynamic equation, Maxwell equation and spin equation. The influence of source capacitance, drain capacitance, spin effects, quantum effects and channel width on the instability of THz plasma waves under the non-ideal boundary conditions is investigated in great detail. The results of numerical simulation show that the THz plasma wave is unstable when the drain capacitance is smaller than the source capacitance; the oscillation frequency with asymmetric boundary conditions is smaller than that under non-ideal boundary conditions; the instability gain of THz plasma waves becomes lower under non-ideal boundary conditions. This finding provides a new idea for finding efficient THz radiation sources and opens up a new mechanism for the development of THz technology.

Instability and growth rate of magnetosonic waves in quantum plasmas with oblique magnetic field due to coupling of neutrino beam and flavor oscillations

Instability and growth rate of magnetosonic waves in quantum plasmas with oblique magnetic field due to coupling of neutrino beam and flavor oscillations

Kinetic Generation of Whistler Waves in the Turbulent Magnetosheath.

The Earth's magnetosheath (MSH) is governed by numerous physical processes which shape the particle velocity distributions and contribute to the heating of the plasma. Among them are whistler waves which can interact with electrons. We investigate whistler waves detected in the quasi‐parallel MSH by NASA's Magnetospheric Multiscale mission. We find that the whistler waves occur even in regions that are predicted stable to wave growth by electron temperature anisotropy. Whistlers are observed in ion‐scale magnetic minima and are associated with electrons having butterfly‐shaped pitch‐angle distributions. We investigate in detail one example and, with the support of modeling by the linear numerical dispersion solver Waves in Homogeneous, Anisotropic, Multicomponent Plasmas, we demonstrate that the butterfly distribution is unstable to the observed whistler waves. We conclude that the observed waves are generated locally. The result emphasizes the importance of considering complete 3D particle distribution functions, and not only the temperature anisotropy, when studying plasma wave instabilities.

Dust-ion acoustic rogue waves in six-component dusty plasma

In this work, we investigate the modulational instability of finite amplitude dust-ion acoustic nonlinear waves in a six-component cometary dusty plasma. Such plasma system is composed of Oxygen ion-pair, negative dust particles, kappa distributed light ions of Hydrogen, solar electrons and cometary electrons of the comet tail. By employing the standard reductive perturbation technique, a nonlinear Schrödinger-type equation is obtained. This equation governs the investigation of the modulational instability of finite amplitude dust-ion acoustic nonlinear waves. Our analysis shows two parametric domains, where the dust-ion acoustic waves are modulationally stable and unstable depending on the plasma configurational parameters. Within the unstable domain, rogue waves could be generated due to the nonlinear and dispersion properties of plasma system. The effects of some relevant plasma parameters on the profile of rogue waves are studied. The obtained results might be useful for better understanding the modulational instability of nonlinear plasma waves and formation of dust-ion acoustic rogue waves in space plasmas.

The effect of nonideal boundary condition on instability of THz plasma waves in quantum field-effect transistors

The instability of THz plasma waves propagating along a channel of field-effect transistors opens up a new mechanism of emission of THz waves. In this work, we investigate the instability of THz plasma waves in field-effect transistors in the presence of quantum effects and nonideal boundary condition at the source and the drain by using the quantum hydrodynamic model. The results show that the THz plasma waves will be unstable when the gate–source capacitances are larger than gate–drain capacitances and the instability increment can be increased by increasing gate–source capacitances or decreasing gate–drain capacitances. The results of this work give nano-field-effect transistors an advantage in achieving real THz oscillations.

Coupling and Instability of Electrostatic Waves in Spin Magnetized Degenerate Plasmas

In this article, we study the coupling of low-frequency electrostatic waves in the electron-ion and the electron-ion-beam-spin quantum plasmas. The quantum effect of electrons are introduced via separate spin evolution-quantum hydrodynamic (SSE-QHD) model while the ion dynamics is governed by classical fluid equations. In the case of electron-ion plasma, it is found that the quantum effects shift both the coupling domain and the phase velocities of coupled waves. Furthermore, the coupling is observed to be strong at small propagation angles. In the beam interacting system, two coupling domains occur corresponding to small and large <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$k$ </tex-math></inline-formula> -values. In the first domain beam mode excites the ion cyclotron (IC) wave and moves with constant phase velocity while in the second domain it gains energy from the ion acoustic (IA) mode and travels with increasing phase velocity. In addition, the beam parameters affect both the coupling domain and the phase velocity. The presence of beam in electron-ion plasma drives the IC mode unstable. The beam parameters, the spin, and the obliqueness affect the instability. Our findings may be helpful in understanding the energy exchange of plasma waves via coupling phenomenon in degenerate plasma systems.

The emission of THz plasma waves in graphene field-effect transistors with quantum effects

The instability of electron fluid in the channel of graphene field-effect transistors has provided a powerful theoretical basis for the radiation and detection of THz waves. In this paper, the quantum hydrodynamic model governing the characteristics of two electron gas in channel of graphene field-effect transistors is presented. The instability of THz plasma waves is analyzed in the presence of boundary condition with quantum effects. The results show that the strength of quantum effects will lead to an increase in oscillation frequency and instability increment of THz plasma oscillation in graphene field-effect transistors. These properties could make the nanometer graphene field-effect transistors advantageous for realization of practical terahertz oscillations.

On the Issue of the Origin of Type II Solar Radio Bursts

Abstract Type II solar radio bursts are among the most powerful events in the solar radio emission in the meter wavelength range. It is generally accepted that the agents generating type II radio bursts are magnetohydrodynamic shock waves. But the relationship between the shock waves and the other manifestations of the large-scale disturbances in the solar atmosphere (coronal mass ejections, Morton waves, EUW waves) remains unclear. To clarify a problem, it is important to determine the conditions of generation of type II radio bursts. Here, the model of the radio source is based on the generation of radio emission within the front of the collisionless shock wave where the Buneman instability of plasma waves is developed. In the frame of this model, the Alfvén magnetic Mach number must exceed the critical value, and there is a strict restriction on the perpendicularity of the front. The model allows us to obtain the information about the parameters of the shock waves and the parameters of the medium by the parameters of type II bursts. The estimates, obtained in this paper for several events with the band splitting of the fundamental and harmonic emission bands of the type II bursts, confirm the necessary conditions of the model. In this case the registration of type II radio bursts is an indication of the propagation of shock waves in the solar atmosphere, and the absence of type II radio bursts is not an indication of the absence of shock waves. Such a situation should be taken into account when investigating the relationship between type II radio bursts and other manifestations of solar activity.

Spin contribution to the instability of THz plasma waves

When the boundary conditions of the source and drain are asymmetric, the plasma waves may become unstable in the channel of a field effect transistor (FET). We use the quantum magnetohydrodynamic model to study the influence of the quantum Bohm potential, Fermi statistical pressure, and electron spin effects on the stability of THz plasma waves propagating perpendicular to the magnetic field in the FET. A dispersion equation governing the THz plasma oscillation is obtained. Numerical results have shown that the presence of spin effects has enlarged the instable range of β, enhanced the instability increment, and made the frequency of THz plasma waves larger. The research shows that nanometer FETs with spin effects have advantages in realizing practical terahertz radiation.

Multi-dimensional instability of dust acoustic waves in magnetized quantum plasmas by two-fluid quantum hydrodynamics model

Multi-dimensional instability of dust acoustic waves in magnetized quantum plasmas by two-fluid quantum hydrodynamics model

The Electron Acoustic Wave and Its Role in Solar Flaring Loops Heating

Abstract From soft X-ray emission, the solar flare temperatures are from several MK to dozens of times MK, which are higher than the preflare coronal temperatures. A combination of several heating mechanisms may contribute to the heating problem in solar flare loops. In this paper, we propose an important mechanism of solar flaring loops heating, in which the excited electron acoustic wave (EAW) by flare-accelerated fast electron beams can lead to electron heating via collisionless Landau damping effect produced by wave–particle resonant interaction. Taking account of the return-current effect of fast electron beams, by use of numerical and analytic solutions, the plasma wave instability driven by fast electron beams is investigated in typical solar flare loop plasma parameters. The results show that the EAW is the strongest unstable wave mode rather than other wave modes. The dissipation of EAW via collisionless Landau damping and its application to solar flaring loops heating are discussed in detail.

Simulation of THz Oscillations in Semiconductor Devices Based on Balance Equations

Instabilities of electron plasma waves in high-mobility semiconductor devices have recently attracted a lot of attention as a possible candidate for closing the THz gap. Conventional moments-based transport models usually neglect time derivatives in the constitutive equations for vectorial quantities, resulting in parabolic systems of partial differential equations (PDE). To describe plasma waves however, such time derivatives need to be included, resulting in hyperbolic rather than parabolic systems of PDEs; thus the fundamental nature of these equation systems is changed completely. Additional nonlinear terms render the existing numerical stabilization methods for semiconductor simulation practically useless. On the other hand there are plenty of numerical methods for hyperbolic systems of PDEs in the form of conservation laws. Standard numerical schemes for conservation laws, however, are often either incapable of correctly handling the large source terms present in semiconductor devices due to built-in electric fields, or rely heavily on variable transformations which are specific to the equation system at hand (e.g. the shallow water equations), and can not be generalized easily to different equations. In this paper we develop a novel well-balanced numerical scheme for hyperbolic systems of PDEs with source terms and apply it to a simple yet non-linear electron transport model.

Effect of viscous electron flow on THz plasma waves in field effect transistors

The instability of plasma waves is influenced by many factors, such as quantum effects and electrical thermal motion. However, in sufficiently small electronic devices, viscous electron flows can be generated from the electronic interactions and govern electronic transport. The strong influence of the viscous electron fluid on plasma wave instability in field effect transistors(FET) was analyzed in this study. The theoretical results show that the instability increment and radiation frequency are functions of the Mach number, and the instability increment. Further, the computer simulative data show that the radiation frequencies increase within a certain range and the instability increment decreases owing to the presence of viscous electron flows. Therefore, it can be concluded that the viscous electron flow FETs exerts considerable influence on the characteristics of the terahertz wave.

Plasma wave oscillations in a nonequilibrium two-dimensional electron gas: Electric field induced plasmon instability in the terahertz frequency range

We have developed a theory of collective electron oscillations in two-dimensional semiconductor heterostructures subjected to a high electric field. The effect of the stationary electric field has been taken into account on both steady-state and high-frequency electron transport. The analysis has been conducted by solving Boltzmann-Vlasov equations in the collisionless approach for high-frequency electron transport. Two actual types of heterostructures with ungated and gated two-dimensional (2D) electron gas have been considered. We have found that the collective excitation spectra of 2D electron gas are of the multibranch character with high-quality plasmonic modes and a set of thermal modes. Applied electric field induces the following effects: strong nonreciprocal behavior of both oscillation frequency and damping; interaction of plasmonic and thermal modes; instability of excitations propagating along the electron drift (effect of negative Landau damping). The mechanism of this plasma wave instability is different from early discussed Cherenkov, Dyakonov-Shur, and Ryzhii-Satou-Shur mechanisms of instabilities in plasmonic systems. It has been shown that the electrically induced plasmon instability provides amplification of terahertz (THz) radiation in grating-based plasmonic structures. We suggest that presented results can be important for deeper understanding of THz plasma physics and developing of electrically pumping devices for THz optoelectronics.

Low relativistic effects on the modulational instability of rogue waves in electronegative plasmas

Relativistic ion-acoustic waves are investigated in an electronegative plasma. The use of the reductive perturbation method summarizes the hydrodynamic model to a nonlinear Schrödinger equation which supports the occurrence of modulational instability (MI). From the MI criterion, we derive a critical value for the relativistic parameter alpha _{1}, below which MI may develop in the system. The MI analysis is then conducted considering the presence and absence of negative ions, coupled to effects of relativistic parameter and the electron-to-negative ion temperature ratio. Under high values of the latter, additional regions of instability are detected, and their spatial expansion is very sensitive to the change in alpha _{1} and may support the appearance of rogue waves whose behaviors are discussed. The parametric analysis of super-rogue wave amplitude is performed, where its enhancement is debated relatively to changes in alpha _{1}, in the presence and absence of negative ions.

Charge-gradient instability of compressional dust lattice waves in electrorheological plasmas

It is shown that the longitudinal dust lattice mode in the one-dimensional string of microparticles oriented along the electric field (it highlights the major aspect of the electrorheological plasmas) can be subjected to a specific charge-gradient instability, associated with inhomogeneous dust charge distribution along the string due to the ion flow. This instability leads to the spontaneous excitation of compressional waves at elevated gas pressures with implications for the electrorheological plasmas studied in the Plasmakristall-4 facility in the ground based conditions and in microgravity on board the International Space Station. The obtained results can also be relevant for the stability analysis of the laboratory multilayer plasma crystals observed in the sheath of gas discharges.

Theoretical Prediction of Asymmetric Instability of Drift Kinetic Alfven Waves in Anisotropic Plasmas

AbstractThe asymmetric instability of drift kinetic Alfvén waves (DKAWs) is analyzed to study the interplay between the density inhomogeneity and the temperature anisotropy, including the wave‐particle interaction and finite ion Larmor radius effects. The asymmetric behavior arises due to the opposite diamagnetic drifts of electrons and ions and quantifies the contribution of electron drift waves and ion drift waves in altering the dispersion characteristic of DKAWs. It is shown that the coupling of drift waves with kinetic Alfvén waves leads to the generation of three different frequency (i.e., higher, intermediate, and lower) modes of DKAWs. The comparison of their propagation characteristics and stability mechanisms applicable to a wide range of plasma parameters is provided. The analytical dispersion relation can be used as an improved theoretical tool for identifying the existence of DKAWs and their source region in the multisatellite observations, especially near the reconnection X‐line.

The instability of terahertz plasma waves in cylindrical FET

In this paper, the Dyakonov–Shur instability of terahertz (THz) plasma waves has been analyzed in gated cylindrical field effect transistor (FET). In the cylindrical FET, the hydrodynamic equations in cylindrical coordinates are used to describe the THz plasma wave in two-dimensional electronic gas. The research results show that the oscillation frequency of the THz plasma wave is increased by increasing the component of wave in the circumferential direction, but instability increment of the THz plasma wave are increased by increasing the radius of channel.

Plasmons in Ballistic Nanostructures With Stubs: Transmission Line Approach

The plasma wave instabilities in ballistic Field Effect Transistors (FETs) have a promise of developing sensitive THz detectors and efficient THz sources. One of the difficulties in achieving efficient resonant plasmonic detection and generation is assuring proper boundary conditions at the contacts and at the heterointerfaces and tuning the plasma velocity. We propose using the tunable narrow channel regions of an increased width, which we call "stubs" for optimizing the boundary conditions and for controlling the plasma velocity. We developed a compact model for THz plasmonic devices using the transmission line (TL) analogy. The mathematics of the problem is similar to the mathematics of a TL with a stub. We applied this model to demonstrate that the stubs could effectively control the boundary conditions and/or the conditions at interfaces. We derived and solved the dispersion equation for the device with the stubs and showed that periodic or aperiodic systems of stubs allow for slowing down the plasma waves in a controllable manner in a wide range. Our results show that the stub designs provide a way to achieve the optimum boundary conditions and could also be used for multi finger structures - stub plasmonic crystals - yielding better performance of THz electronic detectors, modulators, mixers, frequency multipliers and sources.