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Showing 1 to 20 of 20 for “"Landau damping"”.
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Slow wave ion heating and parametric instabilities in the HELIX helicon source
… possible mechanisms have been identified: ion Landau damping of the slow wave and parametrically driven instabilities. Consistent with ion Landau damping of the slow wave, the perpendicular ion temperatures 35 cm downstream of the RF antenna are largest when the RF frequency matches the local …
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Turbulent Dynamics Under Two Ideal Invariants: Dynamic Phase Alignment in Plasmas and Nonionized Fluids
… and finite ion Larmor radius effects as well as Landau damping. We explore the effects of Landau damping and of the generation of plasmoids on the system dynamics.
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Electrostatic oscillations in inhomogeneous plasmas
… equation facilitates the calculation of the landau damping in the inhomogeneous plasma and allows the determination of the effects of collisions on the growth rate of the two-stream instability. The method is capable of treating arbitrary wavelengths, but works best for small degrees of …
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Vlasov simulations of kinetic enhancement of Raman backscatter in laser fusion plasmas
… run for this purpose. Plasma waves are heavily Landau damped in the regimes of interest, and coupled-mode theory predicts back-scattered SRS is a convective instability. Simulations in a finite length, homogeneous plasma show electron trapping drastically elevates the reflected light over …
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Quantification of lower hybrid wave absorption in the edge of the Alcator C-Mod Tokamak
… set stringent requirements in nk for electron Landau damping to cause the edge absorption of LHRF power. Several observed attributes, namely high frequency modulation and low density absorption do not correlate with Landau damping characteristics. However, parasitic collisional absorption in …
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Dynamic polarizability and collective modes in narrow-band electron systems
… particle-hole pairs and thus are not subject to Landau damping. As a result, plasmons acquire longer lifetimes as well as an enhanced spatial optical coherence. The optical coherence manifests itself in spatial interference patterns that provide telltale signatures of over-the-band plasmons that …
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Scattering in Nano-Electronic Devices
… newly proposed criteria for determining Landau damping regimes. Phonon-electron interaction- the most dominant scattering mechanism at room and higher temperatures is also studied. It is concluded that the well known trend for phonon limited mobility, observed in measurements, is not …
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The Effects of Weak Collisions on Nonlinear Plasma Kinetics
… mechanism for fast reconnection. The concept of Landau damping is fundamental to such wave kinetic instabilities in space, and is treated typically within the framework of the collisionless Vlasov equation. It has become clear in recent theoretical and experimental work that weak collisions are a …
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Interacting Elementary Excitations in Ultrarelativistic Plasmas: Damping Mechanisms and Plasma Thermodynamics
… plasmas. Due to Debye screening and Landau damping mechanisms, the interaction fields fall off at large distances, except for static magnetic and color-magnetic fields. The lack of screening of the magnetic interaction leads to a singularity at small momentum transfer in the matrix …
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Contributions to mixing and hypocoercivity in kinetic models
… behaviour. The stability was first described by Landau in 1946 and is a subtle behaviour, because the damping only happens in a suitably weak sense. In fact, the models are not dissipative and cannot be stable in a strong topology. Instead, the so-called Landau damping happens through phase …
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Numerical models for the simulation of Raman amplification in plasma
… Raman amplification. The absence of collisional damping in available PIC codes is found to limit the parameter spaces within which simulations can be carried out. The conventional three-wave model has been extended to improve its accuracy, and to include the effects of plasma wave harmonics. In …
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Interaction elementary excitations in ultrarelativistic plasmas: damping mechanisms and plasma thermodynamics
… plasmas. Due to Debye screening and Landau damping mechanisms, the interaction fields fall off at large distances, except for static magnetic and color-magnetic fields. The lack of screening of the magnetic interaction leads to a singularity at small momentum transfer in the matrix …
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Full-wave modeling of lower hybrid waves on Alcator C-Mod
… in a hot non- Maxwellian plasma. The electron Landau damping (ELD) effect was expressed as a convolution integral along the magnetic field lines and the resultant integro-differential Helmholtz equation was solved iteratively. A 3D Fokker-Planck code and a synthetic Hard X-Ray (HXR) diagnostic …
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Finite temperature effects in free-electron-lasers
… fact can alleviate the decrease in gain due to Landau damping of the plasma wave. The inclusion of the guide magnetic field does not alter the above description, except when operating close to magneto-resonance. For one type of stable orbits, there is a minimum momentum for the integrals in the …
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Continuum Kinetic Simulations of Plasma Sheaths and Instabilities
… to compare well with theoretical predictions of Landau damping of Langmuir waves and the two-stream instability. Benchmarks are also performed using the electromagnetic Weibel instability and excellent agreement is found between theory and simulation. The role of the electric field is significant …
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Energy partition in magnetic reconnection and kinetic turbulence in weakly collisional plasmas
… used to demonstrate the importance of electron Landau damping in kinetic turbulence, approaching the fully-kinetic spectral shape when it is included but deviating significantly and approaching the hybrid-kinetic spectra during isothermal runs when it is explicitly excluded. The limits and …
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Ultrafast terahertz spectroscopy and control of collective modes in semiconductors
… is enforced. We observed the consequential Landau damping of the collective mode, in good agreement with the predictions made within the random-phase approximation. In the second experiment we have invoked plasmon confinement in all three dimensions via a nanowire geometry. We observed …
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Analysis of magnetohydrodynamic (MHD) activity using electron cyclotron emission (ECE) diagnostics on Alcator C-Mod tokamak
… to the ion diamagnetic drift frequency, ion Landau damping was found to be strong enough to drive a kinetic Mercier instability. As a result, a FLR modified kinetic Mercier instability has been identified, possibly for the first time since the Mercier criterion was formulated forty years ago. …
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The Mid-Latitude Ionosphere: Modeling and Analysis of Plasma Wave Irregularities and the Potential Impact on GPS Signals
… for High- Frequency (HF) radars by including Landau damping, finite gyro-radius effects, and tem- perature anisotropy. The kinetic dispersion relation of the Gradient Drift Instability (GDI) including finite ion gyro-radius effects is also solved to consider decameter-scale waves gen- eration. …
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Carrier momentum relaxation in highly doped polar semiconductors and semiconductor heterostructures
Highly doped polar semiconductors are essential components of today’s semiconductor industry. Most strikingly, transistors in modern electronic devices are polar semiconductor heterostructures. It is important to thoroughly understand carrier transport in such structures. In doped polar …