Yanzeng Zhang

Yanzeng Zhang
Los Alamos National Laboratory | LANL · Applied Mathematics and Plasma Physics Group

Doctor of Philosophy

About

34
Publications
2,193
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111
Citations

Publications

Publications (34)
Article
Full-text available
The modified Hasegawa-Mima equation retaining all nonlinearities is investigated from the point of view of the formation of blobs. The linear analysis shows that the amplitude of the drift wave packet propagating in the direction of decreasing background plasma density increases and eventually saturates due to nonlinear effects. Nonlinear modificat...
Article
Full-text available
The dynamics of relativistic electrons in the intense laser radiation and quasi-static electromagnetic fields both along and across the laser propagating direction are studied in the 3/2 dimensional (3/2D) Hamiltonian framework. It is shown that the unperturbed oscillations of the relativistic electron in these electric fields could exhibit a long...
Article
The impact of neutrals on the anomalous edge plasma transport is examined in detail within the resistive drift wave (RDW) turbulence and zonal flow (ZF) system. It is shown that the neutral impact on the RDW turbulence itself is weak, but it can largely damp the zonal flow and thus lead to an enhancement of the anomalous transport. Such an impact i...
Article
Full-text available
The effects of velocity shear on the unstable modes driven by the effective gravity (Rayleigh–Taylor and interchange) and resistive drift wave instabilities for inhomogeneous equilibrium fluid/plasma density are analyzed for the localized eigenmode problems. It is shown that the effect of the velocity shear drastically depends on the type of instab...
Article
Full-text available
The plasma exit flow speed at the sheath entrance is constrained by the Bohm criterion. The so-called Bohm speed regulates the plasma particle and power exhaust fluxes to the wall, and it is commonly deployed as a boundary condition to exclude the sheath region in quasineutral plasma modeling. Here the Bohm criterion analysis is performed in the in...
Preprint
Full-text available
A large class of Laboratory, Space, and Astrophysical plasmas is nearly collisionless. When a localized energy or particle sink, for example, in the form of a radiative cooling spot or a black hole, is introduced into such a plasma, it can trigger a plasma thermal collapse, also known as a thermal quench in tokamak fusion. Here we show that the ele...
Preprint
Full-text available
A large class of Laboratory, Space, and Astrophysical plasmas is nearly collisionless. When a localized energy or particle sink, for example, in the form of a radiative cooling spot or a black hole, is introduced into such a plasma, it can trigger a plasma thermal collapse, also known as a thermal quench in tokamak fusion. Here we show that the ele...
Preprint
Full-text available
The plasma exit flow speed at the sheath entrance is constrained by the Bohm criterion. The so-called Bohm speed regulates the plasma particle and power exhaust fluxes to the wall, and it is commonly deployed as a boundary condition to exclude the sheath region in quasi-neutral plasma modeling. Here the Bohm criterion analysis is performed in the i...
Article
This paper proposes a model of the laser-driven electron acceleration that occurs when a high-intensity laser interacts with a nanoplate target. It shows that quasistatic electric Eqs and magnetic Bqs fields can be formed when the laser, polarized normal to the nanoplates, extracts electrons from the nanoplates. Considering the physical natures of...
Article
The interaction of the drift wave (DW) turbulence and zonal flow (ZF) is investigated with the modified Hasegawa–Mima equation taking into account the backreaction of ZF velocity on DW turbulence. It is shown that the y-averaged enstrophy of DW turbulence and the velocity of ZF are intrinsically related. By utilizing this feature, a nonlinear stage...
Article
Full-text available
The generations of zonal flow (ZF) and density (ZD) and their feedback on the resistive drift wave turbulent transport are investigated within the modified Hasegawa-Wakatani model. With proper normalization, the system is only controlled by an effective adiabatic parameter, α, where the ZF dominates the collisional drift wave (DW) turbulence in the...
Article
An impact of neutrals on anomalous edge plasma transport and zonal flow (ZF) is considered. As an example, it is assumed that edge plasma turbulence is driven by the resistive drift wave (RDW) instability. It is found that the actual effect of neutrals is not related to a suppression of the instability \textit{per se}, but due to an impact on the Z...
Preprint
Full-text available
An impact of neutrals on anomalous edge plasma transport and zonal flow (ZF) is considered. As an example, it is assumed that edge plasma turbulence is driven by the resistive drift wave (RDW) instability. It is found that the actual effect of neutrals is not related to a suppression of the instability per se, but due to an impact on the ZF. Partic...
Article
The impact of velocity shear on the localized solutions of Rayleigh–Taylor (RT) and resistive drift wave (DW) instabilities has been investigated. Slab geometry is used, and the plasma density gradient is assumed to have a finite spatial structure. It demonstrates that the velocity shear has quite different effects on these instabilities: while it...
Article
Full-text available
The mechanisms of stochastic electron acceleration in relativistic laser pulses and stationary periodic electric and magnetic fields are investigated by employing a new Hamiltonian approach. The new Hamiltonian is the dephasing rate between the electron and laser pulse such that it is time independent when the stationary fields are absent. The phys...
Preprint
Full-text available
The effects of velocity shear on the interchange and resistive drift wave (DW) instabilities have been analyzed in detail, considering that the logarithmic gradient of equilibrium plasma density, $\Lambda_n=-dln(n_0)/dx$, has radial variation and thus forms effective potential well enabling localized solutions of perturbed electrostatic potential....
Preprint
The electron dynamics in counter-propagating laser waves is investigated by employing a novel approach, where the new Hamiltonian is time-independent when the perturbative laser wave is absent. The physical picture of stochastic electron dynamics is clearly revealed and the threshold values of the amplitude of the perturbative laser field for trigg...
Article
Full-text available
By deriving the 3/2 dimensional Hamiltonian equations for electrons in the intense laser radiation and quasi-static transverse electric and longitudinal magnetic fields, the electron heating mechanisms are examined both for low harmonic resonance of electron frequency in the static fields with the laser frequency and for high harmonic resonances wh...
Article
By deriving the 3/2 dimensional Hamiltonian equations for electrons in the intense laser radiation and quasi-static transverse electric and longitudinal magnetic fields, the electron heating mechanisms are examined both for low harmonic resonance of electron frequency in the static fields with the laser frequency and for high harmonic resonances wh...
Article
Full-text available
The mechanism of stochastic electron acceleration in colliding laser waves is investigated by employing proper canonical variables and effective time, such that the new Hamiltonian becomes time independent when the perturbative laser wave is absent. The performed analytical analysis clearly reveals the physical picture of stochastic electron dynami...
Preprint
Full-text available
The mechanism of stochastic electron acceleration in colliding laser waves is investigated by employing proper canonical variables and effective time, such that the new Hamiltonian becomes time independent when the perturbative (weaker) laser wave is absent. The performed analytical analysis clearly reveals the physical picture of stochastic electr...
Preprint
The mechanism of stochastic electron acceleration in the colliding laser waves is investigated by employing the 3/2 dimensional (3/2D) Hamiltonian approach. By choosing proper canonical variables and time, the Hamiltonian is time independent when the perturbative (weaker) laser wave disappears, which significantly simplifies the analyses of electro...
Article
Full-text available
The electron dynamics in the ultra-high intensity laser pulse with radiation friction force in the Landau-Lifshitz form are studied. It is demonstrated that widely used approximation, where only the term dominating the dissipation of electron kinetic energy is retained in the expression for the radiation friction, is incorrect for the case of diver...
Preprint
The electron dynamics in the ultra-high intensity laser pulse with radiation friction force in the Landau-Lifshitz form are studied. It is demonstrated that widely used approximation, where only the term dominating the dissipation of electron kinetic energy is retained in the expression for the radiation friction, is incorrect for the case of diver...
Preprint
The dynamics of ultrarelativistic electrons in the intense laser radiation and quasi-static electromagnetic fields both along and across to the laser propagating direction are studied in the 3/2 dimensional Hamiltonian framework. It is shown that the unperturbed oscillations of the ultrarelativistic electron in these electric fields could exhibit a...
Preprint
Full-text available
The dynamics of ultrarelativistic electrons in the intense laser radiation and quasi-static electromagnetic fields both along and across to the laser propagating direction are studied in the 3/2 dimensional Hamiltonian framework. It is shown that the unperturbed oscillations of the ultrarelativistic electron in these electric fields could exhibit a...
Preprint
Full-text available
By deriving the 3/2 dimensional Hamiltonian method for electrons in the intense laser radiation and quasi-static transverse electric and longitudinal magnetic fields, the electron heating mechanisms are examined both for low harmonic resonance of electron frequency in the static fields with the laser frequency and for high harmonic resonances where...
Preprint
The electron dynamics in the ultra-high intensity laser pulse with radiation friction force in theLandau-Lifshitz form are studied. It is demonstrated that widely used approximation, where onlythe term dominating the dissipation of electron kinetic energy is retained in the expression for theradiation friction, is incorrect for the case of divergin...
Article
3/2 dimensional Hamiltonian equations, accounting for arbitrary polarized plane wave laser radiation and arbitrary electric and magnetic fields in the directions both along and across to the direction of the laser beam propagation, are derived for superluminal phase velocity of the laser radiation. An impact of superluminal laser radiation phase ve...
Article
Full-text available
A 2D slab approximation of the interactions of electrons with intense linearly polarized laser radiation and static electric and magnetic fields is widely used for both numerical simulations and simplified semi-analytical models. It is shown that in this case, electron dynamics can be conveniently described in the framework of the 3/2 dimensional H...
Preprint
3/2 dimensional Hamiltonian equations, accounting for arbitrary polarized plane wave laser radiation and arbitrary electric and magnetic fields in the directions both along and across to the direction of the laser beam propagation, are derived for superluminal phase velocity of the laser radiation. An impact of superluminal laser radiation phase ve...
Article
The paper presents an overview of the results of studies on a wide range of the edge plasma related issues. The rollover of the plasma flux to the target during progressing detachment process is shown to be caused by the increase of the impurity radiation loss and volumetric plasma recombination, whereas the ion-neutral friction, although important...
Article
Full-text available
The 2D simulations of edge plasma transport show that unlike some earlier publications, the impurity radiation loss per se does not cause the bifurcation-like transition to detached divertor regime. However, for the case where anomalous plasma transport is increasing with advancement to detachment, like it was recently observed experimentally, the...
Article
Full-text available
Analytic solutions for blob-like structures obtained in S. I. Krasheninnikov [Phys. Lett. A 380, 3905 (2016)], are examined in detail. Numerical solutions for the cases where analytic consideration is not possible are provided.

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Project (1)
Project
Analytically investigate the mechanism of electron heating in the course of laser plasma interactions