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Global Transition From Drift Wave Dominated Regimes To Multi-Instability Plasma Dynamics And Simultaneous Formation Of A Radial Transport Barrier
Published in B. Raneesh, Nandakumar Kalarikkal, Jemy James, Anju K. Nair, Plasma and Fusion Science, 2018
Saikat Chakraborty Thakur, Christian brandt, George R. Tynan
Here we describe new experimental results that help in understanding the plasma dynamics behind the formation of the helicon core. We point out in this study that it is not necessary for core formation to accompany the inductive - helicon transition. A few previous studies have shown that the helicon mode exists even without the formation of the core [27, 42], mostly in the m = 0 (antenna having only circular coils, without the heli- cal connections, [33]) helicon antenna. Moreover, in many cases the word “core” is very loosely used and even any central brightening of the plasma emission is thought to be a “core.” In this chapter, we present experimen- tal results that clearly distinguish between the inductive - helicon mode transition in an RF heated, argon plasma, and the formation of the classic “blue core.” For certain source parameters, helicon plasma (shown by the discrete jump to high densities with increasing power and magnetic field, strong Ar-II emission, peaked central densities, low plasma potential, etc.) can occur without the formation of a distinct core. For such conditions, the plasma is dominated by low frequency resistive drift wave (RDW) instabilities driven by the radial density gradient. Note that in the helicon mode, the central densities are very peaked and the corresponding density gradient is sufficient to drive resistive drift waves [5,21,28]. The RDWs propagate in the electron diamagnetic drift direction and the resulting par- ticle flux is radially outwards for all radii.
Self-Controlled Flashing Nuclear Fusion in Stationary Magnetized Low-Temperature Plasma
Published in Fusion Science and Technology, 2023
V. I. Vysotskii, M. V. Vysotskyy
This analysis makes it possible to predict the implementation of self-sustaining nuclear fusion in a magnetized low-temperature plasma under conditions that are much less critical and easily implemented compared to standard thermonuclear fusion. This analysis is also a kind of bridge between two disparate areas of plasma physics: Study of the features of collective oscillations and waves in a magnetoactive low-temperature plasma (Alfvén waves, magnetosonic waves, cyclotron waves, electron-sound waves, drift waves, etc.).Optimization of hot thermonuclear fusion in the volume of a high-current plasma magnetic pinch formed by the flow of a strong electric current through the plasma in tokamak-type systems.
Electron-acoustic solitons and double layers in a non-uniform plasma with field-aligned shear flow
Published in Waves in Random and Complex Media, 2022
Shaukat Ali Shan, Hamid Saleem
We have shown the effects of the different values of shear flow parameter , the ratio of temperatures and κ factor on the shape of the DLs and solitons using numerical solutions of the nonlinear differential equations (24) and (34), respectively. We do not use the bifurcation theory for the analysis of linear and nonlinear equations. A detailed phase plane analysis of nonlinear and supernonlinear electron-acoustic waves has been presented in Ref. [29] using KdV and modified KdV (mKdV), further modified KdV, and modified Gardner equations. These authors considered the hot electrons to follow the q-nonextensive velocity distribution for hot electrons and homogeneous density plasma. Supernonlinear waves have also been investigated in Ref. [30]. On the other hand, our focus is to investigate the formation of nonlinear structures (DLs and solitons) by the coupled EAW and electron drift waves in a plasma having field-aligned shear flow of cold electrons in the presence of non-thermal hot electrons. In limiting cases, the nonlinear structures formed by EAW and electron drift wave have also been studied by solving the nonlinear equations numerically. We also apply our results to the dayside auroral region plasma to show that the electrostatic DLs and solitons are formed in this region by the EAWs and electron drift waves in the presence of shear flow.
Breakup of transport barriers in plasmas with flow described by symplectic maps
Published in Radiation Effects and Defects in Solids, 2022
Carolina A. Tafoya, Julio J. Martinell
The transport barriers due to the presence of sheared flows in a plasma in combination with drift waves in two dimensions have been analyzed. Plasma wave interactions are modeled by a guiding center approach of test particles with FLR corrections. The description is reduced to a symplectic iterative map which is used to follow the evolution of an ensemble of particles in an efficient way. The chosen wave spectrum (Equation (1)) leads to a map that is a particular case of the well known kicked Harper model, which leads to chaotic orbits when the wave amplitude A is increased. The resulting diffusive transport scales like . FLR effects reduce the level of chaos. When the shear flow is added, the map is modified by the appearance of integrable KAM surfaces that run along the flow direction. These surfaces do not let the chaos propagate to cover all phase space and thus act as transport barriers.