scholarly journals Local Stability Analysis of Three-dimensional Magnetically Confined Plasmas

1997 ◽  
Vol 50 (5) ◽  
pp. 921 ◽  
Author(s):  
J. L. V. Lewandowski
Keyword(s):  
Stability Analysis ◽  
Phase Angle ◽  
Local Stability ◽  
Three Dimensional ◽  
Magnetic Shear ◽  
Confined Plasmas ◽  
Fluid Displacement ◽  
Local Stability Analysis ◽  
Magnetically Confined ◽  
Magnetically Confined Plasmas

Local stability analysis of three-dimensional magnetically confined plasmas is presented using the energy principle. Fluid displacements with long parallel wavelengths by short perpendicular are retained. To lowest order in the mode fluteness the total energy density variation depends on the local magnetic shear, normal and geodesic magnetic curvatures, parallel current density, and magnetic field strength. The perpendicular fluid displacement is written in terms of a slowly-varying amplitude and a phase angle which varies rapidly in (or across) the magnetic surface. Assuming that the fluid displacement is quasi-incompressible, the solution for the phase angle is found in two limiting cases. Local stability analysis of stellarators with low or strong global magnetic shear is discussed.

scholarly journals Energetic electron transport in the presence of magnetic perturbations in magnetically confined plasmas

2015 ◽  
Vol 81 (5) ◽  
Author(s):  
G. Papp ◽  
M. Drevlak ◽  
G. I. Pokol ◽  
T. Fülöp
Keyword(s):  
Test Particle ◽  
Energetic Electron ◽  
Three Dimensional ◽  
Confined Plasmas ◽  
Magnetically Confined ◽  
Magnetic Perturbations ◽  
Open Region ◽  
Particle Simulations ◽  
Drift Orbits ◽  
Magnetically Confined Plasmas

The transport of energetic electrons is sensitive to magnetic perturbations. By using three-dimensional numerical simulation of test particle drift orbits we show that the transport of untrapped electrons through an open region with magnetic perturbations cannot be described by a diffusive process. Based on our test particle simulations, we propose a model that leads to an exponential loss of particles.

scholarly journals Towards a quantitative comparison between global and local stability analysis

2017 ◽  
Vol 819 ◽  
pp. 147-164 ◽  
Author(s):  
L. Siconolfi ◽  
V. Citro ◽  
F. Giannetti ◽  
S. Camarri ◽  
P. Luchini
Keyword(s):  
Stability Analysis ◽  
Saddle Point ◽  
Global Stability ◽  
Local Stability ◽  
Correction Term ◽  
Three Dimensional ◽  
Higher Order ◽  
Order Correction ◽  
Global Stability Analysis ◽  
Local Stability Analysis

A methodology is proposed here to estimate the stability characteristics of bluff-body wakes using local analysis under the assumption of weakly non-parallel flows. In this connection, a generalisation of the classic spatio-temporal stability analysis for fully three-dimensional flows is first described. Secondly, an additional higher-order correction term with respect to the common saddle-point global frequency estimation is included in the analysis. The proposed method is first validated for the case of the flow past a circular cylinder and then applied to two fully three-dimensional flows: the boundary layer flow over a wall-mounted hemispherical body and the wake flow past a fixed sphere. In all the cases considered, both the estimated unstable eigenvalue and the spatial shape of the associated eigenmode are determined by local stability analysis, and they are compared with the reference counterparts obtained at a definitely higher computational cost by a fully three-dimensional global stability analysis. It is shown that the results of local stability analysis, when the higher-order correction term is included, are in excellent agreement with those obtained by global stability analysis. It is also shown that the retained correction term is of crucial importance in this perspective, leading to a remarkable improvement in accuracy with respect to the classical saddle-point estimation.

scholarly journals The field line map approach for simulations of magnetically confined plasmas

2016 ◽  
Vol 198 ◽  
pp. 139-153 ◽  
Author(s):  
Andreas Stegmeir ◽  
David Coster ◽  
Omar Maj ◽  
Klaus Hallatschek ◽  
Karl Lackner
Keyword(s):  
Field Line ◽  
Confined Plasmas ◽  
Magnetically Confined ◽  
Magnetically Confined Plasmas ◽  
Map Approach

scholarly journals Turbulent transport across shear layers in magnetically confined plasmas

2014 ◽  
Vol 21 (10) ◽  
pp. 102304 ◽  
Author(s):  
B. Nold ◽  
P. Manz ◽  
T. T. Ribeiro ◽  
G. Fuchert ◽  
G. Birkenmeier ◽  
...  
Keyword(s):  
Turbulent Transport ◽  
Shear Layers ◽  
Confined Plasmas ◽  
Magnetically Confined ◽  
Magnetically Confined Plasmas
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