One-dimensional full wave treatment of mode conversion process at the ion–ion hybrid resonance in a bounded tokamak plasma

1999 ◽  
Vol 6 (3) ◽  
pp. 885-896 ◽  
Author(s):  
I. Monakhov ◽  
A. Bécoulet ◽  
D. Fraboulet ◽  
F. Nguyen
Keyword(s):  
Mode Conversion ◽  
Conversion Process ◽  
Tokamak Plasma ◽  
One Dimensional ◽  
Wave Treatment ◽  
Full Wave ◽  
Hybrid Resonance

scholarly journals Visualization of the O-X-B Mode Conversion Process With a Full-Wave Code

2008 ◽  
Vol 36 (4) ◽  
pp. 1220-1221 ◽  
Author(s):  
A. Kohn ◽  
E. Holzhauer ◽  
U. Stroth
Keyword(s):  
Mode Conversion ◽  
Conversion Process ◽  
Full Wave

One-dimensional full wave simulation on XB mode conversion in electron cyclotron heating

2014 ◽  
Vol 21 (6) ◽  
pp. 062108 ◽  
Author(s):  
S. H. Kim ◽  
H. Y. Lee ◽  
J. G. Jo ◽  
Y. S. Hwang
Keyword(s):  
Mode Conversion ◽  
Electron Cyclotron ◽  
Electron Cyclotron Heating ◽  
One Dimensional ◽  
Wave Simulation ◽  
Full Wave

Full-wave calculations of the O-X mode conversion process

1988 ◽  
Vol 39 (2) ◽  
pp. 319-337 ◽  
Author(s):  
F. R. Hansen ◽  
J. P. Lynov ◽  
C. Maroli ◽  
V. Petrillo
Keyword(s):  
Wave Propagation ◽  
Boundary Value Problem ◽  
Numerical Solutions ◽  
Mode Conversion ◽  
Inhomogeneous Plasma ◽  
Collisionless Plasma ◽  
Point Boundary ◽  
Full Wave ◽  
Hybrid Resonance ◽  
Scale Length

A two-point boundary-value problem has been formulated that describes the conversion between ordinary (O) and extraordinary (X) wave modes in a cold inhomogeneous plasma. Numerical solutions to this problem have been obtained for various values of the WKB parameter k0L; where k0 is the vacuum wavenumber and L the density-gradient scale length. The results are compared with three different theoretical expressions for the O-X mode conversion efficiency derived by others in the WKB limit of k0 L ≫ l. Most of the results presented in this paper are obtained for a collisionless plasma with finite density near the plasma cut-off density. However, some examples are also given of wave propagation from vacuum. In these examples, collision effects are added to the equations in order to remove the singularity otherwise present at the position of the upper hybrid resonance layer.

Coupled full-wave and ray-tracing numerical treatment of mode conversion in a tokamak plasma

2000 ◽  
Vol 7 (3) ◽  
pp. 911-922 ◽  
Author(s):  
Yu. Petrov ◽  
A. Bécoulet ◽  
I. Monakhov
Keyword(s):  
Ray Tracing ◽  
Mode Conversion ◽  
Tokamak Plasma ◽  
Numerical Treatment ◽  
Full Wave

scholarly journals Interaction of equivalence ratio fluctuations and flow fluctuations in acoustically forced swirl flames

2021 ◽  
pp. 175682772110155
Author(s):  
Vincent Kather ◽  
Finn Lückoff ◽  
Christian O. Paschereit ◽  
Kilian Oberleithner
Keyword(s):  
Equivalence Ratio ◽  
Transfer Functions ◽  
Transport Model ◽  
Mode Conversion ◽  
Fuel Injector ◽  
One Dimensional ◽  
Flow Fluctuations ◽  
Non Linear ◽  
Non Local ◽  
Acoustic Forcing

The generation and turbulent transport of temporal equivalence ratio fluctuations in a swirl combustor are experimentally investigated and compared to a one-dimensional transport model. These fluctuations are generated by acoustic perturbations at the fuel injector and play a crucial role in the feedback loop leading to thermoacoustic instabilities. The focus of this investigation lies on the interplay between fuel fluctuations and coherent vortical structures that are both affected by the acoustic forcing. To this end, optical diagnostics are applied inside the mixing duct and in the combustion chamber, housing a turbulent swirl flame. The flame was acoustically perturbed to obtain phase-averaged spatially resolved flow and equivalence ratio fluctuations, which allow the determination of flux-based local and global mixing transfer functions. Measurements show that the mode-conversion model that predicts the generation of equivalence ratio fluctuations at the injector holds for linear acoustic forcing amplitudes, but it fails for non-linear amplitudes. The global (radially integrated) transport of fuel fluctuations from the injector to the flame is reasonably well approximated by a one-dimensional transport model with an effective diffusivity that accounts for turbulent diffusion and dispersion. This approach however, fails to recover critical details of the mixing transfer function, which is caused by non-local interaction of flow and fuel fluctuations. This effect becomes even more pronounced for non-linear forcing amplitudes where strong coherent fluctuations induce a non-trivial frequency dependence of the mixing process. The mechanisms resolved in this study suggest that non-local interference of fuel fluctuations and coherent flow fluctuations is significant for the transport of global equivalence ratio fluctuations at linear acoustic amplitudes and crucial for non-linear amplitudes. To improve future predictions and facilitate a satisfactory modelling, a non-local, two-dimensional approach is necessary.

scholarly journals Simulation of mode conversion process from upper-hybrid waves to LO-mode waves in the vicinity of the plasmapause

2010 ◽  
Vol 28 (6) ◽  
pp. 1289-1297 ◽  
Author(s):  
M. J. Kalaee ◽  
Y. Katoh ◽  
A. Kumamoto ◽  
T. Ono ◽  
Y. Nishimura
Keyword(s):  
Density Gradient ◽  
Electric Fields ◽  
Numerical Experiments ◽  
Mode Conversion ◽  
Equatorial Region ◽  
Magnetized Plasma ◽  
Conversion Process ◽  
Observation Data ◽  
Linear Mode ◽  
Wave Normal

Abstract. In order to clarify the role of the mode conversion process in the generation mechanism of LO-mode waves in the equatorial region of the plasmasphere, we have investigated the linear mode conversion process among upper-hybrid-resonance (UHR)-mode, Z-mode and LO-mode waves by a numerical simulation solving Maxwell's equations and the equation of motion of a cold electron fluid. The wave coupling process occurring in the cold magnetized plasma are examined in detail. In order to give a realistic initial plasma condition in the numerical experiments, we use initial parameters inferred from observation data obtained around the generation region of LO-mode waves obtained by the Akebono satellite. A density gradient is estimated from the observed UHR frequency, and wave normal angles are estimated from the dispersion relation of cold plasma by comparing observed wave electric fields. Then, we perform numerical experiments of mode conversion processes using the density gradient of background plasma and the wave normal angle of incident upper hybrid mode waves determined from the observation results. We found that the characteristics of reproduced LO-mode waves in each simulation run are consistent with observations.

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