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Scattering of radio frequency waves by cylindrical filaments with general orientation relative to the magnetic field

Part of: PLA 17th European Fusion Theory Conference Focus on Fusion

Published online by Cambridge University Press:  18 December 2018

S. I. Valvis ,
A. K. Ram ,
K. Hizanidis ,
P. Papagiannis ,
A. Papadopoulos ,
A. Zisis ,
I. G. Tigelis  and
E. Glytsis
S. I. Valvis*
Affiliation:
School of Electrical and Computer Engineering, National Technical University of Athens, 9 Iroon Polytechniou Street, Athens 15780, Greece
A. K. Ram
Affiliation:
Plasma Science and Fusion Center, Massachusetts Institute of Technology, 175 Albany Street, Cambridge, MA 02139, USA
K. Hizanidis
Affiliation:
School of Electrical and Computer Engineering, National Technical University of Athens, 9 Iroon Polytechniou Street, Athens 15780, Greece
P. Papagiannis
Affiliation:
School of Electrical and Computer Engineering, National Technical University of Athens, 9 Iroon Polytechniou Street, Athens 15780, Greece
A. Papadopoulos
Affiliation:
School of Electrical and Computer Engineering, National Technical University of Athens, 9 Iroon Polytechniou Street, Athens 15780, Greece
A. Zisis
Affiliation:
Faculty of Physics, National and Kapodistrian University of Athens, University Campus, Zografou, Athens 15784, Greece
I. G. Tigelis
Affiliation:
Faculty of Physics, National and Kapodistrian University of Athens, University Campus, Zografou, Athens 15784, Greece
E. Glytsis
Affiliation:
School of Electrical and Computer Engineering, National Technical University of Athens, 9 Iroon Polytechniou Street, Athens 15780, Greece
*
†Email address for correspondence: jasonv@central.ntua.gr
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Abstract

Radio frequency (RF) waves are routinely used in tokamak fusion plasmas for plasma heating, current control, as well as in diagnostics. These waves are excited by antenna structures placed near the tokamak’s wall and they have to propagate through a turbulent layer known as the scrape-off layer, before reaching the core plasma (which is their target). This layer exhibits coherent density fluctuations in the form of filaments and blobs. The scattering processes of RF plane waves by a single filament is studied with the assumption that the filament has a cylindrical shape and infinite length. Furthermore, besides the major toroidal component of the externally imposed magnetic field, there is also a small poloidal magnetic field component. Considering also that the cylindrical filament’s axis is not necessarily aligned with the toroidal direction, the total magnetic field is in general neither aligned with the axis of the cylinder nor with the toroidal direction. The investigation concerns the case of electron cyclotron (EC) waves (of frequency $f_{0}=170~\text{GHz}$) for tokamak applications. The study covers a variety of density contrasts between the filament and the ambient plasma, different magnetic field inclinations with respect to the cylinder axis (for the same magnitude of magnetic induction $B=4.5T$) and a wide range of filament radii.

Keywords

fusion plasmaplasma waves
Type
Research Article
Information
Journal of Plasma Physics , Volume 84 , Issue 6 , December 2018 , 745840604
Copyright
© Cambridge University Press 2018 

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