Effect of antenna orientation and plasma anisotropy on the directivity of fast wave antenna radiation

Igor Pavlov, Jukka Heikkinen

Research output: Contribution to journalArticleScientificpeer-review

8 Citations (Scopus)

Abstract

Asymmetry in the transverse wave number spectrum of the radiated power of a screenless fast wave antenna at an ion cyclotron range of frequencies is calculated with a model that takes into account the nonsymmetry of the plasma surface impedance matrix for an inhomogeneous tokamak plasma in front of the antenna.
The directivity of the wave number spectrum transverse to the ambient magnetic field caused by the asymmetry in the surface impedance is found to be strongly asymmetric with respect to the parallel wave number by the effect of the nonperpendicular angle between the antenna current strap and the magnetic field. The latter is shown to be responsible also for the asymmetry in the parallel wave number spectrum of an undirected antenna, and can lead to deviations of order ≤30% in the corresponding spectrum of a phased antenna array with directivity.
The consequences of the observed effects to the antenna performance in the current drive applications as well as in excitation of poloidally asymmetric spectra are discussed.
Original languageEnglish
Pages (from-to)3573-3581
JournalPhysics of Plasmas
Volume2
Issue number10
DOIs
Publication statusPublished - 1995
MoE publication typeA1 Journal article-refereed

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directivity
antennas
anisotropy
radiation
asymmetry
impedance
straps
transverse waves
antenna arrays
phased arrays
magnetic fields
cyclotrons
deviation
matrices
excitation
ions

Cite this

Pavlov, Igor ; Heikkinen, Jukka. / Effect of antenna orientation and plasma anisotropy on the directivity of fast wave antenna radiation. In: Physics of Plasmas. 1995 ; Vol. 2, No. 10. pp. 3573-3581.
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abstract = "Asymmetry in the transverse wave number spectrum of the radiated power of a screenless fast wave antenna at an ion cyclotron range of frequencies is calculated with a model that takes into account the nonsymmetry of the plasma surface impedance matrix for an inhomogeneous tokamak plasma in front of the antenna. The directivity of the wave number spectrum transverse to the ambient magnetic field caused by the asymmetry in the surface impedance is found to be strongly asymmetric with respect to the parallel wave number by the effect of the nonperpendicular angle between the antenna current strap and the magnetic field. The latter is shown to be responsible also for the asymmetry in the parallel wave number spectrum of an undirected antenna, and can lead to deviations of order ≤30{\%} in the corresponding spectrum of a phased antenna array with directivity. The consequences of the observed effects to the antenna performance in the current drive applications as well as in excitation of poloidally asymmetric spectra are discussed.",
author = "Igor Pavlov and Jukka Heikkinen",
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Effect of antenna orientation and plasma anisotropy on the directivity of fast wave antenna radiation. / Pavlov, Igor; Heikkinen, Jukka.

In: Physics of Plasmas, Vol. 2, No. 10, 1995, p. 3573-3581.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Effect of antenna orientation and plasma anisotropy on the directivity of fast wave antenna radiation

AU - Pavlov, Igor

AU - Heikkinen, Jukka

N1 - Project code: ENE0630

PY - 1995

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N2 - Asymmetry in the transverse wave number spectrum of the radiated power of a screenless fast wave antenna at an ion cyclotron range of frequencies is calculated with a model that takes into account the nonsymmetry of the plasma surface impedance matrix for an inhomogeneous tokamak plasma in front of the antenna. The directivity of the wave number spectrum transverse to the ambient magnetic field caused by the asymmetry in the surface impedance is found to be strongly asymmetric with respect to the parallel wave number by the effect of the nonperpendicular angle between the antenna current strap and the magnetic field. The latter is shown to be responsible also for the asymmetry in the parallel wave number spectrum of an undirected antenna, and can lead to deviations of order ≤30% in the corresponding spectrum of a phased antenna array with directivity. The consequences of the observed effects to the antenna performance in the current drive applications as well as in excitation of poloidally asymmetric spectra are discussed.

AB - Asymmetry in the transverse wave number spectrum of the radiated power of a screenless fast wave antenna at an ion cyclotron range of frequencies is calculated with a model that takes into account the nonsymmetry of the plasma surface impedance matrix for an inhomogeneous tokamak plasma in front of the antenna. The directivity of the wave number spectrum transverse to the ambient magnetic field caused by the asymmetry in the surface impedance is found to be strongly asymmetric with respect to the parallel wave number by the effect of the nonperpendicular angle between the antenna current strap and the magnetic field. The latter is shown to be responsible also for the asymmetry in the parallel wave number spectrum of an undirected antenna, and can lead to deviations of order ≤30% in the corresponding spectrum of a phased antenna array with directivity. The consequences of the observed effects to the antenna performance in the current drive applications as well as in excitation of poloidally asymmetric spectra are discussed.

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