A parameter study of mode conversion at ion-ion hybrid resonances for ICRF-heating

Jukka Heikkinen, Mikko Alava

Research output: Contribution to journalArticleScientificpeer-review

6 Citations (Scopus)

Abstract

By solving the wave equation for the radial electric field with constant poloidal electric field around the resonance layer of the fast Alfvén wave, various complex characteristics of mode conversion physics can be elucidated and analyzed for ion cyclotron heating of tokamaks.
The validity of the Budden and tunnelling model [Ngan, Y. C. and Swanson, D. G., Phys. Fluids 20, 1920 (1977)] for the conversion studies is explored, and the conversion coefficient for the ion-ion hybrid resonance in the presence of cyclotron damping is found in closed form. The analytical results are compared with the numerical solution of the full wave equations expanded to second order in ion Larmor radius.
It is found that the standard tunnelling solutions can be erroneous, not only in the case of strong damping, but also when the linearization of the plasma parameters around the resonance, peculiar to the tunnelling model, becomes inaccurate.
The effects of the damping and cavity resonances on the conversion are separated in the derived analytical estimates, and the limits of the local theory of conversion are determined.
Original languageEnglish
Pages (from-to)345-357
JournalPhysica Scripta
Volume45
Issue number4
DOIs
Publication statusPublished - 1992
MoE publication typeA1 Journal article-refereed

Fingerprint

Heating
heating
Damping
damping
ions
wave equations
cyclotrons
Wave equation
Electric Field
Larmor radius
electric fields
linearization
Inaccurate
Linearization
Cavity
Closed-form
Plasma
Radius
Physics
Numerical Solution

Cite this

Heikkinen, Jukka ; Alava, Mikko. / A parameter study of mode conversion at ion-ion hybrid resonances for ICRF-heating. In: Physica Scripta. 1992 ; Vol. 45, No. 4. pp. 345-357.
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abstract = "By solving the wave equation for the radial electric field with constant poloidal electric field around the resonance layer of the fast Alfv{\'e}n wave, various complex characteristics of mode conversion physics can be elucidated and analyzed for ion cyclotron heating of tokamaks. The validity of the Budden and tunnelling model [Ngan, Y. C. and Swanson, D. G., Phys. Fluids 20, 1920 (1977)] for the conversion studies is explored, and the conversion coefficient for the ion-ion hybrid resonance in the presence of cyclotron damping is found in closed form. The analytical results are compared with the numerical solution of the full wave equations expanded to second order in ion Larmor radius. It is found that the standard tunnelling solutions can be erroneous, not only in the case of strong damping, but also when the linearization of the plasma parameters around the resonance, peculiar to the tunnelling model, becomes inaccurate. The effects of the damping and cavity resonances on the conversion are separated in the derived analytical estimates, and the limits of the local theory of conversion are determined.",
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A parameter study of mode conversion at ion-ion hybrid resonances for ICRF-heating. / Heikkinen, Jukka; Alava, Mikko.

In: Physica Scripta, Vol. 45, No. 4, 1992, p. 345-357.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - A parameter study of mode conversion at ion-ion hybrid resonances for ICRF-heating

AU - Heikkinen, Jukka

AU - Alava, Mikko

N1 - Project code: YDI0030

PY - 1992

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N2 - By solving the wave equation for the radial electric field with constant poloidal electric field around the resonance layer of the fast Alfvén wave, various complex characteristics of mode conversion physics can be elucidated and analyzed for ion cyclotron heating of tokamaks. The validity of the Budden and tunnelling model [Ngan, Y. C. and Swanson, D. G., Phys. Fluids 20, 1920 (1977)] for the conversion studies is explored, and the conversion coefficient for the ion-ion hybrid resonance in the presence of cyclotron damping is found in closed form. The analytical results are compared with the numerical solution of the full wave equations expanded to second order in ion Larmor radius. It is found that the standard tunnelling solutions can be erroneous, not only in the case of strong damping, but also when the linearization of the plasma parameters around the resonance, peculiar to the tunnelling model, becomes inaccurate. The effects of the damping and cavity resonances on the conversion are separated in the derived analytical estimates, and the limits of the local theory of conversion are determined.

AB - By solving the wave equation for the radial electric field with constant poloidal electric field around the resonance layer of the fast Alfvén wave, various complex characteristics of mode conversion physics can be elucidated and analyzed for ion cyclotron heating of tokamaks. The validity of the Budden and tunnelling model [Ngan, Y. C. and Swanson, D. G., Phys. Fluids 20, 1920 (1977)] for the conversion studies is explored, and the conversion coefficient for the ion-ion hybrid resonance in the presence of cyclotron damping is found in closed form. The analytical results are compared with the numerical solution of the full wave equations expanded to second order in ion Larmor radius. It is found that the standard tunnelling solutions can be erroneous, not only in the case of strong damping, but also when the linearization of the plasma parameters around the resonance, peculiar to the tunnelling model, becomes inaccurate. The effects of the damping and cavity resonances on the conversion are separated in the derived analytical estimates, and the limits of the local theory of conversion are determined.

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