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1997
Electron cyclotron absorption (ECA) of electromagnetic radiation at the second harmonic is of interest in Tokamak physics both for plasma heating and current drive, as well as for some diagnostics. Modelling of the linear wave propagation for such problems is usually done by WKB ray tracing, despite the fact that the WKB theory is not strictly vali…
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1997
We apply a fast wave approximation to the propagation of the fast wave across the magnetic field. This approximation involves replacing the hot plasma conductivity tensor by an approximation which reduces the problem to a second order differential equation. Such a procedure is particularly useful in the high harmonic regime, where many terms with t…
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1996
The stability of the ion hybrid wave in a plasma containing two thermal ion species present in comparable proportions and a low density population of superthermal alpha-particles is analyzed. A simple, model distribution function consisting of a ring distribution in the perpendicular velocity and a Maxwellian in the parallel velocity is used for th…
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1996
In a fusion plasma ion cyclotron heating may be applied to a plasma in a regime where there is a population of ions whose Larmor radius is not small compared to the perpendicular wavelength. In this case the equations describing the propagation and absorption of the wave are integro-differential, describing the non-local response of the plasma to t…
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1995
Absorption of waves propagating across an inhomogenous magnetic field is of crucial importance for cyclotron resonance heating. When the Larmor radius of the resonant particles is small compared to the wavelength then the propagation is described by differential equations, a comparatively simple method for obtaining which has recently been given by…
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1994
When a wave passes through an electron gyroresonance, in a plasma in the presence of a magnetic field gradient, there is a small spread in the resonance due to the electron's Larmor radius. Mathematically this is represented by the inclusion of the so called gyrokinetic term in the resonance condition, Lashmore-Davies and Dendy 1. The smallness of …
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1991
The inclusion of the variation of the equilibrium magnetic field across the Larmor orbits of the resonant particles is crucial for a self-consistent treatment of cyclotron resonance in plasmas. Two contrasting nonrelativistic self-consistent calculations [T. M. Antonsen and W. M. Manheimer, Phys. Fluids 21,2295 (1978); C. N. Lashmore-Davies and R. …
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1991
The Euler-Lagrange equations for a charged particle in a tokamak magnetic fieid, in the limit of large aspect ratio, are obtained in terms of toroidal coordinates from the exact Lagrangian, which is expressed in terms of the toroidal and poloidal magnetic fluxes. It differs fundamentally from the standard guiding-center approach, where the local ma…
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