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1994
Earlier two-dimensional (radial and poloidal angle), analytically tractable ion kinetic models of the scrape-off layer (SOL) in which a steady state is achieved by balancing the streaming loss of ions to the divertor target plates with the radial diffusion of ions from the core are unable to distinguish between limited and diverted plasmas. The mod…
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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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1993
Nearly all kinetic treatments of fast wave minority heating of inhomogeneous plasma in the cyclotron range of frequencies assume the magnetic field varies in the direction perpendicular to the magnetic field. However, the toroidal magnetic field of a tokamak varies along a field line due to the rotational transform and causes a small number of trap…
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1992
A full-wave equation has been obtained from the gyrokinetic theory for the fast wave traversing a minority cyclotron resonance [Phys. Fluids B 4, 493 ( 1992)] with the aid of the fast wave approximation [Phys. Fluids 31, 1614 (1988)]. This theory describes the transmission, reflection, and absorption of the fast wave for arbitrary values of the par…
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1992
A compact seven channel interferometer has been designed and built to measure electron density profiles in the COMPASS (compact assembly) tokamak. Two far-infrared (FIR) laser cavities are optically pumped with a single continuous-wave CO2 laser, generating two similar beams, with a small, tunable difference frequency (0.5-1.0 MHz). The COMPASS fac…
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1992
09The thin beam model of an axis-encircling relativistic electron beam in a uniform, constant, external magnetic field in a cylindrical waveguide is used to develop a unified theory of the various interactions of such a beam with the electromagnetic field. The model includes the gyrotron interaction (longitudinal displacement of the beam) and the p…
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1992
Impurities in fusion plasmas lead to a loss of reactivity by radiation and fuel dilution. 1 The impurity concentration in the plasma is determined both by the production rate and transport in the plasma, particularly the transport in the boundary layer. 1'2 In this layer impurities, usually starting as cold atoms or molecules, are ionised and heate…
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1991
The gyrokinetic theory of ion cyclotron resonance is extended to include propagation at arbitrary angles to a straight equilibrium magnetic field with a linear perpendicular gradient in strength. The case of the compressional Alfvén wave propagating in a D(3He) plasma is analyzed in detail. A self-consistent local dispersion relation is obtained u…
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1991
The question of the influence of nonaxisymmetric field perturbations on tokamaks is investigated. Recent experiments in the COMPASS-C tokamak [in Proceedings of the 15th Symposium on Fusion Technology, Utrecht (North-Holland, Amsterdam, 1989), Vol. 1, p. 3611 with externally applied helical fields reveal that magnetic islands do not appear until th…
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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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