H. R. Wilson J. W. Connor R. J. Hastie C. C. Hegna
A kinetic theory for magnetic islands in a low collision frequency tokamak plasma is presented. Self-consistent equations for the islands’ width, w , and propagation frequency, w , are derived. These include contributions from the perturbed bootstrap current and the toroidally enhanced ion polarization drift. The bootstrap current is ind…
PublishedP. G. Carolan R. O’Connell
A multianode photomultiplier (8X8 anodes of 2.5X2.5 mm2) is used to detect a collection of spectra in a high dispersion echelle spectrometer. A cylindrical lens is placed at the output slit to increase the dispersion at the photomultiplier. The cross talk between adjacent spectra is non-negligible (although
PublishedD. C. Mcdonald R. A. Cairns C. N. Lashmore-Davies
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 …
PublishedPeter J. Catto J. W. Connor
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…
PublishedR. Prentice T. Edlington R. T. C. Smith D. L. Trotman R. J. Wylde et al.
An interferometer with compensation for vibration and large scale mechanical movements has been designed and built to measure the line integral electron density along three different lines of sight through the JET divertor plasma. Overcoming the effects of a long transmission path, having an estimated 65 dB loss, requires oversized waveguide transm…
PublishedN. J. Peacock R. Barnsley A. Patel M. O’Mullane M. Singleton et al.
Quantitative measurements of the line and continua emissivities and the analyses of spectral line profiles are essential steps in the interpretation of the x-ray emission from high-temperature fusion plasmas. One method of placing the emissivities on an absolute basis is to use an absolutely calibrated spectrometer to record the data. The overall s…
PublishedR. O. Dendy C. N. Lashmoredavies K. F. Kam
The magnetoacoustic cyclotron instability is a mechanism by which waves on the perpendicular fast Alfvén-ion Bernstein branch can be excited through cyclotron resonance with an energetic ion population. It is a candidate emission mechanism for the superthermal ion cyclotron radiation, apparently associated with the products of fusion reactions, th…
PublishedR. J. Colchin P. G. Carolan R. Duck T. Edlington S. K. Erents et al.
Low-aspect-ratio tokamaks offer both the economic advantage of smaller size and a number of physics advantages which are not available at conventional aspect ratio. The Small Tight Aspect Ratio Tokamak (START) [Fusion Technology 1990, edited by B. E. Keen, M. Huguet, and R. Hemsworth (North-Holland, Amsterdam, 1991), Vol. 1, p. 353] was conceived a…
PublishedPeter J. Catto C. N. Lashmoredavies T. J. Martin
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…
PublishedA. Thyagaraja F. A. Haas
Both neoclassical theory and certain turbulence theories of particle transport in tokamaks predict the existence of bootstrap (i.e., pressure-driven) currents. Two new applications of this form of noninductive current are considered in this work. In the first, an earlier model of the nonlinearly saturated m= 1 tearing mode is extended to include th…
Published