P. Helander R. D. Hazeltine Peter J. Catto
Edge plasmas, such as the tokamak scrape-off layer, exist as a consequence of a balance between cross-field diffusion and parallel losses. The former is usually anomalous, and is widely thought to be driven by strong electrostatic turbulence. It is shown that the anomalous diffusion affects the parallel ion transport by giving rise to a new type of…
PublishedP. G. Carolan N. J. Conway C. A. Bunting P. Leahy R. O’Connell et al.
Fast charge-coupled device (CCD) detector arrays placed at the output of visible spectrometers are used for multichord Doppler shift analyses on the COMPASS-D and START tokamaks. Unequal magnification in the horizontal and vertical axes allows for optimal matching of throughput and spectral resolution at the CCD detector. This involves cylindrical …
PublishedN. J. Peacock R. Barnsley K. D. Lawson I. M. Melnick M. G. O’Mullane et al.
Crystal and synthetic multilayer diffractors, deployed either as flat Bragg reflectors, or curved, as in the Johann configuration, are used to study the spectrum of COMPASS-D and other tokamaks in the wavelength region of 1–100 A. In this article, we concentrate on the measurement of absolute photon fluxes and the derivation of volume emissivitie…
PublishedR. A. Cairns C. N. Lashmoredavies D. C. Mcdonald M. Taylor
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…
PublishedJ. B. Taylor H. R. Wilson
Short wavelength fluctuations may be a source of anomalous transport in toroidal plasmas. Early investigations concerned electron and ion modes that occur only at a particular radius and have a localised eigenfunction: such modes do not seem important for transport. Recently, Connor, Taylor and Wilson [1] described electron modes that occur at all …
PublishedR. Mcadams M. P. S. Nightingale D. Godden A. J. T. Holmes G. Proudfoot
Cost optimisation studies are carded out for an accelerator based neutron source consisting of a series of linear accelerators. The characteristics of the lowest cost design for a given beam current and energy machine such as power and length are found to depend on the lifetime envisaged for it. For a fixed neutron yield it is preferable to have a …
PublishedR. O. Dendy R. J. Hastie K. G. McClements T. J. Martin
A generalized energy principle is used to determine the effect of ion cyclotron resonant heating (lCRH) on the stability of m = 1 intemal kink displacements in the low-frequency limit: such displacements are associated with sawtooth oscillations. An integral expression is obtained for the contribution to the plasma energy of an ICRH-heated minority…
PublishedR. A. Cairns H. Holt D. C. Mcdonald M. Taylor C. N. Lashmore-Davies
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…
PublishedJ. W. Connor H. R. Wilson
A theory for the existence of noninteracting small-scale, "drift" magnetic islands in a high temperature tokamak plasma is presented. This situation contrasts with that discussed by Rebut and Hugon [Plasma Phys. Controlled Fusion 33, 1085 (1991)] which involves a background "sea" of magnetic turbulence caused by island overlap. The islands are driv…
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