M. J. Forrest R. J. Winfield
Laser-induced fluorescence (LIF) is a well established technique used to determine the neutral hydrogen density in fusion plasmas.There is a requirement to extend these measurements to the Divertor section of large plasma devices, but this is problematical due to the high levels of stray laser light and background plasma emission. Here we describe …
PublishedR. Barnsley A. Abbey J. Dunn S. Lea N. J. Peacock
This spectrometer was designed to give access to a wide range of Bragg angles and crystal focal lengths while using the Rowland circle radius as a free parameter. Stability is achieved using a rigid beam or “Rowland chord,” which provides a reference axis for all the critical alignments, the chord length being variable between about 0.2 and 5 m…
PublishedP. G. Carolan A. C. Selden C. A. Bunting P. Nielson
The superior etendu available from a Fabry-Perot spectrometer is also accessible when used in reflective mode in producing a narrow bandwidth rejection, or “notch,” filter. We consider the instrumental defects and the practical effects involved in realizing a useful device. A simple figure of merit is obtained which allows the Fabry-Perot chara…
PublishedG. M. Mccracken U. Samm
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…
PublishedC. N. Lashmoredavies R. O. Dendy
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…
PublishedK. Avinash F. A. Haas A. Thyagaraja
This Brief Communication investigates the influence of toroidal effects (due to the coupling of various poloidal harmonics) on the nonlinear saturation of the m = 1 island. Bounds are obtained relating the aspect ratio, the shear at the q= 1 surface, and the saturated island width. Provided these bounds are satisfied, it is then found that the cyli…
PublishedR. O. Dendy C. N. Lashmoredavies K. F. Kam
Intense superthermal ion cyclotron emission (ICE) has been observed from tokamak plasmas. The power spectrum displays narrow peaks at multiple harmonics of the background ion cyclotron frequency [Cottrell and Dendy, Phys. Rev. Lett. 60, 33 (1988)] in Ohmic deuterium plasmas, and the radiation appears to be driven by the fusion ion population in the…
PublishedF. S. Zaitsev M. R. O’Brien M. Cox
The three-dimensional nonlinear kinetic equation for low collisionality tokamak plasmas with consistent consideration of neoclassical effects is obtained using an approach differing from the standard neoclassical theory technique. This allows treatment of large-banana widths and large inverse aspect ratios. The equation is suitable for computer mod…
PublishedJ. R. Coupland I. L. S. Gray O. J. Hancock K. P. Martel J. W. Mepham et al.
The experimental performance of a high-brightness neutral-beam system is described which has been designed and manufactured by Culham Laboratory under contract to the Princeton Plasma Physics Laboratory. The neutral beam serves as a diagnostic on the PBX-M experiment and is used to perform studies of high-bet a, bean-shaped, neutral-beam-heated pla…
PublishedJ. W. Connor R. J. Hastie J. B. Taylor
This is Part II of a study of resonant perturbations, such as resistive tearing and ballooning modes, in a torus. These are described by marginal ideal magnetohydrodynamic (MHD) equations in the regions between resonant surfaces; matching across these surfaces provides the dispersion relation. Part I [Phys. Fluids B3, 1532 (1991)] described how all…
Published