Peter J. Catto P. Helander J. W. Connor R. D. Hazeltine
The edge plasma of a tokamak is affected by atomic physics processes and can have density and temperature variations along the magnetic field that strongly modify edge transport. A closed system of equations in the Pfirsch–Schluter regime is presented that can be solved for the radial and poloidal variation of the plasma density, electron and ion…
PublishedR. O. Dendy P. Helander
Self-organized criticality ~SOC! often features in sandpile-type modeling of complex systems such as magnetic fusion plasmas, but its observed role in real sandpiles is equivocal. Here, a probabilistic model displaying some of the observed phenomenology of real sandpiles is proposed. It generates avalanches involving particle loss that, like most e…
PublishedO. Sauter R. J. La Haye Z. Chang D. A. Gates Y. Kamada et al.
The maximum normalized beta achieved in long-pulse tokamak discharges at low collisionality falls significantly below both that observed in short pulse discharges and that predicted by the ideal MHD theory. Recent long-pulse experiments, in particular those simulating the International Thermonuclear Experimental Reactor (ITER) [M. Rosenbluth et al.…
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. 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. 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…
PublishedM. 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 …
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…
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…
PublishedF. A. Haas A. Thyagaraja
The purpose of this paper is to investigate the possible relationships between transport properties such as thermal diffusivity and resistivity on the one hand, and the magnetic properties such as q profile and toroidal flux change on the other, in tokamaks that exist under macroscopically quasistationary conditions. It is experimentally well estab…
Published