R. A. Cairns C. N. Lashmore-Davies
Electron Bernstein waves are analyzed as possible candidates for heating spherical tokamaks. An inhomogeneous plane slab model of the plasma with a sheared magnetic field is used to calculate the linear conversion of the ordinary mode (O-mode) to the extraordinary mode (X-mode). A formula for the fraction of the incident O-mode energy which is conv…
PublishedH. Chen N. C. Hawkes L. C. Ingesson M. Von Hellermann K.-D. Zastrow et al.
Poloidally asymmetric distributions of nickel ions have been observed experimentally in Joint European Torus optimized shear tokamak plasmas following nickel laser injection experiments. Two types of asymmetries occur. In the first type of asymmetry, which has earlier been observed in high-confinement mode plasmas, nickel ions accumulate on the out…
PublishedC. G. Gimblett R. J. Hastie
The finite resistivity of the wall that surrounds any toroidal plasma confinement device can lead to a branch of instabilities known as the resistive wall mode (RWM). Theory indicates that the RWM is potentially activated whenever the plasma equilibrium is unstable with the wall placed at infinity. In particular, advanced tokamak power plant design…
PublishedJ. P. Graves K. I. Hopcraft
The recent Joint European Torus deuterium-tritium campaign has yielded ion-cyclotron-resonanceheated (ICRH) pulses during which both the sawtooth characteristics and the ICRH minority ion population both evolve substantially. At multiple times during each pulse, the evolution of the kinetic-fluid MHD energy is calculated from measurement of the ene…
PublishedR. V. Budny D. R. Ernst T. S. Hahm D. C. McCune J. P. Christiansen et al.
The edge-localized, high-confinement mode regime is of interest for future Tokamak reactors since high performance has been sustained for long durations. Experiments in the Joint European Tokamak [M. Keilhacker et al. , Nuclear Fusion 39 , 209 (1999)] have studied this regime using scans with the toroidal field and plasma current varied together in…
PublishedA. Sykes R. J. Akers L. C. Appel P. G. Carolan J.W. Connor N. J. Conway G. F. Counsell A. Dnestrovskij Yu.N. Dnestrovskij M. Gryaznevich P. Helander M. P. S. Nightingale C. Ribeiro C. M. Roach M. Tournianski M. J. Walsh H. R. Wilson The S
H -mode operation has been achieved in high current I p . 200 kA plasmas in the START spherical tokamak for both neutral-beam-injection-heated and Ohmic discharges. The transition to H mode features the development of well-defined edge pedestals in density and temperature, which signifies the formation of an edge-transport barrier, and associated e…
PublishedT. Fülöp P. Helander
The theory of neoclassical transport in an impure toroidal plasma is extended to allow for larger pressure and temperature gradients and faster toroidal rotation than are usually considered. Under these conditions, the density of heavy impurities is not constant on flux surfaces, and the neoclassical transport becomes a nonlinear function of the gr…
PublishedC. N. Lashmore-Davies J. A. Wesson C. G. Gimblett
A uniform compressible plasma with a uniform flow along the magnetic field in the presence of a resistive wall is shown to be subject to two instabilities. For the first instability, the flow velocity is required to exceed the Alfve´n speed, whereas for the second it need only exceed the sound speed. For a sufficiently high ion temperature, ion La…
Published