J. B. Taylor J. W. Connor C. G. Gimblett H. R. Wilson R. J. Hastie
The resistive wall mode ~ RWM ! poses a threat to many plasma confinement devices. The continuous rotation of the wall relative to the plasma makes it appear perfectly conducting, because of the skin effect, but this is ineffective if the perturbation locks to the wall. This raises the question of whether a nonuniformly rotating wall is more effect…
PublishedJ. W. Connor F. L. Waelbroeck H. R. Wilson
The polarization current plays an important role in the evolution of magnetic islands with a width comparable to the characteristic ion orbit width. Understanding the evolution of such small magnetic islands is important for two reasons: (1) to investigate the threshold mechanisms for growth of large-scale islands (e.g., neoclassical tearing modes)…
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…
PublishedH. R. Wilson R. L. Miller
The peeling mode restricts access to the second stability region of the ideal ballooning mode at the tokamak plasma edge. Using a two-dimensional, high toroidal mode number eigenmode code employing a model tokamak equilibrium, it is shown that a window to second stability exists for a sufficiently deep magnetic well. The different mode structures o…
PublishedH. R. Wilson J. W. Connor A. R. Field S. J. Fielding R. L. Miller et al.
The ideal magnetohydrodynamic (MHD) stability of the tokamak edge is analyzed, with particular emphasis on radially localized instabilities; it is proposed that these are responsible for edge pressure gradient limits and edge localized modes (ELMS). Data and stability calculations from DIII-D [to appear in Proceedings of the 16th International Conf…
PublishedJ. W. Connor R. J. Hastie H. R. Wilson R. L. Miller
A new formalism for analyzing the magnetohydrodynamic stability of a limiter tokamak edge plasma is developed. Two radially localized, high toroidal mode number n instabilities are studied in detail: a peeling mode and an edge ballooning mode. The peeling mode, driven by edge current density and stabilized by edge pressure gradient, has features wh…
PublishedH. 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…
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…
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 …
Published