C. G. Gimblett R. J. Hastie P. Helander
Edge-localized modes (ELMs) are cyclic disturbances in the outer region of tokamak plasmas that are influential in determining present and future tokamak performance. In this Letter, we outline an approach to modeling ELMs in which we envisage toroidal peeling modes initiating a Taylor relaxation [Phys. Rev. Lett. 33 , 1139 (1974)] of a tokamak out…
PublishedG. Van Oost E. Del Bosco M. P. Gryaznevich A. Malaquias G. Mank
Small tokamaks may significantly contribute to the better understanding of phenomena in a wide range of fields such as plasma confinement and energy transport; plasma stability in different magnetic configurations; plasma turbulence and its impact on local and global plasma parameters; processes at the plasma edge and plasma-wall interaction; scena…
PublishedC. G. Gimblett
This paper discusses an approach to modelling Edge Localised Modes (ELMs) in which toroidal peeling modes are envisaged to initiate a constrained relaxation of the tokamak outer region plasma. Relaxation produces both a flattened edge current profile (which tends to further destabilise a peeling mode), and a plasma-vacuum negative current sheet whi…
PublishedH. Smith P. Helander L.-G. Eriksson T. Fülöp
The usual calculation of Dreicer [Phys. Rev. 115 , 238 (1959); 117 , 329 (1960)] generation of runaway electrons assumes that the plasma is in a steady state. In a tokamak disruption this is not necessarily true since the plasma cools down quickly and the collision time for electrons at the runaway threshold energy can be comparable to the cooling …
PublishedK. G. McClements
A full orbit code is used to compute collisionless losses of fusion particles from three proposed burning plasma tokamaks: the International Tokamak Experimental Reactor ITER; a spherical tokamak power plant (STPP) [T. C. Hender, A. Bond, J. Edwards, P. J. Karditsas, K. G. McClements, J. Mustoe, D. V. Sherwood, G. M. Voss, and H. R. Wilson, Fusion …
PublishedS. Shiraiwa S. Ide S. Itoh O. Mitarai O. Naito T. Ozeki Y. Sakamoto T. Suzuki Y. Takase S. Tanaka T. Taniguchi M. Aramasu T. Fujita T. Fukuda X. Gao M. Gryaznevich K. Hanada E. Jotaki Y. Kamada T. Maekawa Y. Miura K. Nakamura T. Nish
A new operational scenario of advanced tokamak formation was demonstrated in the JT-60U tokamak. This was accomplished by electron cyclotron and lower hybrid waves, neutral beam injection, and the loop voltage supplied by the vertical field and shaping coils. The Ohmic heating (OH) solenoid was not used but a small inboard coil (part of the shaping…
PublishedA.J. Webster H.R. Wilson A.M.M. Scaife
A tokamak’s economic performance is strongly affected by the plasma pressure that it may sustain, which in turn is limited by the maximum pressure gradients that may be supported. Ballooning modes are typically driven unstable by increasing the pressure gradient, and because they can radially extend across many rational surfaces, they can serious…
PublishedT.K. March S.C. Chapman R.O. Dendy J. A. Merrifield
Previous observations that suggest a substantial role for nondiffusive energy transport in tokamaks subjected to off-axis electron cyclotron heating (ECH) are compared to the output from a sandpile model. The observations considered include local and global aspects of temperature profile evolution in the DIII-D [for example, C. C. Petty and T. C. L…
PublishedR. J. Akers G. F. Counsell A. Sykes L. C. Appel E. R. Arends C. Byrom P. G. Carolan N. J. Conway G. Cunningham A. Dnestrovskij Yu.N. Dnestrovskij A. R. Field S. J. Fielding M. Gryaznevich P. Helander A. Kirk S. Korsholm R. Martin H. Meye
H -mode plasmas have been achieved on the MAST spherical tokamak at input power considerably higher than predicted by conventional threshold scalings. Following L - H transition, a clear improvement in energy confinement is obtained, exceeding recent international scalings even at densities approaching the Greenwald density limit. Transition is acc…
PublishedS. E. Sharapov B. Alper H. L. Berk D. N. Borba B. N. Breizman et al.
Experiments designed for generating internal transport barriers in the plasmas of the Joint European Torus [JET, P. H. Rebut et al. , Proceedings of the 10th International Conference, Plasma Physics and Controlled Nuclear Fusion, London ~ International Atomic Energy Agency, Vienna, (1985), Vol. I, p. 11 ] reveal cascades of Alfven perturbations wit…
Published