-
2003
A family of Johann configuration curved crystal spectrometers has been designed to share the basic engineering features of compactness, modularity, facility of alignment and focus, and incorporation of solid-state charge coupled device detector arrays. These detectors have intrinsically low noise, useful energy resolution, two-dimensional position …
-
2002
Experiments on the JET tokamak show that the wave-induced pinch in the presence of toroidally asymmetric waves can provide a tool for controlling the profile of ion-cyclotron-resonant 3 He ions. Direct evidence for the wave-induced pinch has been obtained from the measured -ray emission profiles. Concurrent differences in the excitation of Alfve?n …
-
2002
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…
-
2001
The equilibrium state in tokamak core plasmas has been studied using the relative intensities of resonance x-ray lines. A full spatial analysis involves comparison of the line intensities with ion diffusion calculations, including relevant atomic rates. A zero-dimensional model using a global ion loss rate approximation has also been demonstrated b…
-
2001
A region of zero current density in the plasma center has been observed in the advanced tokamak scenarios with off-axis lower-hybrid current drive in the JET and JT-60U tokamak experiments. Significantly, the central current density does not become negative, although this is expected based on conventional current diffusion. In this paper, it is sho…
-
2001
Simultaneous current ramping and application of lower hybrid heating and current drive (LHCD) have produced a region with zero current density within measurement errors in the core of JET tokamak optimized shear discharges. The reduction of core current density is consistent with a simple physical explanation and numerical simulations of radial cur…
-
2001
The RF-induced pinch of 3 He minority ions has been observed in JET affecting the diamagnetic energy, the fast ion energy content, the sawtooth period, the Alfvén eigenmode excitation and the y-emission. Further, the y-emission is consistent with RF-detrapping into co-current passing orbits. The results from the SELFO code are consistent with the …
-
2000
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…
-
1999
An empirical procedure, ‘‘LINT,’’ for relating emission line intensities of intrinsic impurity ions to their elemental contributions to the total, bolometric, radiation loss and the volume-averaged effective ion charge, Zeff , has been developed and applied to limiter plasmas in the JET tokamak. In this article we discuss extensions to the …
-
1999
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…
Showing 51 - 60 of 67 UKAEA Paper Results