-
2000
On JET the coupling resistance averaged over the four straps of the A2 antennas in the Mark II GB divertor configuration was analyzed with particular emphasis on the plasma shape dependence. The measured values were compared with models for the coupling resistance of different levels of sophistication with the ultimate goal of supplying recipes on …
-
2000
Relaxation is the result of turbulence in a plasma that behaves essentially as an ideal conducting fluid, but has a small resistivity and viscosity. These small effects are locally enhanced by the turbulence and lead to reconnection of magnetic field lines. This destroys an infinity of topological constraints, leaving only the total magnetic helici…
-
2000
A model is developed to analyze the stabilization of the resistive wall mode (RWM) by plasma rotation. Central to the model is a cylindrical plasma that is ideal magnetohydrodynamic unstable in the absence of a wall, and possesses an internal resonance [J. M. Finn, Phys. Plasmas 2 , 198 (1995)]. This system is then a qualitative model for the actua…
-
2000
The theory of neoclassical transport near the magnetic axis in a tokamak is discussed. It is shown that the ordinary treatment of transport in the plateau regime holds in most of the region within a trapped orbit width of the magnetic axis, and is not modified by ‘‘potato’’ orbits. It is also demonstrated that transport at low collisionalit…
-
2000
The islands from tearing modes driven unstable and sustained by the helically perturbed neoclassical bootstrap current often provide the practical limit to long-pulse, high confinement tokamak operation. The destabilization of such ‘‘metastable’’ plasmas depends on a ‘‘seed’’ island exceeding a threshold. A database from similar reg…
-
2000
The origin of the effect of inhomogeneous swelling observed near grain boundaries in irradiated materials is examined taking into account both nucleation and diffusional growth of cavities, and the interaction of cavities with mobile interstitial clusters produced in collision cascades. The model shows the formation of a characteristic profile of i…
-
2000
The kinetic theory of runaway electron avalanches caused by close Coulomb collisions is extended to account for radial diffusion. This is found to slow down the growth of avalanches. An approximate analytical formula for the growth rate is derived and is verified by a three-dimensional Monte Carlo code constructed for this purpose. As the poloidal …
-
2000
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…
-
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…
-
2000
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…
Showing 2441 - 2450 of 2581 UKAEA Paper Results