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2009
The stability of ion temperature gradient ITG modes and the quasilinear fluxes driven by them are analyzed in weakly collisional tokamak plasmas using a semianalytical model based on an approximate solution of the gyrokinetic equation, where collisions are modeled by a Lorentz operator. Although the frequencies and growth rates of ITG modes far fro…
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2009
Recent studies on the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42 , 614 (2002)] have elucidated key aspects of the dependence of stability, confinement, and density control on the plasma magnetic configuration, leading to the demonstration of nearly noninductive operation for 1 s with pressure 30% above the ideal no-wall stability limit. Achieving…
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2009
It is found that flow shear has a stabilizing effect on m / n =3/2 neoclassical tearing mode islands through a more negative classical tearing stability index in the DIII-D J. L. Luxon, Nucl. Fusion 42 , 614 2002 tokamak. The heating neutral beams are mixed between co- and counter-directions to vary the torque on the plasma and thus the plasma flow…
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2009
This paper describes physically and mathematically how the plasma-vacuum boundary of a tokamak plasma equilibrium can be perturbed to form a separatrix with an X-point, while having an otherwise negligible affect on the plasma equilibrium. A deliberate consequence of the technique is that the radial and poloidal extent of the perturbed region may b…
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2009
Electron Bernstein wave (EBW) assisted plasma current start-up has been demonstrated for the first time in a tokamak. It was shown that plasma currents up to 17 kA can be generated non- inductively by 100 kW of RF power injected. With optimized vertical field ramps, plasma currents up to 33 kA have been achieved without the use of solenoid flux. It…
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2009
This paper summarizes highlights of research results from the Alcator C-Mod tokamak covering the period 2006 through 2008. Active flow drive, using mode converted waves in the ion cyclotron range of frequencies (ICRF), has been observed for the first time in a tokamak plasma, using a mix of D and 3 He ion species; toroidal and poloidal flows are dr…
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2009
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2009
Recently several tokamak experiments have been completed to try and elucidate the scaling of the confinement with the key dimensionless parameters ρ*, ν* and β. It has been shown theoretically that these 3 parameters are fundamental in determining the scaling of the energy confinement [1-3]. The experimental results, which consist of single scan…
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2009
This workshop on transport in fusion plasmas is the thirteenth in a series. Previously they have been held under the auspices of the EU and US Transport Task Forces (TTFs), with J Connor as the EU TTF chair. However, the EU Transport Task Force has now been subsumed into the EFDA (European Fusion Development Agreement) Topical Group for Transport (…
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2009
Particle confinement processes are studied in detail on the Large Helical Device (LHD). Diffusion coefficients (D) and convection velocities (V) are estimated from density modulation experiments. The magnetic configuration and collisionality are widely scanned in order to investigate parameter dependences of D and V. To study the effect of the magn…
Showing 361 - 370 of 530 UKAEA Paper Results