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2009
Electrostatic turbulence in weakly collisional, magnetized plasma can be interpreted as a cascade of entropy in phase space, which is proposed as a universal mechanism for dissipation of energy in magnetized plasma turbulence. When the nonlinear decorrelation time at the scale of the thermal Larmor radius is shorter than the collision time, a broad…
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2009
The formation of neoclassical tearing modes (NTMs) severely limits the performance of a tokamak plasma by increasing the radial particle and heat fluxes from the core and can even lead to a plasma disruption. Indeed, NTMs are a serious consideration for the next step device, ITER. The appearance of a finite NTM magnetic island requires an initial â…
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2009
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2009
Tearing mode stability is normally analysed using MHD or two-fluid Braginskii plasma models. However for present, or future, large hot tokamaks like JET or ITER the collisionality is such as to place them in the banana regime. Here we develop a linear stability theory for the resonant layer physics appropriate to such a regime. The outcome is a set…
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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
Self-consistent computations are carried out to study the stability of the resistive wall mode RWM in DIII-D J. L. Luxon, Nucl. Fusion 42 , 614 2002 plasmas with slow plasma rotation, using the hybrid kinetic-magnetohydrodynamic code MARS-K [Y. Q. Liu and et al. , Phys. Plasmas 15 , 112503 (2008)]. Based on kinetic resonances between the mode and t…
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2009
The generation of zonal magnetic fields in laboratory fusion plasmas is predicted by theoretical and numerical models and was recently observed experimentally. It is shown that the modification of the current density gradient associated with such corrugations can significantly affect the stability of the tearing mode. A simple scaling law is derive…
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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
‘Advanced tokamak’ (AT) scenarios were developed with the aim of reaching tokamak steady-state operation. They are designed to optimise the self-generated current, whilst also reaching sufficiently high plasma pressure to achieve optimal fusion reaction rates. AT scenarios exhibit non-monotonic to flat safety factor profiles (q, a measure of th…
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2008
A new analytically and numerically manageable model collision operator is developed specifically for turbulence simulations. The like-particle collision operator includes both pitch-angle scattering and energy diffusion and satisfies the physical constraints required for collision operators: it conserves particles, momentum, and energy, obeys Boltz…
Showing 61 - 70 of 118 UKAEA Paper Results