Results 21 to 30 of about 99 (69)
Critical gradient optimisation for quasi-isodynamic stellarators
Journal of Plasma PhysicsWe present new and updated methods for reducing transport caused by electrostatic ion-temperature-gradient (ITG) driven turbulence in quasi-isodynamic (QI) configurations. We first show an updated model for the threshold (critical) gradient of localised toroidal ITG modes.
Gareth Roberg-Clark +3 more
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Geometry effects on zonal flow dynamics and turbulent transport in optimized stellarators
Nuclear FusionGlobal gyrokinetic simulations find a strong suppression of ion temperature gradient (ITG) turbulence by zonal flows in stellarators optimized for neoclassical transport.
Haotian Chen +3 more
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Near-axis quasi-isodynamic database
Journal of Plasma PhysicsIn this work we investigate the landscape of quasi-isodynamic (QI) stellarators using the near-axis expansion of the magnetic field. Building on recent theoretical developments, we construct a database of more than 800 000 stable, approximately QI vacuum magnetic configurations.
Eduardo Rodríguez, Gabriel Plunk
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Exploration of the parameter space of piecewise omnigenous stellarator magnetic fields
Nuclear FusionPiecewise omnigenous fields are stellarator magnetic fields that are optimized with respect to radial neoclassical transport thanks to a second adiabatic invariant that is piecewisely constant on the flux-surface.
J.L. Velasco, E. Sánchez, I. Calvo
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Near-magnetic-axis geometry of a closely quasi-isodynamic stellarator [PDF]
Plasma Physics Reports, 2014 It is shown that the condition of stationary second adiabatic invariant at the magnetic axis of a stellarator configuration can be satisfied to good accuracy for all reflected particles.
Mikhailov, M. +2 more
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Near-axis measures of quasi-isodynamic configurations
Journal of Plasma PhysicsWe present a number of measures and techniques to characterise and effectively construct quasi-isodynamic stellarators within the near-axis framework, without the need to resort to the computation of global equilibria. These include measures of the reliability of the model (including aspect-ratio limits and the appearance of ripple wells ...
Eduardo Rodríguez, Gabriel Plunk
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Direct construction of low-aspect-ratio advanced stellarators via asymptotic expansion
Nuclear FusionAdvanced stellarators are promising candidates for fusion reactors due to their intrinsic steady-state operation capability and excellent plasma confinement properties.
Ke Liu +3 more
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A geometric approach to constructing quasi-isodynamic fields
Journal of Plasma PhysicsThe near-axis theory for quasi-isodynamic stellarator equilibria is reformulated in terms of geometric inputs to allow greater control of the ‘direct construction’ of quasi-isodynamic configurations and to facilitate understanding of the space of such equilibria. This includes a method to construct suitable magnetic axis curves by solving Frenet–Serret
Gabriel Plunk, Eduardo Rodríguez
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Nuclear FusionDesigning a fusion energy device to produce as much energy as possible requires balancing numerous physics constraints and metrics. In stellarators, the geometry is very flexible and involves a large number of free parameters.
R. Laia, R. Jorge, G. Abreu
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Nuclear FusionA four-field-period quasi-isodynamic stellarator configuration is presented that exhibits small neoclassical and electrostatic turbulent transport, good fast-ion confinement over a wide range of β values, small bootstrap current and an edge island ...
E. Sánchez +5 more
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