38 citations · 73 across the 14 of their papers we have counts for
14 papers
Control of the bootstrap current in approximately quasi-axisymmetric magnetic fields
J. L. Velasco, I. Calvo, J. M. García-Regaña
Quasi-axisymmetric stellarators are the stellarator analogue of the axisymmetric tokamak, retaining many of its favorable confinement properties, its compacity and its relative coi…
Strong gradient neoclassical transport in the plateau regime
Silvia Trinczek, Felix I. Parra, Peter J. Catto +1
Strong gradient regions in tokamaks such as the pedestal or internal transport barriers are regions of reduced turbulence where neoclassical transport can play a dominant role. In…
Combination of quasi-isodynamic and piecewise omnigenous magnetic fields
J. L. Velasco, I. Calvo, V. Fernández-Pacheco +5
Due to their simultaneous optimization for radial and parallel neoclassical transport, quasi-isodynamic fields have been the main choice of stellarator magnetic configuration for m…
Role of the radial electric field in the confinement of energetic ions in the Wendelstein 7-X stellarator
M. Arranz, J. L. Velasco, I. Calvo +1
Good fast-ion confinement is an essential requirement for a fusion reactor. The magnetic configuration of the Wendelstein 7-X (W7-X) stellarator is partially optimized in this rega…
CIEMAT-QI4X: a reactor-relevant quasi-isodynamic stellarator configuration compatible with an island divertor
E. Sánchez, J. L. Velasco, I. Calvo +3
A four-field-period quasi-isodynamic stellarator configuration is presented that exhibits small neoclassical and electrostatic turbulent transport, good fast-ion confinement over a…
Modification of ion-temperature-gradient turbulence by impurities in stellarator plasmas
Ivan Calvo, Felix I. Parra, Hanne Thienpondt +1
Recent nonlinear gyrokinetic simulations have shown that impurities can strongly modify the turbulent heat flux in stellarator plasmas. Here, the ion-temperature-gradient (ITG) dis…
Piecewise omnigenous stellarators with zero bootstrap current
Ivan Calvo, Jose Luis Velasco, Per Helander +1
Until now, quasi-isodynamic magnetic fields have been the only known stellarator configurations that, at low collisionality, give small radial neoclassical transport and zero boots…
Exploration of the parameter space of piecewise omnigenous stellarator magnetic fields
J. L. Velasco, E. Sánchez, I. Calvo
Piecewise omnigenous fields are stellarator magnetic fields that are optimized with respect to radial neoclassical transport thanks to a second adiabatic invariant that is piecewis…
Evaluation of neoclassical transport in nearly quasi-isodynamic stellarator magnetic fields using MONKES
Francisco Javier Escoto, José Luis Velasco, Iván Calvo +1
Stellarator magnetic fields that are perfectly optimized for neoclassical transport (with levels of radial neoclassical transport comparable to tokamaks) are called omnigenous. Qua…
Influence of the density gradient on turbulent heat transport at ion-scales: an inter-machine study with the gyrokinetic code stella
H Thienpondt, JM García-Regaña, I Calvo +2
Efficient control of turbulent heat transport is crucial for magnetic confinement fusion reactors. This work discusses the complex interplay between density gradients and micro-ins…
Electrostatic microturbulence in W7-X: comparison of local gyrokinetic simulations with Doppler reflectometry measurements
A. González-Jerez, J. M. García-Regaña, I. Calvo +5
The first experimental campaigns of Wendelstein 7-X (W7-X) have shown that turbulence plays a decisive role in the performance of neoclassically optimized stellarators. This stress…
MONKES: a fast neoclassical code for the evaluation of monoenergetic transport coefficients
F. J. Escoto, J. L. Velasco, I. Calvo +2
MONKES is a new neoclassical code for the evaluation of monoenergetic transport coefficients in stellarators. By means of a convergence study and benchmarks with other codes, it is…
KNOSOS: a fast orbit-averaging neoclassical code for stellarator geometry
J. L. Velasco, I. Calvo, F. I. Parra +1
KNOSOS (KiNetic Orbit-averaging SOlver for Stellarators) is a freely available, open-source code (\href{https://github.com/joseluisvelasco/KNOSOS}{https://github.com/joseluisvelasc…
Electrostatic potential variations along flux surfaces in stellarators
M. A. Pedrosa, J. A. Alonso, J. M. García-Regaña +6
First observations of electrostatic potential variations within the flux surfaces of a toroidal magnetic confinement device are presented. Measurements are taken in the TJ-II stell…