Publications by Alberto Bottino

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The excitation of toroidicity-induced Alfven eigenmodes (TAEs) using prescribed external electromagnetic perturbations (hereafter 'antenna') acting on a confined toroidal plasma, as well as its nonlinear couplings to other modes in the system, is studied. ...

Important steps towards the understanding of turbulent transport have been made with the development of the gyrokinetic framework for describing turbulence and with the emergence of numerical codes able to solve the set of gyrokinetic equations. This paper ...

The implementation of linearized operators describing inter- and like-species collisions in the global gyrokinetic particle-in-cell code ORB5 [ S. Jolliet, Comput. Phys. Commun. 177, 409 (2007) ] is presented. A neoclassical axisymmetric equilibrium with s ...

This paper presents experimental results on the accessibility and the properties of plasmas with improved confinement in TCV. First, the H-mode threshold power is measured in Ohmic plasmas. Above an Ohmic threshold density, the threshold power increases with the density. A lower threshold density is found when additional electron cyclotron heating (ECH) is applied. At these low densities, the threshold power increases dramatically with decreasing density. Only a small fraction of the wide operational domain

On the Tokamak a Configuration Variable (TCV), electron internal transport barriers (eITBs) can be formed during a gradual evolution from a centrally peaked to a hollow current profile while all external actuators are held constant. The formation occurs ra ...

A new diagnostic has been developed to investigate the wave-particle interaction in the phase-space in gyrokinetic particle-in-cell codes. Keeping information about energy transfer terms in the velocity space, the technique has been implemented and tested ...

Long global gyrokinetic turbulence simulations are particularly challenging in situations where the system deviates strongly from its initial state and when fluctuation levels are high, for example, in strong gradient regions. For particle-in-cell simulati ...

A global plasma turbulence simulation code, ORB5, is presented. It solves the gyrokinetic electrostatic equations including zonal flows in axisymmetric magnetic geometry. The present version of the code assumes a Boltzmann electron response on magnetic sur ...

Barely trapped and passing electrons have been recently predicted to strongly enhance the damping rate of Geodesic Acoustic Modes (GAMs) in tokamak plasmas, while keeping their real frequency almost unchanged as compared to the case with adiabatic electron ...

The aim of this paper is to report on recent advances made in global gyrokinetic simulations of ion temperature gradient (ITG) modes and other microinstabilities. The nonlinear development and saturation of ITG modes and the role of E x B zonal flows are studied with a global nonlinear deltaf formulation that retains parallel nonlinearity and thus allows for a check of the energy conservation property as a means of verifying the quality of the numerical simulation. Due to an optimized loading technique, the

It is now widely believed that low frequency turbulence developing from smallscale instabilities is responsible for the phenomenon of anomalous transport generally observed in magnetic confinement fusion experiments. The microinstabilities are driven by gradients of equilibrium density, ion and electron temperatures and magnetic field strength. Gyrokinetic theory is based on the Vlasov-Maxwell equations and, consistent with the ordering, averages out the fast particle gyromotion, reducing the phase space fr

Turbulence and Transport Reduction with Negative Triangularity : Correlation ECE Measurements in TCV Due to turbulence, core energy transport in fusion devices such as tokamaks generally exceeds collisional transport by at least an order of magnitude. It is therefore crucial to understand the instabilities driving the turbulent state and to find ways to control them. Plasma shape is one of these fundamental tools. In low collisionality plasmas, such as in a reactor, changing the plasma shape from Dee-shape

Flux-driven global gyrokinetic codes are now mature enough to make predictions in terms of turbulence and transport in tokamak plasmas. Some of the recent breakthroughs of three such codes, namely GYSELA, ORB5 and XGC1, are reported and compared wherever a ...

The theoretical study of plasma turbulence is of central importance to fusion research. Experimental evidence indicates that the confinement time results mainly from the turbulent transport of energy, the magnitude of which depends on the turbulent state r ...

The mutual interactions of ion temperature gradient (ITG) driven modes, zonal flows and geodesic acoustic modes (GAM) in tokamak plasmas are investigated using a global nonlinear gyrokinetic formulation with totally unconstrained evolution of temperature g ...

In this work, a Fourier solver [B.F. McMillan, S. Jolliet, A. Bottino, P. Angelino, T.M. Tran, L Villard, Comp. Phys. Commun. 181 (2010) 7151 is implemented in the global Eulerian gyrokinetic code GT5D [Y. Idomura, H. Urano, N. Aiba, S. Tokuda, Nucl. Fusio ...

Electrostatic microinstabilities in ion internal barrier (ITB) and H-mode discharges of the ASDEX Upgrade tokamak [O. Gruber, R. Arslanbekov, C. Atanasiu , Nucl. Fusion 41, 1369 (2001)] have been investigated with a full radius gyrokinetic code. The code models linear stability and includes the effect of an equilibrium radial electric field and trapped electrons. In order to simulate plasmas in experimental conditions [k(perpendicular to)rho(L)similar toO(1)], the long wavelength approximation in the quasin

The nonlinear dynamics of beta-induced Alfven eigenmodes (BAEs) driven by energetic particles (EPs) in the presence of ion-temperature-gradient turbulence is investigated, by means of selfconsistent global gyrokinetic simulations and analytical theory. A t ...

Highly variable flux surface averaged heat fluxes are resolved in gyrokinetic simulations of ion temperature gradient (ITG) turbulence, even in large systems. Radially propagating fronts or avalanches are also seen. Their propagation lengths in gyroradii a ...

While in recent years gyrokinetic simulations have become the workhorse for theoretical turbulence and transport studies in the plasma core, their application to the edge and scrape-off layer (SOL) region presents significant challenges. In particular, ste ...

Alberto Bottino

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Linear and nonlinear excitation of TAE modes by external electromagnetic perturbations using ORB5

Gyrokinetic simulations of turbulent transport: size scaling and chaotic behaviour

Neoclassical equilibria as starting point for global gyrokinetic microturbulence simulations

Accessibility and properties of ELMy H-mode and ITB plasmas in TCV

Safety factor profile requirements for electron ITB formation in TCV

Implementation of energy transfer technique in ORB5 to study collisionless wave-particle interactions in phase-space

Gyrokinetic simulations of turbulence and zonal flows driven by steep profile gradients using a delta-f approach with an evolving background Maxwellian

A global collisionless PIC code in magnetic coordinates

Linear collisionless dynamics of the GAM with kinetic electrons: Comparison simulations/theory

Full radius linear and nonlinear gyrokinetic simulations for tokamaks and stellarators: zonal flows, applied E x B flows, trapped electrons and finite beta

First principles based simulations of instabilities and turbulence

Transport and turbulence reduction with negative triangularity : Correlation ECE measurements in TCV

Predictions on heat transport and plasma rotation from global gyrokinetic simulations

The role of plasma elongation on turbulent transport in magnetically confined plasmas

Effects of plasma current on nonlinear interactions of ITG turbulence, zonal flows and geodesic acoustic modes

Parallel filtering in global gyrokinetic simulations

Simulations of global electrostatic microinstabilities in ASDEX Upgrade discharges

Gyrokinetic investigation of Alfven instabilities in the presence of turbulence

Avalanche-like bursts in global gyrokinetic simulations

Gyrokinetic full-f particle-in-cell simulations on open field lines with PICLS