Alessandro Biancalani

@article{korger_3326,

title = {Modulational instability of geodesic-acoustic-mode packets},

author = {David Korger and Emanuele Poli and Alessandro Biancalani and Alberto Bottino and Omar Maj and Juvert Njeck Sama},

url = {https://doi.org/10.1017/S0022377824001284},

year  = {2025},

date = {2025-02-01},

journal = {Plasma Physics And Controlled Fusion},

volume = {91},

number = {1},

pages = {E17},

abstract = {Isolated, undamped geodesic-acoustic-mode (GAM) packets have been demonstrated to

obey a (focusing) nonlinear Schrödinger equation (NLSE) (E. Poli, Phys. Plasmas, 2021).

This equation predicts susceptibility of GAM packets to the modulational instability (MI).

The necessary conditions for this instability are analysed analytically and numerically

using the NLSE model. The predictions of the NLSE are compared with gyrokinetic

simulations performed with the global particle-in-cell code ORB5, where GAM packets

are created from initial perturbations of the axisymmetric radial electric field E r . An

instability of the GAM packets with respect to modulations is observed both in cases in

which an initial perturbation is imposed and when the instability develops spontaneously.

However, significant differences in the dynamics of the small scales are discerned between

the NLSE and gyrokinetic simulations. These discrepancies are mainly due to the radial

dependence of the strength of the nonlinear term, which we do not retain in the solution

of the NLSE, and to the damping of higher radial spectral components k r . The damping

of the high- k r components, which develop as a consequence of the nonlinearity, can be

understood in terms of Landau damping. The influence of the ion Larmor radius ? i as well

as the perturbation wavevector k pert on this effect is studied. For the parameters considered

here the aforementioned damping mechanism hinders the MI process significantly from

developing to its full extent and is strong enough to stabilize some of the (according to the

undamped NLSE model) unstable wavevectors.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ghizzo_3325,

title = {Internal transport barrier triggered by phase synchronization of zonal flow with energetic particle modes},

author = {Alain Ghizzo and Daniele Del Sarto and Juvert Njeck Sama and Alessandro Biancalani},

url = {https://doi.org/10.1088/1361-6587/ad9be6},

year  = {2025},

date = {2025-01-01},

journal = {Plasma Physics And Controlled Fusion},

volume = {67},

number = {1},

pages = {015016},

abstract = {The suppression of the microturbulence associated to the emergence of a spontaneous internal transport barrier has been recently demonstrated in a system showing a possible amplification of the zonal flow component in the low-frequency regime (Ghizzo and Del Sarto 2023 Nucl. Fusion 63 104002). We use here numerical experiments performed with a 'particles modes' model based on a double average over the fast cyclotron phase and over the bounce (or transit) phase to show the major role played by energetic particles and shear flows in this scenario. 'Particle modes' are meant here as classes of particles, identified by some adiabatic invariant after a gyro-average procedure, which are associated to the description of some specific linear modes of the plasma. The introduction of energetic circulating ions or shear flows into the system makes a larger number of particle modes being involved in the synchronization process. A global synchronization of the Fourier modes of the turbulent spectrum can be this way achieved. This process allows for a bifurcation towards self-organization, which is associated to the emergence of a staircase-like structure. This is known to be an essential element in the modification of the zonal flow pattern in phase space during the suppression of microturbulence in tokamaks.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{sama_3198,

title = {Ion temperature gradient mode mitigation by energetic particles, mediated by forced-driven zonal flows},

author = {Juvert Njeck Sama and Alessandro Biancalani and Alberto Bottino and Daniele Del Sarto and Remi Dumont and Giovanni Di Giannatale and Alain Ghizzo and Thomas Hayward-Schneider and Philipp Lauber and Ben McMillan and Alexey Mishchenko and Moahan Muruggapan and Brando Rettino and Baruch Rofman and Francesco Vannini and Laurent Villard and Xin Wang},

url = {https://pubs.aip.org/aip/pop/article/31/11/112503/3318596/Ion-temperature-gradient-mode-mitigation-by?searchresult=1},

year  = {2024},

date = {2024-11-01},

journal = {Physics Of Plasmas},

volume = {31},

number = {11},

pages = {112503},

abstract = {In this work, we use the global electromagnetic and electrostatic gyro kinetic approaches to investigate the effects of zonal flows forced-driven by Alfvén modes due to their excitation by energetic particles on the dynamics of ITG (ion temperature gradient) instabilities. The equilibrium of the 92416 JET tokamak shot is considered. The linear, nonlinear Alfvén modes, and the zonal flow dynamics are investigated, and their respective radial structures and saturation levels are reported. ITG dynamics in the presence of the zonal flows excited by these Alfvén modes are also investigated. The zonal flows forced-driven by Alfvén modes can significantly impact the ITG dynamics. A zonal flow amplitude scan reveals the existence of an inverse relation between the zonal flow amplitude and the ITG growth rate. These results indicate that forced-driven zonal flows can be an important indirect part of turbulence mitigation due to the injection of energetic particles.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{maiti_3237,

title = {A Reduced Model Retaining 1st-Order Vortex Corrections in the Averaged Dynamics of the Wind past Buildings},

author = {Samik Maiti and Aminallah Rabia and Amine Ammar and Alessandro Biancalani and Francisco Chinesta and Yannick Hoarau and Samir Yahiaoui},

url = {https://doi.org/10.18280/ijht.420506},

year  = {2024},

date = {2024-10-01},

journal = {International Journal of Heat and Technology},

volume = {42},

number = {5},

pages = {1534},

abstract = {The nonlinear dynamics of turbulence formed by the wind flowing near solid objects can

be studied with a variety of different physical models, more or less numerically demanding.

An application is the study of the formation of turbulence past buildings, with the goal of

determining the no-fly zones for drones in smart cities. In this paper, we examine the

Reynolds- averaged Navier-Stokes (RANS) model, which is popular in simulating the wind

dynamics in small portions of a city. We compare the results with those of the Large-Eddy-

Simulation (LES) model, more physically comprehensive, but more numerically

demanding. The analysis of the vortex formation in the LES model helps estimating the

1st-order correction to add to the lighter RANS results. This constitutes the scheme of a

reduced model, which takes the RANS model as a basis, on top of which an extra layer of

the dimension of the main vortex, obtained with the LES simulation, is added. This reduce

model can be used, for example, to estimate the no-fly zone with a higher level of accuracy

with respect to the pure RANS, yet with a computational effort comparable to the pure

RANS.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{biancalani_2738,

title = {Nonlinear interaction of Alfvénic instabilities and turbulence via the modification of the equilibrium profiles},

author = {Alessandro Biancalani and Alberto Bottino and Daniele Del Sarto and Matteo Valerio Falessi and Thomas Hayward-Schneider and Philipp Lauber and Alexey Mishchenko and Brando Rettino and Juvert Njeck Sama and Francesco Vannini and Laurent Villard and Xin Wang and Fulvio Zonca},

url = {https://doi.org/10.1017/S0022377823001137},

year  = {2023},

date = {2023-12-01},

journal = {Journal Of Plasma Physics},

volume = {89},

number = {6},

pages = {905890602},

abstract = {Nonlinear simulations of Alfvén modes (AMs) driven by energetic particles (EPs) in

the presence of turbulence are performed with the gyrokinetic particle-in-cell code

ORB5. The AMs carry a heat flux, and consequently they nonlinearly modify the

plasma temperature profiles. The isolated effect of this modification on the dynamics

of turbulence is studied by means of electrostatic simulations. We find that turbulence

is reduced when the profiles relaxed by the AM are used, with respect to the simulation

where the unperturbed profiles are used. This is an example of indirect interaction of

EPs and turbulence. First, an analytic magnetic equilibrium with circular concentric flux

surfaces is considered as a simplified example for this study. Then, an application to an

experimentally relevant case of ASDEX Upgrade is discussed.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{rettino_2737,

title = {Gyrokinetic modelling of non-linear interaction of Alfvén waves and EGAMs in ASDEX-Upgrade},

author = {Brando Rettino and Thomas Hayward-Schneider and Alessandro Biancalani and Alberto Bottino and Philipp Lauber and Markus Weiland and Francesco Vannini and Frank Jenko},

url = {https://doi.org/10.1088/1741-4326/ad0506},

year  = {2023},

date = {2023-11-01},

journal = {Nuclear Fusion},

volume = {63},

number = {12},

pages = {126051},

abstract = {Energetic particle (EP) dynamics and excitation of EP driven instabilities is an important topic

of study for the physics of fusion reactors. In this paper we consider EPs injected in the plasma

by neutral beams at high energies to heat it. EP species exist far from thermal equilibrium in the

form of anisotropic non-Maxwellian distribution functions. EP driven modes, such as Alfvén

waves (AWs) and EP driven geodesic acoustic modes (EGAMs), can redistribute EPs in

phase-space and harm confinement. We examine the effects of experimental-like anisotropic EP

distribution functions on the excitation and the non-linear coupling of such instabilities with the

gyrokinetic particle-in-cell code ORB5. The growth rate of EGAMs is found to be sensitively

dependent on the phase-space shape of the distribution function as well as on the non-linear

wave-wave coupling with AWs. Experimental findings are compared with numerical results.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{sama_2301,

title = {Effect of temperature anisotropy on the dynamics of geodesic acoustic modes},

author = {Juvert Njeck Sama and Alessandro Biancalani and Alberto Bottino and I Chavdarovski and Daniele Del Sarto and Alain Ghizzo and Thomas Hayward-Schneider and Philipp Lauber and B Rettino},

url = {https://www.cambridge.org/core/journals/journal-of-plasma-physics/article/abs/effect-of-temperature-anisotropy-on-the-dynamics-of-geodesic-acoustic-modes/B3084D49F9505CDF3AA53221EE074E46},

year  = {2023},

date = {2023-08-01},

journal = {Journal Of Plasma Physics},

volume = {89},

number = {1},

pages = {905890109},

abstract = {In this work, we revisit the linear gyro-kinetic theory of geodesic acoustic modes (GAMs) and derive a general dispersion relation for an arbitrary equilibrium distribution function of ions. A bi-Maxwellian distribution of ions is then used to study the effects of ion temperature anisotropy on GAM frequency and growth rate. We find that ion temperature anisotropy yields sensible modifications to both the GAM frequency and growth rate as both tend to increase with anisotropy and these results are strongly affected by the electron to ion temperature ratio.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{mishchenko_2378,

title = {Numerical tools for burning plasmas},

author = {Alexey Mishchenko and Alessandro Biancalani and Juvert Njeck Sama and Alberto Bottino and Sergio Briguglio and M Borchardt and Emanuele Poli and Remi Dumont and Jorge Ferreira and J P Graves and Ralf Kleiber and B Rettino and Thomas Hayward-Schneider and Axel Koenies and Emmanuel Lanti and Philipp Lauber and H Leyh and Zhixin Lu and Hinrich Luetjens and Ben McMillan and Martin Campos Pinto and Baruch Rofman and Christoph Slaby and Francesco Vannini and Laurent Villard and Gregorio Vlad and Xin Wang and Fabien Widmer and Fulvio Zonca},

url = {https://iopscience.iop.org/article/10.1088/1361-6587/acce68},

year  = {2023},

date = {2023-04-01},

journal = {Plasma Physics And Controlled Fusion},

volume = {65},

number = {6},

pages = {064001},

abstract = {The software stack under development within a European coordinated effort on tools for burning plasma modelling is presented. The project is organised as a Task (TSVV Task 10) under the new E-TASC initiative (Litaudon et al 2022 Plasma Phys. Control. Fusion64 034005). This is a continued effort within the EUROfusion inheriting from the earlier European coordination projects as well as research projects based at various European laboratories. The ongoing work of the TSVV Tasks is supported by the Advanced Computing Hubs. Major projects requiring the high performance computing (HPC) resources are global gyrokinetic codes and global hybrid particle-magnetohydrodynamics (MHD) codes. Also applications using the integrated modelling tools, such as the Energetic-Particle Workflow, based on the ITER Integrated Modelling & Analysis Suite (IMAS), or the code package for modelling radio-frequency heating and fast-ion generation may require intensive computation and a substantial memory footprint. The continual development of these codes both on the physics side and on the HPC side allows us to tackle frontier problems, such as the interaction of turbulence with MHD-type modes in the presence of fast particles. One of the important mandated outcomes of the E-TASC project is the IMAS-enabling of EUROfusion codes and release of the software stack to the EUROfusion community.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{bottino_2298,

title = {Time evolution and finite element representation of Phase Space Zonal Structures in ORB5},

author = {Alberto Bottino and Matteo Valerio Falessi and Thomas Hayward-Schneider and Alessandro Biancalani and Sergio Briguglio and R Hatzky and Philipp Lauber and Alexey Mishchenko and Emanuele Poli and B Rettino and Francesco Vannini and Xin Wang and Fulvio Zonca},

url = {https://iopscience.iop.org/article/10.1088/1742-6596/2397/1/012019},

year  = {2022},

date = {2022-12-01},

journal = {Journal of Physics: Conference Series},

volume = {2397},

pages = {012019},

abstract = {Phase Space Zonal Structures (PSZSs), obtained by averaging out dependencies on angle-like variables in the energetic particle (EP) distribution function, play a fundamental role in regulating EP transport induced by Alfvén instabilities in burning plasmas, acting as a slowly varying nonlinear equilibrium state. Therefore, they are of great interest for the development of reduced models for the description of EP heat and particle transport on long time scales, comparable with the energy confinement time, for future burning plasma experiments. In this work, we propose an efficient finite element based projection of the time evolution of the PSZS, suited for global particle-in-cell (PIC) gyrokinetic (GK) codes. The resulting algorithm has been implemented in the global GK PIC code ORB5. PSZSs can not only be used for validating reduced models, but also as a diagnostic tool for characterizing the nonlinear interaction in phase space between Alfvén instabilities and EPs in global GK simulations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{vannini_2300,

title = {Gyrokinetic modelling of the Alfvén mode and EGAM activity in ASDEX Upgrade},

author = {Francesco Vannini and Alessandro Biancalani and Alberto Bottino and Thomas Hayward-Schneider and Philipp Lauber and Alexey Mishchenko and Emanuele Poli and B Rettino and Gregorio Vlad and Xin Wang and ASPEX Upgrade Team},

url = {https://dx.doi.org/10.1088/1742-6596/2397/1/012003},

year  = {2022},

date = {2022-12-01},

journal = {Journal of Physics: Conference Series},

volume = {2397},

pages = {012003},

abstract = {Energetic particles present in tokamak machines can drive through resonant wave-particle interaction different plasma instabilities, e.g Alfvén modes and energetic particle-driven geodesic acoustic modes (EGAMs). While the former are potentially detrimental as they can enhance the energetic particle transport and damage the machine wall, the latter are axisymmetric, possibly benign modes that can act to regulate turbulence. A unique scenario, the so-called NLED-AUG case, has been developed in ASDEX Upgrade by tuning the plasma parameters so that the energetic particle kinetic energy is 100 times higher than that of the background plasma, like in ITER. An intense energetic particle-driven activity is observed, most prominently various Alfvén mode bursts triggering chirping EGAMs. The present work reports studies on the Alfvén mode and EGAM dynamics showing, for the first time, many toroidal mode gyrokinetic simulations with ORB5 where the NLED-AUG case scenario is considered. We study the mode dynamics modelling the energetic particles with different equilibrium distribution functions, such as: isotropic slowing-down, double-bump-on-tail and equivalent Maxwellian. We retain, at the beginning, the nonlinearities only in the energetic particle dynamics. Later, also the background plasma species nonlinearities are taken into account.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{vannini_2299,

title = {Gyrokinetic modelling of the Alfvén mode activity in ASDEX Upgrade with an isotropic slowing-down fast-particle distribution},

author = {Francesco Vannini and Alessandro Biancalani and Alberto Bottino and Thomas Hayward-Schneider and Philipp Lauber and Alexey Mishchenko and Emanuele Poli and B Rettino and Gregorio Vlad and Xin Wang and ASPEX Upgrade Team},

url = {https://dx.doi.org/10.1088/1741-4326/ac8b1e},

year  = {2022},

date = {2022-11-01},

journal = {Nuclear Fusion},

volume = {62},

number = {12},

pages = {126042},

abstract = {In the present paper, the evolution of the Alfvén modes (AMs) is studied in a realistic ASDEX Upgrade equilibrium by analyzing the results of simulations with the global, electromagnetic, gyrokinetic particle-in-cell code ORB5. The energetic particles (EPs) are modelled both via the newly implemented isotropic slowing-down and with Maxwellian distribution functions. The comparison of the numerical results shows that modelling the EPs with the equivalent Maxwellian rather than with the slowing-down, does not significantly affect the frequency of the driven AM, while its growth rate appears to be underestimated with a quantitative difference as large as almost 30%. Additionally the choice of the isotropic slowing-down allows a better description of the nonlinear modification of the dominant AM frequency, while an equivalent Maxwellian underestimates it. A good comparison with the experimental spectrogram is found.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{mishchenko_2296,

title = {Gyrokinetic particle-in-cell simulations of electromagnetic turbulence in the presence of fast particles and global modes},

author = {Alexey Mishchenko and Alberto Bottino and Thomas Hayward-Schneider and Emanuele Poli and Xin Wang and C Nührenberg and Alessandro Biancalani and E Lanti and Philipp Lauber and R Hatzky and Francesco Vannini and Laurent Villard and F Widmer and R Keiber},

url = {https://dx.doi.org/10.1088/1361-6587/ac8dbc},

year  = {2022},

date = {2022-09-01},

journal = {Plasma Physics And Controlled Fusion},

volume = {64},

number = {10},

pages = {104009},

abstract = {Global simulations of electromagnetic turbulence in circular-flux-surface tokamak and ASDEX-Upgrade geometry, tearing instabilities and their combination with the electromagnetic turbulence, nonlinear Alfvénic modes in the presence of fast particles and their combination with the electromagnetic turbulence and global electromagnetic turbulence in Wendelstein 7-X stellarator geometry are carried out using the gyrokinetic particle-in-cell code ORB5 (Lanti et al 2020 Comp. Phys. Comm. 251 107072) and EUTERPE (Kornilov et al 2004 Phys. Plasmas 11 3196). Computational feasibility of simulating such complex coupled systems is demonstrated. For simplicity, the reduced mass ratio is used throughout the paper.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{sadr_2736,

title = {Linear and nonlinear excitation of TAE modes by external electromagnetic perturbations using ORB5},

author = {Mohsen Sadr and Alexey Mishchenko and Thomas Hayward-Schneider and Axel Koenies and Alberto Bottino and Alessandro Biancalani and Emmanuel Lanti and Laurent Villard},

url = {https://doi.org/10.1088/1361-6587/ac73eb},

year  = {2022},

date = {2022-07-01},

journal = {Plasma Physics And Controlled Fusion},

volume = {64},

number = {8},

pages = {085010},

abstract = {The excitation of toroidicity-induced Alfvén 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. The antenna is described by

an electrostatic potential resembling the target TAE mode structure along with its corresponding

parallel electromagnetic potential computed from Ohm's law. Numerically stable long-time

linear simulations are achieved by integrating the antenna within the framework of a mixed

representation and pullback scheme (Mishchenko et al 2019 Comput. Phys. Commun. 238 194).

By decomposing the plasma electromagnetic potential into symplectic and Hamiltonian parts

and using Ohm's law, the destabilizing contribution of the potential gradient parallel to the

magnetic field is cancelled in the equations of motion. Besides evaluating the frequencies and

the growth/damping rates of excited modes compared to referenced TAEs, we study the

interaction of antenna-driven modes with fast particles and indicate their margins of instability.

Furthermore, we show the first nonlinear simulations in the presence of a TAE-like antenna

exciting other TAE modes, as well as global Alfvén eigenmodes with different toroidal wave

numbers from that of the antenna.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{gurcan_1825,

title = {Phase and amplitude evolution in the network of triadic interactions of the Hasegawa-Wakatani system},

author = {Özgür Gürcan and Johan Anderson and Sara Moradi and Alessandro Biancalani and Pierre Morel},

url = {https://aip.scitation.org/doi/10.1063/5.0089073},

year  = {2022},

date = {2022-05-01},

journal = {Physics Of Plasmas},

volume = {29},

number = {5},

pages = {052306},

abstract = {The Hasegawa-Wakatani system, commonly used as a toy model of dissipative drift waves in fusion devices, is revisited with considerations

of phase and amplitude dynamics of its triadic interactions. It is observed that a single resonant triad can saturate via three way phase

locking, where the phase differences between dominant modes converge to constant values as individual phases increase in time. This allows

the system to have approximately constant amplitude solutions. Non-resonant triads show similar behavior only when one of its legs is a

zonal wave number. However, when an additional triad, which is a reflection of the original one with respect to the y axis is included, the

behavior of the resulting triad pair is shown to be more complex. In particular, it is found that triads involving small radial wave numbers

(large scale zonal flows) end up transferring their energy to the subdominant mode which keeps growing exponentially, while those involving

larger radial wave numbers (small scale zonal flows) tend to find steady chaotic or limit cycle states (or decay to zero). In order to study the

dynamics in a connected network of triads, a network formulation is considered, including a pump mode, and a number of zonal and non-

zonal subdominant modes as a dynamical system. It was observed that the zonal modes become clearly dominant only when a large number

of triads are connected. When the zonal flow becomes dominant as a ?collective mean field,? individual interactions between modes become

less important, which is consistent with the inhomogeneous wave-kinetic picture. Finally, the results of direct numerical simulation are dis-

cussed for the same parameters, and various forms of the order parameter are computed. It is observed that nonlinear phase dynamics results

in a flattening of the large scale phase velocity as a function of scale in direct numerical simulations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{rettino_2297,

title = {Gyrokinetic modeling of anisotropic energetic particle driven instabilities in tokamak plasmas},

author = {B Rettino and Thomas Hayward-Schneider and Alessandro Biancalani and Alberto Bottino and I Chavdarovski and M Weiland and Francesco Vannini and F Jenko and Philipp Lauber},

url = {https://dx.doi.org/10.1088/1741-4326/ac6680},

year  = {2022},

date = {2022-05-01},

journal = {Nuclear Fusion},

volume = {62},

number = {7},

pages = {076027},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{vlad_1713,

title = {A linear benchmark between HYMAGYC, MEGA and ORB5 codes using the NLED-AUG test case to study Alfvénic modes driven by energetic particles},

author = {Gregorio Vlad and Xin Wang and Francesco Vannini and Sergio Briguglio and Nakia Carlevaro and Matteo Valerio Falessi and Giuliana Fogaccia and Valeria Fusco and Fulvio Zonca and Alessandro Biancalani and Alberto Bottino and Thomas Hayward-Schneider and Philipp Lauber},

url = {https://doi.org/10.1088/1741-4326/ac2522},

year  = {2021},

date = {2021-11-01},

journal = {Nuclear Fusion},

volume = {61},

number = {1},

pages = {116026},

abstract = {One of the major challenges in magnetic confinement thermonuclear fusion research concerns

the confinement of the energetic particles (EPs) produced by fusion reactions and/or by

additional heating systems. In such experiments, EPs can resonantly interact with the shear

Alfvén waves. In the frame of the EUROfusion 2019-2020 Enabling Research project

?multi-scale energetic particle transport in fusion devices' (MET), a detailed benchmark

activity has been undertaken among few of the state-of-the-art codes available to study the

self-consistent interaction of an EP population with the shear Alfvén waves. In this paper

linear studies of EP driven modes with toroidal mode number n = 1 will be presented, in real

magnetic equilibria and in regimes of interest for the forthcoming generation devices (e.g.

ITER, JT-60SA, DTT). The codes considered are HYMAGYC, MEGA, and ORB5, the first

two being hybrid MHD-gyrokinetic codes (bulk plasma is represented by MHD equations,

while the EP species is treated using the gyrokinetic formalism), the third being a global

electromagnetic gyrokinetic code. The so-called NLED-AUG reference case has been

considered, both for the peaked on-axis and peaked off-axis EP density profile cases, using its

shaped cross section version. Comparison of the spatial mode structure, growth rate and real

frequency of the modes observed will be considered in detail. The dependence of mode

characteristics when several parameters are varied, as, e.g. the ratio between EP and bulk ion

density and EP temperature, will be presented. A remarkable agreement is observed among the

three codes for the peaked off-axis case, obtaining all of them a TAE localized close to the

magnetic axis. On the other hand, some differences are observed when considering the peaked

on-axis case, where two modes are observed (a TAE localized in the radial external region, and

an RSAE around mid-radius). A careful analysis of the stability of this equilibrium, in

particular by varying self-consistently the EP drive, will allow to reconcile the results of the

three codes.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{vannini_2790,

title = {Gyrokinetic investigation of the damping channels Alfven modes in ASDEX Upgrade},

author = {Francesco Vannini and Alessandro Biancalani and Alberto Bottino and Thomas Hayward-Schneider and Philipp Lauber and Alexey Mishchenko and Ivan Novikau and Emanuele Poli},

url = {https://doi.org/10.1063/1.5134979},

year  = {2020},

date = {2020-04-01},

journal = {Physics Of Plasmas},

volume = {27},

number = {4},

pages = {042501},

abstract = {The linear destabilization and nonlinear saturation of energetic-particle driven Alfv enic instabilities in tokamaks strongly depend on the

damping channels. In this work, the collisionless damping mechanisms of Alfv enic modes are investigated within a gyrokinetic framework

by means of global simulations with the particle-in-cell code ORB5 and compared with the eigenvalue code LIGKA and reduced models. In

particular, the continuum damping and the Landau damping (of ions and electrons) are considered. The electron Landau damping is found

to be dominant compared to the ion Landau damping for experimentally relevant cases. As an application, the linear and nonlinear dynamics

of toroidicity induced Alfv en eigenmodes and energetic-particle driven modes in ASDEX Upgrade is investigated theoretically and compared

with experimental measurements.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}