Alessandro Biancalani

@inproceedings{biancalani_2781,

title = {Effect of zonal structures excited by Alfven modes, on turbulence},

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

url = {https://www.iaea.org/events/fec2023},

issn = {https://conferences.iaea.org/event/316/contributio},

year  = {2023},

date = {2023-10-01},

booktitle = {29th IAEA Fusion Energy Conference},

address = {London, England},

abstract = {Tokamak plasmas often present turbulence due to the spatial gradients of density and temperature. Alfven modes (AMs) are also present, driven unstable by the energetic particle (EP) population. Both turbulence and AMs can generate zonal, i.e. axisymmetric, structures, via nonlinear interaction. The interaction of turbulence, AMs and EPs is intrinsically a multiscale problem [1,2,3].

In this work, we investigate the dynamics of zonal structures with the global gyrokinetic particle-in-cell code ORB5 [4]. Three examples of zonal structures are studied. Firstly, we show how zonal radial electric fields, force-driven by AMs [5,6], can affect the growth of ITGs [7], demonstrating the mechanism of turbulence reduction proposed in Ref. [1]. Secondly, we show how AMs can modify the equilibrium density and temperature profiles, thus affecting the turbulence drive [8]. Thirdly, we investigate the dynamics of phase space zonal structure (PSZS), obtained by averaging out dependencies on angle-like variables in the EP distribution function [9,10]. In particular, we study the excitation of PSZS by AMs, and compare with the PSZS observed in simulations where both AMs and turbulence are present.},

note = {pwd: #Fusion23},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{wang_2783,

title = {First principe gyrokinetic simulations of frequency chirping Alfven modes in fusion plasmas},

author = {Xin Wang and Alberto Bottino and Thomas Hayward-Schneider and Philipp Lauber and Alexey Mishchenko and Sergio Briguglio and Matteo Valerio Falessi and Fulvio Zonca and Alessandro Biancalani and Juvert Njeck Sama and Baruch Rofman and Laurent Villard},

url = {https://www.iaea.org/events/fec2023},

issn = {https://www.iaea.org/sites/default/files/23/10/cn-},

year  = {2023},

date = {2023-10-01},

booktitle = {29th IAEA Fusion Energy Conference},

address = {London, England},

abstract = {Frequency chirping of Alfvén modes, a phenomenon observed in tokamak fusion plasmas driven by energetic particles,

can lead to significant losses of energetic particles. In this study, we employ the global gyrokinetic code ORB5 [Comp. Phys.

Comm., 251, 107072, 2020] to explore the nonlinear dynamics of non-adiabatic frequency-chirping energetic particle modes.

Our findings reveal non-perturbative characteristics of energetic particle modes that arise due to the presence of energetic

particles. Building on results from a recent study [Plasma Phys. Control. Fusion, 65, 074001, 2023], which demonstrated

that, given a fixed equilibrium and a single toroidal mode number, the frequency chirping rate is linearly proportional to the

mode saturation amplitude (as predicted by theory [Rev. Mod. Phys., 20, 015008, 2016]), we introduce new physics to further

investigate the Alfvén mode chirping mechanism. Our study indicates that zonal flow plays an important role in modulating

chirping behavior. When only the zonal flow component is included in single-n simulations, it appears that the zonal flow is

forced driven by the Alfvén mode, resulting in a reduced amplitude level in the nonlinear stage and consequently, a decreased

chirping rate. Additionally, we conducted simulations in two distinct cases: one involving a range of toroidal mode numbers

from 0 to 6, and another from 0 to 40. Comparisons were made between scenarios with and without zonal flow in each case.

Our results show that the inclusion of zonal flow suppresses frequency chirping.},

note = {pwd: #Fusion23},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{vlad_2782,

title = {Nonlinear benchmark between HYMAGYC, MEGA. ORB5 and XTOR-K 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 Hinrich Luetjens 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 and Baruch Rofman and Laurent Villard},

url = {https://www.iaea.org/events/fec2023},

issn = {https://www.iaea.org/sites/default/files/23/10/cn-},

year  = {2023},

date = {2023-10-01},

booktitle = {29th IAEA Fusion Energy Conference},

address = {Londres, Angleterre},

abstract = {The results of a non-linear benchmark are presented, undertaken among few of the state-of-the-art codes available to

study the self-consistent interaction of an Energetic Particle (EP) population with shear Alfvén waves: HYMAGYC, MEGA,

ORB5 and XTOR-K. The first two codes, HYMAGYC and MEGA, are hybrid MHD-Gyrokinetic codes (bulk plasma is repre-

sented by MHD equations, while the EP species is treated using the gyrokinetic formalism); ORB5 is a global electromagnetic

gyrokinetic code (both bulk and EP species are treated using the gyrokinetic formalism); XTOR-K is a non-linear kinetic-MHD

code (the bulk plasma is described by a set of non-linear resistive two-fluid MHD equations, extended to include kinetic effects

of multiple ion species with a fully kinetic PIC module). The equilibrium of the so-called NLED-AUG reference case, in

its version with peaked off-axis EP density profile, has been used, while considering a n = ?1 perturbation. This non-linear

benchmark is the natural continuation of the linear benchmark already considered in the recent past. Characteristics of the non-

linear saturation of the mode, self-consistent modification to the EP density profile and other features are compared among the

considered codes.},

note = {16-21 October 2023},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{sama_2765,

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 Giovanni Di Giannatale and Alain Ghizzo and Thomas Hayward-Schneider and Philipp Lauber and Alexey Mishchenko and Moahan Muruggapan and Brando Rettino and Baruch Rofman and Francesco Vannini and Laurent Villard and Xin Wang},

url = {https://epsplasma2023.eu/},

issn = {https://epsplasma2023.eu/},

year  = {2023},

date = {2023-07-01},

booktitle = {Europhysics Conference Abstracts, O4.104},

address = {Bordeaux, France},

abstract = {Drift wave turbulence and its associated heat and particle transport have been intensively

studied due to the role they play in deteriorating plasma confinement, which is a concern for

future fusion plasma reactors. The ion-temperature gradient modes (ITG) [1] are drift waves

driven unstable by the ion-temperature gradient. The spontaneous non-linear excitation of

zonal flows by ITG modes [2], is believed to be one of their major saturation mechanisms.

Recently, global simulations with the gyro-kinetic particle-in-cell code ORB5 [3] have been

performed, where the self-consistent interaction of ITG turbulence, zonal flows, and Alfven

modes has been studied. As a result, it has been conjectured that zonal flows forced-driven

by Alfven instabilities might be used to reduce the level of ITG turbulence [4]. This would

represent an indirect way of interaction of energetic particles (driving Alfven modes unstable)

and turbulence.

In this work, we isolate this mechanism in the self-consistent nonlinear simulations and

prove that it is indeed effective. To this aim, we measure the amplitude and radial structure

of the forced-driven zonal flows and we impose them on electrostatic ITG simulations.

Imposing this self-consistent zonal flow leads to a significant mitigation of the ITG instability,

which induces a significant drop of the ITG growth rates. A scan of the zonal flow amplitude

shows an inverse relation between the ITG growth rate and the zonal flow amplitude (figure

1 a)},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{bottino_2763,

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 Philipp Lauber and Alexey Mishchenko and Emanuele Poli and Brando Rettino and Xin Wang and Fulvio Zonca},

url = {https://epsplasma2023.eu/},

issn = {https://epsplasma2023.eu/},

year  = {2023},

date = {2023-07-01},

booktitle = {Europhysics Conference Abstracts},

address = {Bordeaux, France},

abstract = {Phase space zonal structures (PSZS), 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 [1, 2], 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.

The information provided by the finite element projection of the distribution function could also

be used for significantly improving the quality of ?f PIC simulations, by adjusting and updating

the plasma reference state (background distribution function), during the nonlinear evolution

of the system, consistently with PSZS dynamics. In this work, we discuss the implementation

of a PSZS based background distribution function in the global gyrokinetic code ORB5 [3], in

experimentally relevant conditions.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{rettino_2764,

title = {Gyrokinetic investigation of linear and non-linear excitation of energetic particle driven instabilities in ASDEX Upgrade with realistic distribution functions},

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://epsplasma2023.eu/},

issn = {https://epsplasma2023.eu/},

year  = {2023},

date = {2023-07-01},

booktitle = {Europhysics Conference Abstracts},

address = {Bordeaux, France},

abstract = {Excitation of Alfvén Waves (AW) and Geodesic Acoustic Modes (GAM) by

energetic particles (EPs) is an important topic of study for the physics of fusion

reactors. In tokamaks, ions are injected with high energies to heat the plasma.

These energetic particles are very weakly collisional and exist far from thermal

equilibrium. We examine the effects of experimental-like anisotropic in velocity

distribution functions of EPs on the excitation of such instabilities with the

gyrokinetic particle-in-cell code ORB5. The growth rate of GAMs 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.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{vannini_2755,

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 Brando Rettino and Gregorio Vlad and Xin Wang},

url = {https://www.icpc.it/theory/theory-of-fusion-plasmas-2022/},

issn = {https://iopscience.iop.org/collections/0741-3335_2},

year  = {2022},

date = {2022-09-01},

booktitle = {Special Issue on the 2022 Joint Varenna-Lausanne International Workshop on the Theory of Fusion Plasmas},

address = {Varenna, Italie},

abstract = {Energetic particles (EPs) can drive plasma instabilities, Characterization of the driven AMs.

e.g. Alfvén modes (AMs) but also energetic particle EPs modelled via EM.

driven geodesic acoustic modes (EGAMs). The former can enhance the EP transport while the latter can regulate/suppress the turbulent transport.

In view of building ITER/DEMO it is important to be able to predict the EP-driven dynamics. In this regard, a unique ASDEX Upgrade scenario, the so-called ?NLED-AUG case? [1], has been developed. New studies conducted taking into account the NLED-AUG case are here presented.},

note = {12-16/09/2022},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{wang_2756,

title = {Nonlinear dynamics of nonadiabatic chirping-frequency Alfvén modes in Tokamak plasmas},

author = {Xin Wang and Sergio Briguglio and Claudio Di Troia and Giuliana Fogaccia and Valeria Fusco and Gregorio Vlad and Fulvio Zonca and Alexey Mishchenko and Alberto Bottino and Alessandro Biancalani and Thomas Hayward-Schneider and Philipp Lauber and Francesco Vannini and Laurent Villard},

url = {https://www.icpc.it/theory/theory-of-fusion-plasmas-2022/},

issn = {https://iopscience.iop.org/collections/0741-3335_2},

year  = {2022},

date = {2022-09-01},

booktitle = {Special Issue on the 2022 Joint Varenna-Lausanne International Workshop on the Theory of Fusion Plasmas},

address = {Varenna, Italie},

abstract = {Frequency chirping is a common phenomenon in both space and laboratory

plasmas. Chirping Alfvén modes are thought to be detrimental to the confinement of

energetic particles (EPs) in a burning Tokamak plasma and enhancing EP transport.

The nonlinear dynamics of this chirping behaviour has been one of the long-studied

physics problems for decades. For weakly-driven modes near marginal stability, this

phenomenon has been explained based on a 1-D bump-on-tail model with sources and

sinks, which predicts an adiabatic chirping; that is, a chirping characterised by a

frequency variation, in the bounce time of wave-trapped particles, much smaller than

their bounce frequency. A more general model has been developed by Zonca and co-

workers without time scale separation between nonlinear mode evolution and phase

space transport. In the weak drive regime, it reproduces the Berk-Breizman paradigm.

In the opposite limit, in which energetic particle effects have a non-perturbative

character, it predicts a nonlinear dynamic characterised by phase-locking and non-

adiabatic frequency chirping, indeed observed in both laboratory and space plasmas.

In this work, the nonlinear evolution of a single-toroidal-number chirping mode is

analysed by means of numerical simulations. Both hybrid MHD-gyrokinetic

simulations by XHMGC and fully gyrokinetic simulations by ORB5 show that such a

mode can chirp in a wide frequency range along the shear Alfvén continuum. It is

worth mentioning that frequency-chirping studies, by means of the fully gyrokinetic

simulations, offer the possibility to study such nonlinear behaviors of all plasma

species with fully self-consistent kinetic dynamics. In addition, the Hamiltonian-

mapping test particle approach is used to investigate the phase space dynamics.

Nonadiabatic frequency chirping dynamics, such as the mode saturation scaling, the

density flattening, the broadening of the resonance region, the self-consistent modified

mode radial structure, and the trapping-detrapping process of the resonant particles

will be discussed in detail.},

note = {12 - 16 septembre 2022

Conférence Theory of Fusion Plasmas 2022},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{biancalani_2217,

title = {Interaction of Alfvénic modes and turbulence via the nonlinear modification of the equilibrium profiles},

author = {Alessandro Biancalani and Alberto Bottino and Matteo Valerio Falessi and Thomas Hayward-Schneider and Philipp Lauber and Alexey Mishchenko and Francesco Vannini and Laurent Villard and Fulvio Zonca},

url = {http://ocs.ciemat.es/EPS2022PAP/html/author.html},

issn = {979-10-96389-16-2},

year  = {2022},

date = {2022-07-01},

booktitle = {Europhysics Conference Abstracts, P5b.117},

address = {online},

abstract = {A key step towards the achievement of controlled nuclear fusion in magnetic confinement

devices is the mitigation of turbulence. Turbulent tokamak plasmas are intrinsically multiscale

systems. Microturbulence generates meso-scale zonal flows. Additionally, energetic particles

drive Alfvénic modes (AM) unstable, on meso- or macro-scales, and zonal structures.

In this work, we investigate the possible interaction of AMs and turbulence via the evolution

of the equilibrium profiles. Turbulence is known to strongly depend on the gradients of the

equilibrium profiles, for example plasma density and temperature. AMs can nonlinearly modify

the equilibrium profiles [1, 2, 3], and therefore affect turbulence. Viceversa, with the same

mechanism, turbulence can affect the AM dynamics.

We present results obtained by means of global gyrokinetic simulations with the particle-in-

cell code ORB5 [4]. In recent simulations with ORB5, AMs have been shown to carry substan-

tial heat and particle fluxes [5, 6]. Here, we extend that analysis by showing how the profile

modification due to those fluxes can affect turbulence.

References

[1] L. Chen and F. Zonca, Rev. Mod. Phys. 88, 015008 (2016)

[2] M. V. Falessi and F. Zonca, Phys. Plasmas 26, 022305 (2019)

[3] F. Zonca, L. Chen, M. V. Falessi and Z. Qiu, J. Phys. Conf. Ser. 1785, 012005 (2021)

[4] E. Lanti, et al, Comp. Phys. Commun. 251, 107072 (2020)

[5] A. Biancalani, A. Bottino, P. Lauber, A. Mishchenko and F. Vannini, J. Plasma Phys. 86, 825860301A (2020)

[6] A. Biancalani, et al, Plasma Phys. Control. Fusion 63, 065009 (2021)},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{rettino_2753,

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

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

url = {http://ocs.ciemat.es/EPS2022PAP/html/author.html},

issn = {979-10-96389-16-2},

year  = {2022},

date = {2022-07-01},

booktitle = {Europhysics Conference Abstracts, P1a.112},

address = {online},

abstract = {Energetic particles produced by neutral beams are observed to excite

energetic-particle-driven geodesic acoustic modes (EGAMs) in tokamaks.

We study the effects of anisotropy of distribution function of the energetic

particles on the excitation of such instabilities with ORB5, a gyrokinetic

particle-in-cell code. Numerical results are shown for linear electrostatic

simulations with ORB5. The growth rate is found to be sensitively depen-

dent on the phase-space shape of the distribution function. The behavior

of the instability is qualitatively compared to the theoretical analysis of

dispersion relations. Realistic neutral beam energetic particle anisotropic

distributions are obtained from the heating solver RABBIT and are intro-

duced into ORB5 as input distribution function. Results show a depen-

dence of the growth rate on the injection angle. A qualitative comparison

between the numerical results and experimental measurements in ASDEX

Upgrade is presented.An explanation for the differences is proposed.},

note = {48th EPS Conference on Plasma Physics

27 June - 1 July 2022},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{hayward-schneider_2754,

title = {Global electromagnetic gyrokinetic simulations of Energetic Particle driven instabilities in ITER},

author = {Thomas Hayward-Schneider and Brando Rettino and Alberto Bottino and Philipp Lauber and Markus Weiland and Francesco Vannini and Alessandro Biancalani and Roman Hatzky and Zhixin Lu and Ben McMillan and Alexey Mishchenko and Laurent Villard and Xin Wang},

url = {http://ocs.ciemat.es/EPS2022PAP/html/author.html},

issn = {979-10-96389-16-2},

year  = {2022},

date = {2022-07-01},

booktitle = {Europhysics Conference Abstracts, O4.111},

address = {online},

abstract = {Nonlinear global gyrokinetic treatment of electromagnetic instabilities proved almost impossible for a long time. This

work reports on how breakthroughs in global models has allowed results of energetic particle (EP) - Alfvénic instability

interactions, previously plagued by the difficulties of the multiscale nature of global modes in realistic plasma betas such

as kinetic effects and large ion/electron mass ratio.

A large challenge facing burning plasmas such as ITER will be how to deal with the large population of alpha particles

born from fusion reactions. Instabilities such as Alfvén Eigenmodes (AEs) may be driven unstable by 3.5 MeV alpha

particles. The amplitude of these perturbations must be predicted, to estimate if alpha particle transport and losses are

expected. Dedicated experiments [1] at ASDEX Upgrade (AUG) were performed with a scenario tailored to increase the

ratio of the EP to bulk plasma pressure to be closer to a burning plasma, a valuable resource for validating modelling

tools. In order to put AEs on the same footing as other perturbations, for example the EP-driven Geodesic Acoustic

Mode (EGAM) seen in the AUG experiments, or turbulence, our goal is to model everything in a consistent framework,

global electromagnetic gyrokinetics. Reduced models, such as MHD-kinetic hybrid models need higher fidelity results such

as these for validation. Recent work [2] has improved the ability of particle-in-cell codes to move to high beta, allowing

simulations of large scale global instabilities in realistic plasmas such as ITER [3], EP-turbulence interaction [4], and

high-? turbulence [5].

In this work, we present progress that has been made on modelling EP-driven AEs and other instabilities using the

gyrokinetic code ORB5 [6], first global nonlinear simulations of AUG scenarios with realistic EP distribution functions,

and modelling of two ITER scenarios: Q=10 15 MA baseline [7], Pre-fusion Power Operation (PFPO) [8]. For the AUG

scenario, we elaborate on the studied interaction of Alfvénic instabilities and EGAMs [9], reporting on the extension of

ORB5 by coupling with RABBIT [10] to consider realistic Neutral Beam (NBI) distribution functions. We compare the

EGAM growth for cases varying off-axis NBI beam angles. For the ITER 15MA Q=10 scenario, we show predictions that

thresholds to enhanced nonlinear alpha particle transport regimes may be within a factor of 2. By considering realistic

distribution function for the alpha particles, which is found to increase the drive, we report on predictions of AE growth

at nominal EP density with a realistic isotope mix. Finally, we report on the PFPO phase of ITER, a hydrogen plasma

with NBI EPs. We look at EP-driven low-n global AEs, medium-n localized AEs, and we also find that higher-n RSAEs

can be driven by the bulk plasma gradients even in the absence of EPs. For this case, also electromagnetic simulations of

microturbulence instabilities were performed, driven by the background plasma.

[1] Ph. Lauber et al. 27th IAEA FEC 2018 [2] A. Mishchenko et al. CPC 2019 [3] T. Hayward-Schneider et al. NF

2021 [4] A. Biancalani et al. PPCF 2021 [5] A. Mishchenko et al. PPCF 2021 [6] E. Lanti et al. CPC 2020 [7] A. Polevoi

et al. JPFRS 2002 [8] A. Polevoi et al. NF 2021 [9] F. Vannini et al. POP 2021 [10] M. Weiland et al. NF 2018},

note = {48th EPS Conference on Plasma Physics

27 June - 1 July 2022},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}