Alessandro Biancalani

@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 = {2022-01-01},

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{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 Walter 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}

}