Saturation of energetic-particle-driven geodesic acoustic modes due to wave–particle nonlinearity

The nonlinear dynamics of energetic-particle (EP) driven geodesic acoustic modes (EGAM) is investigated here. A numerical analysis with the global gyrokinetic particle-in-cell code ORB5 is performed, and the results are interpreted with the analytical theory, in close comparison with the theory of the beam-plasma instability. Only axisymmetric modes are considered, with a nonlinear dynamics determined by wave–particle interaction. Quadratic scalings of the saturated electric field with respect to the linear growth rate are found for the case of interest. As a main result, the formula for the saturation level is provided. Near the saturation, we observe a transition from adiabatic to non-adiabatic dynamics, i.e. the frequency chirping rate becomes comparable to the resonant EP bounce frequency. The numerical analysis is performed here with electrostatic simulations with circular flux surfaces, and kinetic effects of the electrons are neglected.

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Nonlinear velocity redistribution caused by energetic-particle-driven geodesic acoustic modes, mapped with the beam-plasma system

Journal of Plasma Physics ◽

10.1017/s002237781800123x ◽

2018 ◽

Vol 84 (6) ◽

Cited By ~ 1

Author(s):

A. Biancalani ◽

N. Carlevaro ◽

A. Bottino ◽

G. Montani ◽

Z. Qiu

Keyword(s):

Nonlinear Dynamics ◽

Energetic Particle ◽

Ad Hoc ◽

Hamiltonian Formulation ◽

Plasma Phys ◽

Plasma System ◽

Particle In Cell ◽

Acoustic Modes ◽

Beam Plasma ◽

The Difference

The nonlinear dynamics of energetic-particle (EP) driven geodesic acoustic modes (EGAM) in tokamaks is investigated, and compared with the beam-plasma system (BPS). The EGAM is studied with the global gyrokinetic (GK) particle-in-cell code ORB5, treating the thermal ions and EP (in this case, fast ions) as GK and neglecting the kinetic effects of the electrons. The wave–particle nonlinearity is only considered in the EGAM nonlinear dynamics. The BPS is studied with a one-dimensional code where the thermal plasma is treated as a linear dielectric, and the EP (in this case, fast electrons) with an N-body Hamiltonian formulation. A one-to-one mapping between the EGAM and the BPS is described. The focus is on understanding and predicting the EP redistribution in phase space. We identify here two distinct regimes for the mapping: in the low-drive regime, the BPS mapping with the EGAM is found to be complete, and in the high-drive regime, the EGAM dynamics and the BPS dynamics are found to differ. The transition is described with the presence of a non-negligible frequency chirping, which affects the EGAM but not the BPS, above the identified drive threshold. The difference can be resolved by adding an ad hoc frequency modification to the BPS model. As a main result, the formula for the prediction of the nonlinear width of the velocity redistribution around the resonance velocity is provided. This article is written as the second of a series of articles (the first being Biancalani et al. (J. Plasma Phys., vol. 83 (6), 2017, 725830602)) on the saturation of EGAMs due to wave–particle nonlinearity.

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Nonlinear dynamics of energetic-particle driven geodesic acoustic modes in ASDEX Upgrade

Physics of Plasmas ◽

10.1063/1.5142802 ◽

2020 ◽

Vol 27 (4) ◽

pp. 042512 ◽

Cited By ~ 1

Author(s):

I. Novikau ◽

A. Biancalani ◽

A. Bottino ◽

Ph. Lauber ◽

E. Poli ◽

...

Keyword(s):

Nonlinear Dynamics ◽

Energetic Particle ◽

Acoustic Modes

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Dynamics of a Supported Cylinder in Axial Flow

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.99-100.1059 ◽

2011 ◽

Vol 99-100 ◽

pp. 1059-1062

Author(s):

Ji Duo Jin ◽

Ning Li ◽

Zhao Hong Qin

Keyword(s):

Nonlinear Dynamics ◽

Numerical Analysis ◽

Numerical Simulations ◽

Nonlinear Model ◽

Dynamical Behavior ◽

Axial Flow ◽

Viscous Force ◽

Friction Drag ◽

Flutter Instability ◽

Nonlinear Force

The nonlinear dynamics are studied for a supported cylinder subjected to axial flow. A nonlinear model is presented for dynamics of the cylinder supported at both ends. The nonlinear terms considered here are the quadratic viscous force and the structural nonlinear force induced by the lateral motions of the cylinder. Using two-mode discretized equation, numerical simulations are carried out for the dynamical behavior of the cylinder to explain the flutter instability found in the experiment. The results of numerical analysis show that at certain value of flow velocity the system loses stability by divergence, and the new equilibrium (the buckled configuration) becomes unstable at higher flow leading to post-divergence flutter. The effect of the friction drag coefficients on the behavior of the system is investigated.

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A branch of energetic-particle driven geodesic acoustic modes due to magnetic drift resonance

Physics of Plasmas ◽

10.1063/1.4963397 ◽

2016 ◽

Vol 23 (10) ◽

pp. 102501 ◽

Cited By ~ 15

Author(s):

M. Sasaki ◽

N. Kasuya ◽

K. Itoh ◽

K. Hallatschek ◽

M. Lesur ◽

...

Keyword(s):

Energetic Particle ◽

Acoustic Modes

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A new model suite to determine the influence of cosmic rays on (exo)planetary atmospheric biosignatures

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935888 ◽

2019 ◽

Vol 631 ◽

pp. A101 ◽

Cited By ~ 7

Author(s):

Konstantin Herbst ◽

John Lee Grenfell ◽

Miriam Sinnhuber ◽

Heike Rauer ◽

Bernd Heber ◽

...

Keyword(s):

Cosmic Rays ◽

Energetic Particle ◽

Particle Interaction ◽

Spectral Feature ◽

Ozone Production ◽

Atmospheric Radiation ◽

Solar Energetic Particle Event ◽

Ion Chemistry ◽

Modeling Tools ◽

The Impact

Context. The first opportunity to detect indications for life outside of the Solar System may be provided already within the next decade with upcoming missions such as the James Webb Space Telescope (JWST), the European Extremely Large Telescope (E-ELT) and the Atmospheric Remote-sensing Infrared Exoplanet Large-survey (ARIEL) mission, searching for atmospheric biosignatures on planets in the habitable zone of cool K- and M-stars. Nevertheless, their harsh stellar radiation and particle environment could lead to photochemical loss of atmospheric biosignatures. Aims. We aim to study the influence of cosmic rays on exoplanetary atmospheric biosignatures and the radiation environment considering feedbacks between energetic particle precipitation, climate, atmospheric ionization, neutral and ion chemistry, and secondary particle generation. Methods. We describe newly combined state-of-the-art modeling tools to study the impact of the radiation and particle environment, in particular of cosmic rays, on atmospheric particle interaction, atmospheric chemistry, and the climate-chemistry coupling in a self-consistent model suite. To this end, models like the Atmospheric Radiation Interaction Simulator (AtRIS), the Exoplanetary Terrestrial Ion Chemistry model (ExoTIC), and the updated coupled climate-chemistry model are combined. Results. In addition to comparing our results to Earth-bound measurements, we investigate the ozone production and -loss cycles as well as the atmospheric radiation dose profiles during quiescent solar periods and during the strong solar energetic particle event of February 23, 1956. Further, the scenario-dependent terrestrial transit spectra, as seen by the NIR-Spec infrared spectrometer onboard the JWST, are modeled. Amongst others, we find that the comparatively weak solar event drastically increases the spectral signal of HNO3, while significantly suppressing the spectral feature of ozone. Because of the slow recovery after such events, the latter indicates that ozone might not be a good biomarker for planets orbiting stars with high flaring rates.

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