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

2018 ◽  
Vol 84 (6) ◽  
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.

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

2017 ◽  
Vol 83 (6) ◽  
Author(s):  
A. Biancalani ◽  
I. Chavdarovski ◽  
Z. Qiu ◽  
A. Bottino ◽  
D. Del Sarto ◽  
...  
Keyword(s):  
Nonlinear Dynamics ◽  
Numerical Analysis ◽  
Energetic Particle ◽  
Particle Interaction ◽  
Linear Growth Rate ◽  
Particle In Cell ◽  
Acoustic Modes ◽  
Kinetic Effects ◽  
Beam Plasma Instability ◽  
Frequency Chirping

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.

scholarly journals Nonlinear physics and energetic particle transport features of the beam–plasma instability

2015 ◽  
Vol 81 (5) ◽  
Author(s):  
Nakia Carlevaro ◽  
Matteo V. Falessi ◽  
Giovanni Montani ◽  
Fulvio Zonca
Keyword(s):  
Energetic Particle ◽  
Particle Beam ◽  
Transport Processes ◽  
Model Description ◽  
Plasma System ◽  
One Dimensional ◽  
Beam Plasma ◽  
Local Transport ◽  
Energetic Particle Transport ◽  
Beam Plasma Instability

In this paper we study transport features of a one-dimensional beam–plasma system in the presence of multiple resonances. As a model description of the general problem of a warm energetic particle beam, we assume $n$ cold supra-thermal beams and investigate the self-consistent evolution in the presence of the complete spectrum of nearly degenerate Langmuir modes. A qualitative transport estimation is obtained by computing the Lagrangian Coherent Structures of the system on given temporal scales. This leads to the splitting of the phase space into regions where the local transport processes are relatively faster. The general theoretical framework is applied to the case of the nonlinear dynamics of two cold beams, for which numerical simulation results are illustrated and analysed.

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

2020 ◽  
Vol 27 (4) ◽  
pp. 042512 ◽  
Author(s):  
I. Novikau ◽  
A. Biancalani ◽  
A. Bottino ◽  
Ph. Lauber ◽  
E. Poli ◽  
...  
Keyword(s):  
Nonlinear Dynamics ◽  
Energetic Particle ◽  
Acoustic Modes

Nonlinear dynamics of an electron-beam plasma system

1993 ◽  
Vol 48 (3) ◽  
pp. 367-369
Author(s):  
David K Rollins ◽  
Bhimsen K Shivamoggi
Keyword(s):  
Nonlinear Dynamics ◽  
Electron Beam ◽  
Plasma System ◽  
Beam Plasma ◽  
Electron Beam Plasma

scholarly journals Two-stream instability for a light ion beam-plasma system with external magnetic field

1994 ◽  
Vol 12 (1) ◽  
pp. 13-16
Author(s):  
T. Okada ◽  
H. Tazawa
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Inertial Confinement Fusion ◽  
Ion Beam ◽  
Inertial Confinement ◽  
Plasma System ◽  
Pic Simulation ◽  
Particle In Cell ◽  
Beam Plasma ◽  
Confinement Fusion

For inertial confinement fusion (ICF), a focused light ion beam (LIB) is required to propagate stably through a chamber to a target. It is pointed out that the applied external magnetic field is important for LIB propagation. To investigate the influence of the external magnetic field on the LIB propagation, the electrostatic dispersion relation of the magnetized light ion beam-plasma system was analyzed. The particle in-cell (PIC) simulation results are presented for a light ion beam-plasma system with an external magnetic field.

Spectral Analysis of the Flow of a Neutralized Electron Beam

1997 ◽  
Vol 07 (05) ◽  
pp. 1075-1101 ◽  
Author(s):  
Danny Summers ◽  
Hiroshi Matsumoto ◽  
Takafumi Ohnishi
Keyword(s):  
Nonlinear Dynamics ◽  
Electron Beam ◽  
Differential Equations ◽  
Initial Conditions ◽  
Dimensional System ◽  
Plasma System ◽  
Cold Fluid ◽  
Beam Plasma ◽  
Low Order

The flow of a neutralized electron beam in the classical Pierce beam–plasma system is examined. The system comprises two grounded electrodes containing a stationary background population of neutralizing ions, and electrons are steadily injected with speed V0 from the left-hand electrode at which the charge density is maintained constant. According to cold fluid theory, the system is governed by a single dimensionless parameter α = Lωp/V0, where L is the separation of the electrodes and ωp the plasma frequency. We cast the governing partial differential equations of the cold fluid model in general spectral form, and, by the technique of Galerkin truncation, we reduce the system to low-order systems of ordinary differential equations. Specifically, we reduce the Pierce system to four-dimensional and six-dimensional systems. We examine the nonlinear dynamics of the electron flow, and we find that the nature of the long-term oscillations can be critically dependent on both the value of the parameter α and the initial conditions. While oscillations are typically quasi-periodic, chaotic behavior is also common. For instance, chaotic oscillations in the four-dimensional system can be induced, for any value of α in the range 2.6π ≤ α ≤ 3π, by a suitable choice of initial conditions. That the initial conditions in the Pierce beam–plasma system can play a significant role in influencing the long-term behavior is a main result of our study. We compare our results with computer simulations of the full system, and conclude that whether or not the complex nonlinear dynamics of the Pierce system can be captured in a low-order ordinary differential system remains a challenging question.

Patterns of care in Italian psychiatric services and psychosocial outcome of schizophrenic patients. A three-year prospective study

1989 ◽  
Vol 4 (1) ◽  
pp. 23-31 ◽  
Author(s):  
D. Kemali ◽  
M. Maj ◽  
B. Carpiniello ◽  
R.D. Giurazza ◽  
M. Impagnatiello ◽  
...  
Keyword(s):  
Psychosocial Adjustment ◽  
Ad Hoc ◽  
Social Withdrawal ◽  
Skills Training ◽  
Favourable Outcome ◽  
Stepwise Logistic Regression ◽  
Psychosocial Outcome ◽  
Stepwise Logistic Regression Analysis ◽  
Schizophrenic Patients ◽  
The Difference

Summary141 patients with an ICD-9 diagnosis of schizophrenic psychosis were followed up prospectively for 3 years in 7 Italian centres, representative of the different degrees of application of the psychiatric reform law (Law 180) passed in 1978. It was agreed that each centre would treat the patients according to its routine, and that all contacts with the patients and each intervention performed would be carefully recorded in an ad hoc schedule. The baseline evaluation of psychosocial adjustment was performed by the Disability Assessment Schedule (DAS), and this assessment was then repeated every 6 months during the follow-up period. At the end of this period, the rating on the DAS section 5 was taken as a global measure of patients’ psychosocial outcome. On a stepwise logistic regression analysis, 2 variables were found to be significantly predictive of psychosocial outcome, that is the use of social and/or vocational skills training (associated with a favourable outcome) and the number of days/year of full hospitalization (associated with a poor outcome). Trieste and Arezzo were the only centres in which a significant improvement of the score on some DAS subscales (namely, “occupational role, interest” and “social withdrawal”) was detected. In the whole patient sample, the difference between the final and the baseline score on these subscales correlated significantly with the number/year of outpatient contacts and of home visits. These findings confirm the favourable impact of the community-oriented care provided in some Italian centres on the Psychosocial outcome of schizophrenic patients.

scholarly journals Allometric Equations for Estimating Biomass and Carbon Stocks in Afforested Open Woodlands with Black Spruce and Jack Pine, in the Eastern Canadian Boreal Forest

Forests ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 59
Author(s):  
Olivier Fradette ◽  
Charles Marty ◽  
Pascal Tremblay ◽  
Daniel Lord ◽  
Jean-François Boucher
Keyword(s):  
Large Scale ◽  
Ad Hoc ◽  
Black Spruce ◽  
Tree Height ◽  
Jack Pine ◽  
Carbon Stocks ◽  
Allometric Equations ◽  
C Stocks ◽  
The Difference ◽  
Canadian Boreal Forest

Allometric equations use easily measurable biometric variables to determine the aboveground and belowground biomasses of trees. Equations produced for estimating the biomass within Canadian forests at a large scale have not yet been validated for eastern Canadian boreal open woodlands (OWs), where trees experience particular environmental conditions. In this study, we harvested 167 trees from seven boreal OWs in Quebec, Canada for biomass and allometric measurements. These data show that Canadian national equations accurately predict the whole aboveground biomass for both black spruce and jack pine trees, but underestimated branches biomass, possibly owing to a particular tree morphology in OWs relative to closed-canopy stands. We therefore developed ad hoc allometric equations based on three power models including diameter at breast height (DBH) alone or in combination with tree height (H) as allometric variables. Our results show that although the inclusion of H in the model yields better fits for most tree compartments in both species, the difference is minor and does not markedly affect biomass C stocks at the stand level. Using these newly developed equations, we found that carbon stocks in afforested OWs varied markedly among sites owing to differences in tree growth and species. Nine years after afforestation, jack pine plantations had accumulated about five times more carbon than black spruce plantations (0.14 vs. 0.80 t C·ha−1), highlighting the much larger potential of jack pine for OW afforestation projects in this environment.

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