Autoresonances of 
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 diocotron oscillations in non-neutral electron plasmas

Gomberoff, K.; Higaki, Hidehiko; Kaga, C.; Ito, K.; Okamoto, Hiromi

doi:10.1103/physreve.94.043204

Cited by 9 publications

(4 citation statements)

References 24 publications

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“…On the contrary, most of the experimental and theoretical/numerical studies in non-neutral plasmas have either focused on the formation of coherent structures, possibly under the effects of electric field drives (Fajans, Backhaus & McCarthy 1999 a ; Fajans, Gilson & Friedland 1999 b ; Gomberoff et al. 2016), or have dealt with the analysis of turbulent quantities in conditions of free evolution (Driscoll et al. 1999; Romé & Lepreti 2011).…”

Section: Introductionmentioning

confidence: 99%

Spectral analysis of forced turbulence in a non-neutral plasma

2017

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The paper investigates the dynamics of magnetized non-neutral (electron) plasmas subjected to external electric field perturbations. A two-dimensional (2-D) particle-in-cell code is effectively exploited to model this system with a special attention to the role that non-axisymmetric, multipolar radio frequency (RF) drives applied to the cylindrical (circular) boundary play on the insurgence of azimuthal instabilities and the subsequent formation of coherent structures preventing the relaxation to a fully developed turbulent state, when the RF fields are chosen in the frequency range of the low-order fluid modes themselves. The isomorphism of such system with a 2-D inviscid incompressible fluid offers an insight into the details of forced 2-D fluid turbulence. The choice of different initial density (i.e. fluid vorticity) distributions allows for a selection of conditions where different levels of turbulence and intermittency are expected and a range of final states is achieved. Integral and spectral quantities of interest are computed along the flow using a multiresolution analysis based on a wavelet decomposition of both enstrophy and energy 2-D maps. The analysis of a variety of cases shows that the qualitative features of turbulent relaxation are similar in conditions of both free and forced evolution; at the same time, fine details of the flow beyond the self-similarity turbulence properties are highlighted in particular in the formation of structures and their timing, where the influence of the initial conditions and the effect of the external forcing can be distinguished.

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Section: Introductionmentioning

confidence: 99%

Spectral analysis of forced turbulence in a non-neutral plasma

2017

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“…2021), with a single reference existing for the mode (Gomberoff et al. 2016). Our investigations will be assisted and augmented by simulations with a particle-in-cell code (Maero et al.…”

Section: Discussionmentioning

confidence: 99%

“…a swept-frequency excitation that may result in a locking between the KH wave and the drive. We remark that, while some theoretical works have addressed autoresonant excitation of KH modes/V-states, the phenomenon is extensively documented in experiments only for the l = 1 mode, which is used to control the positioning of plasma samples in the confinement volume (Fajans et al 1999;Singer et al 2021), with a single reference existing for the l = 2 mode (Gomberoff et al 2016). Our investigations will be assisted and augmented by simulations with a particle-in-cell code (Maero et al 2014), which we have adapted to implement the suitable rotating-wall boundary conditions.…”

Section: Discussionmentioning

confidence: 99%

Resonant excitation of single Kelvin–Helmholtz high-order waves in a magnetized electron fluid vortex

Maero,

Panzeri,

Patricelli

et al. 2023

J. Plasma Phys.

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Thanks to the isomorphism between the drift-Poisson and Euler equations, inviscid two-dimensional fluid experiments can be performed in magnetized, single-component plasmas in Penning–Malmberg traps. Within this analogy, a trapped electron plasma column is equivalent to a two-dimensional vortex. Here, we focus our attention on the generation of V-states, i.e. $l$ -fold symmetric rotating vorticity patches where the deformation with respect to the circular cross-section has reached the nonlinear regime. We detail a linear theoretical analysis and devise an experimental routine to generate V-states through the precise excitation of single Kelvin–Helmholtz perturbations in a magnetized electron plasma. This technique makes use of suitable multipolar rotating electric fields, which are shown to be able to select the desired wavemode. In particular, with rotating fields, a hardware limitation in the highest accessible mode is removed and nonlinear Kelvin–Helmholtz waves of generic order $l$ can be attained, which pave the way for further investigations on the evolution and stability properties of V-states. Systematic experimental results for the selective mode growth in the linear and nonlinear regimes up to saturation and collapse are discussed.

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“…(2) are isomorphic to the Euler equations for an inviscid, incompressible, uniform density, two-dimensional (2D) fluid [7], with vorticity ζ = en/ 0 B and stream function ψ = φ/B. Thanks to this analogy, strongly magnetized pure electron plasmas can therefore be used to investigate 2D fluid dynamics phenomena under accurately controlled and almost ideal conditions [8,9,10], possibly under the effect of external forcings (electric field drives) [11,12,13,14], allowing for precise comparisons between experimental results and theoretical models. Experimental studies on (quasi-)2D fluid dynamics are typically performed using thin layers of conducting fluid [15], soap films [16,17], or fluids in rapidly rotating tanks [18,19], but in all these systems forcing and dissipation (due to friction of the fluid at the boundaries or to its internal viscosity) play a non-negligible role.…”

Section: Introductionmentioning

confidence: 99%

Coherent structures and turbulence evolution in magnetized non-neutral plasmas

Romé

Chen²,

Maero

2018

AIP Conference Proceedings

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The evolution of turbulence of a magnetized pure electron plasma confined in a Penning-Malmberg trap is investigated by means of a two-dimensional particle-in-cell numerical code. The transverse plasma dynamics is studied both in the case of free evolution and under the influence of non-axisymmetric, multipolar radio-frequency drives applied on the circular conducting boundary. In the latter case the radio-frequency fields are chosen in the frequency range of the low-order azimuthal (diocotron) modes of the plasma in order to investigate their effect on the insurgence of azimuthal instabilities and the formation and evolution of coherent structures, possibly preventing the relaxation to a fully-developed turbulent state. Different initial density distributions (rings and spirals) are considered, so that evolutions characterized by different levels of turbulence and intermittency are obtained. The time evolution of integral and spectral quantities of interest are computed using a multiresolution analysis based on a wavelet decomposition of density maps. Qualitative features of turbulent relaxation are found to be similar in conditions of both free and forced evolution, but the analysis allows one to highlight fine details of the flow beyond the self-similarity turbulence properties, so that the influence of the initial conditions and the effect of the external forcing can be distinguished. In particular, the presence of small inhomogeneities in the initial density configuration turns out to lead to quite different final states, especially in the presence of competing unstable diocotron modes characterized by similar growth rates.

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Autoresonances of m=2 diocotron oscillations in non-neutral electron plasmas

Cited by 9 publications

References 24 publications

Spectral analysis of forced turbulence in a non-neutral plasma

Spectral analysis of forced turbulence in a non-neutral plasma

Resonant excitation of single Kelvin–Helmholtz high-order waves in a magnetized electron fluid vortex

Coherent structures and turbulence evolution in magnetized non-neutral plasmas

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