Van der Pol behavior of virtual anode oscillations in the sheath around a grid in a double plasma device

Klostermann, H.; Rohde, Andreas; Piel, A.

doi:10.1063/1.872221

Cited by 34 publications

(23 citation statements)

References 30 publications

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“…The sheath instability is in many respects similar to that observed in double plasma devices [37,38,39,33,40,41]. The explanations for the instability mechanism differ widely [42,43,44].…”

Section: Discussionsupporting

confidence: 52%

Experiments on Plasma Turbulence Created by Supersonic Plasma Flows with Shear

Stenzel¹,

Urrutia²

2014

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“…The sheath instability is in many respects similar to that observed in double plasma devices [37,38,39,33,40,41]. The explanations for the instability mechanism differ widely [42,43,44].…”

Section: Discussionsupporting

confidence: 52%

Experiments on Plasma Turbulence Created by Supersonic Plasma Flows with Shear

Stenzel¹,

Urrutia²

2014

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“…These effects cannot be "explained" by a Van der Pol equation model. 11 10. The sheath instability depends on grid geometry and plasma nonuniformities.…”

Section: Introductionmentioning

confidence: 97%

Oscillating plasma bubbles. I. Basic properties and instabilities

Stenzel

Urrutia

2012

Physics of Plasmas

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Plasma bubbles are created in an ambient discharge plasma. A bubble is a plasma volume of typically spherical shape, which is separated from the ambient plasma by a negatively biased grid of high transparency. Ions and electrons from the ambient plasma flow into the bubble volume. In steady state the flow of particles and currents is divergence-free, which is established by the plasma potential inside the bubble. The grid has two sheaths, one facing the ambient plasma, the other the bubble plasma. The inner sheath is observed to become unstable, causing the plasma potential in the bubble to oscillate. The instability arises from an excess of ions and a deficiency of electrons. Its frequency is in the range of the ion plasma frequency but depends on all parameters which influence the charge density in the sheath. When the grid voltage is very negative, electrons cannot enter the outer sheath, and the inner sheath becomes a virtual anode which reflects ions such that the bubble interior is empty. When an electron source is placed into the bubble it can neutralize the ions and the bubble refills. Without plasma sources or sinks the bubble plasma is extremely sensitive to perturbations by probes. Modified current-voltage characteristics of Langmuir and emissive probes are demonstrated. A sequence of papers first describes the basic steady-state properties, then the time evolution of bubbles, the effects of electron sources in bubbles, and the role of the grid and bubble geometry. The physics of plasma bubbles is important to several fields of basic plasma physics such as sheaths, sheath instabilities, diagnostic probes, electrostatic confinement, and current and space charge neutralization of beams. V C 2012 American Institute of Physics. [http://dx.

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“…1,2 Ion-rich sheaths with restricted electron supply can oscillate near the ion plasma frequency. [3][4][5][6][7] Virtual cathodes and anodes are special cases of sheaths which are highly unstable. 8,9 Electron-rich sheaths in magnetized plasmas can destabilize electron drift waves.…”

Section: Introductionmentioning

confidence: 99%

Oscillating plasma bubbles. II. Pulsed experiments

Stenzel

Urrutia

2012

Physics of Plasmas

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Time-dependent phenomena have been investigated in plasma bubbles which are created by inserting spherical grids into an ambient plasma and letting electrons and ions form a plasma of different parameters than the ambient one. There are no plasma sources inside the bubble. The grid bias controls the particle flux. There are sheaths on both sides of the grid, each of which passes particle flows in both directions. The inner sheath or plasma potential develops self consistently to establish charge neutrality and divergence free charge and mass flows. When the electron supply is restricted, the inner sheath exhibits oscillations near the ion plasma frequency. When all electrons are excluded, a virtual anode forms on the inside sheath, reflects all ions such that the bubble is empty. By pulsing the ambient plasma, the lifetime of the bubble plasma has been measured. In an afterglow, plasma electrons are trapped inside the bubble and the bubble decays as slow as the ambient plasma. Pulsing the grid voltage yields the time scale for filling and emptying the bubble. Probes have been shown to modify the plasma potential. Using pulsed probes, transient ringing on the time scale of ion transit times through the bubble has been observed. The start of sheath oscillations has been investigated. The instability mechanism has been qualitatively explained. The dependence of the oscillation frequency on electrons in the sheath has been clarified. V C 2012 American Institute of Physics. [http://dx.

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Van der Pol behavior of virtual anode oscillations in the sheath around a grid in a double plasma device

Cited by 34 publications

References 30 publications

Experiments on Plasma Turbulence Created by Supersonic Plasma Flows with Shear

Experiments on Plasma Turbulence Created by Supersonic Plasma Flows with Shear

Oscillating plasma bubbles. I. Basic properties and instabilities

Oscillating plasma bubbles. II. Pulsed experiments

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