skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Oscillating plasma bubbles. II. Pulsed experiments

Abstract

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 beenmore » 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.« less

Authors:
;  [1]
  1. Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547 (United States)
Publication Date:
OSTI Identifier:
22085997
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 19; Journal Issue: 8; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; AFTERGLOW; BUBBLES; ELECTRONS; IONS; LANGMUIR FREQUENCY; LIFETIME; OSCILLATIONS; PLASMA; PLASMA INSTABILITY; PLASMA POTENTIAL; PLASMA SHEATH; PLASMA WAVES; SPHERICAL CONFIGURATION; TIME DEPENDENCE; TRAPPING

Citation Formats

Stenzel, R L, and Urrutia, J M. Oscillating plasma bubbles. II. Pulsed experiments. United States: N. p., 2012. Web. doi:10.1063/1.4743020.
Stenzel, R L, & Urrutia, J M. Oscillating plasma bubbles. II. Pulsed experiments. United States. https://doi.org/10.1063/1.4743020
Stenzel, R L, and Urrutia, J M. 2012. "Oscillating plasma bubbles. II. Pulsed experiments". United States. https://doi.org/10.1063/1.4743020.
@article{osti_22085997,
title = {Oscillating plasma bubbles. II. Pulsed experiments},
author = {Stenzel, R L and Urrutia, J M},
abstractNote = {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.},
doi = {10.1063/1.4743020},
url = {https://www.osti.gov/biblio/22085997}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 8,
volume = 19,
place = {United States},
year = {Wed Aug 15 00:00:00 EDT 2012},
month = {Wed Aug 15 00:00:00 EDT 2012}
}