Transition from moving to stationary double layers in a single-ended Q machine

Journal Article · Wed Aug 01 00:00:00 EDT 1990 · Physics of Fluids B; (USA)

DOI:https://doi.org/10.1063/1.859413· OSTI ID:6638718

Song, B; Merlino, R L; D'Angelo, N ^[1]

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1. Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242-1479 (USA)

Large-amplitude ({approx lt}100%) relaxation oscillations in the plasma potential are known to be generated when the cold endplate of a single-ended Q machine is biased positively. These oscillations are associated with double layers that form near the hot plate (plasma source) and travel toward the endplate at about the ion-acoustic velocity. At the endplate they dissolve and then form again near the hot plate, the entire process repeating itself in a regular manner. By admitting a sufficient amount of neutral gas into the system, the moving double layers were slowed down and eventually stopped. The production of stationary double layers requires an ion source on the high-potential side of the double layers. These ions are provided by ionization of the neutral gas by electrons that are accelerated through the double layer. The dependence of the critical neutral gas pressure required for stationary double-layer formation on endplate voltage, magnetic field strength, and neutral atom mass has been examined. These results are discussed in terms of a simple model of ion production and loss, including ion losses across the magnetic field.

• OSTI ID: 6638718
• Journal Information: Physics of Fluids B; (USA), Vol. 2:8; ISSN 0899-8221
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
PLASMA
PLASMA POTENTIAL
AMPLITUDES
IONS
MAGNETIC FIELDS
PARTICLE LOSSES
PLASMA DIAGNOSTICS
RELAXATION
STEADY-STATE CONDITIONS
CHARGED PARTICLES
ELECTRIC POTENTIAL
700107* - Fusion Energy- Plasma Research- Instabilities
700102 - Fusion Energy- Plasma Research- Diagnostics