Transition from unstable electrostatic confinement to stable magnetic confinement in a helicon reactor operating with Ar/SF{sub 6} gas mixtures

Journal Article · Mon May 15 00:00:00 EDT 2006 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2191431· OSTI ID:20795810

Corr, C S; Plihon, N; Chabert, P ^[1]

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1. Laboratoire de Physique et Technologie des Plasmas, Ecole Polytechnique, 91128 Palaiseau Cedex (France)

Two types of instabilities were previously identified in inductive discharges having an expanding chamber when negative ions are present: (i) the source instability, occurring in the neighborhood of the capacitive-to-inductive (E to H) transition, and (ii) the downstream instability, which was shown to be the periodic formation and propagation of double layers. These unstable double layers were found over the entire parameter space (pressure/power) of interest, and they were born at the interface of the source and diffusion chambers. They acted as an internal electrostatic barrier separating a low-electronegativity, high-electron-density plasma upstream (in the source) and a high-electronegativity, low-electron-density plasma downstream. In this paper we have investigated the effect of adding a static axial magnetic field, classically used to increase the confinement and the plasma heating via helicon wave propagation. This had the following consequences: (i) the unstable double layers, and therefore the axial electrostatic confinement, were suppressed in a large part of the parameter space, and (ii) the magnetic confinement leads to a radially stratified plasma, the center being a low-electronegativity, high-density plasma and the edges being essentially an ion-ion plasma.

• OSTI ID: 20795810
• Journal Information: Journal of Applied Physics, Vol. 99, Issue 10; Other Information: DOI: 10.1063/1.2191431; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ANIONS
ARGON
DIFFUSION CHAMBERS
ELECTRON DENSITY
ELECTRONEGATIVITY
HELICON WAVES
HIGH-FREQUENCY DISCHARGES
INTERFACES
LAYERS
MAGNETIC CONFINEMENT
MAGNETIC FIELDS
MIXTURES
PERIODICITY
PLASMA
PLASMA DENSITY
PLASMA HEATING
PLASMA INSTABILITY
PLASMA SHEATH
RF SYSTEMS
SULFUR FLUORIDES