Equilibrium theory of cylindrical discharges with special application to helicons

Journal Article · Tue Nov 15 04:00:00 EST 2011 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3656941· OSTI ID:22047089

Curreli, Davide; Chen, Francis F ^[1]

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1. Electrical Engineering Department, University of California, Los Angeles, California 90095-1594 (United States)

Radiofrequency discharges used in industry often have centrally peaked plasma density profiles n(r) although ionization is localized at the edge, even in the presence of a dc magnetic field. This can be explained with a simple cylindrical model in one dimension as long as the short-circuit effect at the endplates causes a Maxwellian electron distribution. Surprisingly, a universal profile can be obtained, which is self-similar for all discharges with uniform electron temperature T{sub e} and neutral density n{sub n}. When all collisions and ionizations are radially accounted for, the ion drift velocity toward the wall reaches the Bohm velocity at a radius which can be identified with the sheath edge, thus obviating a pre-sheath calculation. For non-uniform T{sub e} and n{sub n}, the profiles change slightly but are always peaked on axis. For helicon discharges, iteration with the HELIC code for antenna-wave coupling yields profiles consistent with both energy deposition and diffusion profiles. Calculated density is in absolute-value agreement with experiment.

• OSTI ID: 22047089
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 11 Vol. 18; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ANTENNAS
COMPUTERIZED SIMULATION
CYLINDRICAL CONFIGURATION
DIFFUSION
ELECTRON TEMPERATURE
ELECTRONS
H CODES
HIGH-FREQUENCY DISCHARGES
ION DRIFT
ION TEMPERATURE
IONIZATION
MAGNETIC FIELDS
MAXWELL EQUATIONS
PLASMA
PLASMA DENSITY
PLASMA SHEATH
PLASMA SIMULATION
RADIOWAVE RADIATION