Transport of a cathodic arc plasma in a straight, magnetized duct

Journal Article · Tue Dec 01 04:00:00 EST 1998 · IEEE Transactions on Plasma Science

DOI:https://doi.org/10.1109/27.747882· OSTI ID:321016

Cluggish, B P ^[1]

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1. Los Alamos National Lab., NM (United States)

Cathodic arcs have long been used for depositing metal and ceramic coatings on a variety of substrates. Here, measurements are presented of the transport of a supersonic, cathodic-arc plasma through a straight, magnetized duct. These measurements are compared to previous work on curved ducts, in order to illuminate the effect of duct curvature on the transport. The axial ion flux through the straight duct decays as ions are lost to the walls. This decay is exponential, with a scale length of seven duct radii; this is two to three times longer than in most experiments on curved ducts. The scale length is independent of the magnetic field strength for fields from 5--40 mT. (For this range of magnetic fields, the electron Larmor radius varies from 0.03--0.003 duct radii; while the ion Larmor radius varies from 4--0.5 duct radii.) This differs from previous experiments with curved ducts, where the attenuation length generally increases with magnetic field. Also in contrast to experiments on curved ducts, biasing the duct wall to positive voltages similar to the ion energy produces only a slight decrease in the ion losses to the wall. The observed scale length for ion loss and its independence from the magnetic field strength are in quantitative agreement with a plasma fluid simulation. Differences in plasma transport through straight and curved ducts are discussed.

• Sponsoring Organization: USDOE, Washington, DC (United States)
• OSTI ID: 321016
• Journal Information: IEEE Transactions on Plasma Science, Journal Name: IEEE Transactions on Plasma Science Journal Issue: 6 Vol. 26; ISSN ITPSBD; ISSN 0093-3813
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CATHODES
CERAMICS
CHARGED-PARTICLE TRANSPORT
DUCTS
ELECTRIC ARCS
MAGNETIC FIELDS
METALS
PARTICLE LOSSES
PLASMA PRODUCTION
SURFACE COATING