Ion charge state distributions of vacuum arc plasmas: The origin of species

Journal Article · Wed Jan 01 04:00:00 EST 1997 · Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics

DOI:https://doi.org/10.1103/PhysRevE.55.969· OSTI ID:470825

Anders, A ^[1]

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1. Ernest O. Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)

Vacuum arc plasmas are produced at micrometer-size, nonstationary cathode spots. Ion charge state distributions (CSD{close_quote}s) are experimentally known for 50 elements, but the theoretical understanding is unsatisfactory. In this paper, CSD{close_quote}s of vacuum arc plasmas are calculated under the assumption that the spot plasma experiences an instantaneous transition from equilibrium to nonequilibrium while expanding. Observable charge state distributions are the result of a freezing process at this transition. {open_quotes}Frozen{close_quotes} CSD{close_quote}s have been calculated using Saha equations in the Debye-H{umlt u}ckel approximation of the nonideal plasma for all metals of the Periodic Table and for boron, carbon, silicon, and germanium. The results are presented in a {open_quotes}periodic table of CSD.{close_quotes} The table contains also the mean ion charge state, the neutral vapor fraction, and the effective plasma temperature and density at the freezing point for each element. The validity of the concepts of {open_quotes}instantaneous freezing{close_quotes} and {open_quotes}effective temperature and density{close_quotes} is discussed for low and high currents and for the presence of a magnetic field. Temperature fluctuations have been identified to cause broadening of CSD{close_quote}s. {copyright} {ital 1997} {ital The American Physical Society}

• Research Organization: Lawrence Berkeley National Laboratory
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 470825
• Journal Information: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, Journal Name: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics Journal Issue: 1 Vol. 55; ISSN PLEEE8; ISSN 1063-651X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BORON
CARBON
CATHODES
CHARGE STATES
ELECTRIC ARCS
ELECTRON TEMPERATURE
FLUCTUATIONS
GERMANIUM
LTE
MAGNETIC FIELDS
METALS
MULTICHARGED IONS
PLASMA
PLASMA DENSITY
SAHA EQUATION
SILICON