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Effects of Non‐Ideality and Non‐Equilibrium in the Cathode Spot Plasma of Vacuum Arcs
Author(s) -
Anders S.,
Anders A.
Publication year - 1989
Publication title -
contributions to plasma physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0863-1042
DOI - 10.1002/ctpp.2150290424
Subject(s) - plasma , cathode , atomic physics , ionization , vacuum arc , thermodynamic equilibrium , materials science , electron , ion , electron temperature , physics , thermodynamics , chemistry , nuclear physics , quantum mechanics
The cathode spot plasma of a metal vapour arc in vacuum is non‐ideal (electron density n e ∼ 10 25 –10 27 m −3 , temperature T ∼ 1–5 eV, plasma parameter Γ = 0.6−0.1). The fast expansion of the spot plasma into the ambient vacuum leads to a non‐equilibrium charge state distribution (“frozen” state of ionization). The calculations presented show that the freezing of the different charge states appears at different distances from the spot, therefore at different plasma densities and temperatures. In this way, specific proportions of the ion species are produced which do not agree with any equilibrium state. The freezing of the charge states occurs near the cathode spot (γ = 5–50 μm, γ — distance from the spot centre) where the plasma is weakly non‐ideal (Γ = 0.2–0.6).