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Nonequilibrium phenomena and determination of plasma parameters in the hot core of the cathode region in free-burning arc discharges

Journal Article · · Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
;  [1]
  1. Institut fuer Atom- and Molekuelphysik, Abteilung Plasmaphysik, Universitaet Hannover, Germany Institut fuer Gravitationsphysik, Universitaet Hannover (Germany) and Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Hannover (Germany)
We present spectroscopic measurements of plasma parameters (electron density n{sub e}, electron temperature T{sub e}, gas temperature T{sub g}, underpopulation factor b) in the hot-core region in front of the cathode of a low-current, free-burning arc discharge in argon under atmospheric pressure. The discharge is operated in the hot-core mode, creating a hot cathode region with plasma parameters similar to high-current arcs in spite of the fact that we use comparatively low currents (less than 20 A). We use continuum emission and (optically thin) line emission to determine n{sub e} and T{sub e}. We apply relaxation measurements based on a power-interruption technique to investigate deviations from local thermodynamic equilibrium (LTE). These measurements let us determine the gas temperature T{sub g}. All measurements are performed side-on with charge-coupled-device cameras as detectors, so that all measured plasma parameters are spatially resolved after an Abel inversion. This yields the first ever spatially resolved observation of the non-LTE phenomena of the hot core in the near-cathode region of free-burning arcs. The results only partly coincide with previously published predictions and measurements in the literature.
OSTI ID:
21072282
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. 75; ISSN PLEEE8; ISSN 1063-651X
Country of Publication:
United States
Language:
English

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