Cathode-sheath model for field emission sustained atmospheric pressure discharges

CEJAS, E.; PREVOSTO, L.; MINOTTI, F. O.; FERREYRA, M.; CHAMORRO, J. C.; FINA, B.

PHYSICS OF PLASMAS

AMER INST PHYSICS

Año: 2021 vol. 28

1070-664X

The cathode-sheath region of a discharge in atmospheric pressure air with a flat copper cathode is numerically investigated by using a simple fluid model that takes into account non-local ionization. The effects of the cathode temperature are considered. Results are obtained in a wide current density range of 1?100 A/cm^2, which spans from normal glow discharge, through abnormal glow discharge, up to the early stages of the arcing transition. It is shown that the glow-to-arc transition arises from a field-emission instability at the cathode when the current density is larger than 10 A/cm^2, i.e., when the cathode field exceeds a critical value of about 45 V/um for the conditions considered. It is also shown that the cathode temperature significantly influences the cathode-sheath region. The proposed model is validated by comparing the numerical results with available experimental data.