Cathode-sheath model for field emission sustained atmospheric pressure discharges

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

PHYSICS OF PLASMAS

AMER INST PHYSICS

Año: 2021

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 A/cm2 to 102 A/cm2, that 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/cm2, i.e., when the cathode field exceeds a critical value of about 45 106 V/m 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.