Investigation of Cathodic Arc Plume in an Atmospheric Pressure Environment Using Stark Broadening.

The plume of a cathodic arc operated in atmospheric pressure gas is examined using an intensified camera and a spectrograph. A 0.2-J pulse arc is shown to generate a glowing jet $\approx 10$ mm in extent. Images recorded in the first microseconds after ignition show that the jet has a smaller core \approx 2$ mm in length. A spatially resolved Stark broadening measurement is performed along the jet core. The measured electron density is 1– 2 \times 10^{20} \text{m}^{\vphantom {R^{R}}-3} . A model for the cathodic arc plasma–gas interaction is presented. The obtained equilibrium between the forward and reverse charge exchange processes is suggested as enabling the extended jet core. [ABSTRACT FROM PUBLISHER]