Probe measurements in an ionized-gas flow contaminated with macroscopic-particles

The design of a cylindrical $2$-mm-diam electrostatic probe is discussed which prevents contamination of the electrode surface when used for diagnostics of particle-contaminated plasma flows by protecting the electrode by means of a sharp nose cone mounted on and insulated from the electrode. The electrode is $0.85$ mm in diameter and the nose cone $1.2$ mm in diameter. Both are $7$ mm long.