Aerosols produced from different metal samples with the aid of a high-repetition-rate spark (400 s−1) at medium voltage were investigated with an automated electron microprobe. Particles produced from different aluminium-alloy, brass, and iron samples were mostly spherical in shape, with a mean particle diameter between 1 and 2 μm. The composition of the particles well matches the bulk composition, but elemental redistribution over the different particle size classes occurs. It is postulated from the data obtained that analyte evaporation from a liquid phase in the burning crater and sputtering of material that only partly remelts when passing through the spark channel could be responsible for the aerosol production.
B. Raeymaekers, P. Van Espen, F. Adams, and J. A. C. Broekaert, "A Characterization of Spark-Produced Aerosols by Automated Electron Probe Micro-Analysis," Appl. Spectrosc. 42, 142-150 (1988)