Velocity distribution of carbon macroparticles generated by pulsed vacuum arcs

The velocity distributions of carbon macroparticles have been measured usin g a simple optical technique with a gated charged-coupled device camera, ut ilizing the light emitted by the incandescently bright particles. Distribut ions have been separately determined for macroparticles which have and have not experienced collisions with a solid wall (the anode). The measured vel ocities are in the range 10-370 m s(-1). The distribution without wall coll isions peaks at 80 m s(-1), while the distribution of particles with wall c ollisions peaks at about 50 m s(-1). This indicates that, in the average, a bout one-third of the kinetic energy is lost to the wall when a collision o ccurs, assuming macroparticles remained intact. However, it is shown that m ost carbon macroparticles fracture into even smaller particles when collidi ng with a surface. The velocity measurements do not include either very sma ll (submicrometre) or cooled-off particles.