Processes involved in the triggering of vacuum breakdown by low‐velocity microparticles

The role of low‐velocity microparticles (diameters 109 V/m) are possible at the cathode surface. The emission current not only causes partial neutralization of the initial charge on the microparticle, but also raises the temperature (> 2000°K) of the particle surface. As a consequence, a significant increase in gas pressure (∼ 100 Torr) in the microvolume between the cathode and the particle is possible, resulting in a discharge between the two. Such a discharge could act as a trigger for the breakdown of the main gap. Other possible processes that could arise due to the onset of melting or boiling of the bombarded surface, and which may lead to breakdown of the entire gap, are also discussed.