Meaurements of Particulate Contamination and Migration under Vacuum Using a Large Sensitive Area Particle Counter

A large area (50 cm2) particle counter working under vacuum (10-7 mbar) has been developed at CERN and applied to measurements of particles released by several vacuum components like valves, gauges and ion pumps. This technique has also been applied to study the migration of particles under vacuum with and without an applied electric field. This counter, which is based on the scattering of laser light by particles, will be described and the technical choices commented. The results of the contamination released by vacuum components and the effect of an electric field will be presented.