Abstract: In a method for classifying and separating particles in a fluid stream in which the particles are sprayed and electrically charged and deflected in an electrical field one portion of the stream of the charged or ionized particles respectively is introduced into a first separation device operated as an analyzer (4) and is deflected under variation of the applied high voltage or the electric field respectively, whereby particles reach a detector chamber (10) according to separation criteria like, for example charge or particle size. This high voltage and/or field strength corresponding to a species collected in the detector chamber (10) is read and/or stored as a reference value. The particle stream is fed into a separator (5), in which the previously acquired high voltage and/or field strength is applied and particles of the species deflected in the analyzer (4) into the detector chamber (10) are enriched and discharged correspondingly.

Abstract: A particle measurement apparatus for obtaining accurate information relating to airborne particles in a gas under vacuum from a process chamber including a sampling chamber which can be subjected to a very strong vacuum and used for obtaining a sample of the gas in the process chamber. The interior of the sampling chamber is first flushed with very clean purge gas, and subsequently opened to the process vacuum chamber which is to be sampled so that a sample of the atmosphere of gas from the process vacuum chamber is held in the sampling chamber. The sampling chamber is sealed from the process chamber and the sample is brought to atmospheric pressure by adding a particle-free purified gas. The sample is then flushed from the sampling chamber and passed through a particle counter. Calculations can then be made to determine the original particle concentration in the process vacuum chamber based on the measured particle concentration from the sample of the sampling chamber.