Abstract: A system is disclosed for condensation particle counting in conjunction with modifying an aerosol to enhance the formation and growth of droplets of a selected working fluid, preferably water. Before saturation with the working fluid, the aerosol is exposed to an aerosol modifying component, preferably a vapor including molecules that are adsorbed onto surfaces of the particles or other elements suspended in the aerosol. Adsorption alters the surface character of the suspended elements towards increased affinity for the vapor of the working fluid, to promote the formation and growth of working fluid droplets. The droplets are optically detected to indicate numbers and concentrations of the suspended elements.

Abstract: An apparatus for classifying polydisperse aerosols includes aerosol and sheath gas conduits for conducting a sample aerosol and a sheath gas toward a merger area. At the merger area the sheath gas and about ten percent of the sample aerosol merge, then travel through a differential mobility analyzer (DMA) and along a tubular electrode of the DMA. Selected particles, i.e. particles having electrical mobilities within a narrow range, pass through a collection aperture of the electrode. The DMA output, an aerosol consisting of the selected particles, is provided to a condensation particle counter or other device for determining the aerosol concentration. The remainder of the sample aerosol is conducted away from the merger area along a bypass flow conduit. The bypass flow and an improved aerodynamic design provide for a slit at the merger area that is sufficiently narrow to minimize unwanted electric field penetration at the slit and DMA entrance.

Abstract: An aerodynamic particle size measuring device includes a laser energy source and beam splitting, shaping and polarizing optics for forming two parallel, peripherally overlapping beams. The beams are caused to intersect a gas stream perpendicular to the direction of gas flow, thus to form a measuring volume at the intersection of the beams and flow. Single particles are carried through the measuring volume with the gas flow, each particle scattering and extinguishing light according to the beam profile, as predetermined by the degree of beam overlap and the Gaussian intensity distribution of each beam. A photodetector, responsive either to scattered light or light extinction, generates a time-dependent voltage profile that tends to replicate the intensity profile. The resulting electrical signal is processed to determine an amplitude, set a threshold for minimally acceptable amplitudes, and to derive two negative-going zero crossings for an unambiguous time/velocity determination.

Abstract: An apparatus for measuring nonvolatile residue concentrations in liquid is disclosed. A plurality of fixed and adjustable flow restrictive elements are utilized and arranged in-line from a fluid supply source to provide a constant, pressure controlled flow of liquid to the measuring apparatus and allow for real-time measurements and optimal concentration detection. An atomizer atomizes the liquid into droplets which are dried to nonvolatile residue particles. The nonvolatile residue particle concentration is then determined utilizing an electrostatic aerosol detector. The invention further discloses apparatus for collecting a sample of nonvolatile residue for analysis and identification using a corona precipitator.

Abstract: A measurement system for microelectronic clean rooms to measure ultrafine particle size distribution in the range of 0.002 to 0.2 micrometers is provided which includes four screen diffusion stages each connected in series with a condensation nucleus detector. The input to each screen diffusion stage is connected to a localized area to be measured, and the output of each condensation nucleus detector is connected to a vacuum system which simultaneously draws particle bearing air through the four channels. The output signals of the condensation nucleus detectors present particle size distributiion. In one embodiment of the present invention, one or more optical particle detectors are connected in parallel with the diffusion stage-condensation nucleus detectors to expand the distribution measurements to larger sizes.