Abstract: An electrostatic precipitator has a high voltage electrode including multiple wire segments that are positioned within a surrounding electrically conductive porous media having a central axis and wherein the electrode assembly extends along the central axis. The electrode assembly has a plurality of wire lengths positioned to extend in a direction along the longitudinal axis of the porous media, and the wire segments being arranged to have a substantially longer total length than the length of extension along the longitudinal axis. An aerosol containing droplets is passed into the interior of the porous media, and across the electrode, which is charged with a high voltage. The porous media is at a substantially lower or different voltage from the high voltage electrodes. Flow of the aerosol containing particles charged by the electrode passes through the porous media to the outlet and the charged particles are precipitated by the porous media.

Abstract: An electrostatic precipitator has a high voltage electrode including multiple wire segments that are positioned within a surrounding electrically conductive porous media having a central axis and wherein the electrode assembly extends along the central axis. The electrode assembly has a plurality of wire lengths positioned to extend in a direction along the longitudinal axis of the porous media, and the wire segments being arranged to have a substantially longer total length than the length of extension along the longitudinal axis. An aerosol containing droplets is passed into the interior of the porous media, and across the electrode, which is charged with a high voltage. The porous media is at a substantially lower or different voltage from the high voltage electrodes. Flow of the aerosol containing particles charged by the electrode passes through the porous media to the outlet and the charged particles are precipitated by the porous media.

Abstract: An atomizer has a chamber holding a liquid containing particles of a desired material. Aerosol particles are formed by using an aspirating nozzle or ultrasonic vibrator and the aerosol particles are carried in a gas flow. The aerosol particles are treated by increasing the charge on the aerosol particles by contact with a high voltage electrode and the aerosol particles are passed through inertial separator stages to remove large aerosol particles from the flow so they are not discharged from the atomizer.

Abstract: An atomizer includes a housing that has a plurality of atomizing nozzles which will atomize a solution containing small particles that are to be carried in an output aerosol. The atomizer nozzles are surrounded by a ring-like surface against which the atomized material impinges to collect large droplets and to cause secondary atomization of the liquid impinging on the ring-like surface. The ring-like surface can have many different cross-sectional configurations for obtaining different results in secondary atomization and droplet collection.

Abstract: A method of providing particle deposition on a semiconductor wafer or other surface first provides a flow of clean gas into a deposition chamber that purges the chamber prior to introduction of the wafer, and after introduction, continues the flow of clean gas. An aerosol is mixed into the clean gas flow for a desired length of time, so that as the combined flow passes through the deposition chamber particles are deposited on the wafer supported in the chamber. After the deposition has continued for either a desired particle count or a length of time, the flow of aerosol is discontinued, and a clean gas flow sheath is provided over the wafer as it is removed from the chamber. The apparatus carries out this method by providing a source of a clean gas, valves for controlling aerosol introduction into the clean gas, and a support for the wafer in the path of gas introduced into the chamber.

Abstract: An apparatus for handling exhaust gases, such as diesel exhaust, which cools the exhaust gases as the gases exit a diesel engine, and then filters such gases to remove particulate material. A housing has an inlet pipe with perforations and a filling of a liquid through which gas bubbles as it exits the perforations in the inlet pipe. The gas bubbling through the liquid cools the gases. In order to maintain the bubbles at a desired size, a perforated or porous layer of material is provided in the liquid so that gas moves through the perforated layer before it exits the liquid. Preferably the gas exiting the liquid is then passed through a filter which is maintained in a wet condition by mist carried by the gases that is formed as the gases burst through the surface of the liquid. The fibers of the filter are maintained wetted so that particles of material do not adhere to the fibers and can be flushed therefrom.

Abstract: A particle removal system provides for the removal of submicron particles in gas streams, such as combustion flue gases or diesel exhausts. The gas stream is treated to permit very fine particles to coagulate through a short residence time in the conduits handling the gas stream, and thereafter is conditioned to establish saturation of the gas stream at a low temperature, such as by water injection. The saturated stream of gas containing the particles is then passed through a particle growth chamber or section where steam is injected into the gas to establish a supersaturation condition, causing the particles in the gas stream to grow in size by water condensing around the particles. The particles are grown to a size that is near one micron, and are removed through conventional particulate removal devices.

Abstract: An aerosol generator used to produce, selectively and rapidly, an aerosol that has a specific particle size and is at a known specific concentration. The generator comprises a plurality of aerosol material atomizers that can be selectively used to obtain different atomized aerosol particles that results in different size when combined with the output of a particle seed atomizer. Particles can be selectively operated to provide, quickly and conveniently, a range of individual particle sizes. The seed atomizer output is mixed with the aerosol atomizer output and passed through a unique, compact heating section for heating the mixture in a manner to provide a high flow rate with low pressure drop. The fluid is passed through a condenser to condense known size particles in the fluid stream, which then can be used as desired, for example to test the efficiency of filters.

Abstract: A sampling inlet for sampling aerosols in atmospheric air comprises an inlet housing that has an air flow and an inertial particle classification device in a series flow path from an inlet opening in the sampler to a filter which collects the material. The sampler is a classification device of the virtual impactor type, utilizing nozzles that receive the flow carrying the aerosols, and a receiver tube that is aligned with the nozzle and spaced therefrom, with a major portion of flow being diverted from the space between the nozzle and the receiver tube. The heavier particles are carried by inertia into the receiver tube and then are carried off by minor flow of fluid that passes through the receiver tubes.

Abstract: A particle concentrating sampler utilizes a virtual impactor, which is an inertial classifier, for concentrating airborne particles above a cut size into a smaller volume air. The concentrated particles are counted, or collected on impactor plates or by using other collection techniques, such as filters or electrostatic precipitators. The concentration of the larger particles which are of interest for analysis insures that the number of particles, particularly in clean room environments, is sufficient so that a significant sampler or count can be obtained without sampling large volumes of air.

Abstract: A cleaning system of the apparatus utilizing the effect of surface tension forces (4) and phase changes between a liquid and gas. In one embodiment the surface (21) to be cleaned is submerged within a vessel (30), the pressure within the vessel being increased. A rapid depressurization of the vessel causes a plurality of bubbles (12) to form around undesired particulate matter (13) on the surface (14) of the article to be cleaned, the bubbles rising to the surface of the liquid (27) within the chamber, thereby cleaning the article. A second embodiment utilizes a cleaning fluid (52) which is applied to the surface of the article (49) to be cleaned. The fluid being subsequently frozen on the surface, thereby reducing the adhesion force between the surface of the article and undesired particulate matter. The surface of the article (49) is subsequently heated, and the undesired particulate matter is removed through the medium of the cleaning fluid (52).

Abstract: A cyclone type personal aerosol sampler has a two-stage operation with a standard cyclone sampler providing a cutoff of particles in the range of 10 microns to a secondary cyclone sampler. The secondary cyclone sampler has the ability to inertially separate out particles below about 0.8 microns from larger particles. The secondary sampler has a readily removable cup for collecting the larger particles, and an easily replaceable filter for collecting the smaller particles for analysis.

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.

Abstract: A flow visualization system usable for clean rooms to determine the flow conditions that exist during manufacture, includes a frame mounting a source of steam and a liquid cryogen container. Steam is passed over an interface with the cryogenic material providing a highly visible fog that is neutrally buoyant and non-contaminating. The liquid cryogen level in the container is controlled by a float valve system which controls flow from a liquid cryogen tank.

Abstract: A personal sampling impactor that comprises a compact mounting arrangement using a base, a cover, and an impactor plate cartridge that fits within the cover and is supported on an upper end of the base. A filter is held in place between the impact plate cartridge and the base, and the cover is made so that it can easily be placed over the impaction plate and latched in place to hold the unit together. The cover has inlets that align with a lightly oiled impaction plate surface on which particles will adhere.

Abstract: A cleaning system of the apparatus utilizing the effect of surface tension forces (4) and phase changes between a liquid and gas. In one embodiment the surface (21) to be cleaned is submerged within a vessel (30), the pressure within the vessel being increased. A rapid depressurization of the vessel causes a plurality of bubbles (12) to form around undesired particulate matter (13) on the surface (14) of the article to be cleaned, the bubbles rising to the surface of the liquid (27) within the chamber, thereby cleaning the article. A second embodiment utilizes a cleaning fluid (52) which is applied to the surface of the article (49) to be cleaned. The fluid being subsequently frozen on the surface, thereby reducing the adhesion force between the surface of the article and undesired particulate matter. The surface of the article (49) is subsequently heated, and the undesired particulate matter is removed through the medium of the cleaning fluid (52).

Abstract: A flow visualization system usable for clean rooms to determine the flow conditions that exist during manufacture, includes a non-contaminating source of a visible stream of a fog comprising water droplets which evaporaate and leave no residue. Steam is generated in a boiler and it passed over an interface with a cryogenic material to form a high density fog generator providing a highly visible fog that is neutrally bouyant and non-contaminating.

Abstract: A vacuum processing system for processing semiconductor wafers includes a particle shield (16) disposed above the wafer (10) to block moving particles in a vacuum chamber which would otherwise contact the wafer (10). The particle shield (16) is attached to arm (18), allowing the particle shield (16) to be moved away from the wafer or photomask during processing.

Abstract: A high volume virtual impactor for sampling atmospheric aerosols has a plurality of inlet nozzles and associated receiving tubes mounted in a common frame or housing having passageways which divide the airflow through the inlet nozzles into a major flow and a minor flow. The minor flow, or the smaller volume flow, passes through the respective receiving tube into a common chamber, while the major flow is caused to turn 180.degree. between flow exit of the inlet nozzle and its associated receiving tubes and pass as through a small particle filter. The impactors are arranged in oppositely facing and aligned pairs. The exhaust ends of the receiving tubes in a part face each other, so that the flows from the receiving tubes will intermix in the center of a chamber, to prevent substantial particle impingement against the housing surfaces. The filters are located at the bottom of the housing to minimize losses.

Abstract: Apparatus for controlling particulate emissions from a combustion apparatus, such as a diesel engine. Diesel engine exhaust particles are electrically charged during the formation of the particles in the engine combustion chambers. A particle collector is used to collect the electrically charged particles on collecting structures connected to a high voltage power supply and ground. The collecting structures of the particle collector can be a plurality of parallel metal plates, spaced cylindrical rods, or concentrically located cylindrical members. A fibrous matrix can be located adjacent the particle collecting structure to collect the charged particles as they move through the matrix. In one embodiment, the collected particles separate from the collecting structures and return to the engine intake. In another embodiment, a removable collecting cartridge has electrically conductive plates for collecting the charged particles. The entire cartridge is removed for cleaning or replacement.