Abstract: Disclosed is a filtration enhancement apparatus and an associated method. The apparatus includes a number of electromagnetic grids that are placed in series. The first grid conditions ambient particles to generate particles with both a positive and a negative charge. These charged particles are then delivered to a second and third grid wherein a low, medium, and/or high frequency alternating current is employed to force the positive and negative charged particles to collide and conglomerate with one another. The conglomerated particles are then sent into the ambient environment for subsequent filtration.

Abstract: An apparatus useful for electrostatic deposition (ESD) of aerosol particles and methods of depositing the aerosol particles onto a substrate are disclosed. The ESD apparatus and the method of the present invention are useful for electrostatically depositing nanoparticles produced by gas-phase synthesis onto a substrate where the velocity of the flow of aerosol can be controlled.

Abstract: A modular frame for use in air purification devices is described. In one aspect of the invention, a plurality of frame members are arranged in a linked stack to form a housing for components of an air purification device. The frame members are arranged to define a flow channel through which a fluid stream passes and to support components of the air purification device that receive the fluid stream. In another aspect of the invention, a plurality of rods are arranged to pass through the frame member stack. A first one of the rods serves as an electrical power source at a first potential and a second one of the rods serves as an electrical power source at a second potential. Electrical connectors are provided to electrically couple electrodes on selected components of the air purification device to their associated rods. In devices that utilize electrostatic filters, the electrodes that are connected to the rods may include the electrodes of the electrostatic filters.

Abstract: An oil separator for pressurized systems having flowing vapor with entrained oil particles, the separator including an electrically conducting enclosure having an inlet for the oil bearing vapor and a first outlet for the vapor and a second outlet for the separated oil, an electrically conductive screen positioned within the enclosure to receive the entire flow from said vapor inlet, said screen being electrically insulated from the inlet and enclosure, and a high voltage mono-polarity source connected between the screen and the enclosure. A needle-like electrode at the same potential as the enclosure is positioned at the vapor inlet to accentuate the electric field, thereby improving separation.

Abstract: An air purifier includes a housing, a high voltage power supply, a first electrode assembly in which a wire-like first electrode is either the only first electrode or, alternatively, is spaced sufficiently far from any other such first electrodes so as to avoid undesirable effects upon each other, and a second electrode assembly in which there are a plurality of blade-like second electrodes. The air purifier can be of the type in which air flows through the housing as a result of electro-kinetic effects. To increase air flow velocity, the voltage between first and second electrodes is relatively high, such as 23-50 kV, and the first and second electrodes are accordingly spaced apart a relatively great distance, such as at least 30 mm.

Abstract: A flotage trapping device comprises at least one plus electrode and at least one minus electrode. The plus electrode and minus electrode are alternately disposed. The electrodes trap the flotage floating in the air. Another flotage trapping device comprises at least one electrode of a single polarity and a space ion generating device for generating ions of polarity opposite to that of the electrode so as to form an ion space around or adjacent said electrode. A flotage repelling device comprises at least one electrode of a single polarity, and a space ion generating device for generating ions of the same polarity as that of the electrode so as to form an ion space around or adjacent of the electrode.

Abstract: A pre-ionizer for use with an electrostatic precipitator is provided according to an embodiment of the invention. The pre-ionizer includes two or more corona ground elements arranged in a substantially parallel orientation. A corona ground element of the two or more corona ground elements includes a substantially elongate body including a proximate end and a distal end and first and second projections formed on the proximate end and the distal end. The first and second projections retain the corona ground element in the electrostatic precipitator. The pre-ionizer further includes one or more corona charge elements positioned between two adjacent corona ground elements of the two or more corona ground elements. When a high voltage electrical field is placed across the two or more corona ground elements and the one or more corona charge elements, the pre-ionizer at least partially ionizes airflow through the pre-ionizer.

Abstract: A plane type electric precipitator includes an electrode plate of plane shape, made of electricity-conducting material; a collecting plate, parallel to the electrode plate and made of electricity-conducting material; a plurality of electrode units, placed on the electrode plate and having tips; wherein direct electric voltage is applied between the electrode plate and the collecting plate, so that air passing through is exposed to high electric fields close to the tips of the electrode units, ionizing suspended particles and trapping ionized particles at the collecting plate, so that an air-cleaning effect results.

Abstract: An electrostatic precipitator reduces contamination of the ground electrode by separating charging and collection stages.

Abstract: An electro-mechanical electrostatic air cleaner that combines a low air resistance dielectric fibrous filter material positioned between and electrically charged by two electrically resistant carbon coated screens. The screens are charged by a remotely mounted bi-polar power supply. A pair of post ionization electrodes charge particles in the air with opposite charges, causing the particles to agglomerate. A plurality of screens may be placed in an array for increased one-pass filtration.

Abstract: Ionic emission electrostatic device (1) for depositing on the surface (sp) of a multitude of aerosol particles (p1, p2, . . . , pn) within a fluid (F), a quasi-homogeneous quantity of ions (iq). This electrostatic device (1) is constituted by a conductive discharge corona electrode (EC) and a noncorona conductive receptor electrode (ER). The pseudo-planar active face (SA) of its receptor electrode (ER) is covered by a plurality of craters with sharp edges, in a closed pseudo circle, exhibiting on their end edges (Ai) a section of minimum bend radius, and enclosing the orifices (O1, O2, . . . , On) and terminating towards the outside of the active face (SA). The craters are distributed quasi-uniformly on the active face (SA), in its two geometric directions. The surface flow of ions (iq) originating from the corona electrode (EC) and in the direction of the active face of the receptor electrode (ER) has an increased homogeneity.

Abstract: Disclosed is a filtration enhancement apparatus and an associated method. The apparatus includes a number of electromagnetic grids that are placed in series. The first grid conditions ambient particles to generate particles with both a positive and a negative charge. These charged particles are then delivered to a second and third grid wherein a low, medium, and/or high frequency alternating current is employed to force the positive and negative charged particles to collide and conglomerate with one another. The conglomerated particles are then sent into the ambient environment for subsequent filtration.

Abstract: The present invention relates to a composite gas separation module and to methods for fabricating a composite gas separation module. The present invention also relates to methods for selectively separating hydrogen gas from a hydrogen gas-containing gaseous stream. In one embodiment, the composite gas separation module includes a porous metal substrate; an intermediate porous metal layer, wherein the intermediate porous metal layer overlies the porous metal substrate; and a dense hydrogen-selective membrane, wherein the dense hydrogen-selective membrane overlies the intermediate porous metal layer. The intermediate porous metal layer can include palladium and a Group IB metal. For example, the intermediate porous metal layer can contain alternating layers of palladium and a Group IB metal.

Abstract: An air purifier for removing particles in air includes an outer casing, and an ionizer module. The ionizer module includes a power unit and an ionizing electrode unit, electrically connected to the power unit. The ionizing electrode unit includes a first electrode set as an electrode terminal disposed within the outer casing at an air inlet, a second electrode set disposed within the outer casing at an air outlet, and a third electrode set disposed within the outer casing at a position between the first and second electrode set, wherein a voltage of the third electrode set is higher than a voltage of the first electrode set for drawing the air from the first electrode set to the second electrode set via the second electrode set while dirt particles contained in the air is trapped on the second and the third electrode sets.

Abstract: A filtration system for filtering particulates from air. A plurality of point ionization sources are positioned in the proximity of the periphery of an air flow channel and being oriented to generate ions in the proximity of the air flow channel in a direction generally upstream from each respective one of the plurality of point ionization sources. A particulate collection surface is positioned within the air flow channel in a downstream direction from the plurality of point ionization sources. The particulate collection surface is electrostatically charged in an opposite direction with respect to ground than the electrical charge of the ions. An ion trap is positioned within the air flow channel between the plurality of ionization sources and the particulate collection surface. The ion trap is relatively electrically neutral as compared with the particulate collection surface and the ions.

Abstract: An air filtration system including a filter (4) for separation of particles and an ionizer (3) for ionization of the air. In use of the system, ionization of the air occurs before the air passes the filter (4). The filter (4) is made up of fibers of polypropylene mixed with acrylic.

Abstract: A multistage space-efficient electrostatic collector cleans a gas flowing therethrough along a gas flow path having a first stage provided by a first corona discharge zone along the gas flow path, and a second stage provided by a second corona discharge zone along the gas flow path and spaced along the gas flow path from the first corona discharge zone. A method is provided for increasing residence time within the corona discharge zone of gas flowing through an electrostatic collector.

Abstract: An electrostatic precipitator that removes zinc whiskers from cooling air provided to cool components in an electronics enclosure. The electrostatic precipitator comprises an ionizer configured to apply a charge to zinc whiskers suspended in the cooling air. The electrostatic precipitator also comprises a collector that collects charged zinc whiskers from the contaminated cooling air to generate uncontaminated cooling air for cooling the components of the electronics enclosure. The electrostatic precipitator is configured to be disposed in the cooling air flow path upstream of the components such that the cooling air travels through the electrostatic precipitator prior to impinging on the components.

Abstract: An example airborne conductive contaminant handling system is described. The airborne conductive contaminant handling system may include a handling circuit that is configured to selectively pass an electric current through a conductive contaminant. The airborne conductive contaminant handling system may also include an attracting circuit that is configured to attract an airborne conductive contaminant towards the handling circuit, where it can be subjected to the electric current.

Abstract: Process and apparatus for gas cleaning, as in HVAC systems or semiconductor manufacturing clean rooms, for removing 99.999% of particulate and gaseous contaminants, which may be effectively used to remove and neutralize Bio-chem agents introduced by terrorists, having a first stage in which large quantities of positively charged liquid droplets are introduced into the gas to be cleaned so as to remove virtually all negatively charged particulates and at least 90% of neutral particulates and soluble gases; a second stage in which most positively charged droplets from the first stage are removed and remaining particulates are given a positive charge; a third stage in which large quantities of negatively charged liquid droplets are introduced to remove positively charged particulates and more soluble gas contaminants; and a fourth stage in which the negatively charged droplets are removed from the cleaned gas stream.

Abstract: An electrostatic filter (1) has a chamber (11) into which a gas stream is introduced. An ioniser (19) in the form of an electrode array (20) is located in the chamber (11) and creates an ionising zone through which the gas stream passes. A charged outlet (21) is located downstream from the ioniser (19). As the gas stream passes through the ionising zone, the unwanted particles therein are charged and urged away from the outlet (21) by the ioniser (19). Charged particles approaching the outlet (21) are also electrostatically repelled therefrom, permitting “clean” gas to be extracted through the outlet.

Abstract: An electrostatic precipitator using substantially planar screens of similar charge positioned perpendicular to the gas flow direction. The screens have a similar charge of the same polarity, and particles flowing through the screens are charged, agglomerated and either collected on the screens or fall downwardly into collecting hoppers below the screens. The screens preferably have openings smaller than 3 millimeters and are spaced apart less than 10 millimeters. In an alternative embodiment, the screens have alternating polarities and are spaced about an inch or more apart to prevent sparkover.

Abstract: Fine particles of dust and other pollutants in gas streams are agglomerated to form larger particles which are more easily filtered in downstream processing. In one embodiment, particles in successive portions of the gas stream are charged with opposite polarity, and the gas stream is introduced into an Evasé portion (12) to slow it down. Particles of different sizes have differential deceleration and therefore mix generally in the direction of flow, leading to agglomeration of oppositely-charged particles. In another embodiment, a gas stream is divided into substreams in respective parallel passages, and the particles in adjacent passages are charged to opposite polarity. Deflectors at the downstream end of the passages cause substreams of particles of opposite polarity to mix, with resultant agglomeration of oppositely charged particles.

Abstract: An improved method is disclosed for cleaning a flow of gaseous fluid, such as room air, from particles present in the fluid, the gaseous fluid being ionized, and using a conductive grid placed across and upstream of the filter for protecting the filter from being charged by free ions. An air purifier filter cartridge using the ion-intercepting grid of the invention is also disclosed. The grid may be connected to or electrically insulated from the ionizer ground potential, with equal effect.

Abstract: An air filtration system according to the present invention includes an enclosure having a floor section, a top section and an opening. A ventilation subsystem within the enclosure includes an air duct having an air intake and an exhaust vent. First and second electrode arrays are positioned within the air duct so that the first array is located between the air intake and the second array and the second array is located between the exhaust vent and the first array. A voltage regulator is electrically coupled to the first and second electrode arrays to apply a voltage differential between the electrode arrays that creates an air flow within the air duct drawing air into the air intake and out of the exhaust vent. Airborne particulate matter carried through the air duct collects on the second electrode array.

Abstract: A gas particle partitioner (GPP) removes particles from an aerosol with high efficiency and with no or minimum changes to the thermodynamic conditions and chemical composition of the gas phase of the aerosol. A permeable grid electrode surrounds a corona wire and separates an interior corona discharge area from an exterior aerosol charging zone. A particle free fluid washes the corona discharge area to minimize any transport of gas components produced by corona discharge to the aerosol. The charged particles in the aerosol are deflected by an electric field in a fractionator to selectively produce a particle free sample stream, which is then separated by a flow splitter from the aerosol.

Abstract: A filtration system for filtering particulates from air. A plurality of point ionization sources are positioned in the proximity of the periphery of an air flow channel and being oriented to generate ions in the proximity of the air flow channel in a direction generally upstream from each respective one of the plurality of point ionization sources. A particulate collection surface is positioned within the air flow channel in a downstream direction from the plurality of point ionization sources. The particulate collection surface is electrostatically charged in an opposite direction with respect to ground than the electrical charge of the ions. An ion trap is positioned within the air flow channel between the plurality of ionization sources and the particulate collection surface. The ion trap is relatively electrically neutral as compared with the particulate collection surface and the ions.

Abstract: When an ionization section is taken out of a main body housing of a conventional air cleaner in order to wash the ionization section, an ionization line may be cut by being accidentally touched. In order to avoid this problem, a pre-filter (7) is mounted on a front surface of an ionization and dust collection unit (6) so as to be detachable. The pre-filter (7) is slidably guided by guide furrings (23) in a sub-frame (12), and is mounted on a front surface of the sub-frame (12). When the pre-filter (7) is mounted, ionization lines (15) are not exposed, so that the pre-filter (7) protects the ionization lines (15). When the ionization and dust collection unit (6) is detached from the main body housing, therefore, there is no problem that the ionization lines (15) might be cut by being accidentally touched with worker's hands, for example.

Abstract: An air purification assembly (10) that is adapted to be used in combination with a vehicle incorporating a heating, ventilation and air conditioning (HVAC) system (100). The assembly (10) consists of three elements: an electrostatic stabilizing filter (12), a membrane filter (32) and an electronic ionizer (40). The three assemblies (12, 32, 40) when operating in combination with the HVAC system (100) substantially absorb unpleasant odors, smoke, dust, pollen, mold spores, pet dander and particulate matter produced by a vehicle exhaust emissions.

Abstract: A size preferential electrostatic agglomerator is provided for agglomerating small particles with larger “carrier” particles. The agglomerator includes an inlet for receiving a gas flow, a separator for separating the gas flow into flow streams based on the size of the particles therein, an ionization region for imparting an opposite electrical charge to each of the flow streams, an agglomeration region receiving the flow streams to facilitate the agglomeration of the oppositely charged particles, and an outlet for exhausting the gas flow containing agglomerated particles to facilitate collection, processing or other activity on the agglomerated particles. The present invention provides an efficient system for gathering large amounts of small particles in a gas flow.

Abstract: A device for separating liquid particles from an entraining gas or vapor stream. The device employs mechanical centrifugal forces to concentrate liquid droplets in a limited space for further extraction from the gas flow using an electrical field and an electrically charged collecting surface whereby the particles are attracted to and deposited on the surface for further extraction by the gas flow without reintrainment of the liquid back into the vapor stream. The device is constructed to provide an area of low gas velocity for removing the liquid from the device.

Abstract: The present invention describes a method and an arrangement for purifying the intake air of a gas turbine of solid particles and liquid droplets. According to the invention air is taken into the system of intake air passages (1, 2, 4) of the gas turbine and the particles contained in the intake air are collected by means of at least one plate filter (3) to which a collection voltage has been connected. In order to enable and enhance collection, the air is taken into at least one charging chamber (2) arranged at a distance prior to the plate filters (3) in the flow direction of the air, where an electric field is formed between at least two electrodes (5, 7) by connecting a voltage between the electrodes which exceeds the collection voltage, whereby powerful charging of the particles and at least partial removal of the water contained in the air are effected.

Abstract: An improvement in an electrostatic precipitator and method for removing particulate contaminants entrained in a gas stream passed through an electrode arrangement in which particulates are charged in a first electrostatic field and subjected to a second electrostatic field to be removed and collected for further disposition. The electrode arrangement includes a charging section having a charging electrode and a field electrode, and a collecting section having a repelling electrode and a collecting electrode. The field electrode and the collecting electrode are integrated, providing a relatively compact construction, and the charging electrode and the repelling electrode are electrically separated by high voltage diodes in a single power supply arrangement such that the charging section and the collecting section each are provided with a corresponding electrostatic field operated at an optimum voltage and current for respectively charging and collecting particulate contaminants entrained in the gas stream.

Abstract: An electrofiltration apparatus is provided having at least one electrostatically charged polymeric film layer having surface structures. The film layers may be configured as a collection cell that has the structured film layer defining a plurality of ordered inlet openings through a face of the collection cell and corresponding air pathways, thereby forming an open, porous volume. The air pathways are defined by a plurality of flow channels formed by the structured film layers. The electrofiltration apparatus is coupled with an ionizer which actively induces charges onto the particles to be removed by the collection cell.

Abstract: Disclosed is a portable air filtration system for removing contaminants from room air. In one embodiment, the air filtration system includes a power supply and an air blower module electrically connected to the power supply. The air filtration system further includes an ionization module engaged with the air blower module and including a first control grid and a high voltage grid electrically connected to the power supply. The air filtration system further includes a filter module removably engaged with the ionization module. The filter module includes a filter and a second control grid. Engagement of the filter module and the ionization module creates an electrical connection between the second control grid and the power supply. Activation of the air filtration system creates a first ionization field between the high voltage grid and the first control grid and a second ionization field between the high voltage grid and the second control grid.

Abstract: A hand-holdable electro-kinetic electro-static ionic air refreshener-conditioner for a pet shelter or litter box includes a self-contained ion generator that provides electro-kinetically moved air with ions and safe amounts of ozone. The ion generator includes a high voltage pulse generator whose output pulses are coupled between first and second electrode arrays. Preferably the first array comprises one or more pin-like electrodes and the second array comprises one more washer-like electrodes. Preferably a ratio between effective area of an electrode in the second array compared to effective area of an electrode in the first array exceeds about 15:1 and preferably is about 20:1. An electric field produced by the high voltage pulses between the arrays produces an electrostatic flow of ionized air containing safe amounts of ozone. Optionally, a sensor detects odor adjacent the refreshener-conditioner causes the ion generator to be activated when sensed odor exceeds a predetermined threshold.

Abstract: This invention relates to a method and a device for agglomerating particles in a gaseous flow through an acoustical agglomeration chamber (3). According to the invention a portion of the flow at the outlet of the chamber is selectively extracted by preferring larger particles, and is re-injected into the inlet of the chamber.

Abstract: A silicon article including a silicon base and columns extending from the silicon base. The columns define a gap between the columns which is devoid of material so that the article can act as a filter or heat sink. Also disclosed is a method of making the silicon article.

Abstract: An apparatus for increasing the ozone concentration in the output of an ozone-generating system is disclosed. The invention reduces the concentration of O.sup.+ ions, which would otherwise react with ozone to form diatomic oxygen, by means of an ionic filter. In one embodiment, a gas-permeable electrode within a gas conduit attached to the output of an ozonator is negatively charged to several kilovolts with respect to the distribution line. This electrode attracts the positively charged oxygen ions, removing them before they can react with the ozone. This provides a higher ozone concentration that does not vary as much with distance from the ozone generator.

Abstract: An electrostatic bag filter unit is formed of a plurality of sections arranged in series. One section is a bag filter section containing a plurality of parallel elongated filter fabric bag elements extending across and traverse to a gas flow path therethrough and a plurality of grounded, electrically-conductive support frames, each support frame being internal to and supporting one of the filter fabric bag elements. Optionally, the bag filter section may further include a plurality of non-discharging electrodes disposed parallel to and interspersed among the filter fabric bag elements. A filter precharger section is located immediately upstream of and contiguous with the bag filter section and is formed of a linear array of alternating corona discharge electrodes and grounded electrodes arranged perpendicular to the gas flow path.

Abstract: A process and apparatus for reducing particulate, nitrogen oxides ("NOx"), sulfur dioxide ("SO.sub.2 "), and mercury ("Hg") emissions from the combustion exhaust of fossil fuel fired plants while producing an end product that is commercially useful, comprising the steps of oxidizing Hg, NOx and SO.sub.2 using a barrier, pulse, corona, or electron beam electrical discharge apparatus (100) to produce HgO and the acids HNO.sub.3 and H.sub.2 SO.sub.4 collecting the HgO, acids and particulates in a wet ESP (120), and separating the particulates from the collected acid mixture, then separating and concentrating the acids for industrial use.

Abstract: A method for removing electrostatically charged particles that are difficult to separate from a gas flow within one or more high-voltage fields, wherein only one high-voltage supply source is used for these high-voltage fields. The flows to be cleaned are successively ionized in an ionizing region and the particles are separated in a separating region within the one or more high-voltage fields, wherein the field strength of the ionizing region is weaker than the field strength of the separating region.

Abstract: A two-stage electrostatic separator for separating particles from a particle laden gas stream includes a pre-charging section and spaced-apart gas-permeable grounded and discharge electrodes charged at opposite polarities and defining a separating section between them, the grounded electrode being positioned upstream from the discharge electrode. The particles in the particle laden gas stream are pre-charged to a certain charge in the pre-charging section and penetrate through the grounded electrode into the separating section, where the particles are separated from the particle laden gas stream. As a result, a clean gas stream exits from the separating section through the discharge electrode, and the particles separated from the particle laden gas stream are partially collected on the grounded electrode, and partially are removed with a bleed flow which is recirculated. The electrodes may be of linear or cylindrical shape, and linear electrodes may be arranged in a "zig-zag" order.

Abstract: The system includes a platform assembly which includes a plurality of helium airships for support of an emitting electrode to produce a large amount of electrical charges, in the form of electrons, into the surrounding atmosphere. The electrons may be generated by various apparati, including field induced emission and ultraviolet induced emission and ionization. Also provided are a large bank of solar cells to produce the necessary power for the assembly and a propulsion system, either a propeller system or an ion engine. A positive electrode may also be included which collects the undesirable atmospheric elements, such as chlorine atoms, to which negative charges have become attached. Alternatively, the platform could be arranged to include a negatively charged surface at which chlorofluorocarbons, for instance, can dissociate after they come in contact with negative charges.

Abstract: A simplified electronic air cleaner cell structure having a pair of spaced plastic side support members which provide the entire support for the ionizer elements and collector elements mounted therebetween. Portions of one of the side members are made of an electrically conductive material, and the high voltage ionizer and collector elements are mounted thereto, with electrical interconnections being made between those conductive portions and a power source.

Abstract: An interconnection is made between a pair of electrostatic air cleaner cells which are placed in side-by-side relationship within a housing, such that when one is removed from the housing, the other is also removed.

Abstract: A housing for an electrostatic air cleaner is made adaptable to various sizes of cells by use of the same components. Top and bottom wall members are interconnected by telescoping corner members which can be contracted or expanded to vary the height of the housing as desired. The ends of the housing are closed by way of doors which are also expandable to varying lengths so as to accommodate various housing heights.

Abstract: An electrostatic precipitator includes a dust-collecting electrode group and a discharge electrode group arranged in the recited order with respect to the gas flow direction of a gas to be treated in the electrostatic precipitator. The discharge electrode group includes a plurality of discharge electrodes, each of which is made of a rectangular metal plate. The longitudinal edges of each plate form semicircles, with a series of saw-toothed portions having tips protruding from between each pair of semicircles. The dust-collecting electrode group includes a plurality of dust-collecting electrodes, each of which is made of a chain suspended adjacent the discharge electrode group at a predetermined spacing. The chains of the dust-collecting electrode groups are suspended so that they can rock back and forth.

Abstract: A novel electrostatic precipitator includes an electrostatic collector section with discharge electrodes positioned between pairs of grounded collector electrodes, a gas entry port located upstream of said electrostatic collector section, and a transition section between the gas entry port and said electrostatic collector section into which an aqueous acid gas neutralizing agent is sprayed into a gas stream. An additional collector section may be interposed between the gas entry port and the point where the acid gas neutralizing agent is injected into the gas stream. The collector section may comprise alternating charging and short collection sections in which the grounded electrodes of adjoining charger and collector sections are connected. A liquid spray removes particulates collected on the grounded electrodes of the collector sections.

Abstract: An electrostatic precipitator, and more particularly an electrostatic precipitator having a sets of improved plate type electrodes having opposing surfaces defining collecting and ionization zones therebetween, and with one of the electrodes in each pair of electrodes including a corona source thereon.