Abstract: A system for separating constituents from a base material using RF energy which is coupled to a reaction chamber by way of a windowless transmission line. By eliminating the need for a window, traditional limitations placed on the maximum power delivered to the resonating cavity are eliminated. Thus, the only practical limitation on the RF energy which can be delivered to a resonating cavity are the ability of RF energy source to produce that energy and the ability of the resonating cavity to manage that energy.

Abstract: A method and apparatus for disinfecting material such as a fluid stream, (e.g., water) or various objects (e.g., packaging, fruits, vegetables) using a high temperature expanding plasma emission source (EPES lamp) to generate intense pulses of ultraviolet light primarily in the 200-400 nm range. The EPES lamp is preferably mounted axially in a pipe through which the fluid to be disinfected is flowed or perpendicular to the direction of a fluid flow or an object conveyor. Each pulse is terminated before the resulting plasma within the EPES lamp reaches the inside surface of the EPES lamp wall so that the EPES lamp operates in an expanding plasma emission source mode rather than in a wall stabilized mode. The EPES lamp is operated at a plasma temperature of at least about 15,000.degree. K. and an energy density (Q) of at least about 300.

Abstract: In order to sterilize the inner surfaces and the outer surface area located in the area of a filling opening of pressure sensitive non-electroconductive containers by means of a low-pressure plasma, an evacuable chamber is provided, which is essentially formed by two electrodes which surround the container.

Abstract: A method for hydrogen peroxide vapor sterilization of medical devices and similar instruments having long narrow lumens or diffusion restricted areas includes the step of pretreating the article to be sterilized with a dilute solution of hydrogen peroxide prior to exposure to a vacuum or a vacuum followed by plasma. The method is such that, upon vaporization of the solution caused by the vacuum, the hydrogen peroxide remains in contact with the article for a time sufficient to achieve sterilization.

Abstract: An apparatus for detecting the presence of volatile substances in a gaseous medium, including apparatus for producing within a sensor chamber a localised electric field the energy density of which is sufficient to excite the gaseous medium to a plasma condition, and apparatus for detecting changes in a parameter of the plasma due to the presence of the volatile substances in the gaseous medium.

Abstract: A method and system for separating radioactive waste containing volatiles, into light ions and heavy ions, includes a loader/transporter for transferring the waste into a high vacuum environment in the chamber of a plasma processor. During this transfer, gases of the volatiles are released from the waste, collected in a holding tank, and subsequently ionized in the chamber. As the volatiles are ionized, the ions are directed by a magnetic field into contact with the waste to vaporize the waste. The waste vapors are then ionized in the plasma processor chamber to create a multi-species plasma which includes electrons, light ions and heavy ions. Within the chamber, the density of the multi-species plasma is established to be above its collision density in order to establish a substantially uniform velocity for all ions in the plasma. A nozzle accelerates the multi-species plasma to generate a fluid stream which is directed from the chamber toward an inertial separator.

Abstract: An integrated ozone generator is disclosed. It includes: (a) an upper covering layer having a thin film, and a permanent magnet being installed on the thin film, the permanent magnet having a periphery which is surrounded with a coil on which a plurality of contact points are installed for inputting an oscillating signal, so as to form an electromagnetically actuating micro pump, the upper covering layer further having a hole formed on a first side of the upper covering layer and an upper thin film electrode and a discharging teethed structure installed on an inside surface of the covering layer away from the hole; and (b) a base having a groove which is connected with an inner hole of the upper covering layer to form a gas chamber, a gradually opened channel at one side of the gas chamber for inputting gas, and another gradually reducing channel at another side of the gas chamber.

Abstract: Two methods and corresponding electrode designs are provided for the generation of a plasma at or about one atmosphere. Using these methods, various webs, films and three-dimensional objects are beneficially treated in a reduced amount of time. A first method utilizes a repetitive, asymmetric voltage pulse to generate a plasma discharge between two electrodes. An asymmetric voltage pulse is used to generate a discharge in which a substrate can be exposed predominately to either positive or negative plasma species depending on the voltage polarity used. A second method uses the gap capacitance of an electrode pair and an external inductor in shunt to form a resonant LC circuit. The circuit is driven by a high power radio frequency source operating at 1 to 30 MHz to generate a uniform discharge between the electrode pair. Both methods have temperature controlled discharge surfaces with supply gas temperature, humidity and flow rate control.

Abstract: This invention provides methods and apparatus for continuously and efficiently separating the elements in a complex substance such as radioactive waste with a large volume plasma processor. One principal methods utilizes plasma confinement by toroidal magnetic fields with a poloidal divertor magnetic field and converts the plasma from a process plasma to a product plasma at a rapid rate permitting injection of a series of pellets, droplets or streams while the toroidal current in the plasma is maintained. A second principle method involves reducing the radiation losses in the separation process by eliminating the toroidal section and directly converting the feedstock material to a product plasma in an elongated evacuated container surrounded by magnetic field generating coils which produce magnetic fields that are parallel to the long axis of the evacuated container,The apparatus is a large volume plasma processor with multiple containment vessels.

Abstract: An incandescent Waste disposal system and method for the processing of waste and for rendering a hazardous component of the waste nonhazardous without discharge of harmful emissions are provided. The system includes a waste processing chamber, typically segmented into several sectors, wherein the waste is thermally and mechanically decomposed into a harmless residue by the action of rollers and an unrestricted arc plasma cloud that has a temperature sufficient to decompose the waste and render the hazardous component nonhazardous. The plasma cloud is created in a well-defined area in a reproducible manner and has a central region the temperature of which can reach 15,000.degree.-22,000.degree. F.

Abstract: Gas-cleaning equipment is disclosed, which comprises a housing having an intake vent and an exhaust vent and having disposed between the two vents a fan having at least one rotating blade. Air pollutant-removing system using the gas-cleaning equipment is also disclosed. This gas-cleaning equipment can effectively clean a gas through the action of plasma produced by glow discharge caused by rotation of said fan. When a metal layer having a catalytic activity is fixed onto the surface of said rotating blade, this metal layer also functions to effectively clean the gas. In the case where both the plasma and the metal layer function to clean the gas, there car be obtained synergistic effects. Cleaning of the gas can be conducted with more efficiency by bringing the intake gas into contact with the fan in an oxygen-free state. A magnet provided as an outer wall of the housing serves to generate plasma with higher density, leading to more effective cleaning of the gas.

Abstract: A device for sterilizing the inner surfaces of pressure sensitive containers with ionized particles has an evacuable chamber which takes up the containers. The electrodes allocated to a container and charged by an alternating voltage, are arranged outside of but closely surround the respective container. The container is subject to equal pressure from the inside and the outside, and the inner surface of the container to be sterilized is also essentially the plasma-limiting wall.

Abstract: A system for separating constituents from a base material using RF energy which is coupled to a reaction chamber by way of a windowless transmission line. By eliminating the need for a window, traditional limitations placed on the maximum power delivered to the resonating cavity are eliminated. Thus, the only practical limitation on the RF energy which can be delivered to a resonating cavity are the ability of RF energy source to produce that energy and the ability of the resonating cavity to manage that energy.

Abstract: An apparatus having a first and second zones, for destroying hazardous compounds of a first and second types respectively present in a gas stream. The first zone has a first live electrode and a ground electrode. The first live electrode and the ground electrode define a first gas passage. These electrodes are excitable at a first energy level for generating a first electric field capable of generating a plasma in a gas flowing through the first gas passage. The second zone has a second live electrode spaced apart from the ground electrode. The second live electrode defines with the ground electrode a second gas passage communication with a downstream end of the first gas passage. The second live electrode is excitable at a second energy level for generating with the ground electrode a second electric field capable of sustaining the plasma in the gas flowing through the second gas passage.

Abstract: An apparatus for plasma sterilization of articles includes a plasma generator, a sterilizing chamber, and a source of water vapor in fluid communication with the plasma generator, and may optionally include an autoclave. A method for plasma sterilization comprises exposing an article to be sterilized to a neutral active species of a plasma generated from water vapor. The exposure of the article to the plasma is carried out at reduced pressures and a chamber temperature of less than about 82.degree. C. for a time period sufficient to effect sterilization.

Abstract: A unibody, monolithic, one-piece PBN plasma chamber for an MBE gas plasma source. The chamber has a cylindrical configuration with at least one effusion orifice and a gas inlet opening. The gas inlet opening is preferably communicatively connected to an elongated, tubular inlet member. The inlet member is preferably coupled to a liquid cooled gas source by an intermediary connection member which is preferably constructed of a refxactory metal. The chamber minimizes leakage and maximizes efficiency. A gas plasma source assembly and a method for making the chamber are also disclosed.

Abstract: This invention provides methods and apparatus for ionizing all the elements in a complex substance such as radioactive waste and for separation of some of the elements from the other elements. One principal methods utilizes plasma confinement by toroidal magnetic fields as a gate to regulate when and where specific elements are collected. While the plasma is confined, some of the species are removed by repeatedly cycling all of the species between the plasma and the deposition stages lining the walls, whereby some species preferentially accumulate on the deposition stages. The other species are then diverted into an additional containment vessel for collection or additional separations. The apparatus is a large volume plasma processor with multiple containment vessels. The invention provides for the characterization of waste material, and for its separation all within one serf contained vacuum environment. Other applications include remediation of chemical toxic wastes and chemical and germ warfare weapons.

Abstract: Device for conducting chemical operations, comprising a working chamber (1) delimited by a top (2), a bottom (3), side walls (4, 5) and a door, a microwave energy generator (6) for the chamber, and a reactor (7) having at least one neck (8) and resting in the chamber on a support (9). The chamber (1) is pierced by at least one passage (12) which permits connecting the neck (8) of the reactor (7) with a connection conduit (13) secured to an external device for conducting a chemical reaction. The chamber is also pierced by two other passages (15 and 16) adapted respectively to permit the connection of two other necks (17 and 18) to the reactor (7).

Abstract: A generator is taught which uses alternating current or pulsating direct current to produce ozone from oxygen. The generator comprises a high voltage and ground electrode separated to form a gap for accommodating a dielectric member and gas to be reacted. The generator includes many features which may be used alone or in combination to provide an energy efficient and safe apparatus.

Abstract: The invention provides a method and installation for the production of a desired fluorocarbon compound, which includes the steps of providing a high temperature zone; and feeding at least one input material into the high temperature zone to generate a body of hot gas including fluorine-containing species and carbon-containing species. The molar C:F ratio in the body of hot gas is controlled at a selected value between about 0.4 and 2; and the specific enthalpy of the body of hot gas is controlled between about 1 kWh/kg and about 10 kWh/kg for a time interval, so that a reactive thermal gaseous mixture forms, containing reactive species including reactive fluorine-containing precursors and reactive carbon-containing precursors. Thereafter the reactive thermal mixture is cooled at a cooling rate and to a cooling temperature selected to produce an end product including the desired fluorocarbon compound. The input material is typically a C.sub.1 -C.sub.10 perfluorinated carbon compound of the general formula C.

Abstract: An apparatus for delivering RF-modulated electromagnetic energy into a solution for modifying its characteristics. Characteristic of the delivery apparatus is the use of a coil and a voltage probe in a fluid electrically isolated from the solution to deliver the electromagnetic field. Embodiments of the present invention preferably control the magnitude and duty cycle of the electromagnetic energy and further preferably distribute a plurality of delivery apparatus according to the energy distribution of a selected delivery apparatus.

Abstract: An apparatus for plasma sterilization of articles is provided with a plasma generator, a sterilizing chamber, and a source of water vapor in fluid communication with the plasma generator, and may optionally include an autoclave. A method for plasma sterilization comprises exposing an article to be sterilized to a neutral active species of a plasma generated from water vapor. The exposure of the article to the plasma is carried out at reduced pressures and a chamber temperature of less than about 82.degree. C. for a time period sufficient to effect sterilization.

Abstract: A canister is provided that is adapted for use in a plasma induced sterilization process. The canister contains a gas mixture that is pressurized to between about 2200 psig to about 2500 psig. The gas mixture has about 2.0 to 2.4 (v/v) percent hydrogen and about 2.6 to 3.0 (v/v) percent oxygen, and the rest of the gas mixture is noble gas or a mixture of noble gases.

Abstract: A fluid treatment system includes one or more radiation sources arranged in an irradiation zone with a treatment zone through which fluid to be treated passes and is irradiated. The radiation zone has a closed cross section to maintain the fluid within a predetermined maximum distance form he radiation source. Preferably, the irradiation zone comprises a reduced cross-sectional area perpendicular to the direction of fluid flow and thus the fluid flow velocity is increased through the irradiation zone.

Abstract: An apparatus for producing hydrogen radicals, includes (a) a pipe having a cross-sectional area decreasing toward one end from the other thereof, the pipe being composed of metal having a high melting point, (b) a filament for generating heat by running an electrical current therethrough, the filament being disposed in the pipe free of contact with the pipe, and (c) a hydrogen gas source for supplying hydrogen gas to the pipe through the end of the pipe with the larger cross-sectional area. The pipe is electrically isolated from any peripherals, including the filament. The apparatus provides a high production rate of hydrogen radicals, and also prevents gas leakage therefrom, avoiding contamination.

Abstract: An electrostatic decontamination method and decontamination device (10) is disclosed for decontaminating the surface of a semiconductor substrate. The decontamination device (10) includes particle ionizing device (24) that charges contaminating particles (26) on the surface of semiconductor substrate (16) thereby creating ionized particles. Decontamination device (10) also includes substrate biasing device (12) for creating a charge accumulation layer (14) at the top of semiconductor substrate (16) so that the charge accumulation layer (14) has the same charge sign as the ionized particles. In addition, the invention analytically characterizes particles using contaminating particle isolator (44) which contains a particle ionizing device (24) that charges contaminating particles (26) on the surface of semiconductor substrate (16) thereby creating ionized particles.

Abstract: An ozone generator is disclosed. The ozone generator includes a housing forming a tubular-shaped shell. A tubular ceramic electrode is suspended within the tubular-shaped shell of the housing. An end of the electrode protrudes from the tubular-shaped shell of the housing. The electrode, as suspended, forms a annular space of uniform width between the shell and the electrode, which space serves as the discharge gap. A Teflon.TM. retainer grips the end of the electrode protruding from the tubular-shaped shell of the housing. The retainer connects with the housing to maintain the electrode fixed in position within the tubular-shaped shell.

Abstract: A light/ozone asher includes a process chamber having a sample stage for supporting a sample processed with active oxygen generated by irradiating ozone with UV rays while not irradiating the sample with UV rays. Since the sample is not irradiated with UV rays when an organic substance on the sample surface is removed, an organic substance (scum) left by removal of parts of the organic substance on the sample is removed without destroying the remaining pattern of organic substance.

Abstract: A flow-through type ozone generating system has a fluid conduit and a source of alternating current for generating a corona discharge. An insulated wire may be used as an electrode within the conduit. PTFE is advantageously used as a dielectric material.

Abstract: A microwave introducing device has an endless circular waveguide provided with a plurality of slots. The circular waveguide is provided with a microwave introducing portion connected to a microwave power source, and the plurality of slots are spaced through an inner side of the circular waveguide such that the slots are arranged at the inner side of the circular waveguide at a given interval. A plasma treating apparatus can be provided with the microwave introducing device.

Abstract: A method and apparatus for reacting dense-phase chemicals in an induced plasma state, as well as unique reaction products resulting from the method and apparatus, are described. The dense medium plasma reactor generally includes a reaction vessel containing an upper rotatable electrode and a lower static electrode, a device for rotating the upper electrode, a reactant recirculation line, structural elements capable of maintaining the contents of the reaction vessel at atmospheric temperature, and structural elements for cooling the contents of the reaction vessel. Each electrode constitutes a hollow shaft having a first end and a second end which terminates in a disk-shaped planar face. The electrodes are in vertical alignment with one another so that their disc-shaped planar faces are facing one another with a small planar gap located therebetween. The upper rotatable electrode also includes a plurality of ports located circumferentially about its shaft.

Abstract: To improve a solar energy installation for chemical conversions comprising a receiver assembly for solar radiation and a chemical reactor which is supplied with solar radiation energy by the receiver assembly and in which chemical reactions take place due to the action of the solar radiation energy, such that optimum coupling of the solar radiation energy into the reactor is possible and, in addition, the reactor design is as simple and variable as possible and the reactor is connectable to the necessary supply devices in as easy a way as possible, it is proposed that the receiver assembly include several concentrators which each couple the solar radiation into one light guide respectively and that the light guides feed the solar radiation energy to the chemical reactor.

Abstract: An irradiator apparatus has a plurality of gamma radiation sources mounted in a housing and includes an ozone generator located in the housing and using the irradiator gamma radiation sources to generate the ozone. A plurality of gamma radiation sources are mounted in the irradiator housing with a gas passageway formed around each source for irradiating air or oxygen passing therearound from a gas input through the housing. A fluid passageway is located inside the irradiator housing and adjacent the plurality of gamma radiation sources for irradiating a liquid passing therethrough. The fluid passageway is connected between a liquid input opening and a liquid output opening through the irradiator housing. The gas passageways connect the ozone generator tubes to the fluid passageway for feeding ozone into the liquid being irradiated so that the irradiator generates ozone and feeds the ozone into the fluid being irradiated.

Abstract: The invention relates to a process for producing disilane from monosilane, according to which gaseous monosilane is passed into a reaction zone where it is subject to an electric discharge generated by a high-frequency current.

Abstract: A device for ozonizing small areas or surfaces for therapeutic purposes is provided having a first laminar element including a polyimide film, a similarly shaped second laminar element formed of fiberglass and polytetrafluroethylene, and a third smaller, flexible, conductive gold, silver or copper laminar element which is disposed between the first and second laminar elements. A signal of sufficient strength produces a number of electrical microdischarges between the device and the surface or area to which it is applied, with mass (ground) return, thereby producing an allotropic effect over the local oxygen, which is ionized together with the entire area to which the device is applied.

Abstract: This invention relates to an improved cooling system for a reactor having ultraviolet (UV) lamps, the radiation from which treats a fluid medium, for example, water, air or solvent. More particularly, the reactor system is adapted to treat contaminants in the fluids by use of UV emitting lamps which operate at high temperatures normally in excess of 300.degree. C.

Abstract: An apparatus for producing chemically active species by passing a precursor gaseous medium through a plasma at pressures of at least 50 millibars is described.

Abstract: In a photocatalysis system for degrading toxic compounds to constituent components, an improved photoreactor system optimizes reaction rates on the surface of a wide bandgap semiconductor electrode material. The semiconductor material has a first surface exposed to light having a higher energy than the bandgap and a second surface exposed to the toxic compound. An electrical conductor contacts the semiconductor electrode material in a geometry effective to produce an electric field within the semiconductor material. A controlled voltage source is connected to the electrical conductor for applying a voltage bias effective to produce the electric field. A closed circuit current sensor or an open circuit voltage sensor is connected to the electrical conductor and outputs a current or voltage signal, respectively, that is indicative of an excess electrical charge in the semiconductor material.

Abstract: Gas-cleaning equipment is disclosed, which comprises a housing having an intake vent and an exhaust vent and having disposed between the two vents a fan having at least one rotating blade. Air pollutant-removing system using the gas-cleaning equipment is also disclosed. This gas-cleaning equipment can effectively clean a gas through the action of plasma produced by glow discharge caused by rotation of said fan. When a metal layer having a catalytic activity is fixed onto the surface of said rotating blade, this metal layer also functions to effectively clean the gas. In the case where both the plasma and the metal layer function to clean the gas, there can be obtained synergistic effects. Cleaning of the gas can be conducted with more efficiency by bringing the intake gas into contact with the fan in an oxygen-free state. A magnet provided as an outer wall of the housing serves to generate plasma with higher density, leading to more effective cleaning of the gas.

Abstract: An apparatus for supplying combustion gas to an internal combustion engine. The apparatus generates negatively-charged molecules of the formula [MO.sub.x ].sup.-, where M is a positive ion, O is oxygen and x is a number at least equal to 3, and means for mixing the molecules with combustion gas and fuel supplied to the engine. Molecules [MO.sub.x ].sup.- are produced in an ion generator that comprises a specially shaped anode and cathode spaced apart from each other in a non-conducting housing. When a substantially constant voltage is applied across the anode and cathode, a plasma forms between and around them that in turn forms a magnetic field around the plasma and the anode. Diatomic oxygen molecules enter the housing and are polarized by the magnetic field and the resulting oxygen ions accelerated toward the plasma.

Abstract: A system for testing sterilization processes is provided by a vessel having a chamber, a plasma generator adapted to generate a plasma upstream of the chamber, a monitor associated with the chamber, and a biological or chemical indicator disposable within the chamber. The plasma generator generates upstream plasma that contains a plurality of atomic and/or molecular species, and the monitor is capable of determining a concentration of selected species in the plasma when flowing through the chamber.

Abstract: A water treatment apparatus is provided in which the ozone generation and the water treatment may take place simultaneously. The ozone is generated from a continuous supply of air and/or oxygen at the surface of a running water by means of a high voltage electrode placed in the air or in oxygen at some distance above the water surface. The strong electric field between the high voltage electrode and the surface of the electrically grounded water stream generates a multitude of small Taylor cones at the surface of the water. Each Taylor cone goes into corona and in the process it generates the ozone. As the ozone is generated at the water surface, a substantial amount of ozone is immediately dissolved in water and the ozone that diffuses in the air continues to be in contact with the water surface. The undissolved ozone may be percolated through the same water for an additional primary or secondary ozonation.

Abstract: A weakly ionized plasma is generated by continuous high-power microwave win a dielectric cavity positioned in a slow waveguide. Contaminated air under atmospheric pressure is exposed to the plasma within the waveguide cavity for a limited saturation time controlled by inflow at a regulated flow rate. During such limited saturation time, the contaminated air is purified by sequential ionization and recombination under an electron temperature resulting in a microwave discharge plasma dominated by atomic oxygen at a relatively high saturation density level together with atomic nitrogen at a relatively low density level.

Abstract: A method and apparatus to decompose nonhydrolyzable ambients such as chloluorocarbons and nitrogen trifluoride which enables the conventional disposal of their byproducts are disclosed. It employs photo-decomposition of the nonhydrolyzable ambient using UV light and a mediating species to allow chemical reactions to occur which form an effluent which is hydrolyzed by conventional methods. This abatement process is amenable to point-of-use decomposition systems required for modular cluster tool systems used in microelectronic device fabrication.

Abstract: A method and an apparatus for controlling reactions of a gas and a fluid that makes use of excellent reactivity of carbon soot molecules, metal porphyrin complexes and metal phthalocyanin complexes which are in an excited state has an arrangement that the carbon soot molecules, the metal porphyrin complexes and the metal phthalocyanin complexes which are excited by a physico-chemical method, such as light irradiation, and a gas containing oxygen are brought into contact with each other to generate active oxygen. Further, the gas containing the harmful substance and a fluid are brought into contact with each other so that direct reactions of the active oxygen and the excited molecules decompose the harmful substances.

Abstract: A cooling system for the high voltage electrode of a corona treater includes an elongated hose disposed within the dielectric tube and around which the high voltage wire is spirally wound. The elongated hose is connected to a first port through which cooling fluid is introduced. The cooling fluid flows through the hose and out an open end into the dielectric tube. The cooling fluid then flows out of the dielectric tube through a second port and back to a reservoir after passing through a high voltage isolator.

Abstract: A chemical reactor for oxygenating hydrocarbons includes: a) a dielectric barrier discharge plasma cell, the plasma cell comprising a pair of electrodes having a dielectric material and void therebetween, the plasma cell comprising a hydrocarbon gas inlet feeding to the void; b) a solid oxide electrochemical cell, the electrochemical cell comprising a solid oxide electrolyte positioned between a porous cathode and a porous anode, an oxygen containing gas inlet stream feeding to the porous cathode side of the electrochemical cell; c) a first gas passageway feeding from the void to the anode side of the electrochemical cell; and d) a gas outlet feeding from the anode side of the electrochemical cell to expel reaction products from the chemical reactor. A method of oxygenating hydrocarbons is also disclosed.

Abstract: A method for removing carbon-based polymer residues to effect a cleaning of a reactor, such as a planar plasma reactor, by exciting an ozone containing atmosphere in the reactor, which atmosphere is reactive with the carbon-based residues thereby forming volatile end products, which end products can be evacuated from the reactor.

Abstract: A plasma sterilizer and method employ essentially uncharged, highly reactive free radicals, atoms and excited molecules of a gas mixture to sterilize articles. The gas mixture includes oxidizing and/or reducing agents and is ionized into a plasma having ionization products that include highly destructive components in the form of charged particles and ultra-violet radiation. A plasma distribution device blocks the ultra-violet radiation and facilitates the recombination of the charged particles such that essentially uncharged, highly reactive free radicals, atoms and excited molecules of the gas mixture are delivered to the articles.

Abstract: A fluid treatment system includes one or more radiation sources arranged in an irradiation zone with a treatment zone through which fluid to be treated passes and is irradiated. The radiation zone has a closed cross section to maintain the fluid within a predetermined maximum distance form he radiation source. Preferably, the irradiation zone comprises a reduced cross-sectional area perpendicular to the direction of fluid flow and thus the fluid flow velocity is increased through the irradiation zone.